Stock-based compensation (Tables)

6 Months Ended

Jun. 30, 2026

Share-Based Payment Arrangement [Abstract]

Schedule of stock-based compensation expense

Total stock-based compensation recorded in the condensed statements of operations and comprehensive loss related to stock options, restricted stock units and the ESPP (defined below) for employees and non-employees was as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Stock options	$	2,623	$	1,316	$	4,096	$	2,539
Restricted stock units		1,046		282		1,384		531
Employee stock purchase plan		22		—		50		—
Total stock-based compensation expense	$	3,691	$	1,598	$	5,530	$	3,070
Included in:
General and administrative expense	$	1,726	$	1,366	$	3,259	$	2,614
Research and development expense		1,965		232		2,271		456
Total stock-based compensation expense	$	3,691	$	1,598	$	5,530	$	3,070

During the three months ended June 30, 2026, the Company recognized $1.6 million of incremental stock-based compensation expense in Research and Development expense within the condensed statements of operations and comprehensive loss pertaining to the implicit modification of certain stock options and restricted stock units for a former executive, who continues to act as a service provider.

Schedule of option activity transactions

The following table summarizes stock option activity for the six months ended June 30, 2026 (in thousands, except share and per share data):


						Weighted-
	Number of					Average
	Shares			Weighted-		Remaining
	Underlying			Average		Contractual		Aggregate
	Outstanding			Exercise		Term		Intrinsic
	Options			Price		(in Years)		Value (1)
Outstanding, January 1, 2026		5,722,326		$	6.12		7.1	$	3,799
Granted		1,883,942		$	6.32
Exercised		(15,056	)	$	6.36
Forfeited/expired		(20,282	)	$	5.23
Outstanding, June 30, 2026 (2)		7,570,930		$	6.17		7.3	$	13,928
Vested and expected to vest, June 30, 2026		7,570,930		$	6.17		7.3	$	13,928
Exercisable at June 30, 2026		4,336,591		$	6.44		6.0	$	7,279

(1)

Aggregate intrinsic value represents the difference between the fair value of the Company’s Series A common stock on the last day of the fiscal period and the exercise price, multiplied by the number of options outstanding.

(2)

Includes 462,411 performance-based options with a weighted-average exercise price of $6.44, all of which were fully vested and exercisable.

Schedule of restricted stock unit activity

The following table summarizes restricted stock unit activity:


				Weighted-Average
	Restricted			Grant Date
	Stock Units			Fair Value
Outstanding, January 1, 2026		830,077		$	3.57
Granted		360,540			5.38
Vested/released		(63,508	)		4.71
Outstanding June 30, 2026		1,127,109		$	4.08

Schedule of fair value assumptions

The fair value of each stock option granted was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:


	Six Months Ended June 30,
	2026		2025
Expected volatility	93 - 97 %		95 - 96 %
Risk-free interest rate	3.8 - 4.3 %		4.1 - 4.3 %
Dividend yield		—		—
Expected term (in years)	5.3 - 6.1		5.3 - 6.0