0001437749-24-007865 | 10-K | XBRL Viewer

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Note 3 - Business Combination - Allocation of the Purchase Price to the Fair Value of the Respective Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands	Nov. 30, 2021	Dec. 31, 2023	Dec. 31, 2022
Goodwill, Ending Balance		$ 4,508	$ 4,508
Acquisition of Kindred BioSciences [Member]
Business combination, property and equipment acquired	$ 321
Goodwill, Ending Balance	4,508
Business Combination, Consideration Transferred, Total	$ 4,829

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

Note 15 - Subsequent Events (Details Textual) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	2 Months Ended
	Jan. 31, 2024	Mar. 14, 2024	Feb. 27, 2024	Jan. 12, 2024	Nov. 30, 2022
Grant [Member]
Grants Receivable					$ 3.5
Subsequent Event [Member] \| The 2024 Inducement Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)			3,000,000
Subsequent Event [Member] \| Grant [Member] \| Department of Health and Human Services, ASPR [Member]
Grants Receivable				$ 9.3
Subsequent Event [Member] \| RA Capital Healthcare Fund 2024 [Member]
Stock Issued During Period, Shares, New Issues (in shares)	15,384,615
Shares Issued, Price Per Share (in dollars per share)	$ 0.65
Gross Proceeds from Issuance of Common Stock	$ 10.0
Net Proceeds From Issuance of Common Stock	$ 9.9
Subsequent Event [Member] \| ATM Program [Member]
Stock Issued During Period, Shares, New Issues (in shares)		5,071,472
Net Proceeds From Issuance of Common Stock		$ 5.7

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	September 2021 ATM [Member] Common Stock [Member]	September 2021 ATM [Member] Treasury Stock, Common [Member]	September 2021 ATM [Member] Additional Paid-in Capital [Member]	September 2021 ATM [Member] Retained Earnings [Member]	September 2021 ATM [Member] AOCI Attributable to Parent [Member]	September 2021 ATM [Member]	The 2023 Shelf Registration [Member] Common Stock [Member]	The 2023 Shelf Registration [Member] Treasury Stock, Common [Member]	The 2023 Shelf Registration [Member] Additional Paid-in Capital [Member]	The 2023 Shelf Registration [Member] Retained Earnings [Member]	The 2023 Shelf Registration [Member] AOCI Attributable to Parent [Member]	The 2023 Shelf Registration [Member]	Common Stock [Member]	Treasury Stock, Common [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances (in shares) at Dec. 31, 2021													125,594,393	0
Balances at Dec. 31, 2021													$ 13	$ 0	$ 406,943	$ (219,351)	$ (74)	$ 187,531
Issuance of common stock (in shares)	8,419,700	0
Issuance of common stock	$ 0	$ 0	$ 17,237	$ 0	$ 0	$ 17,237
Issuance of common stock upon exercise of common stock warrants (in shares)													5,000	0
Issuance of common stock upon exercise of common stock warrants													$ 0	$ 0	2	0	0	$ 2
Issuance of common stock upon exercise of options (in shares)													180,336	0				180,336
Issuance of common stock upon exercise of options													$ 0	$ 0	223	0	0	$ 223
Stock-based compensation													0	0	13,587	0	0	13,587
Unrealized loss on available-for-sale investments													0	0	0	0	(225)	(225)
Net loss													$ 0	$ 0	0	(107,758)	0	(107,758)
Balances (in shares) at Dec. 31, 2022													134,199,429	0
Balances at Dec. 31, 2022													$ 13	$ 0	437,992	(327,109)	(299)	$ 110,597
Issuance of common stock (in shares)	1,362,220	0				9,781,920	16,000,000	0
Issuance of common stock	$ 1	$ 0	$ 1,429	$ 0	$ 0	$ 1,430	$ 1	$ 0	$ 13,599	$ 0	$ 0	$ 13,600
Issuance of common stock upon exercise of options (in shares)													54,720	0				54,720
Issuance of common stock upon exercise of options													$ 0	$ 0	17	0	0	$ 17
Stock-based compensation													0	0	14,132	0	0	14,132
Unrealized loss on available-for-sale investments													0	0	0	0	298	298
Net loss													$ 0	$ 0	0	(82,465)	0	(82,465)
Issuance of common stock under ESPP (in shares)													734,675	0
Issuance of common stock under ESPP													$ 0	$ 0	562	0	0	562
Release of common stock for vested restricted stock units (in shares)													1,608,809	0
Release of common stock for vested restricted stock units													$ 0	$ 0	0	0	0	0
Repurchase of common stock to satisfy tax withholding (in shares)													0	(507,020)
Repurchase of common stock to satisfy tax withholding													$ 0	$ (366)	0	0	0	(366)
Balances (in shares) at Dec. 31, 2023													153,959,853	(507,020)
Balances at Dec. 31, 2023													$ 15	$ (366)	$ 467,731	$ (409,574)	$ (1)	$ 57,805

Note 7 - Liabilities Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

NOTE 7. Liabilities Related to Sale of Future Royalties

In April 2016, Aviragen entered into a Royalty Interest Acquisition Agreement (the “RIAA”) with HealthCare Royalty Partners III, L.P. ("HCRP"). Under the RIAA, HCRP made a $20.0 million cash payment to Aviragen in consideration for acquiring certain royalty rights (“Royalty Rights”) related to the approved product Inavir in the Japanese market. The Royalty Rights were obtained pursuant to the collaboration and license agreements (the “License Agreement”) and a commercialization agreement that the Company entered into with Daiichi Sankyo. Per the terms of the RIAA, during the first royalty interest period of April 1, 2016 through March 31, 2025, HCRP is entitled to the first $3.0 million and any cumulative remaining shortfall amount plus 15% of the next $1.0 million in royalties earned in each year commencing on April 1, with any excess revenue being retained by the Company. Further, during the second royalty interest period beginning April 1, 2025 and ending on December 24, 2029, HCRP is entitled to the first $2.7 million and any cumulative remaining shortfall amount, plus 15% of the next $1.0 million in royalties, with any excess revenue being retained by the Company. A shortfall occurs when, during an annual period ending on March 31^st, for the first royalty interest period of April 1, 2016 through March 31, 2025, the Company’s royalty payments fall below $3.0 million; and $2.7 million for the second royalty interest period of April 1, 2025 and ending on December 24, 2029, excluding the period of April 1, 2028 through December 24, 2029.

For avoidance of doubt, the RIAA states, in the event there is a remaining cumulative remaining shortfall amount as of December 24, 2029, the Company shall not be obligated to pay HCRP any royalty payment beyond what the Company is paid from Daiichi Sankyo. The cumulative remaining shortfall amount is the aggregate amount of the remaining shortfall for each annual period, which was $7.0 million and $4.3 million as of December 31, 2023 and 2022, respectively.

Under the relevant accounting guidance, due to a limit on the amount of royalties that HCRP can earn under the RIAA, this transaction was accounted for as a liability that is being amortized using the effective interest method over the life of the arrangement. The Company has no obligation to pay any amounts to HCRP other than to pass through to HCRP its share of royalties as they are received from Daiichi Sankyo. To record the amortization of the liability, the Company is required to estimate the total amount of future royalty payments to be received under the License Agreement and the payments that will be passed through to HCRP over the life of this agreement. Consequently, the Company imputes interest on the unamortized portion of the liability and records non-cash interest expense using an estimated effective interest rate. The royalties earned in each period that will be passed through to HCRP are recorded as non-cash royalty revenue related to sale of future royalties, with any excess not subject to pass-through being recorded as royalty revenue. When the pass-through royalties are paid to HCRP in the following quarter, the imputed liability related to sale of future royalties is commensurately reduced. The Company periodically assesses the expected royalty payments, and to the extent such payments are greater or less than the initial estimate, the Company adjusts the amortization of the liability and interest rate. As a result of this accounting, even though the Company does not retain HCRP’s share of the royalties, it will continue to record non-cash revenue related to those royalties until the amount of the associated liability, including the related interest, is fully amortized.

The following table shows the activity within the liability account during the year ended December 31, 2023 (in thousands):

Total liability related to sale of future royalties, start of year	$	5,716
Non-cash royalty revenue paid to HCRP		(737	)
Non-cash interest expense recognized		1,447
Total liability related to sale of future royalties, end of year		6,426
Current portion		(3,803	)
Long-term portion	$	2,623

Note 11 - Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

							*Weighted*					*Weighted*
	*Shares*			*Number of*			*Option Average*		*Number of*			*RSU Average*
	*Available*			*Options*			*Exercise*		*RSUs*			*Grant Date*
	*For Grant*			*Outstanding*			*Price*		*Outstanding*			*Fair Value*

Balance at January 1, 2022		5,582,742			10,216,106		$	4.96		—		$	—

Authorized under 2019 Plan Amendment		12,000,000			—		$	—		—		$	—
Granted		(7,291,935	)		6,376,657		$	4.10		915,278		$	3.58
Exercised		—			(180,336	)	$	1.24		—		$	—
Forfeited		1,625,133			(1,518,230	)	$	6.19		(106,968	)	$	3.62
Canceled		158,752			(168,936	)	$	7.17		—		$	—

Balance at December 31, 2022		12,074,692			14,725,261		$	4.48		808,310		$	3.57

Granted		(10,631,320	)		7,399,849		$	0.78		3,231,471		$	0.78
Exercised		—			(54,720	)	$	0.31		(1,608,809	)	$	1.09
Forfeited		2,444,486			(2,139,887	)	$	5.00		(304,599	)	$	2.42
Canceled		1,797,948			(1,991,777	)	$	4.51		—		$	—

Balance at December 31, 2023		5,685,806			17,938,726		$	2.90		2,126,373		$	1.37

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	*Year Ended December 31,*
	*2023*			*2022*

Risk-free interest rate		3.45% - 4.15	%		1.62% - 4.02	%
Expected term (in years)		5.50 - 6.00			5.42 - 6.08
Expected volatility		128% - 134	%		125% - 131	%
Dividend yield		—	%		—	%

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	*Year Ended December 31,*
	*2023*		*2022*

Research and development	$	8,362	$	9,183
General and administrative		5,770		4,404
Total stock-based compensation	$	14,132	$	13,587

Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Six-Month Offering Period Ending May 31, 2024			Six-Month Offering Period Ended November 30, 2023			Six-Month Offering Period Ended May 31, 2023

Risk-free interest rate		5.26	%		5.37	%		4.60	%
Expected term (in years)		0.50			0.50			0.50
Expected volatility		75.20	%		98.55	%		84.66	%
Dividend yield		—	%		—	%		—	%

Note 11 - Equity Incentive Plans - Summary of Stock Option Transactions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Shares available for grant, balance (in shares)	12,074,692	5,582,742
Number of options outstanding, beginning balance (in shares)	14,725,261	10,216,106
Weighted average exercise price, balance (in dollars per share)	$ 4.48	$ 4.96
Shares availabe for grant, 2019 Plan Amendment (in shares)		12,000,000
Shares available for grant, granted (in shares)	(10,631,320)	(7,291,935)
Number of options outstanding, granted (in shares)	7,399,849	6,376,657
Weighted average exercise price, granted (in dollars per share)	$ 0.78	$ 4.1
Number of options outstanding, exercised (in shares)	(54,720)	(180,336)
Weighted average exercise price, exercised (in dollars per share)	$ 0.31	$ 1.24
Shares available for grant, forfeited (in shares)	2,444,486	1,625,133
Number of options outstanding, forfeited (in shares)	(2,139,887)	(1,518,230)
Weighted average exercise price, forfeited (in dollars per share)	$ 5	$ 6.19
Shares available for grant, canceled (in shares)	1,797,948	158,752
Number of options outstanding, canceled (in shares)	(1,991,777)	(168,936)
Weighted average exercise price, canceled (in dollars per share)	$ 4.51	$ 7.17
Shares available for grant, balance (in shares)	5,685,806	12,074,692
Number of options outstanding, balance (in shares)	17,938,726	14,725,261
Weighted average exercise price, balance (in dollars per share)	$ 2.9	$ 4.48
Restricted Stock Units (RSUs) [Member]
Number of options outstanding, beginning balance (in shares)	808,310
Weighted average exercise price, balance (in dollars per share)	$ 3.57	$ 0
Number of options outstanding, granted (in shares)		915,278
Weighted average exercise price, granted (in dollars per share)	0.78	$ 3.58
Weighted average exercise price, exercised (in dollars per share)	1.09	$ 0
Number of options outstanding, forfeited (in shares)		(106,968)
Weighted average exercise price, forfeited (in dollars per share)	2.42	$ 3.62
Weighted average exercise price, canceled (in dollars per share)	$ 0	$ 0
Granted (in shares)	3,231,471
Exercised (in shares)	(1,608,809)
Forfeited (in shares)	(304,599)
Number of options outstanding, balance (in shares)		808,310
Weighted average exercise price, balance (in dollars per share)	$ 1.37	$ 3.57
Balance at December 31, 2023 (in shares)	2,126,373

