Stockholders' Equity

6 Months Ended

Jun. 30, 2025

Equity [Abstract]

Stockholders' Equity

7. Stockholders’ Equity

December 2024 Offering and Warrant Issuance

In December 2024, the Company closed on an offering (the “December 2024 Offering”) of 9,679,158 shares of common stock at a price of $0.9520 per share with accompanying warrants to purchase up to 9,679,158 shares of common stock, which have an exercise price of $1.19 per share (the “Warrants”). The gross proceeds from the December 2024 Offering were approximately $9.2 million, before deducting $0.7 million of placement agent fees and other offering expenses payable by the Company. As discussed in Note 4, the Company recorded a liability at fair value related to the issuance of the Warrants, with changes in fair value each reporting period recognized as a component of other income (loss) in the Company’s unaudited condensed statements of operations and comprehensive loss. The accompanying Warrants became exercisable on June 20, 2025 and will expire five years from the date of initial exercisability. There were 9,679,158 Warrants outstanding and exercisable at June 30, 2025.

2020 Equity Incentive Plan

The Company may grant awards of common stock under the 2020 Equity Incentive Plan (the “2020 Plan”) to the Company’s employees, consultants and non-employee directors pursuant to option awards, stock appreciation rights awards, restricted stock awards, restricted stock unit awards, performance stock awards, performance stock unit awards and other stock-based awards. As of June 30, 2025 and December 31, 2024, the total number of common shares authorized for issuance under the 2020 Plan was 12,273,892 and 10,735,431, respectively. On January 1st of each year, commencing with the first January 1st following the effective date of the 2020 Plan, the shares authorized for issuance under the 2020 Plan shall be increased by a number of shares equal to the lesser of 4% of the total number of shares outstanding on the immediately preceding December 31 and such lesser number of shares determined by the Company’s board of directors. The maximum term of the options granted under the 2020 Plan is no more than ten years. Awards under the 2020 Plan generally vest at 25% one year from the vesting commencement date and ratably each month thereafter for a period of 36 months, subject to continuous service.

Stock-based compensation expense for the three and six months ended June 30, 2025 and 2024 has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Research and development	$	567	$	1,164	$	1,342	$	2,243
General and administrative		810		1,332		1,680		2,553
Total	$	1,377	$	2,496	$	3,022	$	4,796

Restricted Stock Units

The following table summarizes RSU activity under the 2020 Plan for the six months ended June 30, 2025:

	Number of Shares			Weighted - Average Grant Date Fair Value
Outstanding at December 31, 2024		1,553,000		$	2.48
Granted		1,863,000		$	0.32
Vested		(561,482	)	$	2.33
Forfeited		(248,005	)	$	1.09
Outstanding at June 30, 2025		2,606,513		$	1.10

As of June 30, 2025, total unrecognized stock-based compensation expense for RSUs was $2.8 million, which is expected to be recognized over a remaining weighted-average period of approximately 3.2 years.

Stock Options

The following table summarizes stock option activity under the 2020 Plan for the six months ended June 30, 2025:

	Number of Options			Weighted - Average Exercise Price Per Share		Weighted -Average Remaining Contractual Term (In Years)		Aggregate Intrinsic Value
Balance at December 31, 2024		6,096,046		$	7.65		7.59	$	—
Forfeited		(149,159	)	$	5.55
Expired		(34,416	)	$	2.12
Balance at June 30, 2025		5,912,471		$	7.73		6.88	$	—
Vested and expected to vest at June 30, 2025		5,912,471		$	7.73		6.88	$	—
Exercisable at June 30, 2025		4,372,552		$	8.91		6.67	$	—

As of June 30, 2025, total unrecognized stock-based compensation cost for unvested common stock options was $4.7 million, which is expected to be recognized over a remaining weighted-average period of approximately 1.53 years. There were no stock options granted during the six months ended June 30, 2025. The total fair value of options vested during the six months ended June 30, 2025 was $2.4 million. Upon option exercise, the Company issues new shares of its common stock.

Employee Stock Purchase Plan (“ESPP”)

The ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. As of June 30, 2025 and December 31, 2024, a total of 3,035,873 shares and 2,281,600 shares, respectively, of common stock were authorized for issuance under the ESPP. The number of shares of common stock authorized for issuance will automatically increase on January 1 of each calendar year, from January 1, 2021 through January 1, 2030 by the least of (i) 1.0% of the total number of common shares of our common stock outstanding on December 31 of the preceding calendar year (calculated on a fully diluted basis), (ii) 929,658 common shares or (iii) a number determined by the Company’s board of directors that is less than (i) and (ii). The Company issued 135,472 and 191,020 shares of common stock under the ESPP during the six months ended June 30, 2025 and 2024, respectively. As of June 30, 2025, 2,310,693 shares of common stock remained available for issuance under the ESPP. Stock-based compensation expense related to the ESPP for the three and six months ended June 30, 2025 and 2024 was immaterial.

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance are as follows in common equivalent shares:

	June 30, 2025		December 31, 2024
Warrants for the purchase of common stock		9,679,158		9,679,158
Common stock options and restricted stock units issued and outstanding		8,518,984		7,649,046
Awards available for future issuance under the 2020 Plan		1,261,376		1,154,335
Awards available for future issuance under the ESPP		2,310,693		1,691,892
Total common stock reserved for future issuance		21,770,211		20,174,431