In 2015, the Company's board of directors adopted the 2015 Equity Incentive Plan, as amended in 2018, 2019 and 2020 (the “2015 Plan”), which provided for the grant of incentive stock options, nonqualified stock options or other awards including stock appreciation rights and restricted stock awards to the Company’s employees, officers, directors, advisors, and consultants. In May 2020, the board of directors adopted the 2020 Stock Option and Incentive Plan (the “2020 Plan”) and suspended the 2015 Plan. Awards outstanding under either the 2015 Plan or 2020 Plan that are cancelled, expire or otherwise terminated subsequent to May 2020 will become available for issuance as common stock under the 2020 Plan. Additionally, the 2020 Plan is subject to automatic increases on January 1 of each year beginning January 1, 2021. The number of shares added each January 1 will be equal to the lesser of: (i) 5% of the outstanding shares on the immediately preceding December 31 or (ii) such amount as determined by the compensation committee of the board of directors.

The 2020 Plan provides for the grant of incentive stock options, nonqualified stock options or other awards including stock appreciation rights, restricted stock awards and restricted stock units to the Company’s employees, officers, directors, advisors and consultants.

Options under the 2020 Plan and Inducement Plan may be granted for periods of up to 10 years and at prices no less than the market price of the Company’s common stock on the date of grant, provided, however, that the exercise price of an incentive stock option granted to a 10% shareholder shall not be less than 110% of the fair value of the shares on the date of grant and the option is not exercisable after the expiration of five years from the date of grant.

Stock options issued under either the 2015 Plan, the 2020 Plan or the Inducement Plan generally vest over four years and expire ten years from the date of grant. Certain options provide for accelerated vesting if there is a change in control, as defined in the respective plans.


	Three Months Ended June 30,		Six Months Ended June 30,
	2025	2024	2025	2024
Expected volatility	88.02% - 89.30%	85.58% - 86.46%	86.82% - 89.30%	85.28% - 86.46%
Risk-free interest rate	3.98% - 4.12%	4.17% - 4.60%	3.98% - 4.45%	4.04% - 4.60%
Expected dividend	—	—	—	—
Expected term (in years)	5.34 - 6.07	5.31 - 6.08	5.34 - 6.08	5.31 - 6.08
Underlying common stock fair value	$1.37 - $1.61	$11.51 - $15.36	$1.37 - $12.63	$11.51 - $17.44


	Number of Options	Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value
Outstanding as of December 31, 2024	8,300,804	$	17.23	7.49	$	13,769
Granted	2,271,680	$	9.68
Exercised	(4,921)	$	12.18
Forfeited	(1,530,487)	$	14.88
Outstanding as of June 30, 2025	9,037,076	$	15.73	6.78	$	—
Exercisable as of June 30, 2025	5,613,168	$	16.74	5.50	$	—
Vested and expected to vest as of June 30, 2025	9,037,076	$	15.73	6.78	$	—

As of June 30, 2025, there were $33.7 million of unrecognized compensation costs that are expected to be recognized over the weighted-average period of 2.6 years related to stock options. Aggregate intrinsic value represents the difference between the fair value of the underlying common stock and the exercise price as of June 30, 2025.


	Restricted Stock Units	Weighted Average Grant Date Fair Value
Unvested and outstanding as of December 31, 2024	932,634	$	24.28
Granted	840,341	$	10.67
Released	(370,437)	$	26.09
Forfeited	(341,888)	$	14.64
Unvested and outstanding as of June 30, 2025	1,060,650	$	15.97

Performance-based restricted stock units (“PSUs”) were granted in 2022 and vested upon the achievement of market and performance conditions. Market conditions include the Company's total shareholder return (“TSR”) relative to the Nasdaq Biotechnology Index over the term of the award ending on June 30, 2024. Additionally, the number of shares of common stock issuable upon vesting ranged from 0% to 200% of the PSUs based on achievement of certain targets.

The measurement period for the PSUs associated with TSR concluded on the last trading day of the second quarter 2024 and in July 2024, upon certification of the TSR results by the compensation committee of the board of directors, the award recipients vested in a total of 155,292 shares of common stock, representing 55% achievement. Such 155,292 shares of common stock were issued to award recipients as of September 30, 2024. There were no outstanding PSUs as of June 30, 2025.

In June 2020, the Company adopted the Company's 2020 Employee Stock Purchase Plan (the “2020 ESPP”). The 2020 ESPP provides that the number of shares reserved and available for issuance will automatically increase on January 1 of each calendar year, beginning January 1, 2021, by the least of (1) 1.0% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, (2) 700,000 shares or (3) such lesser amount as determined by the administrator of the 2020 ESPP, which is the compensation committee of the board of directors of the Company.

Under the 2020 ESPP, eligible employees may purchase shares of our common stock through payroll deductions that cannot exceed 15% of each employee’s salary. The 2020 ESPP provides for a six-month offering period. At the end of the purchase period, eligible employees are permitted to purchase shares of common stock at the lower of 85% of the fair market value at the beginning of the offering period or 85% of the fair market value at the end of the purchase period, subject to tax limitations on the total value of the purchase. The 2020 ESPP is considered a compensatory plan, and the Company recorded $0.1 million in stock-based compensation expense for both the three and six months ended June 30, 2025, and $0.1 million and $0.3 million for the three and six months ended June 30, 2024, respectively. During the three and six months ended June 30, 2025, 0 and 149,987 shares of common stock were issued respectively under the 2020 ESPP with 1,753,367 shares remaining available for issuance under the 2020 ESPP. The Company used Black-Scholes option pricing model to estimate stock-based compensation expense for the 2020 ESPP with the following assumptions:


	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Stock options and ESPP	$	4,406	$	6,287	$	10,367	12,645
Restricted stock units	1,976		3,314		4,927		6,560
Performance-based restricted stock units	—		1,043		—		1,105
Total stock-based compensation expense	$	6,382	$	10,644	$	15,294	$	20,310
Research and development expenses	$	1,935	$	4,102	$	5,637	$	7,172
General and administrative expenses	$	4,447	$	6,542	$	9,657	$	13,138