Note 5 - Balance Sheet Components - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Intangible assets, gross	$ 5,080	$ 5,080
Less: accumulated amortization	(791)	(60)
Intangible assets, net	4,289	5,020
Developed Technology Rights [Member]
Intangible assets, gross	5,000	5,000
Intellectual Property [Member]
Intangible assets, gross	$ 80	$ 80

Note 8 - Leases (Details Textual) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jul. 31, 2019
Operating Lease, Right-of-Use Asset	$ 24,840	$ 25,715
Operating Lease, Weighted Average Discount Rate, Percent	9.80%
Operating Lease, Weighted Average Remaining Lease Term (Year)	5 years 1 month 13 days
Right of Use for Office and Manufacturing Facilities with Initial Terms Exceeding One Year [Member]
Lessee, Operating Lease, Number of Right-of-Use Leases	6
South San Francisco Real Estate [Member]
Lessee, Operating Lease, Renewal Term (Year)	8 years			5 years
September 2021 Lease for Facility in South San Francisco [Member]
Lessee, Operating Lease, Renewal Term (Year)	8 years
Lease for Facility in South San Francisco Commenced in First Quarter of 2023 [Member]
Operating Lease, Right-of-Use Asset			$ 3,100
Facility in South San Francisco [Member]
Lessee, Operating Lease, Renewal Term (Year)	5 years
Facility in Burlingame, California [Member]
Lessee, Operating Lease, Renewal Term (Year)	30 months
Operating Lease, Right-of-Use Asset	$ 3,100	$ 15,000
Lessee, Short-term Lease, Number of Leases	2
Lessee, Operating Lease, Number of Renewal Option	2

Note 10 - Stockholders' Equity - Shares of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2023	Dec. 31, 2022
Common stock reserved for issuance (in shares)	27,043,664	29,635,697
Common Warrants [Member]
Common stock reserved for issuance (in shares)	227,434	227,434
Share-Based Payment Arrangement, Option [Member]
Common stock reserved for issuance (in shares)	17,938,726	14,725,261
Restricted Stock Units (RSUs) [Member]
Common stock reserved for issuance (in shares)	2,126,373	808,310
Future Grants of Equity Awards [Member]
Common stock reserved for issuance (in shares)	5,685,806	12,074,692
ESPP [Member]
Common stock reserved for issuance (in shares)	1,065,325	1,800,000

Note 2 - Summary of Significant Accounting Policies - Estimated Useful Lives (Details)	Dec. 31, 2023
Laboratory Equipment [Member]
Laboratory equipment (in years) (Year)	5 years
Office Equipment [Member]
Laboratory equipment (in years) (Year)	3 years

Note 11 - Equity Incentive Plans - Total Stock-based Compensation Recognized for Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement, Expense	$ 14,132	$ 13,587
Research and Development Expense [Member]
Share-Based Payment Arrangement, Expense	8,362	9,183
General and Administrative Expense [Member]
Share-Based Payment Arrangement, Expense	$ 5,770	$ 4,404

Note 11 - Equity Incentive Plans (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023	Jun. 30, 2023	Aug. 04, 2022	Dec. 31, 2021	Jun. 16, 2021	Jun. 08, 2020	Apr. 23, 2019
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number (in shares)	17,938,726	14,725,261				10,216,106
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 2.9	$ 4.48				$ 4.96
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)	8 years 2 months 4 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value	$ 26,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number (in shares)	9,667,285
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.17
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term (Year)	7 years 8 months 12 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 26,000
Proceeds from Stock Options Exercised	$ 17,000	$ 223,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)	54,720	180,336
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 31,000	$ 481,000
Share Price (in dollars per share)	$ 0.57
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	27,043,664	29,635,697
Proceeds from Stock Plans	$ 562,000	$ 0
Share-Based Payment Arrangement, Expense	$ 14,132,000	$ 13,587,000
Share-Based Payment Arrangement, Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 0.78	$ 4.1
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	17,938,726	14,725,261
Options and RSU [Member]
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 20,500,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	2 years 1 month 17 days
The 2019 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)					28,900,000		16,900,000	8,000,000	1,600,000
The 2022 ESPP [Member]
Share Price (in dollars per share)	$ 0.27		$ 0.54	$ 0.46
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	1,065,325				1,800,000
Proceeds from Stock Plans	$ 600,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)	734,675
Share-Based Payment Arrangement, Expense	$ 400,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 100,000

Note 9 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions		12 Months Ended
	Nov. 02, 2022	Dec. 31, 2023
Himmelberg V. Vaxart, Inc. et al. [Member]
Litigation Settlement, Amount Awarded to Other Party		$ 12.0
Payments for Legal Settlements	$ 2.0
Lease for Facility in South San Francisco, California [Member]
Purchase Obligation		$ 3.8

Note 8 - Leases

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Lessee, Operating Leases [Text Block]

NOTE 8. Leases

The Company has obtained the right of use for office and manufacturing facilities under six operating lease agreements with initial terms exceeding one year.

The Company obtained the right of use of real estate located in South San Francisco, California, in November 2020 under a lease that was scheduled to terminate on September 30, 2025, which has been extended until March 31, 2029, with no additional extension option. The Company obtained the right of use of another property also located in South San Francisco, California, in June 2015 that was scheduled to terminate on April 30, 2020, with a five-year extension option that the Company exercised in July 2019, extending the lease until April 30, 2025, which has been further extended until March 31, 2029, with an option to extend for an additional eight years. In September 2021, the Company executed a lease for a facility in South San Francisco, California, with an initial term expiring on March 31, 2029, with an option to extend for an additional eight years. This lease includes a component for tenant improvements that were substantially completed in the three months ended September 30, 2022, when the lease for this component was deemed to have commenced for accounting purposes. It also includes a component for which tenant improvements of $3.1 million were completed and were recorded within right-of-use assets in the consolidated balance sheets when they were substantially completed in the three months ended March 31, 2023. Further, the Company has the right of use of a facility located in South San Francisco, California, under a lease that terminates on March 30, 2029, with a five-year renewal option. The Company also has the right of use of two facilities in Burlingame, California, under leases that terminate on May 31, 2025, both of which have two 30-month extension options.

As of December 31, 2023, the weighted average discount rate for operating leases with initial terms of more than one year was 9.80% and the weighted average remaining term of these leases was 5.12 years. Discount rates were determined using the Company’s marginal rate of borrowing at the time each lease was executed or extended.

The following table summarizes the Company’s undiscounted cash payment obligations for its operating lease liabilities with initial terms of more than twelve months as of December 31, 2023 (in thousands):

Year Ending December 31,	Amount
2024	$	4,381
2025		4,511
2026		5,031
2027		5,207
2028		5,389
Thereafter		1,348
Undiscounted total		25,867
Less: imputed interest		(5,779	)
Present value of future minimum payments		20,088
Current portion of operating lease liability		(2,703	)
Operating lease liability, net of current portion	$	17,385

Certain operating lease agreements for facilities include non-lease costs, such as common area maintenance, which are recorded as variable lease costs. Operating lease expenses for the years ended December 31, 2023 and 2022, including variable lease costs for one lease that has not yet commenced for accounting purposes, are summarized as follows (in thousands):

	*Year Ended December 31,*
	*2023*		*2022*

Operating lease cost	$	6,170	$	4,159
Short-term lease cost		52		436
Variable lease cost		1,864		1,312
Total operating lease cost	$	8,086	$	5,907

Note 5 - Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property and equipment, gross	$ 18,562	$ 18,857
Less: accumulated depreciation	(6,831)	(3,272)
Property and equipment, net	11,731	15,585
Laboratory Equipment [Member]
Property and equipment, gross	13,448	12,035
Office Equipment [Member]
Property and equipment, gross	1,105	1,078
Leasehold Improvements [Member]
Property and equipment, gross	3,985	1,760
Construction in Progress [Member]
Property and equipment, gross	$ 24	$ 3,984

Note 15 - Subsequent Events

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Subsequent Events [Text Block]

NOTE 15. Subsequent Events

Securities Purchase Agreement

In January 2024, the Company entered into a securities purchase agreement (the “2024 Securities Purchase Agreement”) with RA Capital Healthcare Fund, L.P. in which 15,384,615 shares of its common stock were sold at an offering price of $0.65 per share pursuant to the Company’s 2023 Shelf Registration. The gross proceeds from the 2024 Securities Purchase Agreement were $10.0 million and, after deducting underwriting discounts, commission and estimated offering expenses, the net proceeds were $9.9 million.

Update on September 2021 ATM

Since December 31, 2023, the Company has issued 5,071,472 shares of common stock under the September 2021 ATM (see Note 1) for gross proceeds net of commissions totaling $5.7 million through March 12, 2024.

ASPR Contract

On January 12, 2024, the Company was awarded a contract (“ASPR Contract”) by the U.S. Government through the Department of Health and Human Services, Office of the Administration for Strategic Preparedness and Response (“ASPR”) with a base and all options value of $9.3 million. Under the ASPR Contract, the Company will receive an award to support clinical trial planning activities for a Phase 2b clinical trial that would compare the Company’s XBB vaccine candidate to an mRNA comparator to evaluate efficacy for symptomatic and asymptomatic disease, systemic and mucosal immune induction, and adverse events.

Changes in Management and Board of Directors

On January 15, 2024, Andrei Floroiu resigned (i) as President and Chief Executive Officer of the Company, and (ii) as a member of the Company’s Board of Directors.

On January 16, 2024, the Company’s Board of Directors announced that, effective as of January 16, 2024, the current Chair of the Board of Directors, Michael J. Finney, Ph.D., has been appointed as Interim Chief Executive Officer of the Company. Dr. Finney also serves as the Company’s principal executive officer and will continue to serve on the Company's Board of Directors while serving as Interim Chief Executive Officer.

Subsequently, on March 4, 2024, the Board of Directors appointed Steven Lo as the Company’s Chief Executive Officer, President, and principal executive officer, as well as a member of the Board of Directors, in each case effective as of March 18, 2024. In connection with Mr. Lo’s appointment, it is anticipated that Michael J. Finney, Ph.D. will step down as the Company’s Interim Chief Executive Officer and principal executive officer on March 17, 2024; however, Dr. Finney will continue to serve as Chair of the Board of Directors. In addition, David Wheadon, M.D., will resign as Lead Director of the Board of Directors effective as of March 31, 2024. Dr. Wheadon will continue to serve as a director on the Board of Directors.

2024 Inducement Award Plan

On February 27, 2024, the Board of Directors adopted the Vaxart, Inc. 2024 Inducement Award Plan (the “2024 Inducement Plan”). The 2024 Inducement Plan was adopted without stockholder approval pursuant to Nasdaq Listing Rule 5635(c)(4) and will be administered by the Compensation Committee of the Board of Directors or the independent members of the Board of Directors. The Board of Directors reserved 3,000,000 shares of the Company’s common stock for issuance under the 2024 Inducement Plan, subject to adjustment as provided in the plan document.

The terms of the 2024 Inducement Plan are substantially similar to the terms of the Company’s 2019 Equity Incentive Plan, with the exception that incentive stock options may not be issued under the 2024 Inducement Plan and equity awards under the 2024 Inducement Plan (including nonqualified stock options, restricted stock, restricted stock units, and other stock-based awards) may be issued only to an employee who is commencing employment with the Company or any subsidiary or who is being rehired following a bona fide interruption of employment by the Company or any subsidiary, in either case if he or she is granted such award in connection with his or her commencement of employment and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary.

Note 1 - Organization and Nature of Business

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

NOTE 1. Organization and Nature of Business

General

Vaxart Biosciences, Inc. was originally incorporated in California in March 2004, under the name West Coast Biologicals, Inc. The Company changed its name to Vaxart, Inc. (“Private Vaxart”) in July 2007, and reincorporated in the state of Delaware. In February 2018, Private Vaxart completed a business combination with Aviragen Therapeutics, Inc. (“Aviragen”), pursuant to which Aviragen merged with Private Vaxart, with Private Vaxart surviving as a wholly-owned subsidiary of Aviragen (the “Merger”). Pursuant to the terms of the Merger, Aviragen changed its name to Vaxart, Inc. (together with its subsidiaries, the “Company” or “Vaxart”) and Private Vaxart changed its name to Vaxart Biosciences, Inc.

On September 15, 2021, the Company entered into a Controlled Equity Offering Sales Agreement (the “September 2021 ATM”), pursuant to which it may offer and sell, from time to time through sales agents, shares of its common stock having an aggregate offering price of up to $100 million. The Company filed a prospectus supplement with the SEC on September 16, 2021, and will pay sales commissions of up to 3.0% of gross proceeds from the sale of shares. In the year ended December 31, 2023, 1,362,220 shares were issued and sold under the September 2021 ATM for gross proceeds of $1.5 million, which, after deducting sales commissions and expenses incurred to date, resulted in net proceeds of $1.4 million. As of December 31, 2023, a total of 9,781,920 shares had been issued and sold under the September 2021 ATM since its inception for gross proceeds of $19.6 million which, after deducting sales commissions and expenses, resulted in net proceeds of $18.6 million.

