0001397702-24-000015 | 10-K | XBRL Viewer

Stock-Based Compensation Plans (Information by Exercise Price) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock-Based Compensation Plans [Abstract]
Options Outstanding (in shares)	3,632,684	3,839,858	3,780,939	4,237,828
Weighted Average Remaining Contractual Term (in Years)	5 years 6 months 7 days	6 years 4 months 28 days	6 years 8 months 15 days	7 years 4 months 17 days
Weighted Average Exercise Price (in USD per share)	$ 25.02	$ 24.22	$ 20.45	$ 16.56
Number Exercisable (in shares)	3,184,646
Weighted Average Exercise Price (in USD per share)	$ 22.62

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Measurements [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents and investments. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value:

•Level 1 – quoted prices in active markets are identical assets and liabilities;

•Level 2 – observable inputs other than quoted prices in active markets for identical assets and liabilities;

•Level 3 – unobservable inputs.

Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The Company’s investments are classified within Level 1 of the fair value hierarchy include money market funds valued using quoted market prices and U.S. treasury bills valued using broker or dealer quotations with reasonable levels of price transparency. Investments classified within Level 2 include commercial paper, which are valued using model-based valuation techniques, and corporate bonds/notes, U.S. government securities and agency bonds/notes, which are valued based upon quoted market prices for similar instruments in active markets or quoted prices for identical or similar

instruments in markets that are not active for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets.

The following tables set forth by level within the fair value hierarchy the Company’s assets that are reported at fair value as of December 31, 2023 and 2022 using the inputs defined above (in thousands):


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	19,483	$	—	$	—	$	19,483
U.S. treasury bills		11,899		—		—		11,899
Commercial paper		—		33,150		—		33,150
Corporate bonds/notes		—		39,438		—		39,438
U.S. government securities		—		17,556		—		17,556
Agency bonds/notes		—		68,677		—		68,677
Total	$	31,382	$	158,821	$	—	$	190,203


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	55,158	$	—	$	—	$	55,158
U.S. treasury bills		19,776		—		—		19,776
Commercial paper		—		48,875		—		48,875
Corporate bonds/notes		—		1,515		—		1,515
U.S. government securities		—		83,270		—		83,270
Asset-backed securities		—		1,996		—		1,996
Agency notes		—		2,884		—		2,884
Total	$	74,934	$	138,540	$	—	$	213,474

There were no transfers between fair value hierarchy levels during the years ended December 31, 2023, 2022, and 2021.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Stockholders' Equity (Shares Reserved for Future Issuance) (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	9,867,196	8,758,908
Exercise of options under stock plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	7,168,881	5,169,682
Issuance of options and restricted stock units under stock plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	532,627	2,209,072
Performance Stock Units, Overperformance [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	809,225	207,468
ESPP [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	1,356,463	1,172,686

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Stock-Based Compensation Plans (Summary of Shares Available for Issuance) (Details) - 2019 Equity Incentive Plan [Member] - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Shares Available for Grant
Beginning balance (in shares)	2,209,072	2,477,212	1,790,687
Authorized (in shares)	1,534,238	1,399,235	1,369,985
Allowance for Performance Stock Units for overperformance (in shares)	(601,757)	207,468
Granted/Awarded (in shares)	(2,893,796)	(1,600,996)	(847,080)
Canceled (in shares)	284,870	141,089	163,620
Ending balance (in shares)	532,627	2,209,072	2,477,212

Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2023

Long-term Debt [Abstract]

Future Payment Under the Term Loan


Year Ending December 31:	Amount
2024	$	5,719
2025		5,703
2026		45,699
2027		34,517
		91,638
Add: Accretion of closing fees		1,329
		92,967
Less: Amount representing interest		(16,638)
Less: Amount representing debt discount and debt issuance costs		(703)
Present value of minimum payments	$	75,626

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of year	$ 3,788	$ 3,314	$ 2,019
Increases related to current years’ tax positions	571	474	704
Increases related to prior years’ tax positions	5		591
Balance at end of year	$ 4,364	$ 3,788	$ 3,314

Stock-Based Compensation Plans (Fair Value of Stock Options) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 3 months
Expected volatility	55.10%
Risk-free interest rate	3.94%
Common Stock Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		5 years 3 months	5 years 3 months
Expected volatility		48.20%	45.00%
Risk-free interest rate		1.60%	0.41%
Common Stock Options [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years 3 months	6 years 3 months
Expected volatility		51.40%	50.40%
Risk-free interest rate		3.84%	1.08%
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
ESPP [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	47.40%	51.60%	46.90%
Risk-free interest rate	4.64%	0.07%	0.03%
ESPP [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	119.50%	74.50%	51.60%
Risk-free interest rate	5.43%	4.64%	0.10%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Balance Sheets - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 20,210,000	$ 55,358,000
Short-term investments	161,264,000	158,316,000
Accounts receivable, net of allowances of $26 and $3 at December 31, 2023 and December 31, 2022, respectively	23,573,000	18,007,000
Inventories	29,876,000	19,293,000
Prepaid expenses and other current assets	5,912,000	3,924,000
Total current assets	240,835,000	254,898,000
Long-term investments	9,456,000
Property and equipment, net	8,114,000	9,372,000
Restricted cash	0	155,000
Other non-current assets	6,904,000	5,260,000
Total assets	265,309,000	269,685,000
Current liabilities:
Accounts payable	5,676,000	2,523,000
Accrued liabilities	24,607,000	21,965,000
Total current liabilities	30,283,000	24,488,000
Long-term debt	75,626,000	74,596,000
Other liabilities	8,249,000	6,726,000
Total liabilities	114,158,000	105,810,000
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.001 par value Shares authorized: 5,000,000 at December 31, 2023 and 2022 Shares issued and outstanding: none at December 31, 2023 and 2022
Common stock, $0.001 par value Shares authorized: 100,000,000 at December 31, 2023 and 2022 Shares issued and outstanding: 39,165,481 and 38,355,972 at December 31, 2023 and 2022, respectively	39,000	38,000
Additional paid-in capital	550,495,000	507,715,000
Accumulated other comprehensive income (loss)	72,000	(166,000)
Accumulated deficit	(399,455,000)	(343,712,000)
Total stockholders’ equity	151,151,000	163,875,000
Total liabilities and stockholders’ equity	$ 265,309,000	$ 269,685,000

Schedule II - Valuation and Qualifying Accounts - Schedule II (Details) - Allowance for doubtful accounts receivable: - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 3	$ 6	$ 13
Charged to expenses	45	(3)	6
Write offs	22		13
Balance at End of Year	$ 26	$ 3	$ 6

Balance Sheet Components (Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 15,685	$ 14,410
Less: Accumulated depreciation and amortization	(7,907)	(5,355)
Total property and equipment, net	8,114	9,372
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,052	1,822
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,776	5,046
Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	296	296
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,561	7,246
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 336	$ 317

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Increase (decrease) in deferred tax asset valuation allowance	$ 11,549,000	$ 18,237,000	$ 17,918,000
Unrecognized tax benefits	4,364,000	3,788,000	3,314,000	$ 2,019,000
Unrecognized tax benefits that would impact effective tax rate	0
Unrecognized tax benefits, income tax penalties and interest expense	0	$ 0	$ 0
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	331,957,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	288,608,000
Research Tax Credit Carryforward \| Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	10,122,000
Research Tax Credit Carryforward \| State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 5,869,000

Balance Sheet Components (Fair Value of Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 190,131	$ 213,641
Gross Unrealized Gains	145	14
Gross Unrealized Losses	(73)	(181)
Estimated Fair Value	190,203	213,474
Cash equivalents	19,483	55,158
Short-term investments	161,264	158,316
Long-term Investments	9,456
Total	190,203	213,474
Money Market Funds [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	19,483	55,158
Estimated Fair Value	19,483	55,158
US Treasury Bills [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	11,896	19,772
Gross Unrealized Gains	3	4
Estimated Fair Value	11,899	19,776
Commercial Paper [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	33,160	48,875
Gross Unrealized Gains	5
Gross Unrealized Losses	(15)
Estimated Fair Value	33,150	48,875
Corporate Bonds/Notes [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	39,398	1,528
Gross Unrealized Gains	55
Gross Unrealized Losses	(15)	(13)
Estimated Fair Value	39,438	1,515
U.S. Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,501	83,432
Gross Unrealized Gains	55	2
Gross Unrealized Losses		(164)
Estimated Fair Value	17,556	83,270
Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		2,000
Gross Unrealized Losses		(4)
Estimated Fair Value		1,996
Agency bonds/notes [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	68,693	2,876
Gross Unrealized Gains	27	8
Gross Unrealized Losses	(43)
Estimated Fair Value	$ 68,677	$ 2,884

Stock-Based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Nov. 30, 2023	Mar. 31, 2023	Nov. 30, 2022	Mar. 31, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised					$ 7,857	$ 17,575	$ 29,355
Weighted average grant date fair value (in USD per share)					$ 17.67	$ 37.69	$ 23.83
Fair value of options vested					$ 9,207	$ 9,816	$ 9,076
Common stock reserved for future issuance (in shares)					9,867,196	8,758,908
ISO and NSO [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term					4 years
ISO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise threshold as a percentage of fair value of shares					100.00%
Percent of purchase of price of common stock					10.00%
NSO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise threshold as a percentage of fair value of shares					85.00%
Percent of purchase of price of common stock					110.00%
2019 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expensed not yet recognized, period for recognition					4 months 17 days
Unrecognized compensation costs related to the ESPP					$ 679
Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expensed not yet recognized					$ 5,645
Compensation expensed not yet recognized, period for recognition					1 year 7 months 17 days
Expected volatility					55.10%
Risk-free interest rate					3.94%
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expensed not yet recognized, period for recognition					2 years 9 months 3 days
Unrecognized compensation costs of unvested RSUs					$ 73,195
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					2,162,465	806,513	524,023
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			207,468		711,433	207,468
Expected volatility						60.60%
Risk-free interest rate						0.41%
Dividend yield						0.00%
Performance Stock Units [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term			3 years
Performance Stock Units [Member] \| Benchmark [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility						59.40%
Minimum [Member] \| Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility						48.20%	45.00%
Risk-free interest rate						1.60%	0.41%
Minimum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate						4.09%
Maximum [Member] \| Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility						51.40%	50.40%
Risk-free interest rate						3.84%	1.08%
Maximum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate						4.20%
Award Date One [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		99,350
Expected volatility					61.20%
Risk-free interest rate					0.38%
Dividend yield					0.00%
Award Date One [Member] \| Performance Stock Units [Member] \| Benchmark [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility					62.30%
Risk-free interest rate					4.58%
Award Date Two [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	612,083
Expected volatility					71.10%
Risk-free interest rate					0.35%
Dividend yield					0.00%
Award Date Two [Member] \| Performance Stock Units [Member] \| Benchmark [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility					56.90%
Risk-free interest rate					4.72%
2019 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance (in shares)								2,317,000
Number of additional shares allowable under the plan (in shares)					3,000,000
Percent of outstanding shares of common stock					4.00%
Common stock reserved for future issuance (in shares)					7,952,134
2019 Equity Incentive Plan [Member] \| Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)				434,000
Additional Common Stock Capital Shares Reserved For Future Issuance				1,200,000
Percent Of Outstanding Shares				1.00%
2019 Equity Incentive Plan [Member] \| Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term					4 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grant Date Fair Value					$ 46,939	$ 30,486	$ 28,110
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value					$ 13,203	6,135	$ 1,893
2019 Equity Incentive Plan [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term					3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grant Date Fair Value					$ 14,950	$ 16,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance					100.00%
2019 Equity Incentive Plan [Member] \| Minimum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance					0.00%
2019 Equity Incentive Plan [Member] \| Maximum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance					200.00%
2019 Equity Incentive Plan [Member] \| Award Date One [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term					3 years
2019 Equity Incentive Plan [Member] \| Award Date One [Member] \| Maximum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance		200.00%
2019 Equity Incentive Plan [Member] \| Award Date Two [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting term					3 years
2019 Equity Incentive Plan [Member] \| Award Date Two [Member] \| Maximum [Member] \| Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance	200.00%
ESPP, 2019 [Member] \| Common Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued					465,952
Shares available for future issuance (in shares)					1,356,463
Fair Market Value Of Common Stock					85.00%

