Stock-based Compensation

9 Months Ended

Sep. 30, 2022

Share-based Payment Arrangement [Abstract]

Stock-based Compensation

8. Stock-based Compensation

The Company’s 2015 Stock Plan, as amended, is our primary equity incentive compensation plan through which equity based grants are awarded. The 2015 Stock Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock and other stock-based compensation awards to employees, officers, directors, and consultants of the Company. The administration of the 2015 Stock Plan is under the general supervision of the Compensation Committee of the Board of Directors. The terms of stock options awarded under the 2015 Stock Plan, in general, are determined by the Compensation Committee, provided the exercise price per share generally shall not be set at less than the fair market value of a share of the common stock on the date of grant and the term shall not be greater than ten years from the date the option is granted. As of September 30, 2022, the Company had options outstanding to purchase 3,026,163 shares of its common stock, which includes options outstanding under its prior incentive compensation plan, the 2006 Stock Plan. As of September 30, 2022, 936,704 shares were available for future issuance under the 2015 Stock Plan.

The following table summarizes stock option activity during the nine months ended September 30, 2022:

	Shares			Weighted average exercise price
Outstanding at January 1, 2022		2,301,574		$	78.90
Options granted		809,745			82.11
Options cancelled		(85,156	)		101.61
Outstanding at September 30, 2022		3,026,163		$	79.11
Exercisable at September 30, 2022		1,746,699		$	70.94

The total cash received by the Company as a result of stock option exercises was $0 million and $0.5 million, respectively, for the nine months ended September 30, 2022 and 2021. The total intrinsic value of options exercised was $0 million and $0.1 million, respectively, for the nine months ended September 30, 2022 and 2021. The weighted-average grant date fair values, based on the Black-Scholes option model, of options granted during the nine months ended September 30, 2022 and 2021 were $55.14 and $75.71, respectively.

Stock-Based Compensation Expense

Stock-based compensation expense during the nine months ended September 30, 2022 and 2021 was as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Stock-based compensation expense by type of award:
Stock options	$	8,122	$	6,241	$	23,543	$	20,517
Total stock-based compensation expense	$	8,122	$	6,241	$	23,543	$	20,517
Effect of stock-based compensation expense by line item:
Research and development	$	3,596	$	2,622	$	10,084	$	8,120
General and administrative		4,526		3,619		13,459		12,397
Total stock-based compensation expense included in net loss	$	8,122	$	6,241	$	23,543	$	20,517

Unrecognized stock-based compensation expense on stock options as of September 30, 2022 was $64.2 million with a weighted average remaining period of 2.80 years.