In June 2023, Vaxart completed an underwritten public offering (the “June 2023 Offering”) in which 16,000,000 shares of its common stock were sold at an offering price of $0.8680 per share pursuant to the Company’s effective shelf registration statement on Form S-3 (the “2023 Shelf Registration”). The net proceeds from the June 2023 Offering were $13.6 million after deducting underwriting discounts and commission and estimated offering expenses payable by Vaxart.

The Company’s principal operations are based in South San Francisco, California, and it operates in one reportable segment, which is the discovery and development of oral recombinant protein vaccines, based on its proprietary oral vaccine platform.

Note 8 - Leases - Lease Liabilities Payment Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
2024	$ 4,381
2025	4,511
2026	5,031
2027	5,207
2028	5,389
Thereafter	1,348
Undiscounted total	25,867
Less: imputed interest	(5,779)
Present value of future minimum payments	20,088
Current portion of operating lease liability	(2,703)	$ (2,228)
Operating lease liability, net of current portion	$ 17,385	$ 19,477

Note 14 - Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	*Year Ended December 31,*
	*2023*			*2022*

Net loss	$	(82,465	)	$	(107,758	)

Shares used to compute net loss per share, basic and diluted		144,819,781			127,683,813

Net loss per share attributable to common stockholders, basic and diluted	$	(0.57	)	$	(0.84	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	*Year Ended December 31,*
	*2023*		*2022*

Options to purchase common stock	17,270,980			13,567,390
Restricted stock unit to purchase common stock		2,931,662		460,975
Warrants to purchase common stock	227,434			228,725
Employee Stock Purchase Plan		402,699		392,095

Total potentially dilutive securities excluded from denominator of the diluted earnings per share computation		20,832,775		14,649,185

Note 2 - Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Significant Accounting Policies [Text Block]

NOTE 2. Summary of Significant Accounting Policies

Basis of Presentation, Liquidity and Going Concern – The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the accounting and disclosure rules and regulations of the Securities and Exchange Commission (the “SEC”), assuming the Company will continue as a going concern.

The Company is a clinical-stage biotechnology company with no product sales. Its primary source of capital is from the sale and issuance of common stock and common stock warrants. As of December 31, 2023, the Company had cash, cash equivalents and investments of $39.7 million. The Company’s cash, cash equivalents and investments are not sufficient to fund the Company’s planned operations for a period of 12 months from the date the consolidated financial statements are issued. In the first quarter of 2023, the Company implemented a restructuring plan to reduce operating costs and better align its workforce with the needs of its business. The plan resulted in a reduction of approximately 27% of the Company’s workforce and severance costs of $0.5 million for the year ended December 31, 2023.

The Company will be dependent upon raising additional capital through placement of its common stock, notes or other securities, borrowings, or entering into a partnership with a strategic party in order to implement its business plan.

Based on management's current plan, the Company expects to have enough cash runway into the fourth quarter of 2024. If the Company is unable to raise additional capital in sufficient amounts or on acceptable terms, management’s plans include further reducing or delaying operating expenses. These conditions raise substantial doubt about the Company’s ability to continue as a going concern for a period of one year from the date of the issuance of these consolidated financial statements. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business.

These consolidated financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.

Basis of Consolidation – The consolidated financial statements include the financial statements of Vaxart, Inc. and its subsidiaries. All significant transactions and balances between Vaxart, Inc. and its subsidiaries have been eliminated in consolidation.

Use of Estimates – The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities (including accrued clinical and manufacturing accruals described within this Note 2), revenues and expenses and disclosure of contingent assets and liabilities in the consolidated financial statements and accompanying notes. Actual results and outcomes could differ from these estimates and assumptions.

Foreign Currencies – Foreign exchange gains and losses for assets and liabilities of the Company’s non-U.S. subsidiaries for which the functional currency is the U.S. dollar are recorded in foreign exchange gain or loss, net within other income and (expenses) in the Company’s consolidated statements of operations and comprehensive loss. The Company has no subsidiaries for which the local currency is the functional currency.

Cash, Cash Equivalents and Restricted Cash – The Company considers all highly liquid debt investments with an original maturity of three months or less when purchased to be cash equivalents. Cash equivalents, which may consist of amounts invested in money market funds, corporate bonds and commercial paper, are stated at fair value. The Company’s restricted cash includes refundable advance payments received as of December 31, 2023 and 2022, of zero and $2.0 million, respectively.

Investments – Excess cash balances may be invested in marketable debt securities. All marketable debt securities that are readily convertible to known amounts of cash with stated maturities greater than three months when purchased are classified as investments.

The Company determines the appropriate classification of its investments in marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. Marketable debt securities are classified and accounted for as available-for-sale. After consideration of the Company’s objectives to preserve capital, as well as its liquidity requirements, it may sell any debt securities prior to their stated maturities.

Marketable debt securities are carried at fair value and unrealized gains and losses, net of taxes, are reported as a component of stockholders’ equity. Any realized gains or losses on the sale of marketable debt securities are determined on a specific identification method, and such gains and losses are recorded as a component of other income (expense). Available-for-sale investments are classified as either current or non-current assets based on each instrument’s underlying effective maturity date and whether the Company has the intent and ability to hold the investment for a period of greater than 12 months. Marketable debt securities with remaining maturities of 12 months or less are classified as current and are reported as short-term investments in the consolidated balance sheets. Marketable debt securities with remaining maturities of more than 12 months for which the Company has the intent and ability to hold the investment for more than 12 months are classified as non-current and are included in long-term investments in the consolidated balance sheets.

At each reporting date, the Company evaluates marketable debt securities with unrealized losses to determine whether such losses, if any, are due to credit-related factors. The Company records an allowance for credit losses when unrealized losses are due to credit-related factors. The Company evaluates, among other factors, whether the Company has the intention to sell any of its investments and whether it is more likely than not that the Company will be required to sell any of them before recovery of the amortized cost basis. Neither of these criteria were met in any period presented. In addition, the Company invests in marketable debt securities with high credit ratings that are classified in Level 1 and 2 of the fair value hierarchy and it has received and expects to continue to receive interest and principal payments as the investments become due. Based on this evaluation, as of December 31, 2023, and 2022, the Company determined that unrealized losses of its marketable debt securities were primarily attributable to changes in interest rates and other non-credit related factors. As such, no allowance for credit losses were recorded for the years ended December 31, 2023 and 2022.

Concentration of Credit Risk – Financial instruments that potentially subject the Company to significant concentrations of credit risk consist principally of cash, cash equivalents, restricted cash, available-for-sale investments and accounts receivable. The Company places its cash, cash equivalents, restricted cash and available-for-sale investments at financial institutions that management believes are of high credit quality. The Company is exposed to credit risk in the event of default by the financial institutions holding the cash, cash equivalents and restricted cash to the extent such amounts are in excess of the federally insured limits. Losses incurred or a lack of access to such funds could have a significant adverse impact on the Company’s financial condition, results of operations, and cash flows.

The primary focus of the Company’s investment strategy is to preserve capital and meet liquidity requirements. The Company’s investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating.

Accounts Receivable – Accounts receivable arise from the Company’s royalty revenue receivable for sales, net of estimated returns, of Inavir and are reported at amounts expected to be collected in future periods. An allowance for expected credit losses over the life of the receivables is reserved for based on a combination of historical experience, aging analysis, current economic trends and information on specific accounts, with related amounts recorded as a reserve against revenue recognized. The reserve is re-evaluated on a regular basis and adjusted as needed. Once a receivable is deemed to be uncollectible, such balance is charged against the reserve. The Company has provided no allowance for credit losses as of December 31, 2023 and 2022.

Accounts receivable are subject to concentration risk whenever a customer has a balance that meets or exceeds 10% of the Company's total accounts receivable balance. As of December 31, 2023 and 2022, Daiichi Sankyo Company, Limited ("Daiichi Sankyo"), represented 100% of the Company's total accounts receivable balance.

Property and Equipment – Property and equipment is carried at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets. Depreciation begins at the time the asset is placed in service. Maintenance and repairs are charged to operations as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation are removed from the consolidated balance sheets and the resulting gain or loss is reflected in other income and (expenses) in the period realized.

The useful lives of the property and equipment are as follows:

Laboratory equipment (in years)			5
Office and computer equipment (in years)			3
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Goodwill and Other Intangible Assets – Goodwill, which represents the excess of the purchase price over the fair value of assets acquired, is not amortized. Intangible assets comprise developed technology and intellectual property. Intangible assets are carried at cost less accumulated amortization. Amortization is computed using the straight-line method over useful life of 11.75 years for developed technology and 20 years for intellectual property.

Impairment of Long-Lived Assets – The Company reviews its long-lived assets, including property and equipment, goodwill and intangible assets with finite lives, for impairment in the fourth quarter of each year, and more frequently whenever events or changes in circumstances indicate the carrying amount of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows the asset is expected to generate over its remaining life. When indications of impairment are present and the estimated undiscounted future cash flows from the use of these assets is less than the assets’ carrying value, the related assets will be written down to fair value. The Company assessed its developed technology as not impaired in the year ended December 31, 2023 and impaired in the year ended December 31, 2022 (see Note 5).

Accrued Clinical and Manufacturing Expenses – The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical studies and clinical trials, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided and includes the costs incurred but not yet invoiced within other accrued liabilities in the consolidated balance sheets and within research and development expense in the consolidated statements of operations and comprehensive loss. These costs can be a significant component of the Company’s research and development expenses.

The Company estimates the amount of services provided through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fee to be paid for such services. The Company makes significant judgments and estimates in determining the accrued balance in each reporting period. As actual costs become known, it adjusts its accrued estimates. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed, the number of subjects enrolled, and the rate of enrollment may vary from its estimates and could result in the Company reporting amounts that are too high or too low in any particular period. The Company’s accrued expenses are dependent, in part, upon the receipt of timely and accurate reporting from contract research organizations and other third-party service providers. To date, the Company has not experienced any material differences between accrued costs and actual costs incurred.

Leases – The Company records operating leases as right-of-use assets and operating lease liabilities in its consolidated balance sheets for all operating leases with terms exceeding one year. Right-of-use assets represent the right to use an underlying asset for the lease term, including extension options considered reasonably certain to be exercised, and operating lease liabilities to make lease payments. Right-of-use assets and operating lease liabilities are recognized based on the present value of lease payments over the lease term. To the extent that lease agreements do not provide an implicit rate, the Company uses its incremental borrowing rate based on information available at the lease commencement date to determine the present value of lease payments. The expense for operating lease payments is recognized on a straight-line basis over the lease term and is included in operating expenses in the Company’s consolidated statement of operations and comprehensive loss. The Company has elected to not separate lease and non-lease components of facilities leases, whereas non-lease components of equipment leases are accounted for separately from lease components.

Revenue Recognition – The Company recognizes revenue when it transfers control of promised goods or services to its customers, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition, the Company performs the following five steps:

(i)

identification of the promised goods or services in the contract;

(ii)

determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract;

(iii)

measurement of the transaction price, including the constraint on variable consideration;

(iv)

allocation of the transaction price to the performance obligations based on estimated selling prices; and

(v)

recognition of revenue when (or as) the Company satisfies each performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account.

Revenue from royalties earned as a percentage of end-user sales, including milestone payments based on achieving a specified level of sales, where a license is deemed to be the predominant item to which the royalties relate, is recognized as revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied), as required under the sales- and usage-based royalty exception.

Revenue from contracts with customers is recognized ratably, based on costs incurred, as the Company provides promised services to its customers in amounts that reflect the consideration that the Company expects to receive for those services.

In 2022, the Company accepted a $3.5 million grant to perform research and development work for the Bill & Melinda Gates Foundation (the “BMGF Grant”). The BMGF Grant funds received represent a contribution with a donor imposed condition under Accounting Standards Codification 958-605. The BMGF Grant involved the transfer of an advance deposit to the Company before specified conditions were substantially met. Therefore, the transfer of cash was recorded as restricted cash and deferred revenue. When conditions were substantially met, the refundable advance was recognized as revenue. The Company recognizes revenue under research contracts only when a contract has been executed and the contract price is fixed or determinable. Revenue from the BMGF Grant is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the contract have been met. Costs of contract revenue are recorded as a component of operating expenses in the consolidated statements of operations and comprehensive loss. The Company recognized $3.5 million and zero revenue from the BMGF Grant for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023 and 2022, restricted cash and deferred revenue were zero and $2.0 million, respectively (see Note 6).

Research and Development Costs – Research and development costs are expensed as incurred. Research and development costs consist primarily of salaries and benefits, stock-based compensation, consultant fees, third-party costs for conducting clinical trials and the manufacture of clinical trial materials, certain facility costs and other costs associated with clinical trials. Payments made to other entities are under agreements that are generally cancelable by the Company. Advance payments for research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related services are performed.