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net loss	$ (55,743)	$ (55,010)	$ (49,811)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	2,696	2,127	1,032
Stock-based compensation expense	38,893	25,023	14,612
Amortization of premiums (accretion of discounts) on investments, net	(6,497)	(1,419)	577
Amortization of debt discount and debt issuance costs	232	218	158
Amortization of right-of-use asset	1,096	1,041	887
Non-cash interest expense	819	1,037
Loss on extinguishment of debt		245
Loss on disposal of property and equipment	160	180	9
Provision for (recovery of) doubtful accounts receivable	45	(3)	6
Provision for excess and obsolete inventories	198	6	77
Changes in operating assets and liabilities:
Accounts receivable	(5,610)	(6,172)	(2,769)
Inventories	(10,781)	(1,447)	(5,563)
Prepaid expenses and other current assets	(1,988)	(525)	(772)
Other assets	(236)	(27)	(117)
Accounts payable	3,063	967	(1,159)
Accrued liabilities	2,854	1,868	4,418
Other liabilities	(1,215)	(690)	(520)
Net cash used in operating activities	(32,014)	(32,581)	(38,935)
Cash flows from investing activities
Purchases of property and equipment	(1,507)	(5,005)	(4,758)
Proceeds from sale of property and equipment			2
Purchases of investments	(174,969)	(168,163)
Proceeds from maturity of investments	169,300	11,100	77,400
Net cash provided by (used in) investing activities	(7,176)	(162,068)	72,644
Cash flows from financing activities
Proceeds from public offerings, net of underwriting discount, commissions and offering costs paid		108,992
Proceeds from long-term debt, net		73,911
Proceeds from issuance of common stock	3,887	5,796	6,946
Principal repayment of long-term debt		(49,000)
Proceeds from disgorgement of short-swing profits, net			32
Net cash provided by financing activities	3,887	139,699	6,978
Net change in cash, cash equivalents and restricted cash	(35,303)	(54,950)	40,687
Cash, cash equivalents and restricted cash, beginning of year	55,513	110,463	69,776
Cash, cash equivalents and restricted cash, end of year	20,210	55,513	110,463
Supplemental disclosure of cash flow information
Cash paid for interest	5,821	3,843	2,360
Noncash investing and financing activities:
Accounts payable and accrued liabilities for purchases of property and equipment	67	117	1,138
Right-of-use asset obtained in exchange for lease obligation	$ 2,504	$ 903	$ 3,307

Commitments and Contingencies (Operating Lease Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies [Abstract]
2024	$ 1,991
2025	2,130
2026	2,255
2027	2,068
2028	1,233
Thereafter	1,158
Total lease payments	10,835
Less: imputed interest	(1,828)
Present value of lease liabilities	$ 9,007	$ 7,842

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Stockholders’ Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuances


	December 31,
	2023	2022
Outstanding stock options and equity awards	7,168,881	5,169,682
Reserved for grants of future stock options and equity awards	532,627	2,209,072
Reserved for Performance Stock Units for overperformance	809,225	207,468
Reserved for employee stock purchase plan	1,356,463	1,172,686
Total common stock reserved for future issuance	9,867,196	8,758,908

Formation and Business of the Company

12 Months Ended

Dec. 31, 2023

Formation and Business of the Company [Abstract]

Formation and Business of the Company

1. Formation and Business of the Company

The Company

Silk Road Medical, Inc., or the Company, was incorporated in the state of Delaware on March 21, 2007. The Company, has developed a technologically advanced, minimally-invasive solution for patients with carotid artery disease who are at risk for stroke. The Company's portfolio of products enable a procedure referred to as transcarotid artery revascularization, or TCAR, that combines the benefits of endovascular techniques and surgical principles. The Company manufactures and sells in the United States its portfolio of TCAR products which are designed to provide direct access to the carotid artery, effective reduction in stroke risk throughout the procedure, and long-term restraint of carotid plaque. The Company commercialized its products in the United States beginning in late 2015.

Liquidity

In the course of its activities, the Company has incurred losses and negative cash flows from operations since its inception. As of December 31, 2023, the Company had an accumulated deficit of $399,455,000. The Company expects to incur losses for the foreseeable future. The Company believes that its cash and cash equivalents and available-for-sale securities of $190,930,000 as of December 31, 2023, as well as its expected revenues will provide sufficient funds to allow the Company to fund its planned current operations for the next 12 months from the issuance of these financial statements.

Public Offering

In October 2022, the Company completed an underwritten public offering of 2,674,419 shares of its common stock at a public offering price of $43.00 per share. The shares include the full exercise of the underwriters’ option to purchase an additional 348,837 shares pursuant to the underwriting agreement. The Company received cash proceeds of approximately $108,992,000 after deducting underwriting discounts and commissions of approximately $5,750,000 and expenses of approximately $258,000.

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statements of Operations and Comprehensive Loss [Abstract]
Revenue	$ 177,134	$ 138,638	$ 101,475
Cost of goods sold	50,048	37,876	25,446
Gross profit	127,086	100,762	76,029
Operating expenses:
Research and development	41,324	36,449	27,110
Selling, general and administrative	145,033	116,317	96,387
Total operating expenses	186,357	152,766	123,497
Loss from operations	(59,271)	(52,004)	(47,468)
Interest income	9,957	2,527	198
Interest expense	(6,871)	(5,098)	(2,518)
Loss on debt extinguishment		(245)
Other income (expense), net	442	(190)	(23)
Net loss	(55,743)	(55,010)	(49,811)
Other comprehensive income (loss):
Unrealized gain (loss) on investments, net	238	(166)	(39)
Other comprehensive income (loss)	238	(166)	(39)
Comprehensive loss	$ (55,505)	$ (55,176)	$ (49,850)
Net loss per share, basic	$ (1.44)	$ (1.54)	$ (1.44)
Net loss per share, diluted	$ (1.44)	$ (1.54)	$ (1.44)
Weighted average common shares used to compute net loss per share, basic	38,804,343	35,775,672	34,635,358
Weighted average common shares used to compute net loss per share, diluted	38,804,343	35,775,672	34,635,358

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Taxes [Abstract]

Schedule of Components of Income Tax Expense (Benefit)


	Year Ended December 31,
	2023		2022		2021
United States	$	(55,743)	$	(55,010)	$	(49,811)
International		—		—		—
Net loss before income taxes	$	(55,743)	$	(55,010)	$	(49,811)

Schedule of Effective Income Tax Rate Reconciliation


	Year Ended December 31,
	2023		2022		2021
Tax at federal statutory rate	$	(11,706)	$	(11,552)	$	(10,460)
State taxes, net of federal benefit		(2,311)		(2,206)		(1,852)
Permanent differences		(392)		(2,893)		(5,224)
Change in valuation allowance		11,549		18,237		17,918
Limitation of compensation deduction under IRS Sec.162(m)		4,320		10		—
General business credits		(1,536)		(1,166)		(852)
Other		119		(401)		490
Provision for income taxes	$	43	$	29	$	20

Schedule of Deferred Tax Assets and Liabilities


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss carryforwards	$	85,945	$	82,768
Research and development credits		10,753		8,898
Capitalized start-up costs/Intangibles		—		1
Section 174 R&D capitalization		12,892		7,816
Accruals and reserves		2,775		2,820
Stock-based compensation		10,353		8,209
Operating lease liability		2,272		1,973
Interest limitation		1,114		2,013
Total deferred tax assets		126,104		114,498
Less: Valuation allowance		(122,993)		(111,444)
Deferred tax liabilities:
Operating lease asset		(1,636)		(1,278)
Property and equipment		(1,475)		(1,776)
Total deferred tax liabilities		(3,111)		(3,054)
Net deferred tax assets	$	—	$	—

Reconciliation of Unrecognized Tax Benefits


	December 31,
	2023		2022		2021
Balance at the beginning of year	$	3,788	$	3,314	$	2,019
Increases related to current years’ tax positions		571		474		704
Increases related to prior years’ tax positions		5		—		591
Balance at end of year	$	4,364	$	3,788	$	3,314

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Summary of Significant Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Preparation

The accompanying financial statements have been prepared in accordance with the accounting principles generally accepted in the United States of America, or U.S. GAAP.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses judgment when making estimates related to provisions for accounts receivable and excess and obsolete inventories, the valuation of deferred tax assets, the reserves for sales returns, and stock-based compensation. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately differ from these estimates and assumptions.

Fair Value of Financial Instruments

The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2023 and 2022. The carrying amounts of certain of the Company’s financial instruments, which include accounts receivable, accounts payable and accrued liabilities approximate their respective fair values because of the short-term nature of these instruments. Management believes that its debt bears interest at the prevailing market rates for instruments with similar characteristics (Level 2 within the fair value hierarchy); accordingly, the carrying value of this instrument approximates its fair value.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents. Cash equivalents are recorded at fair value, based on quoted market prices. As of

December 31, 2023 and 2022, the Company’s cash equivalents were entirely comprised of investments in money market funds.

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the balance sheets that sum to the total of the same amounts shown in the statements of cash flows (in thousands):


	December 31,
	2023		2022
Cash and cash equivalents	$	20,210	$	55,358
Restricted cash		—		155
Total cash, cash equivalents and restricted cash	$	20,210	$	55,513

The Company had no restricted cash as of December 31, 2023. Restricted cash as of December 31, 2022 consisted of a letter of credit of $155,000 representing collateral for the Company’s facility lease in California.

Investments

Short-term and long-term investments consist of debt securities classified as available-for-sale. Short-term investments have original maturities greater than 90 days, but less than one year as of the balance sheet date. Long-term investments have maturities greater than one year as of the balance sheet date. All investments are recorded at fair value based on the fair value hierarchy. Unrealized gains and losses, deemed temporary in nature, are reported as a separate component of accumulated other comprehensive income (loss). Realized gains and losses are included in earnings and are derived based on the specific-identification method for determining the costs of investments sold and were insignificant for the years ended December 31, 2023, 2022 and 2021. Amortization of premiums and accretion of discounts are reported as a component of interest income.

A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the investment. The Company evaluates the securities in an unrealized loss position for expected credit losses by considering factors such as historical experience, market data, issuer-specific factors, current economic conditions and credit ratings. The Company did not recognize any credit losses on its available-for-sale securities during the years ended December 31, 2023, 2022 or 2021 and there were no impairment charges for unrealized losses in the periods presented.

Concentration of Credit Risk, and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents, investments and accounts receivable to the extent of the amounts recorded on the balance sheet. Cash, cash equivalents, and investments are deposited in financial institutions which, at times, may be in excess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financial instruments, such as, but not limited to, commercial paper, corporate bonds/notes, U.S. government securities, U.S. treasury bills, agency bonds/notes, and, by policy, limits the amount of credit exposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cash equivalents or investments during the years ended December 31, 2023, 2022 and 2021.

As of December 31, 2023 and December 31, 2022, a portion of the Company’s cash and cash equivalents was maintained with Silicon Valley Bank, a division of First Citizens Bank, or SVB, and exceeded federally insured limits. Substantially all of the Company’s cash equivalents and investments reside in a custodial account held by a third party, in which SVB Asset Management is the advisor. On March 10, 2023, SVB was shut down and placed under receivership with the Federal Deposit Insurance Corporation, or FDIC, by the California Department of Financial Protection and Innovation. On March 26, 2023, the FDIC announced it had entered into a purchase and assumption agreement with First Citizens Bank & Trust Company under which all of SVB’s deposits were assumed. As of the issuance date of these financial statements, the Company has not experienced any losses on its deposits and all of the Company’s cash deposited with SVB has been accessible to the Company.

The Company’s accounts receivable are due from a variety of hospitals and medical centers in the United States. As of December 31, 2023 and 2022, no customer represented 10% or more of the Company’s accounts receivable. For the years ended December 31, 2023, 2022 and 2021, there were no customers that represented 10% or more of revenue.

The Company provides for uncollectible amounts when specific credit problems are identified. In doing so, the Company analyzes historical bad debt trends, customer credit worthiness, current economic trends and changes in customer payment patterns when evaluating the adequacy of the allowance for expected credit losses on customer accounts.

The Company manufactures certain of its commercial products in-house. Certain of the Company’s finished goods, components and sub-assemblies continue to be manufactured by sole suppliers, the most significant of which is the ENROUTE Transcarotid Stent System, manufactured by Cordis Corporation, or Cordis. Disruption in finished goods, component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations.

The Company is subject to certain risks, including that its devices may not be approved or cleared for marketing by governmental authorities or be successfully marketed. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, competition, dependence upon government and third-party payers to provide adequate coverage and reimbursement, dependence on key personnel and suppliers, protection of proprietary technology, product liability claims, and compliance with government regulations.

Existing or future devices developed by the Company may require approvals or clearances from the U.S. Food and Drug Administration, or FDA, or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If the Company were denied or delayed in receiving such approvals or clearances, it may be necessary to adjust operations to align with the Company’s currently approved portfolio. If clearance for the products in the current portfolio were withdrawn by the FDA, this would have a material adverse impact on the Company.

