STOCKHOLDERS' EQUITY (Tables)

9 Months Ended

Sep. 30, 2022

STOCKHOLDERS' EQUITY

Schedule of status of stock options

				Weighted
		Weighted		Average	Aggregate
	Number	Average		Remaining	Intrinsic
	of	Exercise		Contract	Value
	Options	Price		Life	(in thousands)
Outstanding at December 31, 2021	12,520,865	$	25.05
Issued	2,976,652		14.24
Exercised	(203,579)		8.06
Expired/Cancelled	(434,264)		29.90
Outstanding at September 30, 2022	14,859,674	$	22.98	7.43	$	3,728
Ending vested and expected to vest at September 30, 2022	14,859,674	$	22.98	7.43	$	3,728
Options exercisable at September 30, 2022	8,916,117	$	22.22	6.43	$	3,633

Schedule of summary of RSU activity including PRSUs

		Weighted
	Number	Average
	of	Grant Date
	RSUs and PRSUs	Fair Value
Outstanding, non-vested as of December 31, 2021	1,110,010	$	23.87
Granted	2,386,203		14.15
Vested/Released	(894,760)		23.87
Canceled/Forfeited	(146,670)		18.13
Outstanding, non-vested as of September 30, 2022	2,454,783	$	14.76

Schedule of stock-based compensation

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2022		2021		2022		2021
Research and development	$	11,272	$	11,504	$	38,863	$	29,291
General and administrative		8,508		7,802		25,650		21,370
Total stock-based compensation expense	$	19,780	$	19,306	$	64,513	$	50,661

Schedule of stock-based compensation by type of award

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2022		2021		2022		2021
Stock option expense	$	14,270	$	13,339	$	44,267	$	42,782
Restricted stock expense		5,100		5,788		19,346		6,887
ESPP expense		410		179		900		992
Total stock-based compensation expense	$	19,780	$	19,306	$	64,513	$	50,661