Stock-Based Compensation

6 Months Ended

Jun. 30, 2022

Stock-Based Compensation

Stock-Based Compensation

(8)  Stock-Based Compensation

A summary of stock option activity for the six months ended June 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	1,570,900	$	22.79
Exercised	(29,910)	$	8.05
Canceled	(28,444)	$	36.24
Options outstanding at June 30, 2022	5,590,213	$	28.07	8.20
Options vested and expected to vest at June 30, 2022	5,428,921	$	28.25	8.17
Options exercisable at June 30, 2022	2,135,506	$	39.84	6.76
Shares available for grant under the 2021 Plan	1,761,761

The weighted average grant-date fair value of stock options granted during the three and six ended June 30, 2022 was $17.20 and $17.29, respectively.

The aggregate intrinsic value of stock options vested and expected to vest at June 30, 2022 was $48.6 million. The aggregate intrinsic value of stock options exercisable at June 30, 2022 was $26.2 million. As of June 30, 2022, total compensation cost related to non-vested employee, consultant and non-employee director stock options not yet recognized was approximately $51.2 million, net of estimated forfeitures, which is expected to be recognized as expense over a weighted average period of 3.0 years.

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

	Three months ended June 30,				Six months ended June 30,
	2022		2021		2022		2021
	(In thousands)				(In thousands)
Research and development	$	1,798	$	762	$	3,412	$	1,423
General and administrative		1,656		747		3,195		1,361
Total stock-based compensation expense	$	3,454	$	1,509	$	6,607	$	2,784

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

	Three months ended June 30,		Six months ended June 30,
	2022	2021	2022	2021
Expected stock price volatility	90 – 91%	97 – 98%	90 – 97%	97 – 98%
Expected option term	6.0 Years	6.0 Years	6.0 Years	6.0 Years
Risk-free interest rate	2.7 – 3.6%	1.2 – 1.3%	1.7 – 3.6%	0.8 – 1.3%
Expected dividend yield	None	None	None	None