Accounts Receivable

Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The Company estimates allowances for expected credit losses. Specifically, the Company makes estimates on the collectability of customer accounts based primarily on analysis of historical trends and experience and changes in customers’ financial condition. The Company uses its judgment, based on the best available facts and circumstances, and records an allowance against amounts due to reduce the receivable to the amount that is expected to be collected. These specific allowances are reevaluated and adjusted as additional information is received that impacts the amount reserved. During the years ended December 31, 2023, 2022 and 2021, the Company did not experience any material credit-related losses.

Inventories

Inventories are valued at the lower of cost to purchase or manufacture the inventory or net realizable value. Cost is determined using the first-in, first-out method for all inventories. Net realizable value is determined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company regularly reviews inventory quantities in consideration of actual loss experiences, projected future demand, and remaining shelf life prior to sale to record a provision for excess and obsolete inventory when appropriate. The Company’s policy is to write down inventory that has become obsolete, inventory that has a cost basis in excess of its expected lower of cost or net realizable value, and inventory in excess of expected requirements. The estimate of excess quantities is judgmental and primarily dependent on the Company’s estimates of future demand for a particular product. If the estimate of future demand is too high, the Company may have to increase the reserve for excess inventory for that product and record a charge to the cost of goods sold.

Property and Equipment

Property and equipment are recorded at cost less accumulated depreciation or amortization. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, typically three years to five years. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful economic life of the asset. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the assets and their eventual disposition are less than their carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of the long-lived assets exceeds their fair value. The Company did not record any impairment of long-lived assets during the years ended December 31, 2023, 2022 and 2021.

Leases

The Company accounts for its leasing arrangements in accordance with Accounting Standards Codification, or ASC 842, “Leases.” The Company considers if an arrangement is a lease at inception if it obtains the right to control the use of an identified asset under a leasing arrangement with an initial term greater than twelve months. The Company determines whether a contract conveys the right to control the use of an identified asset for a period of time if the contract contains both the right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the identified asset. The Company also evaluates the nature of each lease to determine whether it is an operating or financing lease and recognizes the right-of-use asset and lease liabilities based on the present value of future minimum lease payments over the expected lease term. The Company’s leases do not generally contain an implicit interest rate and therefore the Company uses the incremental borrowing rate it would expect to pay to borrow on a similar collateralized basis over a similar term in order to determine the present value of its lease payments. The Company considers renewal options in the determination of the lease term if the option to renew is reasonably certain. Variable lease costs represent payments that are dependent on usage, a rate or index. Variable lease costs, which consists primarily of taxes, insurance and common area maintenance costs, are expensed as incurred. The Company elected to account for contracts that contain lease and non-lease components as a single component, consistent with its historical practice. The Company does not have any finance leases.

Revenue Recognition

The Company recognizes revenue in accordance with ASC Topic 606, "Revenue from Contracts with Customers." Under ASC 606, revenue is recognized when a customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services.

The Company’s revenue is generated from the sale of its products to hospitals and medical centers in the United States through direct sales representatives and is primarily comprised of product revenue net of returns, administration fees and sales rebates. Revenue is recognized when obligations under the terms of a contract with customers are satisfied, which occurs with the transfer of control of the Company’s products to its customers, either upon shipment of the product or delivery of the product to the customer. The Company’s products are readily available for usage as soon as the customer possesses it. Upon receipt, the customer controls the economic benefits of the product, has significant risks and rewards, and the legal title. The Company has present right to payment; therefore, the transfer of control is deemed to happen at a point in time. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring the goods. The Company is entitled to the total consideration for the products ordered by customers as product pricing is fixed according to the terms of customer contracts and payment terms are short. Administration fees and sales rebates are accounted for as a reduction in revenue, calculated based on the terms agreed to with the customer.

As of December 31, 2023 and 2022, the Company recorded $227,000 and $148,000, respectively, of unbilled receivables, which are included in accounts receivable, net on the balance sheet, as the Company has an unconditional right to payment as of the end of the applicable period.

The Company excludes taxes assessed by governmental authorities on revenue-producing transactions from the measurement of the transaction price. Costs associated with product sales, which include commissions and royalties, are expensed when incurred because the expense is incurred at a point in time and the amortization period is less than one year. Commissions are recorded as selling expense and royalties are recorded as cost of goods sold in the statements of operations and comprehensive loss.

The Company accepts product returns at its discretion or if the product is defective as manufactured. The Company establishes estimated provisions for returns based on historical experience and considers other factors that it believes could significantly impact its expected returns, which provisions are classified within accrued liabilities on the balance sheet. The Company elected to expense shipping and handling costs as incurred and includes them in the cost of goods

sold. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed as a component of revenue.

Cost of Goods Sold

The Company manufactures certain of its portfolio of TCAR products at its California and Minnesota facilities and purchases other products from third party manufacturers. Cost of goods sold consists primarily of costs related to materials, components and sub-assemblies, manufacturing overhead costs, direct labor, scrap, product rework, reserves for excess, obsolete and non-sellable inventories as well as logistics-related expenses. A significant portion of the Company’s cost of goods sold currently consists of manufacturing overhead costs. These overhead costs include the cost of quality control, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs and royalties. The Company entered into the lease for its additional facility in Minnesota in May 2021 and did not begin commercial production of the ENROUTE Neuroprotection System until the third quarter of 2022. During this time, the Company experienced additional overhead expenses related to its investment in the start-up phase of its manufacturing capacity expansion, which were recorded as a period expense.

Research and Development

The Company expenses research and development costs as incurred. Research and development expenses consist primarily of engineering, product development, clinical studies to develop and support the Company’s products, regulatory expenses, medical affairs and other costs associated with products and technologies that are in development. Research and development expenses include employee compensation, including stock-based compensation, supplies, consulting, prototyping, testing, materials, travel expenses, depreciation and an allocation of facility overhead expenses. Additionally, clinical studies include costs associated with clinical trial design, clinical site reimbursement, data management, travel expenses and the cost of products used for clinical trials and internal and external costs associated with the Company’s regulatory compliance and quality assurance functions, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs.

Clinical Trials

The Company accrues and expenses costs for its clinical trial activities performed by third parties, including any clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these accruals through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services.

Advertising Costs

The Company expenses advertising costs as incurred. Advertising costs include design and production costs, including website development, physician and patient testimonial videos, written media campaigns, and other items. Advertising costs of $461,000, $347,000 and $221,000 were expensed during the years ended December 31, 2023, 2022 and 2021, respectively.

Foreign Currency

The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange gains or losses in other income (expense), net. The Company had no material foreign currency exchange gains or losses during the years ended December 31, 2023, 2022 and 2021.

Stock–Based Compensation

The Company accounts for stock-based compensation in accordance with Financial Accounting Standards Board, or FASB, ASC 718, “Compensation-Stock Compensation.” ASC 718 requires the recognition of compensation expense, using a fair-value based method, for costs related to all share-based payments including stock options, restricted stock units, performance stock units, and shares issued under its employee stock purchase plan. ASC 718 requires companies to estimate the fair value of all share-based payment option awards on the date of grant using an option pricing model. The fair value of stock options is recognized over the period during which an optionee is required to provide services in

exchange for the option award, known as the requisite service period (usually the vesting period), on a straight-line basis. The Company accounts for option forfeitures as they occur.

The Company accounts for stock-based compensation for restricted stock units at their fair value, based on the closing market price of the Company's common stock on the date of grant. These costs are recognized on a straight-line basis over the requisite service period, which is usually the vesting period.

The Company accounts for stock-based compensation for performance stock units with market-based conditions at their fair value on the date of the award using the Monte Carlo simulation model. These costs are recognized over the requisite service period, which is usually the vesting period, regardless of the likelihood of achievement of the market-based performance criteria.

The Company accounts for stock-based compensation for its employee stock purchase plan based on the estimated fair value on the first day of the offering period using an option pricing model for each purchase period. These costs are recognized on a straight-line basis over the offering period.

Income Taxes

The Company accounts for income taxes under the liability method, whereby deferred tax assets and liabilities are determined based on the difference between the financial statements and tax bases of assets and liabilities using the enacted tax rates in effect for the year in which the differences are expected to affect taxable income. A valuation allowance is established when necessary to reduce deferred tax assets to the amounts expected to be realized. As the Company has historically incurred operating losses, it has established a full valuation allowance against its net deferred tax assets, and there is no provision for income taxes.

The Company also follows the provisions of ASC 740-10, “Accounting for Uncertainty in Income Taxes.” ASC 740-10 prescribes a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that have been taken or expected to be taken on a tax return. No liability related to uncertain tax positions is recorded on the financial statements. It is the Company’s policy to include penalties and interest expense related to income taxes as part of the provision for income taxes.

Comprehensive Loss

Comprehensive loss consists of net loss and changes in unrealized gains and losses on investments classified as available-for-sale. For the years ended December 31, 2023, 2022 and 2021, the Company’s unrealized gains and losses on available-for-sale investments represent the only component of other comprehensive loss that are excluded from the reported net loss and that are presented in the statements of operations and comprehensive loss. Accumulated other comprehensive income (loss) is presented in the accompanying balance sheets as a component of stockholders' equity.

Net Loss per Share

Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, common stock options, restricted stock units and performance stock units are considered to be potentially dilutive securities. Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share as the inclusion of all potential dilutive common shares would have been anti-dilutive.

Net loss per share was determined as follows (in thousands, except share and per share data):


	Year Ended December 31,
	2023		2022		2021
Net loss	$	(55,743)	$	(55,010)	$	(49,811)
Weighted average common stock outstanding used to compute net loss per share, basic and diluted		38,804,343		35,775,672		34,635,358
Net loss per share, basic and diluted	$	(1.44)	$	(1.54)	$	(1.44)

The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss:


	December 31,
	2023		2022		2021
Common stock options		3,632,684		3,839,858		3,780,939
Restricted stock units and performance stock units		3,536,197		1,329,824		530,274
Total		7,168,881		5,169,682		4,311,213

Segment and Geographical Information

The Company operates and manages its business as one reportable and operating segment. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. Primarily all of the Company’s long-lived assets are based in the United States. Long-lived assets are comprised of property and equipment. All of the Company’s revenue was in the United States for the years ended December 31, 2023, 2022 and 2021, based on the shipping location of the external customer.

Insider Trading Arrangements	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Insider Trading Arrangements [Line Items]
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Stockholders’ Equity

12 Months Ended

Dec. 31, 2023

Stockholders’ Equity [Abstract]

Stockholders’ Equity

8. Stockholders’ Equity

Preferred Stock

As of December 31, 2023, the Company’s restated certificate of incorporation authorizes the Company to issue up to 5,000,000 shares of preferred stock with $0.001 par value per share, of which no shares were issued and outstanding.

Common Stock

As of December 31, 2023, the Company’s restated certificate of incorporation authorizes the Company to issue up to 100,000,000 shares of common stock with $0.001 par value per share, of which 39,165,481 shares were issued and outstanding. The holders of common stock are also entitled to receive dividends whenever funds are legally available, when and if declared by the Board of Directors. As of December 31, 2023, no dividends have been declared to date. Each share of common stock is entitled to one vote.

As of December 31, 2023 and 2022, the Company had reserved common stock for future issuances as follows:


	December 31,
	2023	2022
Outstanding stock options and equity awards	7,168,881	5,169,682
Reserved for grants of future stock options and equity awards	532,627	2,209,072
Reserved for Performance Stock Units for overperformance	809,225	207,468
Reserved for employee stock purchase plan	1,356,463	1,172,686
Total common stock reserved for future issuance	9,867,196	8,758,908

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Formation and Business of the Company (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2022	Dec. 31, 2022	Dec. 31, 2023
Subsequent Event [Line Items]
Accumulated deficit		$ (343,712)	$ (399,455)
Cash, Cash Equivalents And Available For Sale Investments			$ 190,930
Issued and sold common stock (in shares)	2,674,419
Net proceeds	$ 108,992
Stock issued, price per share (in USD per share)	$ 43.00
Payments of deferred offering costs	$ 258	$ 6,008
Payment of stock issuance underwriting discounts and commissions	$ 5,750
Underwriters' Option [Member]
Subsequent Event [Line Items]
Issued and sold common stock (in shares)	348,837

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Balance Sheet Components (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Components [Abstract]
Weighted average days to maturity	163 days
Work-in-process inventories	$ 0	$ 0
Depreciation and amortization	2,696,000	2,127,000	$ 1,032,000
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 0	$ 0

401(k) Plan

12 Months Ended

Dec. 31, 2023

401(k) Plan [Abstract]

401(k) Plan

11. 401(k) Plan

The Company has a qualified retirement plan under section 401(k) of the Internal Revenue Code, or the IRC, under which participants may contribute up to 90% of their eligible compensation, subject to maximum deferral limits specified by the IRC. The Company may make a discretionary matching contribution to the 401(k) plan and may make a discretionary employer contribution to each eligible employee each year. Beginning in January 2020, the Company started matching employees' contributions to the 401(k) plan at 50% of the first 5% of compensation deferred to the 401(k) plan and at 50% of the first 6% of compensation deferred effective January 1, 2022. The Company's matching contributions were $2,256,000, $1,872,000 and $1,313,000 for the years ended December 31, 2023, 2022 and 2021, respectively.

