v3.26.1
Stock-Based Compensation
 6 Months Ended
Jun. 30, 2026
Share-Based Payment Arrangement [Abstract]  
Stock-Based Compensation Stock-Based Compensation
Equity Incentive Plans
In July 2021, our board of directors adopted, and our stockholders approved, the 2021 Equity Incentive Plan (“2021 Plan”) that became effective on July 22, 2021. As of June 30, 2026, we had 9,524,119 shares available for future issuances under the 2021 Plan.
Stock Options
The following table summarizes stock option activity, including performance-based stock options (“PBSOs”), under our equity incentive plans during the six months ended June 30, 2026:
Stock Options and PBSOs
Weighted-
Average
Exercise Price		Weighted-
Average
Remaining
Contractual
Term (years)
Aggregate
Intrinsic Value (in thousands)(1)
Outstanding as of December 31, 202512,511,072$5.49 7.6$466 
Options granted3,472,9271.80 
Options exercised(15,456)1.34 
Options cancelled or forfeited(174,210)3.49 
Outstanding as of June 30, 202615,794,333$4.70 7.6$913 
Exercisable as of June 30, 20268,359,997$6.66 6.5$375 
Vested and expected to vest as of June 30, 202615,794,333$4.70 7.6$913 
(1)The aggregate intrinsic value is calculated as the difference between the stock option exercise price and the estimated fair value of the underlying common stock as of the end of each reporting period referenced above.
Grant Date Fair Value of Stock Options
During the three months ended June 30, 2026, we did not grant any stock options. During the three months ended June 30, 2025, we granted 29,400 stock options under the 2021 Plan to employees with a weighted average grant date fair value of $0.83.
During the six months ended June 30, 2026, and June 30, 2025, we granted 3,472,927 and 3,365,288 stock options, respectively, under the 2021 Plan to employees with a weighted average grant date fair value of $1.36 and $1.07, respectively.
We estimated the fair value of each employee stock option award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:
Three Months Ended June 30,Six Months Ended June 30,
2026202520262025
Volatility—
88.4%
89.9% to 90.6%
86.1% to 89.7%
Expected term (in years)—
6.0
5.0 to 6.0
5.0 to 6.0
Risk-free interest rate—
4.2%
3.7% to 3.8%
4.2% to 4.6%
Expected dividend yield—0.0%
0.0%
0.0%
As of June 30, 2026, there was $11.5 million of unrecognized stock-based compensation expense related to employee stock options that is expected to be recognized over a weighted-average period of 2.6 years.
Grant Date Fair Value of PBSOs
On July 21, 2025, we granted a total of 1,092,165 PBSOs under the 2021 Plan to our officers with a weighted average grant date fair value of $1.00. We estimated the fair value of each PBSO on the grant date using the Black-Scholes option-pricing model based on a volatility of 88.7%, expected term of 1.9 years, risk-free interest rate of 3.9%, and expected dividend yield of 0.0%. Vesting of the PBSOs is conditioned on achievement of certain clinical development milestones during a two-year performance period ending June 30, 2027, and contingent on each executive officer’s continued employment on the vesting dates. As of June 30, 2026, there were 1,092,165 PBSOs outstanding with a weighted average grant date fair value of $1.00. As of June 30, 2026, we have concluded that it is not yet deemed probable, as required by ASC Topic 718 Compensation - Stock Compensation, that the clinical milestones will be achieved, and as such, no stock-based compensation expense has been recorded for PBSOs. As of June 30, 2026, there was $1.1 million of unrecognized stock-based compensation expense related to PBSOs, which will be recognized if the awards are deemed to be probable of vesting.
Restricted Stock Units (“RSUs”)
During the six months ended June 30, 2026, we granted 1,220,599 RSUs under the 2021 Plan to employees. A summary of the status of and change in unvested RSUs as of June 30, 2026, was as follows:
Number of Shares Underlying Outstanding RSUs
Weighted-Average Grant Date Fair Value per RSU
Unvested, December 31, 20252,173,234$2.74 
Granted1,220,5991.80
Vested(403,052)3.42
Forfeited(93,288)1.78
Unvested, June 30, 20262,897,493$2.28 
As of June 30, 2026, the total unrecognized stock-based compensation expense related to unvested RSUs was $5.4 million, which is expected to be recognized over the remaining weighted-average vesting period of 2.7 years.
Employee Stock Purchase Plan (“ESPP”)
In July 2021, our board of directors adopted, and our stockholders approved, the ESPP, which became effective on July 22, 2021. We issued 1,454,552 shares of common stock under the ESPP as of June 30, 2026. We recorded $0.3 million in accrued liabilities related to contributions withheld as of June 30, 2026.
Stock-Based Compensation Expense
We recorded stock-based compensation expense related to employee equity-based awards grants as follows (in thousands):
Three Months Ended June 30,Six Months Ended June 30,
2026202520262025
Research and development$1,142 $1,298 $2,267 $3,041 
General and administrative1,335 1,831 2,567 3,970 
Total$2,477 $3,129 $4,834 $7,011 
The above stock-based compensation expense related to the following equity-based awards (in thousands):
Three Months Ended June 30,Six Months Ended June 30,
2026202520262025
Stock options$1,779 $2,645 $3,445 $5,820 
RSUs604 383 1,178 968 
ESPP94 101 211 223 
Total$2,477 $3,129 $4,834 $7,011