Stock-based Compensation

6 Months Ended

Jun. 30, 2023

Share-based Payment Arrangement [Abstract]

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, restricted stock units 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 June 30, 2023, the Company had restricted stock units and options outstanding to purchase

an aggregate of

2,805,840 shares of its common stock, which includes options outstanding under its prior incentive compensation plan, the 2006 Stock Plan. As of June 30, 2023, 670,634 shares were available for future issuance under the 2015 Stock Plan.

Stock Options

The following table summarizes stock option activity during the six months ended June 30, 2023:


	Shares			Weighted average exercise price
Outstanding at January 1, 2023		2,857,054		$	81.78
Options granted		5,205			283.08
Options exercised		(270,609	)		89.26
Options cancelled		(8,110	)		84.12

Outstanding at June 30, 2023		2,583,540		$	81.40

Exercisable at June 30, 2023		1,719,944		$	76.62

The total cash received by the Company as a result of stock option exercises was $21.8 million and $0 million, respectively, for the six months ended June 30, 2023 and 2022. The total intrinsic value of options exercised was $48.9 million and $0 million, respectively, for the six months ended June 30, 2023 and 2022. The weighted-average grant date fair values, based on the Black-Scholes option model, of options granted during the six months ended June 30, 2023 and 2022 were $219.02 and $55.84, respectively.

Restricted Stock Units

The Company’s share-based compensation plan provides for awards of restricted stock units to employees, officers, directors and consultants to the Company. Restricted stock units vest over the service period, and are subject to forfeiture if employment or service terminates before vesting. As of June 30, 2023, the Company had 222,300 restricted stock units outstanding, with a weighted average grant date fair value of $294.19 per unit.

Stock-Based Compensation Expense

Stock-based compensation expense during the six months ended June 30, 2023 and 2022 was as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Stock-based compensation expense by type of award:
Stock options	$	7,431	$	7,944	$	16,029	$	15,421
Restricted stock units		3,542		—		6,194		—

Total stock-based compensation expense	$	10,973	$	7,944	$	22,223	$	15,421

Effect of stock-based compensation expense by line item:
Research and development	$	5,184	$	3,301	$	10,570	$	6,488
General and administrative		5,789		4,643		11,653		8,933

Total stock-based compensation expense included in net loss	$	10,973	$	7,944	$	22,223	$	15,421

Unrecognized stock-based compensation expense as of June 30, 2023 was $98.2 million with a weighted average remaining period of 2.90 years.