Stock-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2023

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Shares Available for Issuance


	Number of Shares
Balances, December 31, 2020		1,790,687
Authorized		1,369,985
Granted/Awarded		(847,080)
Cancelled		163,620
Balances, December 31, 2021		2,477,212
Authorized		1,399,235
Allowance for Performance Stock Units for overperformance		(207,468)
Granted/Awarded		(1,600,996)
Cancelled		141,089
Balances, December 31, 2022		2,209,072
Authorized		1,534,238
Allowance for Performance Stock Units for overperformance		(601,757)
Granted/Awarded		(2,893,796)
Cancelled		284,870
Balances, December 31, 2023		532,627

Summary of Stock Option Activity


	Options Outstanding
	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value (in thousands)
Balances, December 31, 2020	4,237,828	$	16.56	7.38	$	197,407
Options granted	323,057		53.94
Options exercised	(643,507)		7.49
Options cancelled	(136,439)		40.30
Balances, December 31, 2021	3,780,939	$	20.45	6.71	$	91,900
Options granted	587,015		37.69

Options exercised	(453,199)		7.42
Options cancelled	(74,897)		41.16
Balances, December 31, 2022	3,839,858	$	24.22	6.41	$	112,755
Options granted	19,898		33.57
Options exercised	(199,642)		7.44
Options cancelled	(27,430)		47.09
Balances, December 31, 2023	3,632,684	$	25.02	5.52	$	7,942
Vested and exercisable at December 31, 2023	3,184,646	$	22.62	5.19	$	7,942
Vested and expected to vest at December 31, 2023	3,632,684	$	25.02	5.52	$	7,942

Summary of Stock-Based Compensation


	Year Ended December 31,
	2023		2022		2021
Cost of goods sold	$	1,671	$	1,138	$	635
Research and development expenses		7,589		5,240		2,909
Selling, general and administrative expenses		29,633		18,645		11,068
Total stock-based compensation expense	$	38,893	$	25,023	$	14,612

Common Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Fair Value Assumptions


	Year Ended December 31,
	2023	2022	2021
Expected term (in years)	5.25	5.25 - 6.25	5.25 - 6.25
Expected volatility	55.1%	48.2% - 51.4%	45.0% - 50.4%
Risk-free interest rate	3.94%	1.60% - 3.84%	0.41% - 1.08%
Dividend yield	—%	—%	—%

ESPP [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Fair Value Assumptions


	Year Ended December 31,
	2023	2022	2021
Expected term (in years)	0.50	0.50	0.50
Expected volatility	47.4% - 119.5%	51.6% - 74.5%	46.9% - 51.6%
Risk-free interest rate	4.64% - 5.43%	0.07% - 4.64%	0.03% - 0.10%
Dividend yield	—%	—%	—%

Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock Unit Activity


	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Balances, December 31, 2020		68,396	$	46.16
Awards granted		524,023		53.64
Awards vested		(34,964)		49.95
Awards cancelled		(27,181)		51.99
Balances, December 31, 2021		530,274	$	53.01
Awards granted		806,513		37.80
Awards vested		(148,239)		52.14
Awards cancelled		(66,192)		44.38
Balances, December 31, 2022		1,122,356	$	42.70
Awards granted		2,162,465		21.71
Awards vested		(410,085)		43.44
Awards cancelled		(147,764)		41.23
Balances, December 31, 2023		2,726,972	$	26.02
Expected to vest at December 31, 2023		2,726,972	$	26.02

Performance Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock Unit Activity


	Number of Performance Stock Units		Weighted Average Grant Date Fair Value
Balances, December 31, 2021		—	$	—
Awards granted		207,468		77.12
Awards vested		—		—
Awards cancelled		—		—
Balances, December 31, 2022		207,468	$	77.12
Awards granted		711,433		21.01
Awards vested		—		—
Awards cancelled		(109,676)		76.66
Balances, December 31, 2023		809,225	$	27.86
Expected to vest at December 31, 2023		809,225	$	27.86

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Balance Sheet Components [Abstract]

Fair Value of the Available-For-Sale Investments


	December 31, 2023
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	19,483	$	—	$	—	$	19,483
U.S. treasury bills		11,896		3		—		11,899
Commercial paper		33,160		5		(15)		33,150
Corporate bonds/notes		39,398		55		(15)		39,438
U.S. government securities		17,501		55		—		17,556
Agency bonds/notes		68,693		27		(43)		68,677
Total	$	190,131	$	145	$	(73)	$	190,203

Classified as:
Cash equivalents							$	19,483
Short-term investments								161,264
Long-term investments								9,456
Total							$	190,203


	December 31, 2022
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	55,158	$	—	$	—	$	55,158
U.S. treasury bills		19,772		4		—		19,776
Commercial paper		48,875		—		—		48,875
Corporate bonds/notes		1,528		—		(13)		1,515
U.S. government securities		83,432		2		(164)		83,270
Asset-backed securities		2,000		—		(4)		1,996
Agency notes		2,876		8		—		2,884
Total	$	213,641	$	14	$	(181)	$	213,474

Classified as:
Cash equivalents							$	55,158
Short-term investments								158,316
Total							$	213,474

Fair Value of Cash Equivalents, Short-Term and Long-Term Equivalents


	December 31, ‎2023		December 31, ‎2022
Amounts maturing within one year	$	180,747	$	213,474
Amounts maturing after one year through two years		9,456		—
Total	$	190,203	$	213,474

Available-For-Sale Investments in Unrealized Loss Position


	December 31, 2023				December 31, 2022
	Less than 12 months				Less than 12 months
Assets:	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate bonds/notes	$	21,842	$	(15)	$	1,490	$	(13)
Commercial paper		19,684		(15)		—		—
U.S. government securities		—		—		73,329		(164)
Asset-backed securities		—		—		1,994		(4)
Agency bonds/notes		48,964		(43)		—		—
Total	$	90,490	$	(73)	$	76,813	$	(181)

Schedule of Inventories


	December 31,
	2023		2022
Raw materials	$	6,512	$	4,913
Finished products		23,364		14,380
Total inventories	$	29,876	$	19,293

Property, Plant and Equipment


	December 31,
	2023		2022
Furniture and fixtures	$	2,052	$	1,822
Equipment		5,776		5,046
Software		296		296
Leasehold improvements		7,561		7,246
		15,685		14,410
Less: Accumulated depreciation		(7,907)		(5,355)
Add: Construction-in-progress		336		317
Total property and equipment, net	$	8,114	$	9,372

Schedule of Accrued Liabilities


	December 31,
	2023		2022
Accrued payroll and related expenses	$	17,113	$	15,216
Operating lease liability		1,703		1,844
Accrued travel expenses		944		775
Accrued interest payable		517		519
Provision for sales returns		500		540
Accrued royalty expense		405		973
Accrued administration fees and sales rebates		405		338
Accrued professional services		326		781
Accrued clinical expenses		256		249
Deferred revenue		143		253
Accrued other expenses		2,295		477
Total accrued liabilities	$	24,607	$	21,965

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Stock-Based Compensation Plans

12 Months Ended

Dec. 31, 2023

Stock-Based Compensation Plans [Abstract]

Stock-Based Compensation Plans

9. Stock-Based Compensation Plans

In March 2019, the Company's Board of Directors [and stockholders] approved the 2019 Equity Incentive Plan, or 2019 Plan, effective immediately prior to the Company’s IPO. The 2019 Plan replaced the prior 2007 Stock Option Plan, or 2007 Plan, and the NeuroCo 2015 Equity Incentive Plan, which the Company assumed in connection with its acquisition of NeuroCo in December 2018, with respect to future grants. The 2019 Plan provides for the grant of ISOs to employees and for the grant of NSOs, restricted stock, restricted stock units, stock appreciation rights, performance units and performance shares to employees, directors and consultants. A total of 2,317,000 shares of common stock were initially reserved for issuance pursuant to the 2019 Plan. In addition, the shares reserved for issuance under the 2019 Plan also include shares reserved but not issued under the prior 2007 Plan, plus any share awards granted under the 2007 Plan that expire or terminate without having been exercised in full or that are forfeited or repurchased. In addition, the number of shares available for issuance under the 2019 Plan also include an annual increase on the first day of each fiscal year, equal to the lesser of (i) 3,000,000 shares; (ii) 4.0% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) an amount as determined by the Board of Directors. As of December 31, 2023, the Company has reserved 7,952,134 shares of common stock for issuance under the 2019 Plan.

A summary of the shares available for issuance under the 2019 Plan is as follows:


	Number of Shares
Balances, December 31, 2020		1,790,687
Authorized		1,369,985
Granted/Awarded		(847,080)
Cancelled		163,620
Balances, December 31, 2021		2,477,212
Authorized		1,399,235
Allowance for Performance Stock Units for overperformance		(207,468)
Granted/Awarded		(1,600,996)
Cancelled		141,089
Balances, December 31, 2022		2,209,072
Authorized		1,534,238
Allowance for Performance Stock Units for overperformance		(601,757)
Granted/Awarded		(2,893,796)
Cancelled		284,870
Balances, December 31, 2023		532,627

The exercise price of Incentive Stock Options and Non-Statutory Stock Options shall not be less than 100% and 85%, respectively, of the estimated fair value of the shares on the date of grant as determined by the Board of Directors. The exercise price of options granted to a 10% stockholder shall not be less than 110% of the estimated fair value of the shares on the date of grant as determined by the Board of Directors. To date, options have a term of ten years and generally vest over four years from the date of grant.

Stock option activity under the Company’s 2007 Stock Option Plan, 2015 Equity Incentive Plan and 2019 Plan is set forth below:


	Options Outstanding
	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value (in thousands)
Balances, December 31, 2020	4,237,828	$	16.56	7.38	$	197,407
Options granted	323,057		53.94
Options exercised	(643,507)		7.49
Options cancelled	(136,439)		40.30
Balances, December 31, 2021	3,780,939	$	20.45	6.71	$	91,900
Options granted	587,015		37.69

Options exercised	(453,199)		7.42
Options cancelled	(74,897)		41.16
Balances, December 31, 2022	3,839,858	$	24.22	6.41	$	112,755
Options granted	19,898		33.57
Options exercised	(199,642)		7.44
Options cancelled	(27,430)		47.09
Balances, December 31, 2023	3,632,684	$	25.02	5.52	$	7,942
Vested and exercisable at December 31, 2023	3,184,646	$	22.62	5.19	$	7,942
Vested and expected to vest at December 31, 2023	3,632,684	$	25.02	5.52	$	7,942

The aggregate intrinsic value of options exercised during the years ended December 31, 2023, 2022 and 2021 was $7,857,000, $17,575,000 and $29,355,000, respectively. The aggregate intrinsic value was calculated as the difference between the exercise prices of the underlying options and the estimated fair value of the common stock on the date of exercise. The weighted-average grant date fair value of options granted during the years ended December 31, 2023, 2022 and 2021 was $17.67, $37.69 and $23.83 per share, respectively. The total fair value of options vested during the years ended December 31, 2023, 2022 and 2021 was $9,207,000, $9,816,000 and $9,076,000, respectively, based on the grant date fair value.

Restricted Stock Units

In March 2020, the Company began awarding restricted stock units, or RSUs, under the 2019 Plan. RSUs generally vest and are settled in shares of common stock over four years in annual equal increments. The total award date fair value of awards provided during the years ended December 31, 2023, 2022 and 2021 was $46,939,000, $30,486,000 and $28,110,000, respectively. The total fair value of awards vested during the years ended December 31, 2023, 2022 and 2021 was $13,203,000, $6,135,000 and $1,893,000, respectively. The fair value of RSUs is based on the closing price of the Company’s common stock on the date of award.

