Stock-Based Compensation

9 Months Ended

Sep. 30, 2022

Stock-Based Compensation

Stock-Based Compensation

(8)  Stock-Based Compensation

A summary of stock option activity for the nine months ended September 30, 2022 is as follows:

		Weighted		Weighted
		Average		Average
		Exercise		Remaining
		Price		Contractual
	Shares	Per Share		Term (In Years)
Options outstanding at December 31, 2021	4,077,667	$	30.02	8.0
Granted	1,584,900	$	22.89
Exercised	(353,622)	$	6.71
Canceled	(118,974)	$	50.12
Options outstanding at September 30, 2022	5,189,971	$	28.97	8.07
Options vested and expected to vest at September 30, 2022	5,031,072	$	29.21	8.05
Options exercisable at September 30, 2022	1,985,506	$	41.56	6.74
Shares available for grant under the 2021 Plan	1,838,291

The weighted average grant-date fair value of stock options granted during the three and nine months ended September 30, 2022 was $25.38 and $17.36, respectively.

The aggregate intrinsic value of stock options vested and expected to vest at September 30, 2022 was $45.6 million. The aggregate intrinsic value of stock options exercisable at September 30, 2022 was $23.6 million. As of September 30, 2022, total compensation cost related to non-vested employee, consultant and non-employee director stock options not yet recognized was approximately $46.7 million, net of estimated forfeitures, which is expected to be recognized as expense over a weighted average period of 2.8 years.

Stock-based compensation expense for the three and nine months ended September 30, 2022 and 2021 was recorded as follows:

	Three months ended September 30,				Nine months ended September 30,
	2022		2021		2022		2021
	(In thousands)				(In thousands)
Research and development	$	2,342	$	1,504	$	5,754	$	2,927
General and administrative		2,154		1,525		5,349		2,886
Total stock-based compensation expense	$	4,496	$	3,029	$	11,103	$	5,813

The fair values of employee, consultant and non-employee director stock options granted during the three and nine months ended September 30, 2022 and 2021 were valued using the Black-Scholes option pricing model with the following assumptions:

	Three months ended September 30,		Nine months ended September 30,
	2022	2021	2022	2021
Expected stock price volatility	91%	98%	90 – 97%	97 – 98%
Expected option term	6.0 Years	6.0 Years	6.0 Years	6.0 Years
Risk-free interest rate	2.9 – 3.5%	1.1 – 1.2%	1.7 – 3.6%	0.8 – 1.3%
Expected dividend yield	None	None	None	None