Stock-Based Compensation – Stock-based compensation arrangements include stock option grants and restricted stock units (“RSU”s) awards under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (“ESPP”), through which employees may purchase our common stock at a discount to the market price. Stock-based compensation is measured at the grant date for all stock-based awards made to employees and non-employees based on the fair value of the awards, net of estimated forfeitures. Compensation expense for purchases under the ESPP is recognized based on the fair value of the award on the date of offering. The fair value of these awards is estimated using the Black-Scholes valuation model. The expected term of each option is estimated by taking the arithmetic average of its original contractual term and its average vesting term.

Net Income (Loss) Per Share – Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of common shares outstanding during the period, without consideration of potential common shares.

Diluted net income (loss) per common share is computed giving effect to all potential dilutive common shares, comprising common stock issuable upon exercise of stock options, warrants, RSUs and ESPP. The Company uses the treasury-stock method to compute diluted income (loss) per share with respect to its stock options, warrants, RSUs and ESPP. For purposes of this calculation, options, warrants, RSUs and ESPP plan grants to purchase common stock are considered to be potential common shares and are only included in the calculation of diluted net income per share when their effect is dilutive. In the event of a net loss, the effects of all potentially dilutive shares are excluded from the diluted net loss per share calculation as their inclusion would be antidilutive.

Recent Accounting Pronouncements

The Company has reviewed all significant newly-issued accounting pronouncements that are not yet effective and concluded that they are either not applicable to its operations or their adoption will not have a material impact on its financial position or results of operations.

Note 4 - Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Fair Value Disclosures [Text Block]

NOTE 4. Fair Value of Financial Instruments

Fair value accounting is applied for all financial assets and liabilities and nonfinancial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis (at least annually). Financial instruments include cash and cash equivalents, investments, accounts receivable, accounts payable and accrued liabilities that approximate fair value due to their relatively short maturities.

Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with inputs used to measure their fair values. The accounting guidance for fair value provides a framework for measuring fair value and requires certain disclosures about how fair value is determined. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance also establishes a three-level valuation hierarchy that prioritizes the inputs to valuation techniques used to measure fair value based upon whether such inputs are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions made by the reporting entity.

The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows:

Level 1 – Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level 2 – Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3 – Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.

The following table sets forth the fair value of the Company’s financial assets that are measured on a recurring basis as of December 31, 2023 and 2022 (in thousands):

	*Level 1*		*Level 2*		*Level 3*		*Total*
December 31, 2023
Financial assets:
Money market funds	$	31,403	$	—	$	—	$	31,403
U.S. Treasury securities		—		4,958		—		4,958

Total assets	$	31,403	$	4,958	$	—	$	36,361

	*Level 1*		*Level 2*		*Level 3*		*Total*
December 31, 2022
Financial assets:
Money market funds	$	30,834	$	—	$	—	$	30,834
U.S. Treasury securities		—		41,542		—		41,542
Corporate securities		—		8,162		—		8,162

Total assets	$	30,834	$	49,704	$	—	$	80,538

The Company held no financial liabilities measured on a recurring basis as of December 31, 2023 or 2022.

- 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

Note 3 - Business Combination (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

Property and equipment	$	321
Goodwill		4,508

Total purchase price	$	4,829

Note 13 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	*Year Ended December 31,*
	*2023*		*2022*

Current:
Federal	$	—	$	—
State		3		3
Foreign		258		64

Total Current		261		67

Deferred:
Federal		—		—
State		—		—
Foreign		—		—

Total Deferred		—		—

Provision for income taxes	$	261	$	67

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	*December 31, 2023*			*December 31, 2022*
Deferred tax assets:
Net operating loss carryforwards	$	47,720		$	39,822
Research and development tax credits		10,187			7,943
Capitalized research and development		21,676			14,260
Sale of future royalties		1,623			2,886
Lease liability		4,206			4,581
Accruals, reserves and other		4,827			5,004
Total deferred tax assets		90,239			74,496
Valuation allowance		(82,500	)		(66,323	)
Deferred tax assets net of valuation allowance		7,739			8,173
Deferred tax liabilities:
Intangible assets		(2,308	)		(2,614	)
Right-of-use assets		(5,216	)		(5,427	)
Depreciation on property and equipment		(215	)		(132	)
Total deferred tax liabilities		(7,739	)		(8,173	)

Net deferred tax assets	$	—		$	—

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended December 31,
	2023			2022

U.S. federal taxes at statutory rate		21.0	%		21.0	%
State taxes (net of federal benefit)		0.1			0.1
Foreign rate differential		(1.1	)		(0.3	)
Permanently non-deductible items		(1.1	)		(1.5	)
Tax credits		2.7			3.0
Change in valuation allowance		(19.7	)		(22.0	)
Prior year true-up		(0.1	)		(0.2	)
Other		(2.1	)		(0.2	)

Provision for income taxes		(0.3	)%		(0.1	)%

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	*Year Ended December 31,*
	*2023*		*2022*

Beginning Balance	$	4,945	$	2,422
Additions based on tax positions related to the current year		1,621		2,589
Increase (decreases) related to prior years’ tax positions		—		(66	)

Ending Balance	$	6,566	$	4,945

Note 5 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash and cash equivalents	$ 34,755	$ 44,013
Cash, cash equivalents and restricted cash	34,755	46,013	$ 143,745
Gross Unrealized Loss	(1)	(299)
Short-term investments	4,958	49,704
Investments and Cash	39,714	96,016
Investments and Cash, Fair Value Disclosure	39,713	95,717
Corporate securities	(1)	(299)
Corporate securities	4,958	49,704
US Treasury Securities [Member]
Amortized Cost	4,959	41,812
Gross Unrealized Loss	(1)	(270)
Estimated Fair Value	4,958	41,542
Short-term investments	4,958	41,542
Corporate securities	4,959	41,812
Corporate securities	(1)	(270)
Corporate securities	4,958	41,542
Corporate securities	4,958	41,542
Corporate Debt Securities [Member]
Amortized Cost		8,191
Gross Unrealized Loss		(29)
Estimated Fair Value		8,162
Short-term investments		8,162
Corporate securities		8,191
Corporate securities		(29)
Corporate securities		8,162
Corporate securities		8,162
Cash [Member]
Cash and cash equivalents	3,352	15,179
Money market funds, Fair Value	3,352	15,179
Cash, cash equivalents and restricted cash	3,352	15,179
Money Market Funds [Member]
Cash and cash equivalents	31,403	30,834
Money market funds, Fair Value	31,403	30,834
Cash, cash equivalents and restricted cash	$ 31,403	$ 30,834

Note 10 - Stockholders' Equity

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Equity [Text Block]

NOTE 10. Stockholders’ Equity

(a) Preferred Stock

The Company is authorized to issue 5,000,000 shares of preferred stock, $0.0001 par value per share. The Company’s board of directors may, without further action by the stockholders, fix the rights, preferences, privileges and restrictions of up to an aggregate of 5,000,000 shares of preferred stock in one or more series and authorize their issuance. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of our common stock. The issuance of preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deterring or preventing a change of control or other corporate action. No shares of preferred stock are currently outstanding, and the Company has no present plan to issue any shares of preferred stock.

(b) Common Stock

As of December 31, 2023, the Company was authorized to issue 250,000,000 shares of common stock, $0.0001 par value per share, which includes an increase of 100,000,000 on August 4, 2022, when the Company’s stockholders approved an amendment to the Company’s certificate of incorporation to increase the number of authorized shares of common stock from 150,000,000. Except as otherwise required by law or as otherwise provided in any certificate of designation for any series of preferred stock, the holders of common stock possess all voting power for the election of the Company’s directors and all other matters requiring stockholder action. Holders of common stock are entitled to one vote per share on matters to be voted on by stockholders. Holders of common stock are entitled to receive such dividends, if any, as may be declared from time to time by the Company’s board of directors in its discretion out of funds legally available therefor. In no event will any stock dividends or stock splits or combinations of stock be declared or made on common stock unless the shares of common stock at the time outstanding are treated equally and identically. As of December 31, 2023, no dividends had been declared by the board of directors.

In the event of the Company’s voluntary or involuntary liquidation, dissolution, distribution of assets or winding-up, the holders of the common stock will be entitled to receive an equal amount per share of all the Company’s assets of whatever kind available for distribution to stockholders, after the rights of the holders of the preferred stock have been satisfied. There are no sinking fund provisions applicable to the common stock.

The Company had shares of common stock reserved for issuance as follows:

	*December 31, 2023*		*December 31, 2022*

Options issued and outstanding		17,938,726		14,725,261
RSUs issued and outstanding		2,126,373		808,310
Available for future grants of equity awards		5,685,806		12,074,692
Common stock warrants		227,434		227,434
2022 Employee Stock Purchase Plan		1,065,325		1,800,000
Total		27,043,664		29,635,697

(c) Warrants

The Company has the following warrants outstanding as of December 31, 2023, all of which contain standard anti-dilution protections in the event of subsequent rights offerings, stock splits, stock dividends or other extraordinary dividends, or other similar changes in the Company’s common stock or capital structure, and none of which have any participating rights for any losses:

Securities into which warrants are convertible	Warrants outstanding		Exercise Price		Expiration Date

Common Stock		44,148	$	1.10	April 2024
Common Stock		26,515	$	1.375	April 2024
Common Stock		29,150	$	2.50	March 2025
Common Stock		100,532	$	3.125	February 2025
Common Stock		16,175	$	3.125	March 2024
Common Stock		10,914	$	22.99	December 2026
Total		227,434

In the event of a Fundamental Transaction (a transfer of ownership of the Company as defined in the warrant) within the Company’s control, the holders of the unexercised common stock warrants exercisable for $1.10 and $2.50 and those exercisable for $3.125 expiring in February 2025 shall be entitled to receive cash consideration equal to a Black-Scholes valuation, as defined in the warrant. If such Fundamental Transaction is not within the Company’s control, the warrant holders would only be entitled to receive the same form of consideration (and in the same proportion) as the holders of the Company’s common stock, hence these warrants are classified as a component of permanent equity.

- Definition

The entire disclosure for equity.

+ References

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+ Details

Note 5 - Balance Sheet Components (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Interest Receivable	$ 100,000	$ 200,000
Accounts Receivable, after Allowance for Credit Loss, Current	3,008,000	20,000
Accounts Receivable, Allowance for Credit Loss, Current	0	0
Depreciation, Total	3,800,000	2,000,000
Tangible Asset Impairment Charges, Total	0	0
Operating Lease, Right-of-Use Asset	24,840,000	25,715,000
Amortization of Intangible Assets	700,000	1,300,000
Goodwill, Ending Balance	4,508,000	4,508,000
Goodwill, Impairment Loss	$ 0	0
Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)	5 years 10 months 24 days
Impairment of Intangible Assets (Excluding Goodwill), Total		4,300,000
Intellectual Property [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)	4 years
Facility in Burlingame, California [Member]
Operating Lease, Right-of-Use Asset	$ 3,100,000	15,000,000
Royalty [Member]
Accounts Receivable, after Allowance for Credit Loss, Current	$ 3,000,000	$ 20,000

Note 11 - Equity Incentive Plans - Assumptions of Options (Details) - Share-Based Payment Arrangement, Option [Member]	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Minimum [Member]
Risk-free interest rate	3.45%	1.62%
Expected term (in years) (Year)	5 years 6 months	5 years 5 months 1 day
Expected volatility	128.00%	125.00%
Maximum [Member]
Risk-free interest rate	4.15%	4.02%
Expected term (in years) (Year)	6 years	6 years 29 days
Expected volatility	134.00%	131.00%

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash, cash equivalents and restricted cash	$ 34,755	$ 46,013
Short-term investments	4,958	49,704
Accounts receivable	3,008	20
Prepaid expenses and other current assets	2,815	3,714
Total current assets	45,536	99,451
Property and equipment, net	11,731	15,585
Right-of-use assets, net	24,840	25,715
Intangible assets, net	4,289	5,020
Goodwill	4,508	4,508
Other long-term assets	926	3,568
Total assets	91,830	153,847
Current liabilities:
Accounts payable	1,584	5,514
Deferred grant revenue	0	2,000
Other accrued current liabilities	5,634	8,084
Current portion of operating lease liability	2,703	2,228
Current portion of liability related to sale of future royalties	3,803	95
Total current liabilities	13,724	17,921
Operating lease liability, net of current portion	17,385	19,477
Liability related to sale of future royalties, net of current portion	2,623	5,621
Other long-term liabilities	293	231
Total liabilities	34,025	43,250
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred Stock: $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding as of December 31, 2023 or 2022	0	0
Common Stock: $0.0001 par value; 250,000,000 shares authorized as of December 31, 2023 and 2022; 153,959,853 shares issued and 153,452,833 shares outstanding as of December 31, 2023 and 134,199,429 shares issued and outstanding as of December 31, 2022	15	13
Additional paid-in capital	467,731	437,992
Treasury Stock at cost, 507,020 shares and none as of December 31, 2023 and 2022, respectively	(366)	0
Accumulated deficit	(409,574)	(327,109)
Accumulated other comprehensive loss	(1)	(299)
Total stockholders’ equity	57,805	110,597
Total liabilities and stockholders’ equity	$ 91,830	$ 153,847

Note 11 - Equity Incentive Plans

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

NOTE 11. Equity Incentive Plans

On April 23, 2019, the Company’s stockholders approved the adoption of the 2019 Equity Incentive Plan (the “2019 Plan”), under which the Company is authorized to issue incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, RSUs, other stock awards and performance awards that may be settled in cash, stock, or other property. The 2019 Plan is designed to secure and retain the services of employees, directors and consultants, provide incentives for the Company’s employees, directors and consultants to exert maximum efforts for the success of the Company and its affiliates, and provide a means by which employees, directors and consultants may be given an opportunity to benefit from increases in the value of the Company’s common stock. Following adoption of the 2019 Plan, all previous plans were frozen, and on forfeiture, cancellation and expiration, awards under those plans are not assumed by the 2019 Plan.