A summary of RSU activity for the years ended December 31, 2023, 2022 and 2021 is as follows:


	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Balances, December 31, 2020		68,396	$	46.16
Awards granted		524,023		53.64
Awards vested		(34,964)		49.95
Awards cancelled		(27,181)		51.99
Balances, December 31, 2021		530,274	$	53.01
Awards granted		806,513		37.80
Awards vested		(148,239)		52.14
Awards cancelled		(66,192)		44.38
Balances, December 31, 2022		1,122,356	$	42.70
Awards granted		2,162,465		21.71
Awards vested		(410,085)		43.44
Awards cancelled		(147,764)		41.23
Balances, December 31, 2023		2,726,972	$	26.02
Expected to vest at December 31, 2023		2,726,972	$	26.02

Performance Stock Units

In November 2022, the Company began awarding performance stock units, or PSUs, under the 2019 Plan to certain executive officers and key employees. PSUs generally vest at the end of a three year service period, subject to continued service to the Company. The total number of shares of common stock to be issued upon vesting and settlement of the PSUs will be determined based on the total stockholder return, or TSR, of the Company’s common stock price relative to a group of Benchmark Companies over a three year performance period and range from 0% to 200% of the target value of shares awarded, depending on the Company’s performance against the targeted Benchmark Companies. The total award date fair value of awards provided during the years ended December 31, 2023 and 2022 was $14,950,000 and $16,000,000, respectively.

There was no PSU activity for the year ended December 31, 2021. A summary of PSU activity for the years ended December 31, 2023 and 2022 is as follows:


	Number of Performance Stock Units		Weighted Average Grant Date Fair Value
Balances, December 31, 2021		—	$	—
Awards granted		207,468		77.12
Awards vested		—		—
Awards cancelled		—		—
Balances, December 31, 2022		207,468	$	77.12
Awards granted		711,433		21.01
Awards vested		—		—
Awards cancelled		(109,676)		76.66
Balances, December 31, 2023		809,225	$	27.86
Expected to vest at December 31, 2023		809,225	$	27.86

The shares expected to vest as of December 31, 2023 reflects PSUs awards performance and vesting at 100% of the target value of shares granted.

2019 Employee Stock Purchase Plan

In March 2019, the Company's Board of Directors [and stockholders] adopted the 2019 Employee Stock Purchase Plan, or the ESPP, under which eligible employees are permitted to purchase common stock at a discount through payroll deductions. A total of 434,000 shares of common stock were initially reserved for issuance and is increased on the first day of each fiscal year by an amount equal to the lesser of (i) 1,200,000 shares (ii) 1.0% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) an amount as determined by the Board of Directors. The price of the common stock purchased will be the lower of 85% of the fair market value of the common stock at the beginning of an offering period or at the end of a purchase period. The ESPP was effective upon adoption by the Company's Board of Directors but was not in use until the completion of the Company's IPO in April 2019. The ESPP is intended to qualify as an "employee stock purchase plan" within the meaning of Section 423 of the Internal Revenue Code of 1986, as amended.

As of December 31, 2023, 465,952 shares of common stock have been issued to employees participating in the ESPP and 1,356,463 shares were available for future issuance under the ESPP.

Stock-Based Compensation

The Company estimated the fair value of stock options using the Black–Scholes option pricing model. The fair value of stock options is being amortized on a straight–line basis over the requisite service period of the awards. The fair value of stock options was estimated using the following assumptions for the years ended December 31, 2023, 2022 and 2021:


	Year Ended December 31,
	2023	2022	2021
Expected term (in years)	5.25	5.25 - 6.25	5.25 - 6.25
Expected volatility	55.1%	48.2% - 51.4%	45.0% - 50.4%
Risk-free interest rate	3.94%	1.60% - 3.84%	0.41% - 1.08%
Dividend yield	—%	—%	—%

The fair value of the underlying common stock is based on the closing price of the Company's common stock on The Nasdaq Global Select Market on the date of grant. The expected term of stock options represents the weighted-average period the stock options are expected to remain outstanding. The Company does not have sufficient historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term of options and has opted to use the “simplified method,” whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. The expected stock price volatility assumption was determined by supplementing its historical stock trading volatility with the historical volatilities for industry peers, as the Company does not have sufficient trading history for the Company’s common stock. The Company will continue to analyze the historical stock price volatility and expected term assumption as more historical data for the Company’s common stock becomes available. The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the Company’s stock options. The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has elected to recognize forfeitures of share-based payment awards as they occur.

In November 2022, the Company awarded an aggregate of 207,468 PSUs to certain executive officers that vest at the end of a three year service period based on the TSR of the Company’s common stock price relative to a group of Benchmark Companies measured over three performance periods. The Company estimated the fair value of the PSUs using the Monte Carlo simulation model, which is being amortized over the requisite service period of the awards. The fair value of the PSUs was estimated using the following assumptions for the year ended December 31, 2022: peer companies volatility of 59.4%, Company volatility of 60.6%, risk-free interest rate of 4.09%-4.20%, correlation with index of 0.41, and dividend yield of 0%.

In March 2023, the Company awarded an aggregate of 99,350 PSUs, assuming target performance. Up to one-third of the target award can be earned and vested at the end of the first and second annual measurement periods based on the total stockholder return, or TSR, of the Company’s common stock price relative to a group of peer companies, and up to 200% of the target award at the end of the three year performance measurement period. The fair value of the PSUs was estimated using the Monte Carlo simulation model and the following assumptions for the year ended December 31, 2023: peer companies volatility of 62.3%, Company volatility of 61.2%, risk-free interest rate of 4.58%, correlation with index of 0.38, and dividend yield of 0%.

In November 2023, the Company awarded an aggregate of 612,083 PSUs, assuming target performance. Up to one-third of the target award can be earned and vested at the end of the first and second annual measurement periods based on the total stockholder return, or TSR, of the Company’s common stock price relative to a group of peer companies, and up to 200% of the target award at the end of the three year performance measurement period. The fair value of the PSUs was estimated using the Monte Carlo simulation model and the following assumptions for the year ended December 31, 2023: peer companies volatility of 56.9%, Company volatility of 71.1%, risk-free interest rate of 4.72%, correlation with index of 0.35, and dividend yield of 0%.

The fair value of the shares to be issued under the Company’s ESPP was estimated using the Black-Scholes valuation model with the following assumptions for the years ended December 31, 2023, 2022 and 2021:


	Year Ended December 31,
	2023	2022	2021
Expected term (in years)	0.50	0.50	0.50
Expected volatility	47.4% - 119.5%	51.6% - 74.5%	46.9% - 51.6%
Risk-free interest rate	4.64% - 5.43%	0.07% - 4.64%	0.03% - 0.10%
Dividend yield	—%	—%	—%

The following table summarizes the total stock-based compensation expense included in the statements of operations and comprehensive loss for all periods presented (in thousands):


	Year Ended December 31,
	2023		2022		2021
Cost of goods sold	$	1,671	$	1,138	$	635
Research and development expenses		7,589		5,240		2,909
Selling, general and administrative expenses		29,633		18,645		11,068
Total stock-based compensation expense	$	38,893	$	25,023	$	14,612

As of December 31, 2023, there was total unrecognized compensation costs of $5,645,000 related to stock options expected to be recognized over a period of approximately 1.63 years, a total of $73,195,000 of unrecognized compensation costs related to unvested RSUs and PSUs expected to be recognized over a period of approximately 2.76

years and $679,000 of unrecognized compensation costs related to the ESPP, which the Company will recognize over 0.38 years.

Balance Sheet Components (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components [Abstract]
Accrued payroll and related expenses	$ 17,113	$ 15,216
Operating lease liability	1,703	1,844
Accrued travel expenses	500	540
Accrued interest payable	326	781
Provision for sales returns	405	973
Accrued royalty expense	944	775
Accrued administration fees and sales rebates	405	338
Accrued professional services	517	519
Accrued clinical expenses	143	253
Deferred revenue	256	249
Accrued other expenses	2,295	477
Total accrued liabilities	$ 24,607	$ 21,965

Statements of Stockholders’ Equity (Parenthetical) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2022	Dec. 31, 2022
Statements of Stockholders' Equity [Abstract]
Offering costs	$ 258	$ 6,008

Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning balance (in shares) at Dec. 31, 2020	34,249,649
Beginning balance at Dec. 31, 2020	$ 34	$ 346,318	$ (238,891)	$ 39	$ 107,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 1	4,841			$ 4,842
Exercise of stock options (in shares)	643,507				643,507
Issuance of common stock upon vesting of restricted stock units (in shares)	34,964
Issuance of common stock under employee stock purchase plan		2,104			$ 2,104
Issuance of common stock under employee stock purchase plan (in shares)	52,776
Stock-based compensation		14,612			14,612
Disgorgement of short-swing profits, net		32			32
Net loss			(49,811)		(49,811)
Change in unrealized loss on investments, net				(39)	(39)
Ending balance (in shares) at Dec. 31, 2021	34,980,896
Ending balance at Dec. 31, 2021	$ 35	367,907	(288,702)		79,240
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock	$ 3	108,989			108,992
Issuance of common stock (in shares)	2,674,419
Exercise of stock options		3,364			$ 3,364
Exercise of stock options (in shares)	453,199				453,199
Issuance of common stock upon vesting of restricted stock units (in shares)	148,239
Issuance of common stock under employee stock purchase plan		2,432			$ 2,432
Issuance of common stock under employee stock purchase plan (in shares)	99,219
Stock-based compensation		25,023			25,023
Net loss			(55,010)		(55,010)
Change in unrealized loss on investments, net				(166)	(166)
Ending balance (in shares) at Dec. 31, 2022	38,355,972
Ending balance at Dec. 31, 2022	$ 38	507,715	(343,712)	(166)	163,875
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options		1,486			$ 1,486
Exercise of stock options (in shares)	199,642				199,642
Issuance of common stock upon vesting of restricted stock units	$ 1				$ 1
Issuance of common stock upon vesting of restricted stock units (in shares)	410,085
Issuance of common stock under employee stock purchase plan		2,401			2,401
Issuance of common stock under employee stock purchase plan (in shares)	199,782
Stock-based compensation		38,893			38,893
Net loss			(55,743)		(55,743)
Change in unrealized loss on investments, net				238	238
Ending balance (in shares) at Dec. 31, 2023	39,165,481
Ending balance at Dec. 31, 2023	$ 39	$ 550,495	$ (399,455)	$ 72	$ 151,151

Stock-Based Compensation Plans (Summary of Stock Unit Activity) (Details) - $ / shares	1 Months Ended	12 Months Ended
	Nov. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Units [Member]
Number of Stock Units
Beginning balance (in shares)		1,122,356	530,274	68,396
Awards granted (in shares)		2,162,465	806,513	524,023
Awards vested (in shares)		410,085	148,239	34,964
Awards cancelled (in shares)		(147,764)	(66,192)	(27,181)
Ending balance (in shares)		2,726,972	1,122,356	530,274
Expected to vest (in shares)		2,726,972
Weighted Average Grant Date Fair Value
Beginning balance (in USD per share)		$ 42.70	$ 53.01	$ 46.16
Awards granted (in USD per share)		21.71	37.80	53.64
Awards vested (in USD per share)		43.44	52.14	49.95
Awards cancelled (in USD per share)		41.23	44.38	51.99
Ending balance (in USD per share)		26.02	$ 42.70	$ 53.01
Expected to vest (in USD per share)		$ 26.02
Performance Stock Units [Member]
Number of Stock Units
Beginning balance (in shares)		207,468
Awards granted (in shares)	207,468	711,433	207,468
Awards cancelled (in shares)		(109,676)
Ending balance (in shares)		809,225	207,468
Expected to vest (in shares)		809,225
Weighted Average Grant Date Fair Value
Beginning balance (in USD per share)		$ 77.12
Awards granted (in USD per share)		21.01	$ 77.12
Awards cancelled (in USD per share)		76.66
Ending balance (in USD per share)		27.86	$ 77.12
Expected to vest (in USD per share)		$ 27.86

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Allowances for accounts receivables	$ 26	$ 3
Preferred stock, $0.001 par value
Preferred shares (in USD per share)	$ 0.001	$ 0.001
Preferred shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, $0.001 par value
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	39,165,481	38,355,972
Shares outstanding (in shares)	39,165,481	38,355,972

Long-term Debt

12 Months Ended

Dec. 31, 2023

Long-term Debt [Abstract]

Long-term Debt

6. Long-term Debt

Stifel Bank

In October 2020, the Company entered into a Loan and Security Agreement with Stifel Bank which provided for a $50,000,000 loan facility, comprised of a $50,000,000 secured revolving credit facility, with a $2,000,000 subfacility for the issuance of letters of credit and other ancillary banking services, and a $50,000,000 secured term loan facility, provided that amounts outstanding under both facilities may not exceed an aggregate principal amount of $50,000,000 at any time. Interest under the revolving credit facility was the greater of a) 0.5% above the "Prime Rate" as published by The Wall Street Journal or b) 4.75%. Interest under the term loan facility was the greater of a) 0.75% above the "Prime Rate" as published by The Wall Street Journal or b) 4.75%. The Company drew down $49,000,000 under the term loan facility in October 2020. Concurrent with the Loan and Security Agreement, the Company entered in a Success Fee Agreement in October 2020 with Stifel Bank, which requires that the Company pay Stifel Bank the lesser of 0.75% of the original principal amount of all credit extensions made under the Loan and Security Agreement or $375,000 in the event the Company completes a Liquidity Event (liquidation, merger, sale of the Company or change in control).

