As of June 30, 2026, there is an aggregate of approximately 2.3 million shares of common stock available for issuance under the Company’s equity incentive plans, including 0.1 million shares of common stock remaining available for issuance under the Amended and Restated 2017 Employee Stock Purchase Plan.

The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted:


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Risk-free interest rate	4.2	%	4.0	%	3.8	%	4.2	%
Expected term (in years)	6.1		6.1		6.0		6.1
Expected volatility	108.5	%	103.7	%	109.8	%	103.8	%
Expected dividend yield	0	%	0	%	0	%	0	%

As of June 30, 2026, total unrecognized compensation expense related to unvested stock options and restricted stock units was $18.9 million, which is expected to be recognized over a weighted average period of 2.6 years.

The following table summarizes the Company’s stock option activity for the six months ended June 30, 2026:


	Number of Shares	Weighted Average Exercise Price		Weighted Average Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2025	12,080,718	$	2.34	9.6	$	28,329
Granted	4,020,000	4.01

Forfeited and expired	(767,283)	7.68			$	—
Outstanding as of June 30, 2026	15,333,435	$	2.51	9.2	$	38,490
Exercisable as of June 30, 2026	1,030,803	$	6.39	9.0	$	2,687
Vested and expected to vest as of June 30, 2026	12,858,006	$	2.53	9.2	$	32,770

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock to the extent the stock option had a lower exercise price. There were no options exercised for the six months ended June 30, 2026 and 2025. The weighted average grant-date fair value per share of stock options granted during the six months ended June 30, 2026 and 2025 was $3.37 and $8.13, respectively.

The following table summarizes the Company’s restricted stock unit activity for the six months ended June 30, 2026:


	Number of Shares	Weighted-Average Grant Date Fair Value
Unvested as of December 31, 2025	73,381	$	15.48
Granted	773,016	4.50
Vested	(115,403)	5.06
Forfeited	(16,759)	20.05
Unvested as of June 30, 2026	714,235	$	5.25

Outstanding restricted stock units include performance-based restricted stock units (“PRSUs”), which will vest based on the achievement of an operational milestone. The Company considers the achievement of the remaining operational milestone

related to outstanding PRSUs to be probable. Stock-based compensation expense has been recognized for these awards using the accelerated attribution model based on the fair value of the awards as of the date of grant and management’s best estimate of the date the probable operational milestone will be achieved. The Company updates its estimates related to the probability and timing of achievement of the operational milestones each period until the award either vests or is forfeited.

Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2026		2025		2026		2025
Research and development expense	$	484	$	340	$	1,199	$	599
General and administrative expense	2,602		408		4,300		668
Total stock-based compensation	$	3,086	$	748	$	5,499	$	1,267