The aggregate number of shares of common stock authorized for issuance under the 2019 Plan was initially 1,600,000 shares, which was increased through an amendment to the 2019 Plan adopted by the Company’s stockholders (a “Plan Amendment”) on June 8, 2020, to 8,000,000, by a Plan Amendment on June 16, 2021, to 16,900,000, and by a Plan Amendment on August 4, 2022, to 28,900,000. Further amendments to the 2019 Plan to increase the share reserve would require stockholder approval. Awards that are forfeited or canceled generally become available for issuance again under the 2019 Plan. Awards have a maximum term of ten years from the grant date and may vest over varying periods, as specified by the Company’s board of directors for each grant.

A summary of stock option and RSU transactions for the years ended December 31, 2023 and 2022 follows:

							*Weighted*					*Weighted*
	*Shares*			*Number of*			*Option Average*		*Number of*			*RSU Average*
	*Available*			*Options*			*Exercise*		*RSUs*			*Grant Date*
	*For Grant*			*Outstanding*			*Price*		*Outstanding*			*Fair Value*

Balance at January 1, 2022		5,582,742			10,216,106		$	4.96		—		$	—

Authorized under 2019 Plan Amendment		12,000,000			—		$	—		—		$	—
Granted		(7,291,935	)		6,376,657		$	4.10		915,278		$	3.58
Exercised		—			(180,336	)	$	1.24		—		$	—
Forfeited		1,625,133			(1,518,230	)	$	6.19		(106,968	)	$	3.62
Canceled		158,752			(168,936	)	$	7.17		—		$	—

Balance at December 31, 2022		12,074,692			14,725,261		$	4.48		808,310		$	3.57

Granted		(10,631,320	)		7,399,849		$	0.78		3,231,471		$	0.78
Exercised		—			(54,720	)	$	0.31		(1,608,809	)	$	1.09
Forfeited		2,444,486			(2,139,887	)	$	5.00		(304,599	)	$	2.42
Canceled		1,797,948			(1,991,777	)	$	4.51		—		$	—

Balance at December 31, 2023		5,685,806			17,938,726		$	2.90		2,126,373		$	1.37

As of December 31, 2023, there were 17,938,726 options outstanding with a weighted average exercise price of $2.90, a weighted average remaining contractual term of 8.18 years and an aggregate intrinsic value of $26,000. Of these options, 9,667,285 were vested, with a weighted average exercise price of $3.17, a weighted average remaining contractual term of 7.70 years and an aggregate intrinsic value of $26,000.

The Company received $17,000 for the 54,720 options exercised in the year ended December 31, 2023, which had an intrinsic value of $31,000. The aggregate intrinsic value represents the total pre-tax value (i.e., the difference between the Company’s stock price and the exercise price) of stock options outstanding as of December 31, 2023, based on the Company’s common stock closing price of $0.57 on December 29, 2023, the prior business day, which would have been received by the option holders had all their in-the-money options been exercised as of that date. The Company received $223,000 for the 180,336 options exercised during the year ended December 31, 2022, which had an intrinsic value of $481,000.

The weighted average grant date fair value of options awarded in the years ended December 31, 2023 and 2022, was $0.78 and $4.10, respectively. Fair values were estimated using the following assumptions:

	*Year Ended December 31,*
	*2023*			*2022*

Risk-free interest rate		3.45% - 4.15	%		1.62% - 4.02	%
Expected term (in years)		5.50 - 6.00			5.42 - 6.08
Expected volatility		128% - 134	%		125% - 131	%
Dividend yield		—	%		—	%

The Company measures the fair value of all stock-based awards on the grant date and records the fair value of these awards, net of estimated forfeitures, to compensation expense over the service period. Total stock-based compensation recognized for options was as follows (in thousands):

	*Year Ended December 31,*
	*2023*		*2022*

Research and development	$	8,362	$	9,183
General and administrative		5,770		4,404
Total stock-based compensation	$	14,132	$	13,587

As of December 31, 2023, the unrecognized stock-based compensation cost related to outstanding stock options and RSUs expected to vest was $20.5 million, which the Company expects to recognize over an estimated weighted average period of 2.13 years.

On August 4, 2022, the 2022 Employee Stock Purchase Plan (the “2022 ESPP”) was approved by the Company’s stockholders and the Company reserved 1,800,000 shares of the Company’s common stock for purchase under the 2022 ESPP. The 2022 ESPP has a 6-month offering period comprised of one purchase period. The purchase price of the stock is equal to 85% of the lesser of the market value of such shares at the beginning of the 6-month offering period or the end of such offering period. During the year ended December 31, 2023, the Company received $0.6 million and issued 734,675 shares under the 2022 ESPP. As of December 31, 2023, 1,065,325 shares are available and reserved for future issuance under the 2022 ESPP.

The estimated fair value used for the six-month offering period beginning December 1, 2023 and ending May 31, 2024, was $0.27 per share. The estimated fair value used for the six-month offering period beginning June 1, 2023 and ending November 30, 2023, was $0.54 per share. The estimated fair value used for the six-month offering period beginning December 1, 2022 and ending May 31, 2023 was $0.46 per share. Stock-based compensation expense related to the ESPP for the years ended December 31, 2023 and 2022, was $0.4 million and zero, respectively. As of December 31, 2023, the unrecognized stock-based compensation cost related to outstanding ESPP expected to be recognized is $0.1 million by May 2024. The fair value of the ESPP shares was estimated using the Black-Scholes option pricing model using the following assumptions:

	Six-Month Offering Period Ending May 31, 2024			Six-Month Offering Period Ended November 30, 2023			Six-Month Offering Period Ended May 31, 2023

Risk-free interest rate		5.26	%		5.37	%		4.60	%
Expected term (in years)		0.50			0.50			0.50
Expected volatility		75.20	%		98.55	%		84.66	%
Dividend yield		—	%		—	%		—	%

Note 13 - Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Net operating loss carryforwards	$ 47,720	$ 39,822
Research and development tax credits	10,187	7,943
Capitalized research and development	21,676	14,260
Sale of future royalties	1,623	2,886
Lease liability	4,206	4,581
Accruals, reserves and other	4,827	5,004
Total deferred tax assets	90,239	74,496
Valuation allowance	(82,500)	(66,323)
Deferred tax assets net of valuation allowance	7,739	8,173
Intangible assets	(2,308)	(2,614)
Right-of-use assets	(5,216)	(5,427)
Depreciation on property and equipment	(215)	(132)
Total deferred tax liabilities	(7,739)	(8,173)
Net deferred tax assets	$ 0	$ 0

Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Property, Plant, and Equipment, Useful Life [Table Text Block]

Laboratory equipment (in years)			5
Office and computer equipment (in years)			3
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Consolidated Statements of Stockholders' Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
September 2021 ATM [Member]
Offering costs	$ 103	$ 786
The 2023 Shelf Registration [Member]
Offering costs	$ 284

Note 13 - Income Taxes - Reconciliation of Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2019
U.S. federal taxes at statutory rate	21.00%	21.00%	21.00%
State taxes (net of federal benefit)	0.10%	0.10%
Foreign rate differential	(1.10%)	(0.30%)
Permanently non-deductible items	(1.10%)	(1.50%)
Tax credits	2.70%	3.00%
Change in valuation allowance	(19.70%)	(22.00%)
Prior year true-up	(0.10%)	(0.20%)
Other	(2.10%)	(0.20%)
Provision for income taxes	(0.30%)	(0.10%)

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer, Including Assessed Tax	$ 7,379	$ 107
Operating expenses:
Research and development	68,142	81,054
General and administrative	22,584	29,386
Impairment of intangible assets	0	4,254
Total operating expenses	90,726	114,694
Operating loss	(83,347)	(114,587)
Other income (expense):
Interest income	2,652	1,247
Non-cash interest expense related to sale of future royalties	(1,447)	(1,305)
Gain on remeasurement of future royalty liability	0	6,960
Other expense, net	(62)	(6)
Loss before income taxes	(82,204)	(107,691)
Provision for income taxes	261	67
Net loss	$ (82,465)	$ (107,758)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.57)	$ (0.84)
Shares used to compute net loss per share, basic and diluted (in shares)	144,819,781	127,683,813
Comprehensive loss:
Net loss	$ (82,465)	$ (107,758)
Unrealized gain (loss) on available-for-sale investments, net of tax	298	(225)
Comprehensive loss	(82,167)	(107,983)
Non Cash Royalty Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax	3,920	107
Grant [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 3,459	$ 0

Note 1 - Organization and Nature of Business (Details Textual) - USD ($) $ / shares in Units, $ in Millions		7 Months Ended	12 Months Ended
	Sep. 15, 2021	Dec. 31, 2023	Dec. 31, 2023	Jun. 30, 2023
The September 2021 ATM [Member]
Open Market Sale Agreement, Maximum Aggregate Offering Price	$ 100.0
Open Market Sale Agreement, Sales Commission, Percentage	3.00%
Stock Issued During Period, Shares, New Issues (in shares)			1,362,220
Proceeds from Issuance of Common Stock			$ 1.5
Proceeds from Issuance of Common Stock, Net			$ 1.4
September 2021 ATM [Member]
Stock Issued During Period, Shares, New Issues (in shares)			9,781,920
Proceeds from Issuance of Common Stock			$ 19.6
Proceeds from Issuance of Common Stock, Net			$ 18.6
June 2023 Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)		16,000,000
Proceeds from Issuance of Common Stock, Net		$ 13.6
Shares Issued, Price Per Share (in dollars per share)				$ 0.868

Note 14 - Net Loss Per Share

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Earnings Per Share [Text Block]

NOTE 14. Net Loss Per Share Attributable to Common Stockholders

The following table presents the calculation of basic and diluted net loss per share (in thousands, except share and per share amounts):

	*Year Ended December 31,*
	*2023*			*2022*

Net loss	$	(82,465	)	$	(107,758	)

Shares used to compute net loss per share, basic and diluted		144,819,781			127,683,813

Net loss per share attributable to common stockholders, basic and diluted	$	(0.57	)	$	(0.84	)

No adjustment has been made to the net loss attributable to common stockholders as the effect would be anti-dilutive due to the net loss.

The following potentially dilutive weighted average securities were excluded from the computation of weighted average shares outstanding because they would have been antidilutive:

	*Year Ended December 31,*
	*2023*		*2022*

Options to purchase common stock	17,270,980			13,567,390
Restricted stock unit to purchase common stock		2,931,662		460,975
Warrants to purchase common stock	227,434			228,725
Employee Stock Purchase Plan		402,699		392,095

Total potentially dilutive securities excluded from denominator of the diluted earnings per share computation		20,832,775		14,649,185

Note 13 - Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Beginning Balance	$ 4,945	$ 2,422
Additions based on tax positions related to the current year	1,621	2,589
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions		(66)
Ending Balance	$ 6,566	$ 4,945

Note 3 - Business Combination

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Business Combination Disclosure [Text Block]

NOTE 3. Business Combination

On November 30, 2021, the Company closed its acquisition of Kindred BioSciences, Inc.’s GMP manufacturing line in Burlingame, California in exchange for $4.8 million in cash. The transaction was accounted for as a business combination and the Company incurred transaction related expenses totaling $82,000, which were recorded within general and administrative expenses in the consolidated statement of operations in the year ended December 31, 2021.

The fair value of the assets acquired in connection with the acquisition are as follows (in thousands):

Property and equipment	$	321
Goodwill		4,508

Total purchase price	$	4,829

Goodwill, which represents the excess of the purchase price over the fair value of assets acquired, is attributable primarily to the expected cost savings of manufacturing internally, as opposed to outsourcing, and the assembled workforce. All of the goodwill is expected to be deductible for income tax purposes.