On May 27, 2022, in connection with the consummation of the Loan and Security Agreement with Oxford Finance, as noted below, the Company repaid all amounts outstanding under the term loan with Stifel Bank. The Success Fee Agreement obligation of $367,500 survives the Stifel Bank debt repayment and terminates on October 29, 2025. The Company has determined the probability of a Liquidity Event to be remote and accordingly, has not recognized a liability as of December 31, 2023 and 2022.

Oxford Finance

In May 2022, the Company entered into a Loan and Security Agreement, or Loan Agreement, with Oxford Finance LLC and its agents, or Oxford Finance, which provides for a $225,000,000 loan facility, comprised of a $25,000,000 secured revolving credit facility and a $200,000,000 secured term loan facility. The term loans are available in three tranches. The first $75,000,000 tranche of term loans was available at closing in May 2022. A second tranche of $75,000,000 of term loans is available through December 31, 2024. A third tranche of $50,000,000 would be available through December 31, 2024 so long as, at the time of draw, the Company has consolidated trailing 12-month revenues equal to at least 90% of the sum of the outstanding term loans plus the amount of any requested third tranche term loans.

Upon request of the Company, the revolving credit facility will be increased from $25,000,000 to $50,000,000. The revolving loans are available subject to a borrowing base equal to 85% of eligible receivables plus 50% of eligible inventory, up to the lesser of 40% of the borrowing base or $10,000,000, in the case of eligible inventory.

The revolving loans and the term loans mature on May 1, 2027. The principal amount of outstanding revolving loans, together with accrued and unpaid interest, is due on the maturity date. The term loans begin to amortize in equal monthly installments beginning on July 1, 2026. As the Company achieved a specified consolidated trailing twelve-month revenue target, it has the option to extend the first amortization date for the term loans to July 1, 2027. Such election may be made no earlier than June 30, 2023 and no later than thirty (30) days prior to July 1, 2026. If the Company exercises this option, then the maturity date for both the revolving loans and the term loans will be May 1, 2028.

The revolving loans accrue interest at the greater of 1-month Secured Overnight Financing Rate (SOFR), or the Index Rate, and 0.85%, plus a margin of 3.00%. The term loans accrue interest at the greater of the Index Rate and 0.85%, plus a margin of 5.00%. The Index Rate is capped at 2.50% for purposes of the Loan Agreement. Interest on both revolving loans and term loans is payable monthly in arrears. The Company may borrow, prepay and reborrow revolving loans, without premium or penalty. The term loans once repaid or prepaid may not be reborrowed. Term loans may be prepaid in full, or in part in increments of $10,000,000. The Company is required to pay a prepayment fee of 3.0% for prepayments of term loans made in the first year after closing, 2.0% for prepayments of term loans made in the second year after closing, 1.0% for prepayments of term loans made in the third year after closing and no prepayment fees thereafter. Upon the earlier of prepayment or maturity of the term loans, the Company is required to pay a fee of 5.0% of the aggregate original principal amount of the funded term loans, which fee increases to 6.75% if the Company exercises its option to extend the amortization date and maturity date. The Company is also obligated to pay other customary fees for a loan facility of this size and type.

Also in May 2022, the Company borrowed the first $75,000,000 tranche of the term loan and used a portion of the proceeds to pay off and terminate the prior term loan agreement with Stifel Bank totaling $49,181,000, which included a final interest payment of $181,000. The Company recognized a loss on debt extinguishment of $245,000 in connection with the early termination of its prior term loan agreement with Stifel Bank.

Obligations under the Loan Agreement are secured by substantially all of the Company's assets. The Loan Agreement requires the Company to maintain consolidated trailing twelve-month revenues of at least 75% of the outstanding principal amount of the term loans, measured as of the last day of each fiscal quarter; or if the revenue target is not achieved, the Company must have maintained unrestricted cash and cash equivalents (net of outstanding revolving loans) subject to control agreements in favor of Oxford Finance equal to at least 50% of the outstanding principal amount of the term loans. Additionally, the Loan Agreement contains customary affirmative and negative covenants, including covenants limiting the Company's ability and the ability of the Company's subsidiaries to, among other things, dispose of assets, effect certain mergers, incur debt, grant liens, pay dividends and distributions on capital stock, make investments and acquisitions, and enter into transactions with affiliates, in each case subject to customary exceptions for a loan facility of this size and type.

The events of default under the Loan Agreement include, among others, payment defaults, material misrepresentations, breaches of covenants, cross defaults with certain other material indebtedness, bankruptcy and insolvency events, and judgment defaults. The occurrence of an event of default could result in the acceleration of the Company’s obligations under the Loan Agreement, the termination of the lender’s commitments, a 5% increase in the applicable rate of interest and the exercise by the lender of other rights and remedies provided for under the Loan Agreement.

As of December 31, 2023, the aggregate outstanding principal balance under the term loan facility was $75,000,000 with the variable interest rate capped at the maximum rate of 7.50%, and no amounts were outstanding under the revolving credit facility of the Loan Agreement. As of December 31, 2023, the Company was in compliance with all applicable financial covenants.

Future payments under the Oxford Finance term loan agreement as of December 31, 2023 are as follows (in thousands):


Year Ending December 31:	Amount
2024	$	5,719
2025		5,703
2026		45,699
2027		34,517
		91,638
Add: Accretion of closing fees		1,329
		92,967
Less: Amount representing interest		(16,638)
Less: Amount representing debt discount and debt issuance costs		(703)
Present value of minimum payments	$	75,626

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Summary of Significant Accounting Policies [Abstract]

Schedule of Cash and Cash Equivalents


	December 31,
	2023		2022
Cash and cash equivalents	$	20,210	$	55,358
Restricted cash		—		155
Total cash, cash equivalents and restricted cash	$	20,210	$	55,513

Schedule of Net Loss Per Share Determination


	Year Ended December 31,
	2023		2022		2021
Net loss	$	(55,743)	$	(55,010)	$	(49,811)
Weighted average common stock outstanding used to compute net loss per share, basic and diluted		38,804,343		35,775,672		34,635,358
Net loss per share, basic and diluted	$	(1.44)	$	(1.54)	$	(1.44)

Schedule of Potentially Dilutive Securities Outstanding Excluded from Diluted Weighted Average Shares Outstanding


	December 31,
	2023		2022		2021
Common stock options		3,632,684		3,839,858		3,780,939
Restricted stock units and performance stock units		3,536,197		1,329,824		530,274
Total		7,168,881		5,169,682		4,311,213

Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2023	Feb. 23, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38847
Entity Registrant Name	SILK ROAD MEDICAL, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8777622
Entity Address, Address Line One	1213 Innsbruck Dr.
Entity Address, City or Town	Sunnyvale
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94089
City Area Code	408
Local Phone Number	720-9002
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	SILK
Security Exchange Name	NASDAQ
Entity Public Float			$ 1.2
Entity Common Stock, Shares Outstanding		39,174,619
Entity Central Index Key	0001397702
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Financial Statement Error Correction Flag	false
Documents Incorporated by Reference [Text Block]	Portions of the definitive proxy statement for our 2024 Annual Meeting of Stockholders, or the 2024 Proxy Statement, are incorporated by reference into Part III of this report where indicated. The 2024 Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Minneapolis, Minnesota
Auditor Firm ID	238

401(k) Plan (Details) - USD ($) $ in Thousands	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
401(k) Plan [Abstract]
Percentage employee contribution	90.00%
Employer discretionary contribution	$ 2,256	$ 1,872	$ 1,313
Employer contribution match percentage	50.00%
Percent of matching contribution of the employee's pay	5.00%

Long-term Debt (Future Payment Under the Term Loan) (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Long-term Debt [Abstract]
2024	$ 5,719
2025	5,703
2026	45,699
2027	34,517
Long-term debt, gross before accretion of closing fees	91,638
Add: Accretion of closing fees	1,329
Long-Term Debt, Gross, After Accretion Of Closing Fees	92,967
Less: Amount representing interest	(16,638)
Less: Amount representing debt discount and debt issuance costs	(703)
Present value of minimum payments	$ 75,626

Summary of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unbilled receivables	$ 227,000	$ 148,000
Provision for income taxes
Liability for uncertain tax positions	$ 0
Number of reportable segments \| segment	1
Number of operating segments \| segment	1
Advertising expense	$ 461,000	347,000	$ 221,000
Asset Impairment Charges	0	0	0
Available-for-sale securities, credit losses	0	0	$ 0
Restricted cash	$ 0	155,000
Letter of Credit [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash		$ 155,000
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life	3 years
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life	5 years

Balance Sheet Components (Schedule of Inventory) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components [Abstract]
Raw materials	$ 6,512	$ 4,913
Finished products	23,364	14,380
Total inventories	$ 29,876	$ 19,293

Commitments and Contingencies (Balance Sheet Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies [Abstract]
Operating lease right-of-use assets in other non-current assets	$ 6,489	$ 5,081
Operating lease liabilities in accrued liabilities	1,703	1,844
Operating lease liabilities in other liabilities	7,304	5,998
Total operating lease liabilities	$ 9,007	$ 7,842
Operating lease, right-of-use asset, statement of financial position extensible list	Other non-current assets	Other non-current assets
Operating lease, liability, current, statement of financial position extensible list	Accrued liabilities	Accrued liabilities
Operating lease, liability, noncurrent, statement of financial position extensible list	Other liabilities	Other liabilities
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Liabilities	Liabilities

Fair Value Measurements (Financial Assets Measured on a Recurring Basis) (Details) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 190,203	$ 213,474
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19,483	55,158
US Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	11,899	19,776
Commercial Papers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	33,150	48,875
Corporate Bonds/Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	39,438	1,515
U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	17,556	83,270
Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		1,996
Agency bonds/notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	68,677	2,884
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	31,382	74,934
Level 1 [Member] \| Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	19,483	55,158
Level 1 [Member] \| US Treasury Bills [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	11,899	19,776
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	158,821	138,540
Level 2 [Member] \| Commercial Papers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	33,150	48,875
Level 2 [Member] \| Corporate Bonds/Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	39,438	1,515
Level 2 [Member] \| U.S. Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	17,556	83,270
Level 2 [Member] \| Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		1,996
Level 2 [Member] \| Agency bonds/notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 68,677	$ 2,884

Stockholders' Equity (Narrative) (Details) - USD ($)	12 Months Ended
Stockholders' Equity (Narrative) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Stockholders’ Equity [Abstract]
Preferred shares authorized (in shares)	5,000,000	5,000,000
Preferred shares (in USD per share)	$ 0.001	$ 0.001
Shares authorized (in shares)	100,000,000	100,000,000
Par value (in USD per share)	$ 0.001	$ 0.001
Shares issued (in shares)	39,165,481	38,355,972
Shares outstanding (in shares)	39,165,481	38,355,972
Dividends declared	$ 0

Income Taxes - Reconciliation of U.S Statutory Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Abstract]
Tax at federal statutory rate	$ (11,706)	$ (11,552)	$ (10,460)
State taxes, net of federal benefit	(2,311)	(2,206)	(1,852)
Permanent differences	(392)	(2,893)	(5,224)
Change in valuation allowance	11,549	18,237	17,918
Limitation of compensation deduction under IRS Sec.162(m)	4,320	10
General business credits	(1,536)	(1,166)	(852)
Other	119	(401)	490
Provision for income taxes	$ 43	$ 29	$ 20

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Taxes [Abstract]

Income Taxes

10. Income Taxes

The components of income before taxes are as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
United States	$	(55,743)	$	(55,010)	$	(49,811)
International		—		—		—
Net loss before income taxes	$	(55,743)	$	(55,010)	$	(49,811)

A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Tax at federal statutory rate	$	(11,706)	$	(11,552)	$	(10,460)
State taxes, net of federal benefit		(2,311)		(2,206)		(1,852)
Permanent differences		(392)		(2,893)		(5,224)
Change in valuation allowance		11,549		18,237		17,918
Limitation of compensation deduction under IRS Sec.162(m)		4,320		10		—
General business credits		(1,536)		(1,166)		(852)
Other		119		(401)		490
Provision for income taxes	$	43	$	29	$	20

The Company's provision for income taxes amounts are not significant and are included within other income (expense) on the statements of operations and comprehensive loss.

