STOCKHOLDERS' EQUITY (Tables)

6 Months Ended

Jun. 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	2,425,652		14.70
Exercised	(163,579)		8.65
Expired/Cancelled	(263,432)		29.78
Outstanding at June 30, 2022	14,519,506	$	23.42	7.61	$	6,993
Ending vested and expected to vest at June 30, 2022	14,519,506	$	23.42	7.61	$	6,993
Options exercisable at June 30, 2022	8,319,230	$	21.45	6.61	$	6,794

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	(102,275)		18.90
Outstanding, non-vested as of June 30, 2022	2,499,178	$	14.79

Schedule of stock-based compensation

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
Research and development	$	13,940	$	8,585	$	27,591	$	17,787
General and administrative		8,528		5,829		17,142		13,568
Total stock-based compensation expense	$	22,468	$	14,414	$	44,733	$	31,355

Schedule of stock-based compensation by type of award

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
Stock option expense	$	15,130	$	12,783	$	29,997	$	29,443
Restricted stock expense		7,084		1,099		14,246		1,099
ESPP expense		254		532		490		813
Total stock-based compensation expense	$	22,468	$	14,414	$	44,733	$	31,355