Note 13 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2019	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 16,200	$ 23,700
Unrecognized Tax Benefits, Ending Balance	6,566	4,945		$ 2,422
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total	0	0
Domestic Tax Authority [Member]
Operating Loss Carryforwards	201,100	162,100
Operating Loss Carryforwards, Subject to Expiration	1,800
Operating Loss Carryforward, Carried Forward Indefinitely	199,300
Domestic Tax Authority [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	9,400	6,900
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	87,500	85,000
Operating Loss Carryforwards, Subject to Expiration	2,900
Operating Loss Carryforward, Carried Forward Indefinitely	$ 84,600
Open Tax Year	2016 2017 2018 2019 2020 2021
State and Local Jurisdiction [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 8,500	$ 7,000
Foreign Tax Authority [Member] \| Australian Taxation Office [Member]
Operating Loss Carryforwards	$ 4,900

Note 12 - Benefit Plan

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Retirement Benefits [Text Block]

NOTE 12. Benefit Plan

The Company provides a tax-qualified employee savings and retirement plan commonly known as a 401(k) plan (the “Plan”), which covers the Company’s eligible employees. Pursuant to the Plan, employees may elect to defer their current compensation up to the IRS annual contribution limit of $22,500 for calendar year 2023 and $20,500 for calendar year 2022. Employees age 50 or over may elect to contribute an additional $7,500 annually for 2023 and $6,500 for 2022.

Employees direct their contributions, which vest immediately, across a series of mutual funds. In the years ended December 31, 2023 and 2022, the Company matched employee contributions up to 3% of each employee’s eligible earnings, vesting immediately. The Company’s matching contributions totaled $0.6 million and $0.7 million in the years ended December 31, 2023 and 2022, respectively. The costs of administering the Plan totaled $28,000 and $19,000 in the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
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-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
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-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
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-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Subparagraph (l)
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-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
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-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

These consolidated financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.

Consolidation, Policy [Policy Text Block]

Use of Estimates, Policy [Policy Text Block]

Foreign Currency Transactions and Translations Policy [Policy Text Block]

Cash and Cash Equivalents, Policy [Policy Text Block]

Investment, Policy [Policy Text Block]

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Receivable [Policy Text Block]

Property, Plant and Equipment, Policy [Policy Text Block]

The useful lives of the property and equipment are as follows:

Laboratory equipment (in years)			5
Office and computer equipment (in years)			3
Leasehold improvements			Shorter of remaining lease term or estimated useful life

Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Accrued Clinical And Manufacturing Expenses Policy [Policy Text Block]

Lessee, Leases [Policy Text Block]

Revenue [Policy Text Block]

(i)

identification of the promised goods or services in the contract;

(ii)

determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract;

(iii)

measurement of the transaction price, including the constraint on variable consideration;

(iv)

allocation of the transaction price to the performance obligations based on estimated selling prices; and

(v)

Research and Development Expense, Policy [Policy Text Block]

Share-Based Payment Arrangement [Policy Text Block]

Earnings Per Share, Policy [Policy Text Block]

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

Note 5 - Balance Sheet Components - Estimated Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2023 USD ($)
2024	$ 731
2025	732
2026	731
2027	731
2028	727
Thereafter	637
Total	$ 4,289

Note 11 - Equity Incentive Plans - Assumptions of Employee Purchase Plan (Details) - The 2022 ESPP [Member]	6 Months Ended
	May 31, 2024	Nov. 30, 2023	May 31, 2023
Risk-free interest rate		5.37%	4.60%
Expected term (in years) (Year)		6 months	6 months
Expected volatility		98.55%	84.66%
Dividend yield		0.00%	0.00%
Forecast [Member]
Risk-free interest rate	5.26%
Expected term (in years) (Year)	6 months
Expected volatility	75.20%
Dividend yield	0.00%

Note 9 - Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Commitments and Contingencies Disclosure [Text Block]

NOTE 9. Commitments and Contingencies

(a) Purchase Commitments

As of December 31, 2023, the Company had approximately $3.8 million of non-cancelable purchase commitments, principally for contract manufacturing and clinical services and leasehold improvements which are expected to be paid within the next year. In addition, the Company has operating lease commitments as detailed in Note 8.

(b) Indemnifications

In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend indemnified parties for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has also entered into indemnification agreements with certain officers and directors which provide, among other things, that the Company will indemnify and advance expenses incurred in connection with certain actions, suits or proceedings to such officer or director, under the circumstances and to the extent provided for therein, for expenses, damages, judgments, fines and settlements he or she may be required to pay in actions or proceedings which he or she is or may be made a party by reason of his or her position as a director, officer or other agent of the Company, and otherwise to the fullest extent permitted under Delaware law and the Company’s Bylaws. The Company currently has directors’ and officers’ insurance.

(c) Litigation

From time to time the Company may be involved in legal proceedings arising in connection with its business. Based on information currently available, the Company believes that the amount, or range, of reasonably possible losses in connection with any pending actions against it in excess of established reserves, in the aggregate, is indeterminable to its consolidated financial condition or cash flows. However, any current or future dispute resolution or legal proceeding, regardless of the merits of any such proceeding, could result in substantial costs and a diversion of management’s attention and resources that are needed to run the Company successfully, and could have a material adverse impact on its business, financial condition and results of operations.

In August and September 2020, two substantially similar securities class actions were filed in the U.S. District Court for the Northern District of California. The first action, titled Himmelberg v. Vaxart, Inc. et al. was filed on August 24, 2020. The second action, titled Hovhannisyan v. Vaxart, Inc. et al. was filed on September 1, 2020 (together, the “Putative Class Action”). By Order dated September 17, 2020, the two actions were deemed related. On December 9, 2020, the court appointed lead plaintiffs and lead plaintiffs’ counsel.

On January 29, 2021, lead plaintiffs filed their consolidated amended complaint. On July 8, 2021, all defendants moved to dismiss the consolidated amended complaint. On May 14, 2021, the court granted lead plaintiffs’ request to amend the consolidated amended complaint and denied defendants’ motions to dismiss as moot. On June 10, 2021, lead plaintiffs filed a first amended consolidated complaint, and on August 9, 2021, lead plaintiffs filed a corrected first amended consolidated complaint. The first amended consolidated complaint, as corrected, named certain of Vaxart’s current and former executive officers and directors, as well as Armistice Capital, LLC (“Armistice”), as defendants. It claimed three violations of federal civil securities laws; violation of Section 10(b) of the Exchange Act and SEC Rule 10b-5, as against the Company and all individual defendants; violation of Section 20(a) of the Exchange Act, as against Armistice and all individual defendants; and violation of Section 20A of the Exchange Act against Armistice. The first amended consolidated complaint, as corrected, alleged that the defendants violated securities laws by misstating and/or omitting information regarding the Company’s development of a norovirus vaccine, the vaccine manufacturing capabilities of a business counterparty, and the Company’s involvement with Operation Warp Speed (“OWS”); and by engaging in a scheme to inflate Vaxart’s stock price. The first amended consolidated complaint sought certification as a class action for similarly situated shareholders and sought, among other things, an unspecified amount of damages and attorneys’ fees and costs. On July 8, 2021, all defendants moved to dismiss the first amended consolidated complaint. By Order dated December 22, 2021, the court granted the motion to dismiss by Armistice with leave to amend and otherwise denied the motions to dismiss. On July 27, 2022, lead plaintiffs filed a notice announcing that they had reached a partial settlement (the “Partial Settlement”) to resolve all claims against the Company and its current or former officers and/or directors in their capacity as officers and/or directors of the Company (the “Settling Defendants”). Pursuant to the Partial Settlement, the Company agreed to a settlement amount of $12.0 million with $2.0 million to be paid by the Company and the remainder to be paid by the Company’s insurers. On November 2, 2022, the Company paid the $2.0 million settlement amount with respect to the Putative Class Action pursuant to the terms of the settlement agreement reached in that case. On November 14, 2022, lead plaintiffs filed a second amended consolidated class action complaint that purported to include new allegations to support claims against Armistice. By Orders dated January 25, 2023, the court approved the Partial Settlement and entered judgment dismissing with prejudice all claims asserted in the Putative Class Action against the Settling Defendants.

On October 23, 2020, a complaint was filed in the U.S. District Court for the Southern District of New York, entitled Roth v. Armistice Capital LLC, et al. The complaint names Armistice and certain Armistice-related parties as defendants, asserting a violation of Exchange Act Section 16(b) and seeking the disgorgement of short-swing profits. The complaint purports to bring the lawsuit on behalf of and for the benefit of the Company and names the Company as a “nominal defendant” for whose benefit damages are sought.

On January 8, 2021, a purported shareholder, Phillip Chan, commenced a pro se lawsuit in the U.S. District Court for the Northern District of California titled Chan v. Vaxart, Inc. et al. (the “Opt-Out Action”), opting out of the consolidated Himmelberg v. Vaxart, Inc. et al. and Hovhannisyan v. Vaxart, Inc. et al. class actions, (together, the “Putative Class Action”). Because this complaint is nearly identical to an earlier version of a complaint filed in the Putative Class Action, the Opt-Out Action has been stayed while the Putative Class Action is pending.

Note 10 - Stockholders' Equity - Summary of Warrants Outstanding (Details)	Dec. 31, 2023 $ / shares shares
Securities into which warrants are convertible (in shares)	227,434
First Set of Warrants Expiring September 2024 [Member]
Securities into which warrants are convertible (in shares)	44,148
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 1.1
First Set of Warrants Expiring April 2024 [Member]
Securities into which warrants are convertible (in shares)	26,515
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 1.375
Second Set of Warrants Expiring April 2024 [Member]
Securities into which warrants are convertible (in shares)	29,150
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 2.5
Warrants Expiring March 2025 [Member]
Securities into which warrants are convertible (in shares)	100,532
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 3.125
Warrants Expiring February 2025 [Member]
Securities into which warrants are convertible (in shares)	16,175
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 3.125
Warrants Expiring March 2024 [Member]
Securities into which warrants are convertible (in shares)	10,914
Securities into which warrants are convertible (in dollars per share) \| $ / shares	$ 22.99

Note 14 - Net Loss Per Share Attributable to Common Stockholders - Calculation of Basic and Diluted Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Net loss	$ (82,465)	$ (107,758)
Shares used to compute net loss per share, basic and diluted (in shares)	144,819,781	127,683,813
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.57)	$ (0.84)

- Definition

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

+ References

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-Topic 250
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-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Nov. 30, 2022	Dec. 31, 2021
Cash, Cash Equivalents, and Short-Term Investments	$ 39,700
Reduction in Workforce, Percentage	27.00%
Severance Costs	$ 500
Restricted Cash, Total	0	$ 2,000
Accounts Receivable, Allowance for Credit Loss, Ending Balance	0	0
Revenue from Contract with Customer, Including Assessed Tax	7,379	107
Deferred Revenue, Current, Total	0	2,000	$ 2,000
Grant [Member]
Grants Receivable			$ 3,500
Revenue from Contract with Customer, Including Assessed Tax	$ 3,459	$ 0
Developed Technology Rights [Member] \| Maximum [Member]
Finite-Lived Intangible Asset, Useful Life (Year)				11 years 9 months
Intellectual Property [Member]
Finite-Lived Intangible Asset, Useful Life (Year)				20 years
Customer Concentration Risk [Member] \| Accounts Receivable [Member] \| Daiichi Sankyo [Member]
Concentration Risk, Percentage	100.00%	100.00%

Note 10 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Aug. 04, 2022	Dec. 31, 2023	Dec. 31, 2022	Aug. 03, 2022
Preferred Stock, Shares Authorized (in shares)		5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001	$ 0.0001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)		0	0
Common Stock, Shares Authorized (in shares)		250,000,000	250,000,000	150,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001	$ 0.0001
Common Stock, Increase in Shares Authorized (in shares)	100,000,000
Dividends, Total		$ 0
First Set of Warrants Expiring April 2024 [Member]
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		$ 1.1
Warrants Expiring March 2025 [Member]
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		2.5
Warrants Expiring February 2025 [Member]
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		$ 3.125

Insider Trading Arrangements	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Insider Trading Arr Line Items
Material Terms of Trading Arrangement [Text Block]	Item *9B.* Other Information During our last fiscal quarter, no director or officer, as defined in Rule 16a-1(f), adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” each as defined in Regulation S-K Item 408.
Rule 10b5-1 Arrangement Adopted [Flag]	false
Rule 10b5-1 Arrangement Terminated [Flag]	false
Non-Rule 10b5-1 Arrangement Adopted [Flag]	false
Non-Rule 10b5-1 Arrangement Terminated [Flag]	false

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, 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, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	153,959,853	134,199,429
Common stock, shares outstanding (in shares)	153,452,833	134,199,429
Treasury Stock, Common, Shares (in shares)	507,020	0

Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2023	Mar. 07, 2024	Jun. 30, 2023
Document Information [Line Items]
Entity Central Index Key	0000072444
Entity Registrant Name	Vaxart, Inc.
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2023
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Document Transition Report	false
Entity File Number	001-35285
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	59-1212264
Entity Address, Address Line One	170 Harbor Way, Suite 300
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	550-3500
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	VXRT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 110,318,242
Entity Common Stock, Shares Outstanding		173,861,684
Auditor Name	WithumSmith+Brown, PC
Auditor Location	San Francisco, California
Auditor Firm ID	100

Note 3 - Business Combination (Details Textual)	Nov. 30, 2021 USD ($)
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed	$ 82,000
Acquisition of Kindred BioSciences [Member]
Business Combination, Consideration Transferred, Total	$ 4,829,000

Note 6 - Revenue

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Revenue [Text Block]

NOTE 6. Revenue

Royalty agreement

The Company generates royalty revenue from the sale of Inavir in Japan, pursuant to a collaboration and license agreement that Aviragen entered into with Daiichi Sankyo, in 2009. In September 2010, laninamivir octanoate was approved for sale by the Japanese Ministry of Health and Welfare for the treatment of influenza in adults and children, which Daiichi Sankyo markets as Inavir. Under the agreement, the Company currently receives a 4% royalty on net sales of Inavir in Japan. The last patent related to Inavir is set to expire in December 2029 in Japan, at which time royalty revenue will cease. The royalty revenue related to Inavir recognized for the years ended December 31, 2023 and 2022, was zero. The Company recognized non-cash royalty revenue related to sale of future royalties of $3.9 million and $0.1 million for the years ended December 31, 2023 and 2022, respectively (see Note 7). Both the royalty revenue and the non-cash royalty revenue related to sale of future royalties have been subjected to a 5% withholding tax in Japan, for which $0.2 million and $5,000 was included in income tax expense in the years ended December 31, 2023 and 2022, respectively.