Significant components of the Company’s net deferred tax assets as of December 31, 2023 and 2022 consist of the following (in thousands):


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss carryforwards	$	85,945	$	82,768
Research and development credits		10,753		8,898
Capitalized start-up costs/Intangibles		—		1
Section 174 R&D capitalization		12,892		7,816
Accruals and reserves		2,775		2,820
Stock-based compensation		10,353		8,209
Operating lease liability		2,272		1,973
Interest limitation		1,114		2,013
Total deferred tax assets		126,104		114,498
Less: Valuation allowance		(122,993)		(111,444)
Deferred tax liabilities:
Operating lease asset		(1,636)		(1,278)
Property and equipment		(1,475)		(1,776)
Total deferred tax liabilities		(3,111)		(3,054)
Net deferred tax assets	$	—	$	—

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management believes it is more likely than not that the deferred tax assets will not be realized; accordingly, a valuation allowance has been established on U.S. net deferred tax assets. The valuation allowance increased $11,549,000, $18,237,000 and $17,918,000 during the years ended December 31, 2023, 2022 and 2021, respectively.

As of December 31, 2023, the Company had net operating loss carryforwards of approximately $331,957,000 and $288,608,000 for federal and state income tax purposes, respectively. The federal and state net operating loss carryforwards begin to expire in 2027 and 2024, respectively. Federal NOL carryforwards generated in tax years beginning in 2018 are not subject to expiration. Federal NOLs that arose on or after January 1, 2018 can be carried forward indefinitely against future income, but can only be used to offset a maximum of 80% of the Company's federal taxable income in any year.

The federal and state net operating loss carryforwards may be subject to significant limitations under Section 382 and Section 383 of the Internal Revenue Code and similar provisions under state law. Federal tax legislation enacted in December 2017, commonly known as the Tax Cuts and Jobs Act, contains provisions that limit the federal net operating loss carryforwards that may be used in any given year in the event of special occurrences, including significant ownership changes. A Section 382 “ownership change” generally occurs if one or more stockholders or groups of stockholders, who own at least 5% of the Company’s stock, increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. The Company may have previously experienced, and may in the future experience, one or more Section 382 “ownership changes,” including in connection with the Company’s initial public offering. If so, the Company may lose some or all of the tax benefits of its NOLs and tax credits. The extent of such limitations for prior years, if any, has not yet been formally determined.

Under the Tax Cuts and Jobs Act, research and development expenditures are no longer fully deductible and are required to be capitalized and amortized under Section 174 of the Internal Revenue Code in tax years beginning on or after January 1, 2022. The capitalized research expenses must be amortized over five years for research performed in the U.S. and 15 years for research performed outside the U.S. The mandatory capitalization requirement increased the Company’s deferred tax assets, which were fully offset by a valuation allowance.

At December 31, 2023, the Company had $10,122,000 and $5,869,000 of federal and state research and development credit carryforwards, respectively, on a tax return basis. If not utilized, the federal credits will expire beginning in 2027. The California research and development credits can be carried forward indefinitely.

As of December 31, 2023, the Company had $4,364,000 of unrecognized tax benefits. The Company does not have any tax positions for which it is reasonably possible that the total amount of gross unrecognized tax benefits would increase or decrease within twelve months of the year ended December 31, 2023. If recognized, $0 would affect the effective tax rate.

The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. There was no such expense recorded during the years ended December 31, 2023, 2022 and 2021.

A reconciliation of the unrecognized tax benefits from January 1, 2021 to December 31, 2023 is as follows (in thousands)


	December 31,
	2023		2022		2021
Balance at the beginning of year	$	3,788	$	3,314	$	2,019
Increases related to current years’ tax positions		571		474		704
Increases related to prior years’ tax positions		5		—		591
Balance at end of year	$	4,364	$	3,788	$	3,314

The Company currently has no federal or state tax examinations in progress nor has it had any federal or state tax examinations since its inception. As a result of the Company’s net operating loss carryforwards, all of its tax years are subject to federal and state tax examination.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
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-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (b)
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 2
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies [Abstract]
Cash and cash equivalents	$ 20,210,000	$ 55,358,000
Restricted cash	0	155,000
Total cash, cash equivalents and restricted cash	$ 20,210,000	$ 55,513,000	$ 110,463,000	$ 69,776,000

Stock-Based Compensation Plans (Summary of Stock-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 38,893	$ 25,023	$ 14,612
Cost of Goods Sold [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,671	1,138	635
Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	7,589	5,240	2,909
Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 29,633	$ 18,645	$ 11,068

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies [Abstract]

Commitments and Contingencies

7. Commitments and Contingencies

Operating Lease and Rights-of-Use

The Company’s operating lease obligation at its corporate headquarters in California consists of leased office, laboratory, and manufacturing space under a non-cancellable operating lease that expires in October 2027. In May 2023, the Company extended the lease term for an additional three years and recorded an additional $2,504,000 right-of-use asset and lease liability from the remeasurement. The lease agreement includes a renewal provision allowing the Company to extend this lease for an additional period of five years.

The Company’s non-cancelable operating lease obligation at its facility in Minnesota consists of additional office, laboratory and manufacturing space and expires in November 2029. The lease agreement includes a renewal provision allowing the Company to extend this lease for two additional five year terms.

Balance sheet information as of December 31, 2023 and 2022 consists of the following (in thousands):


	December 31,
Operating Lease:	2023		2022
Operating lease right-of-use asset in other non-current assets	$	6,489	$	5,081
Operating lease liability in accrued liabilities	$	1,703	$	1,844
Operating lease liability in other liabilities		7,304		5,998
Total operating lease liabilities	$	9,007	$	7,842

The following table summarizes the Company's operating lease payments as of December 31, 2023 (in thousands):


Year Ending December 31:	Amount
2024	$	1,991
2025		2,130
2026		2,255
2027		2,068
2028		1,233
Thereafter		1,158
Total lease payments		10,835
Less: imputed interest		(1,828)
Present value of lease liabilities	$	9,007

Purchase Obligations

Purchase obligations consist of agreements to purchase goods and services entered into in the ordinary course of business. As of December 31, 2023, the Company had non-cancellable purchase obligations to suppliers of $15,660,000. In addition, the Company has minimum purchase commitments under its amended supply agreement with Cordis from July 2024 through February 2029 which require a specified minimum volume commitment based on the actual units purchased during the prior year period from July 1 through June 30, with the unit purchase price dependent upon annual volume during the same prior year period.

Indemnification

In the normal course of business, the Company enters into contracts and agreements with suppliers and other parties that contain a variety of representations and warranties and may provide for indemnification of the counterparty. The Company’s exposure under these agreements is unknown because it involves claims that may be made against it in the future but have not yet been made. To date, the Company has not been subject to any claims or been required to defend any action related to its indemnification obligations.

The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director or officer is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director or officer may be subject to any proceeding arising out of acts or omissions of such director or officer in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations as of December 31, 2023.

Contingencies

The Company is not involved in any pending legal proceedings that it believes could have a material adverse effect on its financial condition, results of operations or cash flows. From time to time, the Company may pursue litigation to assert its legal rights and such litigation may be costly and divert the efforts and attention of its management and technical personnel which could adversely affect its business. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. There were no contingent liabilities requiring accrual as of December 31, 2023 and 2022.

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies [Abstract]

Balance Sheet Information


	December 31,
Operating Lease:	2023		2022
Operating lease right-of-use asset in other non-current assets	$	6,489	$	5,081
Operating lease liability in accrued liabilities	$	1,703	$	1,844
Operating lease liability in other liabilities		7,304		5,998
Total operating lease liabilities	$	9,007	$	7,842

Operating Lease Maturities


Year Ending December 31:	Amount
2024	$	1,991
2025		2,130
2026		2,255
2027		2,068
2028		1,233
Thereafter		1,158
Total lease payments		10,835
Less: imputed interest		(1,828)
Present value of lease liabilities	$	9,007

Income Taxes - Components of Income Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Abstract]
United States	$ (55,743)	$ (55,010)	$ (49,811)
Net loss before income taxes	$ (55,743)	$ (55,010)	$ (49,811)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
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-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-Paragraph 1
-SubTopic 20
-Topic 940
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481913/940-20-25-1

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Balance Sheet Components (Fair Value of Cash Equivalents, Short-Term and Long-Term Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Balance Sheet Components [Abstract]
Amounts maturing within one year	$ 180,747	$ 213,474
Amounts maturing after one year through two years	9,456
Total	$ 190,203	$ 213,474

Commitments and Contingencies (Narrative) (Details) - USD ($)		12 Months Ended
	May 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Purchase obligation		$ 15,660,000
Indemnification obligations, liability recognized		0
Contingent liabilities requiring accrual		0	$ 0
Additional extended lease period	3 years
Right-of-use asset obtained in exchange for lease obligation	$ 2,504,000	$ 2,504,000	$ 903,000	$ 3,307,000
Headquarters [Member]
Lessee, Lease, Description [Line Items]
Renewal term		5 years
Additional Office, Laboratory And Manufacturing Space [Member]
Lessee, Lease, Description [Line Items]
Renewal term		5 years

Balance Sheet Components (Available-for-Sale Investments in Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	$ 90,490	$ 76,813
Unrealized Loss, Less than 12 months	(73)	(181)
Commercial Paper [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	19,684
Unrealized Loss, Less than 12 months	(15)
Corporate Bonds/Notes [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	21,842	1,490
Unrealized Loss, Less than 12 months	(15)	(13)
U.S. Government Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months		73,329
Unrealized Loss, Less than 12 months		(164)
Asset-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months		1,994
Unrealized Loss, Less than 12 months		$ (4)
Agency bonds/notes [Member]
Debt Securities, Available-for-sale [Line Items]
Fair Value, Less than 12 months	48,964
Unrealized Loss, Less than 12 months	$ (43)

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (d)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
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-Paragraph 3
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Balance Sheet Components [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Investments

The fair value of the Company's available-for-sale investments as of December 31, 2023 and 2022 are as follows (in thousands):


	December 31, 2023
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	19,483	$	—	$	—	$	19,483
U.S. treasury bills		11,896		3		—		11,899
Commercial paper		33,160		5		(15)		33,150
Corporate bonds/notes		39,398		55		(15)		39,438
U.S. government securities		17,501		55		—		17,556
Agency bonds/notes		68,693		27		(43)		68,677
Total	$	190,131	$	145	$	(73)	$	190,203

Classified as:
Cash equivalents							$	19,483
Short-term investments								161,264
Long-term investments								9,456
Total							$	190,203


	December 31, 2022
			Gross Unrealized				Estimated
	Amortized Cost		Gains		Losses		Fair Value
Money market funds	$	55,158	$	—	$	—	$	55,158
U.S. treasury bills		19,772		4		—		19,776
Commercial paper		48,875		—		—		48,875
Corporate bonds/notes		1,528		—		(13)		1,515
U.S. government securities		83,432		2		(164)		83,270
Asset-backed securities		2,000		—		(4)		1,996
Agency notes		2,876		8		—		2,884
Total	$	213,641	$	14	$	(181)	$	213,474

Classified as:
Cash equivalents							$	55,158
Short-term investments								158,316
Total							$	213,474

The following table summarizes the fair value of the Company’s cash equivalents, and available-for-sale investments classified by maturity as of December 31, 2023 and 2022 (in thousands):


	December 31, ‎2023		December 31, ‎2022
Amounts maturing within one year	$	180,747	$	213,474
Amounts maturing after one year through two years		9,456		—
Total	$	190,203	$	213,474

Available-for-sale investments held as of December 31, 2023 had a weighted average days to maturity of 163 days.

The following table presents the Company's available-for-sale investments that were in an unrealized loss position as of December 31, 2023 and 2022 (in thousands):


	December 31, 2023				December 31, 2022
	Less than 12 months				Less than 12 months
Assets:	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate bonds/notes	$	21,842	$	(15)	$	1,490	$	(13)
Commercial paper		19,684		(15)		—		—
U.S. government securities		—		—		73,329		(164)
Asset-backed securities		—		—		1,994		(4)
Agency bonds/notes		48,964		(43)		—		—
Total	$	90,490	$	(73)	$	76,813	$	(181)

There were no available-for-sale investments in an unrealized loss position greater than twelve months as of December 31, 2023 and 2022.

Inventories

Components of inventories were as follows (in thousands):


	December 31,
	2023		2022
Raw materials	$	6,512	$	4,913
Finished products		23,364		14,380
Total inventories	$	29,876	$	19,293

As of December 31, 2023 and 2022, there were no work-in-process inventories.

