XML 26 R14.htm IDEA: XBRL DOCUMENT v3.25.2
Stock-Based Compensation
 6 Months Ended
Jun. 30, 2025
Share-Based Payment Arrangement [Abstract]  
Stock-Based Compensation Stock-Based Compensation
Employee Stock Purchase Plan
In May 2017, the Company’s stockholders approved the 2016 Employee Stock Purchase Plan (the 2016 ESPP). The 2016 ESPP is structured as a qualified employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended, and is not subject to the provisions of the Employee Retirement Income Security Act of 1974. The Company reserved 800,000 shares of common stock for issuance under the 2016 ESPP. The 2016 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 10% of their eligible compensation, subject to any plan limitations. The 2016 ESPP provides for six-month offering periods ending on May 31 and November 30 of each year. At the end of each offering period, employees are able to purchase shares at 85% of the fair market value of the Company’s common stock on the last day of the offering period. During the six months ended June 30, 2025 and 2024, 56,880 and 44,129 shares of common stock were purchased under the 2016 ESPP, respectively.
Employee Stock Incentive Plans
In October 2013, the Company implemented the 2013 Equity Incentive Plan (2013 Plan). In May 2023, the 2013 Plan was terminated, and no further awards may be issued under the plan. If an option granted under the 2013 Plan expires or terminates for any reason without having been fully exercised, if any shares of restricted stock are forfeited, or if any award terminates, expires or is settled without all or a portion of the shares of common stock covered by the award being issued, such shares will become available for issuance under the 2023 Equity Incentive Plan (2023 Plan).
The 2023 Plan was effective as of stockholder approval in May 2023. The 2023 Plan provides for grants of stock options and other stock-based awards, as well as cash-based performance awards. The 2023 Plan originally authorized the issuance of up to an aggregate of 4,850,000 shares of common stock. In May 2024 and May 2025, the board and stockholders of the Company approved amendments to the 2023 Plan to increase the number of shares of common stock available to a total of 8,100,000 shares. If an option expires or terminates for any reason without having been fully exercised, if any shares of restricted stock are forfeited, or if any award terminates, expires or is settled without all or a portion of the shares of common stock covered by the award being issued, such shares are available for the grant of additional awards. However, any shares that are withheld (or delivered) to pay withholding taxes or to pay the exercise price of an option are not available for the grant of additional awards.
The following stock-based compensation expense was recognized for the periods indicated (in thousands):
Three Months Ended June 30,Six Months Ended June 30,
2025202420252024
Research and development$2,237 $3,264 $5,320 $6,093 
Selling, general and administrative1,453 3,387 2,756 6,111 
Total stock-based compensation expense$3,690 $6,651 $8,076 $12,204 
Employee stock options
The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated:
Six Months Ended June 30,
20252024
Expected dividend yield0%0%
Expected volatility
110.7% - 115.6%
94.9% - 114.3%
Risk-free interest rate
3.9% - 4.5%
4.0% - 4.7%
Expected term6.11 years6.06 years
The following table summarizes stock option activity during the six months ended June 30, 2025:
SharesWeighted-
Average
Exercise Price		Weighted-Average
Remaining
Contractual Term
(Years)		Aggregate
Intrinsic
Value
 (in thousands)
Outstanding, December 31, 202412,939,517 $14.80 6.4
Granted2,093,044 2.40 
Exercised— — 
Forfeited(276,402)9.55 
Expired(96,765)22.04 
Outstanding, June 30, 202514,659,394 $13.08 6.4$— 
As of June 30, 2025:
Exercisable10,148,089 $15.81 5.4$— 
Vested and expected to vest14,304,994 $9.43 6.3$— 
As of June 30, 2025, the total unrecognized compensation expense related to unvested stock options, net of related forfeiture estimates, was approximately $18.1 million, which the Company expects to recognize over a weighted-average period of approximately 1.3 years. The following table summarizes additional information on stock options (in thousands, except per share amounts):
Six Months Ended June 30,
20252024
Weighted-average fair value per share of stock options granted
$2.03 $12.99 
Total intrinsic value of stock options exercised
$— $2,615 
Total cash received for stock options exercised
$— $3,117 
Total grant date fair value of stock options vested
$9,494 $7,344 
Restricted Stock Units
Restricted stock units (RSUs) are valued based on the closing price of the Company’s common stock on the date of the grant. The fair value of RSUs is recognized and amortized on a straight-line basis over the requisite service period of the award.
The following table summarizes RSU activity during the six months ended June 30, 2025:
Shares
Weighted-Average
Grant Date Fair Value
Outstanding, December 31, 20241,068,994 $11.97 
Granted349,420 2.49 
Vested(491,146)10.71 
Forfeited(78,029)10.25 
Outstanding, June 30, 2025849,239 $8.96 

At June 30, 2025, there was $5.1 million of total unrecognized compensation cost related to unvested RSUs, which the Company expects to recognize over a remaining weighted-average period of approximately 1.2 years.