Grant Revenue

In November 2022, the Company accepted the $3.5 million BMGF Grant to perform research and development work for the Bill & Melinda Gates Foundation and received $2.0 million in advance that was recorded as restricted cash and deferred revenue. The Company received an additional $1.5 million in July 2023 upon completion of certain milestones. The Company recognizes revenue under research contracts only when a contract has been executed and the contract price is fixed or determinable. Revenue from the BMGF Grant is recognized in the period during which the related costs are incurred and the related services are rendered, provided that the applicable conditions under the contract have been met. Costs of contract revenue are recorded as a component of operating expenses in the consolidated statements of operations and comprehensive loss. The Company recognized revenue from the BMGF Grant of $3.5 million and zero for the years ended December 31, 2023 and 2022, respectively. As December 31, 2023 and 2022, restricted cash and deferred revenue were zero and $2.0 million, respectively.

Note 8 - Leases - Operating Lease Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating lease cost	$ 6,170	$ 4,159
Short-term lease cost	52	436
Variable lease cost	1,864	1,312
Total operating lease cost	$ 8,086	$ 5,907

Note 5 - Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	Amortized		Gross Unrealized					Estimated		Cash and Cash		Short-Term
	Cost		Gains		Losses			Fair Value		Equivalents		Investments
December 31, 2023
Cash at banks	$	3,352	$	—	$	—		$	3,352	$	3,352	$	—
Money market funds		31,403		—		—			31,403		31,403		—
U.S. Treasury securities		4,959		—		(1	)		4,958		—		4,958
Total	$	39,714	$	—	$	(1	)	$	39,713	$	34,755	$	4,958

	Amortized		Gross Unrealized					Estimated		Cash, Cash Equivalents		Short-Term
	Cost		Gains		Losses			Fair Value		and Restricted Cash		Investments
December 31, 2022
Cash at banks	$	15,179	$	—	$	—		$	15,179	$	15,179	$	—
Money market funds		30,834		—		—			30,834		30,834		—
U.S. Treasury securities		41,812		—		(270	)		41,542		—		41,542
Corporate securities		8,191		—		(29	)		8,162		—		8,162
Total	$	96,016	$	—	$	(299	)	$	95,717	$	46,013	$	49,704

Property, Plant and Equipment [Table Text Block]

	*December 31, 2023*			*December 31, 2022*

Laboratory equipment	$	13,448		$	12,035
Office and computer equipment		1,105			1,078
Leasehold improvements		3,985			1,760
Construction in progress		24			3,984
Total property and equipment		18,562			18,857
Less: accumulated depreciation		(6,831	)		(3,272	)
Property and equipment, net	$	11,731		$	15,585

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	*December 31, 2023*			*December 31, 2022*

Developed technology	$	5,000		$	5,000
Intellectual property		80			80
Total cost		5,080			5,080
Less: accumulated amortization		(791	)		(60	)
Intangible assets, net	$	4,289		$	5,020

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Year Ending December 31,	Amount
2024	$	731
2025		732
2026		731
2027		731
2028		727
Thereafter		637
Total	$	4,289

Schedule of Accrued Liabilities [Table Text Block]

	*December 31, 2023*		*December 31, 2022*

Accrued compensation	$	4,576	$	3,112
Accrued clinical and manufacturing expenses		312		2,413
Accrued professional and consulting services		211		691
Accrued other expenses		535		1,868
Total	$	5,634	$	8,084

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (82,465,000)	$ (107,758,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8,624,000	5,805,000
Loss on disposal of property and equipment	55,000	0
Amortization of discount on investments, net	(659,000)	(163,000)
Impairment of intangible assets	0	4,254,000
Stock-based compensation	14,132,000	13,587,000
Gain on remeasurement of future royalty liability	0	(6,960,000)
Non-cash interest expense related to sale of future royalties	1,447,000	1,305,000
Non-cash revenue related to sale of future royalties	(737,000)	(151,000)
Change in operating assets and liabilities:
Accounts receivable	(2,988,000)	51,000
Prepaid expenses and other assets	3,561,000	(3,783,000)
Accounts payable	(2,444,000)	357,000
Deferred grant revenue	(2,000,000)	2,000,000
Accrued liabilities	(6,979,000)	(3,323,000)
Net cash used in operating activities	(70,453,000)	(94,779,000)
Cash flows from investing activities:
Purchase of property and equipment	(1,871,000)	(9,601,000)
Proceeds from sale of property and equipment	120,000	0
Purchases of investments	(27,497,000)	(55,014,000)
Proceeds from maturities of investments	73,200,000	44,200,000
Net cash provided by (used in) investing activities	43,952,000	(20,415,000)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of warrants	0	2,000
Proceeds from issuance of common stock upon exercise of stock options	17,000	223,000
Shares acquired to settle employee tax withholding liabilities	(366,000)	0
Proceeds from issuance of common stock under the employee stock purchase plan	562,000	0
Net cash provided by financing activities	15,243,000	17,462,000
Net decrease in cash, cash equivalents and restricted cash	(11,258,000)	(97,732,000)
Cash, cash equivalents and restricted cash at beginning of the period	46,013,000	143,745,000
Cash, cash equivalents and restricted cash at end of the period	34,755,000	46,013,000
Supplemental disclosure of non-cash investing and financing activity:
Operating lease liabilities arising from obtaining right-of-use assets	495,000	9,997,000
Acquisition of property and equipment included in accounts payable and accrued expenses	4,000	1,803,000
Cash and cash equivalents	34,755,000	44,013,000
Restricted cash	0	2,000,000
Cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows	34,755,000	46,013,000
Registered Direct Offering [Member]
Cash flows from financing activities:
Net proceeds from issuance of common stock	13,600,000	0
At-the-market Facility [Member]
Cash flows from financing activities:
Net proceeds from issuance of common stock	$ 1,430,000	$ 17,237,000

Note 5 - Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Supplemental Balance Sheet Disclosures [Text Block]

NOTE 5. Balance Sheet Components

(a) Cash, Cash Equivalents, Restricted Cash and Investments

Cash, cash equivalents, restricted cash and investments consisted of the following (in thousands):

	Amortized		Gross Unrealized					Estimated		Cash and Cash		Short-Term
	Cost		Gains		Losses			Fair Value		Equivalents		Investments
December 31, 2023
Cash at banks	$	3,352	$	—	$	—		$	3,352	$	3,352	$	—
Money market funds		31,403		—		—			31,403		31,403		—
U.S. Treasury securities		4,959		—		(1	)		4,958		—		4,958
Total	$	39,714	$	—	$	(1	)	$	39,713	$	34,755	$	4,958

	Amortized		Gross Unrealized					Estimated		Cash, Cash Equivalents		Short-Term
	Cost		Gains		Losses			Fair Value		and Restricted Cash		Investments
December 31, 2022
Cash at banks	$	15,179	$	—	$	—		$	15,179	$	15,179	$	—
Money market funds		30,834		—		—			30,834		30,834		—
U.S. Treasury securities		41,812		—		(270	)		41,542		—		41,542
Corporate securities		8,191		—		(29	)		8,162		—		8,162
Total	$	96,016	$	—	$	(299	)	$	95,717	$	46,013	$	49,704

As of December 31, 2023 and 2022, all investments were available-for-sale debt securities with remaining maturities of 12 months or less. As of December 31, 2023 and 2022, the Company held 1 and 18 securities, respectively, in an unrealized loss position for 12 months or less. Interest receivable as of December 31, 2023 and 2022, was $0.1 million and $0.2 million, respectively and is recorded as a component of prepaid expenses and other current assets on the consolidated balance sheets.

(b) Accounts Receivable

Accounts receivable comprises royalties receivable of $3.0 million and $20,000 as of December 31, 2023 and 2022, respectively. The Company has provided no allowance for credit losses as of December 31, 2023 and 2022, based on past events and subsequent receipts.

(c) Property and Equipment, Net

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

	*December 31, 2023*			*December 31, 2022*

Laboratory equipment	$	13,448		$	12,035
Office and computer equipment		1,105			1,078
Leasehold improvements		3,985			1,760
Construction in progress		24			3,984
Total property and equipment		18,562			18,857
Less: accumulated depreciation		(6,831	)		(3,272	)
Property and equipment, net	$	11,731		$	15,585

Depreciation expense was $3.8 million, and $2.0 million for the years ended December 31, 2023 and 2022, respectively. There were no impairments of the Company’s property and equipment recorded for the years ended December 31, 2023 or 2022.

(d) Right-of-Use Assets, Net

Right-of-use assets, net comprises facilities of $24.8 million and $25.7 million as of December 31, 2023 and 2022, respectively. The right of use of additional leased premises in California commenced in 2023 and 2022, resulting in an additional $3.1 million and $15.0 million right-of-use assets recorded in the year ended December 31, 2023 and 2022 respectively.

(e) Intangible Assets, Net

Intangible assets comprise developed technology, intellectual property and, until it was considered fully impaired, in-process research and development. Intangible assets are carried at cost less accumulated amortization. As of December 31, 2023, developed technology and intellectual property had remaining lives of 5.9 and 4.0 years, respectively. Intangible assets consist of the following (in thousands):

	*December 31, 2023*			*December 31, 2022*

Developed technology	$	5,000		$	5,000
Intellectual property		80			80
Total cost		5,080			5,080
Less: accumulated amortization		(791	)		(60	)
Intangible assets, net	$	4,289		$	5,020

Intangible asset amortization expense was $0.7 million and $1.3 million for the years ended December 31, 2023 and 2022, respectively. The Company assessed its developed technology as not impaired in the year ended December 31, 2023. Due to a decline in royalties earned since the outbreak of COVID-19 (see Note 7), developed technology was assessed as partially impaired as of December 31, 2022, and accordingly an impairment charge of $4.3 million were recorded within operating expenses.

As of December 31, 2023, the estimated future amortization expense by year is as follows (in thousands):

Year Ending December 31,	Amount
2024	$	731
2025		732
2026		731
2027		731
2028		727
Thereafter		637
Total	$	4,289

(f) Goodwill

Goodwill, which represents the excess of the purchase price over the fair value of assets acquired, comprises $4.5 million for both years ended December 31, 2023 and 2022. For the years ended December 31, 2023 and 2022, there was no change in goodwill. As of December 31, 2023 and 2022, there have been no indicators of impairment.