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2023		2022
Furniture and fixtures	$	2,052	$	1,822
Equipment		5,776		5,046
Software		296		296
Leasehold improvements		7,561		7,246
		15,685		14,410
Less: Accumulated depreciation		(7,907)		(5,355)
Add: Construction-in-progress		336		317
Total property and equipment, net	$	8,114	$	9,372

Depreciation and amortization expense was $2,696,000, $2,127,000 and $1,032,000 for the years ended December 31, 2023, 2022 and 2021, respectively.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):


	December 31,
	2023		2022
Accrued payroll and related expenses	$	17,113	$	15,216
Operating lease liability		1,703		1,844
Accrued travel expenses		944		775
Accrued interest payable		517		519
Provision for sales returns		500		540
Accrued royalty expense		405		973
Accrued administration fees and sales rebates		405		338
Accrued professional services		326		781
Accrued clinical expenses		256		249
Deferred revenue		143		253
Accrued other expenses		2,295		477
Total accrued liabilities	$	24,607	$	21,965

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Summary of Significant Accounting Policies [Abstract]

Basis of Preparation

The accompanying financial statements have been prepared in accordance with the accounting principles generally accepted in the United States of America, or U.S. GAAP.

Use of Estimates

Fair Value of Financial Instruments

Cash, Cash Equivalents and Restricted Cash

December 31, 2023 and 2022, the Company’s cash equivalents were entirely comprised of investments in money market funds.


	December 31,
	2023		2022
Cash and cash equivalents	$	20,210	$	55,358
Restricted cash		—		155
Total cash, cash equivalents and restricted cash	$	20,210	$	55,513

Investments

Concentration of Credit Risk, and Other Risks and Uncertainties

Accounts Receivable

Inventories

Property and Equipment

Impairment of Long-Lived Assets

Leases

Revenue Recognition

sold. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed as a component of revenue.

Cost of Goods Sold

Research and Development and Clinical Trials

Research and Development

Clinical Trials

Advertising Costs

Foreign Currency

Stock-Based Compensation

Stock–Based Compensation

exchange for the option award, known as the requisite service period (usually the vesting period), on a straight-line basis. The Company accounts for option forfeitures as they occur.

Income Taxes

Comprehensive Loss

Net Loss per Share

Net loss per share was determined as follows (in thousands, except share and per share data):


	Year Ended December 31,
	2023		2022		2021
Net loss	$	(55,743)	$	(55,010)	$	(49,811)
Weighted average common stock outstanding used to compute net loss per share, basic and diluted		38,804,343		35,775,672		34,635,358
Net loss per share, basic and diluted	$	(1.44)	$	(1.54)	$	(1.44)


	December 31,
	2023		2022		2021
Common stock options		3,632,684		3,839,858		3,780,939
Restricted stock units and performance stock units		3,536,197		1,329,824		530,274
Total		7,168,881		5,169,682		4,311,213

Segment and Geographical Information

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Measurements [Abstract]

Financial Assets Measured on a Recurring Basis


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	19,483	$	—	$	—	$	19,483
U.S. treasury bills		11,899		—		—		11,899
Commercial paper		—		33,150		—		33,150
Corporate bonds/notes		—		39,438		—		39,438
U.S. government securities		—		17,556		—		17,556
Agency bonds/notes		—		68,677		—		68,677
Total	$	31,382	$	158,821	$	—	$	190,203


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	55,158	$	—	$	—	$	55,158
U.S. treasury bills		19,776		—		—		19,776
Commercial paper		—		48,875		—		48,875
Corporate bonds/notes		—		1,515		—		1,515
U.S. government securities		—		83,270		—		83,270
Asset-backed securities		—		1,996		—		1,996
Agency notes		—		2,884		—		2,884
Total	$	74,934	$	138,540	$	—	$	213,474

Long-term Debt (Narrative) (Details) - USD ($)	1 Months Ended		12 Months Ended
Long-term Debt (Narrative) (Details) - USD ($)	May 31, 2022	Oct. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	May 27, 2022
Subsequent Event [Line Items]
Loss on debt extinguishment				$ (245,000)
Stifel Bank [Member]
Subsequent Event [Line Items]
Proceeds from debt		$ 49,000,000
Percent of original principal threshold			0.75%
Redemption amount			$ 375,000
Term Loan [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Facility amount			50,000,000
Loan Facility [Member]
Subsequent Event [Line Items]
Facility amount			50,000,000
Loan Facility [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Repayment of outstanding loan amount	$ 49,181,000
Debt pay off	181,000
Facility fee					$ 367,500
Loss on debt extinguishment	245,000
Debt Instrument, Fee Amount					$ 367,500
Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			225,000,000
Aggregate outstanding principal balance			$ 75,000,000
Annual interest rate			7.50%
Aggregate principal amount			50.00%
Percentage of prepayment fees			5.00%
Debt, Covenant, Revenue Covenant			75.00%
Loan Facility [Member] \| Term Loan [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Stated interest rate			4.75%
Loan Facility [Member] \| Term Loan [Member] \| Prime Rate [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Variable interest rate			0.75%
Secured Revolving Credit Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			$ 25,000,000
Maturity date			May 01, 2027
Secured Revolving Credit Facility [Member] \| Index Rate [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Variable interest rate			0.85%
Debt instrument margin rate			3.00%
Secured Revolving Credit Facility [Member] \| Secured Debt [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Facility amount			$ 50,000,000
Secured Revolving Credit Facility, Amended [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			$ 50,000,000
Percent of borrowing base of eligible receivables			85.00%
Percent of eligible inventory			50.00%
Percent of borrowing base in case eligible inventory			40.00%
Borrowing base amount in case eligible inventory			$ 10,000,000
Secured Term Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			$ 200,000,000
Percentage of prepayment fees			3.00%
Percentage of prepayment fees in second year			2.00%
Percentage of prepayment fees in third year			1.00%
Percent aggregate original principal amount			5.00%
Term loan prepaid in increments			$ 10,000,000
Secured Term Loan Facility [Member] \| Index Rate [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Variable interest rate			0.85%
Debt instrument margin rate			5.00%
Secured Revolving Credit Facility, Subfacility [Member] \| Term Loan [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Facility amount			$ 2,000,000
Loan Agreement [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Facility amount			$ 50,000,000
Stated interest rate			4.75%
Loan Agreement [Member] \| Prime Rate [Member] \| Stifel Bank [Member]
Subsequent Event [Line Items]
Variable interest rate			0.50%
Term Loan, First Tranche [Member] \| Secured Term Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			$ 75,000,000
Proceeds from debt	$ 75,000,000
Term Loan, Second Tranche [Member] \| Secured Term Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			75,000,000
Term Loan, Third Tranche [Member] \| Secured Term Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Facility amount			$ 50,000,000
Debt, Covenant, Revenue Covenant			90.00%
Maximum [Member] \| Loan Facility [Member] \| Index Rate [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Variable interest rate			2.50%
Maximum [Member] \| Secured Term Loan Facility [Member] \| Oxford Finance [Member]
Subsequent Event [Line Items]
Percent aggregate original principal amount			6.75%

Recent Accounting Pronouncements

12 Months Ended

Dec. 31, 2023

Recent Accounting Pronouncements [Abstract]

Recent Accounting Pronouncements

3. Recent Accounting Pronouncements

Recently Issued Accounting Standards

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, or ASU 2023-07, which improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segments expenses. ASU 2023-07 became effective for the Company on January 1, 2024. The Company does not believe that the adoption of this new guidance will have a material impact on its segment reporting disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, or ASU 2023-09, which enhances income tax disclosure requirements by requiring specified categories and greater disaggregation within the rate reconciliation table, disclosure of income taxes paid by jurisdiction, and providing clarification on uncertain tax positions and related financial statement impacts. ASU 2023-09 is effective for the Company on January 1, 2025 with early adoption permitted. The Company is currently evaluating the impact of adoption of this new guidance on its income tax disclosures.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(i)
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-URI https://asc.fasb.org//1943274/2147480016/944-40-65-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(ii)
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-URI https://asc.fasb.org//1943274/2147480016/944-40-65-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Section 65
-Paragraph 2
-Subparagraph (g)(2)(iii)
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-URI https://asc.fasb.org//1943274/2147480016/944-40-65-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(iv)
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-URI https://asc.fasb.org//1943274/2147480016/944-40-65-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (h)(2)
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-URI https://asc.fasb.org//1943274/2147480016/944-40-65-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 11.M.Q2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480530/250-10-S99-5

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-Name Accounting Standards Codification
-Section 65
-Paragraph 6
-Subparagraph (i)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480528/815-20-65-6

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 5
-Subparagraph (f)(1)
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-URI https://asc.fasb.org//1943274/2147479832/842-10-65-5

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
-Paragraph 5
-Subparagraph (f)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479832/842-10-65-5

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (c)(2)
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (e)(1)
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-URI https://asc.fasb.org//1943274/2147480530/250-10-S99-6

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
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Reference 32: http://www.xbrl.org/2003/role/disclosureRef
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Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
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Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147481925/310-20-65-2

+ Details

Stock-Based Compensation Plans (Summary of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Beginning balance (in shares)	3,839,858	3,780,939	4,237,828
Options granted (in shares)	19,898	587,015	323,057
Options exercised (in shares)	(199,642)	(453,199)	(643,507)
Options cancelled (in shares)	(27,430)	(74,897)	(136,439)
Ending balance (in shares)	3,632,684	3,839,858	3,780,939	4,237,828
Vested and exercisable (in shares)	3,184,646
Vested and expect to vest (in shares)	3,632,684
Weighted Average Exercise Price
Beginning balance (in USD per share)	$ 24.22	$ 20.45	$ 16.56
Options granted (in USD per share)	33.57	37.69	53.94
Options exercised (in USD per share)	7.44	7.42	7.49
Options cancelled (in USD per share)	47.09	41.16	40.30
Ending balance (in USD per share)	25.02	$ 24.22	$ 20.45	$ 16.56
Vested and exercisable (in USD per share)	22.62
Vested and expected to vest (in USD per share)	$ 25.02
Weighted Average Remaining Contractual Term (in Years)
Awards outstanding	5 years 6 months 7 days	6 years 4 months 28 days	6 years 8 months 15 days	7 years 4 months 17 days
Vested and exercisable	5 years 2 months 8 days
Vested and expected to vest	5 years 6 months 7 days
Aggregate Intrinsic Value (in thousands)
Awards outstanding	$ 7,942	$ 112,755	$ 91,900	$ 197,407
Vested and exercisable	7,942
Vested and expected to vest	$ 7,942

Summary of Significant Accounting Policies (Schedule of Potentially Dilutive Securities Not Included in Calculation of Earnings per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	7,168,881	5,169,682	4,311,213
Common Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,632,684	3,839,858	3,780,939
Restricted Stock Units and Performance Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,536,197	1,329,824	530,274

Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 85,945	$ 82,768
Research and development credits	10,753	8,898
Capitalized start-up costs/Intangibles		1
Deferred Tax Assets, Section 174	12,892	7,816
Accruals and reserves	2,775	2,820
Stock-based compensation	10,353	8,209
Operating lease liability	2,272	1,973
Interest limitation	1,114	2,013
Total deferred tax assets	126,104	114,498
Less: Valuation allowance	(122,993)	(111,444)
Deferred tax liabilities:
Operating lease asset	(1,636)	(1,278)
Property and equipment	(1,475)	(1,776)
Total deferred tax liabilities	(3,111)	(3,054)
Net deferred tax assets

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

All other schedules have been omitted because the information required to be set forth therein is not applicable or is shown in the financial statements or notes thereto. The table below presents Schedule II, Valuation and Qualifying Accounts, detailing the activity of the allowance for credit losses for the years ended December 31, 2023, 2022 and 2021 (in thousands):


Description	Balance at Beginning of Year		Charged to Expenses		Write Offs		Balance at ‎End of Year
Allowance for credit losses:
Year ended December 31, 2023	$	3	$	45	$	22	$	26
Year ended December 31, 2022	$	6	$	(3)	$	—	$	3
Year ended December 31, 2021	$	13	$	6	$	13	$	6

Summary of Significant Accounting Policies (Schedule of Net Loss Per Share Determination) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary of Significant Accounting Policies [Abstract]
Net loss	$ (55,743)	$ (55,010)	$ (49,811)
Weighted average common stock outstanding used to compute net loss per share, basic (in shares)	38,804,343	35,775,672	34,635,358
Weighted average common stock outstanding used to compute net loss per share, diluted (in shares)	38,804,343	35,775,672	34,635,358
Net loss per share, basic	$ (1.44)	$ (1.54)	$ (1.44)
Net loss per share, diluted	$ (1.44)	$ (1.54)	$ (1.44)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
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