(g) Other Accrued Liabilities

Other accrued liabilities consist of the following (in thousands):

	*December 31, 2023*		*December 31, 2022*

Accrued compensation	$	4,576	$	3,112
Accrued clinical and manufacturing expenses		312		2,413
Accrued professional and consulting services		211		691
Accrued other expenses		535		1,868
Total	$	5,634	$	8,084

Note 4 - Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	*Level 1*		*Level 2*		*Level 3*		*Total*
December 31, 2023
Financial assets:
Money market funds	$	31,403	$	—	$	—	$	31,403
U.S. Treasury securities		—		4,958		—		4,958

Total assets	$	31,403	$	4,958	$	—	$	36,361

	*Level 1*		*Level 2*		*Level 3*		*Total*
December 31, 2022
Financial assets:
Money market funds	$	30,834	$	—	$	—	$	30,834
U.S. Treasury securities		—		41,542		—		41,542
Corporate securities		—		8,162		—		8,162

Total assets	$	30,834	$	49,704	$	—	$	80,538

Note 14 - Net Loss Per Share Attributable to Common Stockholders- Summary of Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	20,832,775	14,649,185
Share-Based Payment Arrangement, Option [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	17,270,980	13,567,390
Restricted Stock Units (RSUs) [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	2,931,662	460,975
Warrant [Member] \| Common Stock [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	227,434	228,725
Employee Stock Purchase Plan [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	402,699	392,095

Note 12 - Benefit Plan (Details Textual) - USD ($)	12 Months Ended
Note 12 - Benefit Plan (Details Textual) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		3.00%
Defined Contribution Plan, Cost	$ 600,000	$ 700,000
Defined Contribution Plan, Administrative Expense	$ 28,000	$ 19,000

Note 5 - Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued compensation	$ 4,576	$ 3,112
Accrued clinical and manufacturing expenses	312	2,413
Accrued professional and consulting services	211	691
Accrued other expenses	535	1,868
Total	$ 5,634	$ 8,084

Note 7 - Liabilities Related to Sale of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Deferred Revenue, by Arrangement, Disclosure [Table Text Block]

Total liability related to sale of future royalties, start of year	$	5,716
Non-cash royalty revenue paid to HCRP		(737	)
Non-cash interest expense recognized		1,447
Total liability related to sale of future royalties, end of year		6,426
Current portion		(3,803	)
Long-term portion	$	2,623

Note 13 - Income Taxes

12 Months Ended

Dec. 31, 2023

Notes to Financial Statements

Income Tax Disclosure [Text Block]

NOTE 13. Income Taxes

The provision for income taxes consists of the following (in thousands):

	*Year Ended December 31,*
	*2023*		*2022*

Current:
Federal	$	—	$	—
State		3		3
Foreign		258		64

Total Current		261		67

Deferred:
Federal		—		—
State		—		—
Foreign		—		—

Total Deferred		—		—

Provision for income taxes	$	261	$	67

The components of the deferred tax assets are as follows (in thousands):

	*December 31, 2023*			*December 31, 2022*
Deferred tax assets:
Net operating loss carryforwards	$	47,720		$	39,822
Research and development tax credits		10,187			7,943
Capitalized research and development		21,676			14,260
Sale of future royalties		1,623			2,886
Lease liability		4,206			4,581
Accruals, reserves and other		4,827			5,004
Total deferred tax assets		90,239			74,496
Valuation allowance		(82,500	)		(66,323	)
Deferred tax assets net of valuation allowance		7,739			8,173
Deferred tax liabilities:
Intangible assets		(2,308	)		(2,614	)
Right-of-use assets		(5,216	)		(5,427	)
Depreciation on property and equipment		(215	)		(132	)
Total deferred tax liabilities		(7,739	)		(8,173	)

Net deferred tax assets	$	—		$	—

A reconciliation of the provision for income taxes with the expected provision for income taxes computed by applying the federal statutory income tax rate of 21% to the net loss before provision for income taxes:

	Year Ended December 31,
	2023			2022

U.S. federal taxes at statutory rate		21.0	%		21.0	%
State taxes (net of federal benefit)		0.1			0.1
Foreign rate differential		(1.1	)		(0.3	)
Permanently non-deductible items		(1.1	)		(1.5	)
Tax credits		2.7			3.0
Change in valuation allowance		(19.7	)		(22.0	)
Prior year true-up		(0.1	)		(0.2	)
Other		(2.1	)		(0.2	)

Provision for income taxes		(0.3	)%		(0.1	)%

The Company’s actual tax expense differed from the statutory federal income tax expense using a tax rate of 21% for the years ended December 31, 2023 and 2022, respectively, primarily due to foreign income taxes being taxed at different rates, nondeductible expenses, research and development tax credits, and the change in valuation allowance.

As of December 31, 2023 and 2022, the Company had net operating loss (“NOL”) carryforwards of $201.1 million and $162.1 million for federal purposes, and $87.5 million and $85.0 million for state purposes, respectively. If not utilized, federal net operating losses of $1.8 million will begin to expire in 2024 and $199.3 million will be carried forward indefinitely; state net operating losses of $2.9 million will begin to expire in 2028 and $84.6 million will be carried forward indefinitely.

As of December 31, 2023, the Company also has accumulated tax losses of $4.9 million for Australia available for carryforward against future earnings, which under relevant tax laws do not expire but may not be available under certain circumstances.

As of December 31, 2023 and 2022, the Company had research and development tax credit carryforwards for federal purposes of $9.4 million and $6.9 million, respectively, and state research and development tax credit carryforwards of $8.5 million and $7.0 million, respectively. The federal research and development tax credit carryforwards will expire at various dates between 2039 and 2043. The state research and development tax credit carryforwards do not expire.

Beginning on January 1, 2022, the Tax Cuts and Jobs Act (“the Act”), enacted in December 2017, eliminated the option to deduct research and development expenditures in the current period and requires taxpayers to capitalize and amortize U.S.-based and non-U.S. based research and development expenditures over five and fifteen years, respectively. This legislation does not impact the Company's current tax obligations.

Sections 382 and 383 of the Internal Revenue Code provide for a limitation on the annual use of NOL and tax credit carryforwards following certain ownership changes that could limit the Company’s ability to utilize these carryforwards. The Company has completed an analysis to determine if such ownership changes have occurred and concluded it was more likely than not that there were changes in ownership. Due to the existence of a full valuation allowance, limitations under Section 382 and 383 will not impact the Company’s effective tax rate. Further analyses will be performed prior to recognizing the benefits of any losses or credits in the consolidated financial statements.

The Company is required to reduce its deferred tax assets by a valuation allowance if it is more likely than not that some or all of its deferred tax assets will not be realized. Management must use judgment in assessing the potential need for a valuation allowance, which requires an evaluation of both negative and positive evidence. The weight given to the potential effect of negative and positive evidence should be commensurate with the extent to which it can be objectively verified. In determining the need for and amount of the valuation allowance, if any, the Company assesses the likelihood that it will be able to recover its deferred tax assets using historical levels of income, estimates of future income and tax planning strategies. As a result of historical cumulative losses, the Company determined that, based on all available evidence, there was substantial uncertainty as to whether it will recover recorded net deferred taxes in future periods. Accordingly, the Company recorded a valuation allowance against all of its net deferred tax assets as of December 31, 2023 and 2022. The net change in total valuation allowance was an increase of approximately $16.2 million and $23.7 million for the years ended December 31, 2023 and 2022, respectively.

The Company records unrecognized tax benefits, where appropriate, for all uncertain income tax positions. The Company recorded unrecognized tax benefits for uncertain tax positions of approximately $6.6 million and $4.9 million as of December 31, 2023 and 2022, respectively, of which none would impact the effective tax rate, if recognized, because the benefit would be offset by an increase in the valuation allowance.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	*Year Ended December 31,*
	*2023*		*2022*

Beginning Balance	$	4,945	$	2,422
Additions based on tax positions related to the current year		1,621		2,589
Increase (decreases) related to prior years’ tax positions		—		(66	)

Ending Balance	$	6,566	$	4,945

The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. During the year ended December 31, 2023 and 2022, the Company recognized no interest and penalties associated with unrecognized tax benefits. There are no tax positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly increase or decrease within twelve months of the reporting date.

The Company files income tax returns in the U.S, Australia, as well as with various U.S. states. The Company is subject to tax audits in all jurisdictions in which it files income tax returns. Tax audits by their very nature are often complex and can require several years to complete. There are currently no tax audits that have commenced with respect to income tax returns in any jurisdiction.

Under the tax statute of limitations applicable to the Internal Revenue Code, the Company and its U.S. subsidiary, either standalone or as part of the consolidated group, is no longer subject to U.S. federal income tax examinations by the Internal Revenue Service for tax years before tax year 2017. Under the statute of limitations applicable to most state income tax laws, the Company is no longer subject to state income tax examinations by tax authorities for tax years before 2016 in states in which it has filed income tax returns. However, because the Company is carrying forward income tax attributes, such as net operating losses and tax credits from 2004 and earlier tax years, these attributes can still be audited when utilized on returns filed in the future. The Company is subject to foreign tax examinations by tax authorities for fiscal year 2015 and forward.

- 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
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

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

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

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

Note 6 - Revenue (Details Textual) - USD ($)	1 Months Ended	12 Months Ended
Note 6 - Revenue (Details Textual) - USD ($)	Jul. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Nov. 30, 2022
Revenue from Contract with Customer, Including Assessed Tax		$ 7,379,000	$ 107,000
Income Tax Expense (Benefit)		261,000	67,000
Deferred Revenue, Current, Total		$ 0	2,000,000	$ 2,000,000
Foreign Tax Authority [Member] \| National Tax Agency, Japan [Member]
Royalty Withholding Tax		5.00%
Income Tax Expense (Benefit)		$ 200,000	5,000
Royalty [Member] \| Daiichi Sankyo Collaberation and License Agreement [Member]
Royalty Percentage		4.00%
Non Cash Royalty Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax		$ 3,920,000	107,000
Non Cash Royalty Revenue [Member] \| Daiichi Sankyo Collaberation and License Agreement [Member]
Revenue from Contract with Customer, Including Assessed Tax		3,900,000	100,000
Grant [Member]
Revenue from Contract with Customer, Including Assessed Tax		$ 3,459,000	$ 0
Grants Receivable				$ 3,500,000
Grant Milestone Completion [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,500,000

Note 7 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current portion	$ (3,803)	$ (95)
Long-term portion	2,623	$ 5,621
HealthCare Royalty Partners III, L.P. [Member] \| Royalty Arrangement [Member]
Total liability related to sale of future royalties, start of year	5,716
Non-cash royalty revenue paid to HCRP	(737)
Non-cash interest expense recognized	1,447
Total liability related to sale of future royalties, end of year	6,426
Current portion	(3,803)
Long-term portion	$ 2,623

Note 8 - Leases (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block]

Year Ending December 31,	Amount
2024	$	4,381
2025		4,511
2026		5,031
2027		5,207
2028		5,389
Thereafter		1,348
Undiscounted total		25,867
Less: imputed interest		(5,779	)
Present value of future minimum payments		20,088
Current portion of operating lease liability		(2,703	)
Operating lease liability, net of current portion	$	17,385

Lease, Cost [Table Text Block]

	*Year Ended December 31,*
	*2023*		*2022*

Operating lease cost	$	6,170	$	4,159
Short-term lease cost		52		436
Variable lease cost		1,864		1,312
Total operating lease cost	$	8,086	$	5,907

Note 4 - Fair Value of Financial Instruments - Financial Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Money Market Funds [Member]
Money market funds, Fair Value	$ 31,403	$ 30,834
Fair Value, Recurring [Member]
Investments, Fair Value Disclosure		8,162
Total assets	36,361	80,538
Fair Value, Recurring [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	4,958	41,542
Fair Value, Recurring [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Investments, Fair Value Disclosure		0
Total assets	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	31,403	30,834
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Investments, Fair Value Disclosure		8,162
Total assets	4,958	49,704
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	4,958	41,542
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Investments, Fair Value Disclosure		0
Total assets	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Money market funds, Fair Value	$ 0	$ 0

Note 10 - Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

Schedule of Common Stock Reserved for Issuance [Table Text Block]

	*December 31, 2023*		*December 31, 2022*

Options issued and outstanding		17,938,726		14,725,261
RSUs issued and outstanding		2,126,373		808,310
Available for future grants of equity awards		5,685,806		12,074,692
Common stock warrants		227,434		227,434
2022 Employee Stock Purchase Plan		1,065,325		1,800,000
Total		27,043,664		29,635,697

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

Securities into which warrants are convertible	Warrants outstanding		Exercise Price		Expiration Date

Common Stock		44,148	$	1.10	April 2024
Common Stock		26,515	$	1.375	April 2024
Common Stock		29,150	$	2.50	March 2025
Common Stock		100,532	$	3.125	February 2025
Common Stock		16,175	$	3.125	March 2024
Common Stock		10,914	$	22.99	December 2026
Total		227,434

Note 7 - Liabilities Related to Sale of Future Royalties (Details Textual) - HCRP [Member] - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2016	Dec. 31, 2023	Dec. 31, 2022
Proceeds from Sale of Future Royalties, Net	$ 20.0
Royalty Interest, Percentage of Additional Royalties Due Each Year	15.00%
Royalty Interest, Additional Royalties Due Each Year	$ 1.0
Royalty Interest, Covenant, Cumulative Remaining Shortfall Amount		$ 7.0	$ 4.3
Royalty Payment, Interest, First Period [Member]
Royalty Interest, Covenant, Shortfall in Royalty Payments	3.0
Royalty Payment, Interest, Second Period [Member]
Royalty Interest, Covenant, Shortfall in Royalty Payments	$ 2.7

Note 4 - Fair Value of Financial Instruments (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Recurring [Member]
Financial Liabilities Fair Value Disclosure, Total	$ 0	$ 0

Note 13 - Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current:
Federal	$ 0	$ 0
State	3	3
Foreign	258	64
Total Current	261	67
Deferred:
Federal	0	0
State	0	0
Foreign	0	0
Total Deferred	0	0
Provision for income taxes	$ 261	$ 67