Convertible Preferred Stock and Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2023

Convertible Preferred Stock And Stockholders Equity Disclosure [Abstract]

Summary of stock option activity and related information under all equity plans

The following table summarizes stock option activity and related information under all equity plans for the year ended June 30, 2023:

	Number of Options			Weighted- Average Price
Balance at December 31, 2022		7,267,226		$	22.37
Granted		5,430,000			6.69
Exercised		(93,787	)		3.24
Cancelled		(1,106,618	)		35.85
Balance at June 30, 2023		11,496,821		$	13.82

Summary of restricted stock unit activity under the Plan

Restricted stock unit activity under all equity and stock option plans is summarized as follows:

	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value per Share
Balance at December 31, 2022		5,862,733		$	48.13
Granted		1,136,340			6.73
Vested		(966,809	)		42.38
Cancelled		(2,252,363	)		45.68
Balance at June 30, 2023		3,779,901		$	38.53

Schedule of allocation of stock-based compensation for all stock awards

The allocation of stock-based compensation for all stock awards is as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Research and development	$	6,851	$	13,570	$	11,907	$	26,264
General and administrative		6,046		6,972		11,973		13,609
Total	$	12,897	$	20,542	$	23,880	$	39,873

Schedule of weighted-average assumptions used to determine the fair value of employee and nonemployee stock option grants

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows:

	Six Months Ended June 30,
	2023			2022
Risk-free interest rate		3.8	%		1.9	%
Expected volatility		89.6	%		76.2	%
Expected term (in years)		6.5			5.8
Expected dividend yield		0.0	%		0.0	%

Summary of changes in stockholders' equity

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three and six months ended June 30, 2023 (in thousands, except share data):

	Convertible Preferred Stock					Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares			Amount		Shares		Amount		Capital		Gain (Loss)			Deficit			Equity
Balance at December 31, 2022		2,794,549		$	3		97,294,917	$	97	$	1,536,497	$	(1,854	)	$	(1,050,804	)	$	483,939
Exercise of stock options, net of issuance costs		—			—		68,847		—		222		—			—			222
Issuance of common stock upon vesting of restricted stock units		—			—		827,251		1		—		—			—			1
Stock-based compensation		—			—		—		—		10,983		—			—			10,983
Unrealized gain on investments		—			—		—		—		—		1,208			—			1,208
Net loss		—			—		—		—		—		—			(18,881	)		(18,881	)
Balance at March 31, 2023		2,794,549		$	3		98,191,015	$	98	$	1,547,702	$	(646	)	$	(1,069,685	)	$	477,472
Exercise of stock options, net of issuance costs		—			—		24,940		—		81		—			—			81
Issuance of common stock upon vesting of restricted stock units		—			—		139,558		—		—		—			—			—
Conversion of preferred shares to common stock		(33,441	)		—		167,205		1		—		—			—			1
Stock-based compensation		—			—		—		—		12,897		—			—			12,897
Unrealized gain on investments		—			—		—		—		—		59			—			59
Net loss		—			—		—		—		—		—			(52,755	)		(52,755	)
Balance at June 30, 2023		2,761,108		$	3		98,522,718	$	99	$	1,560,680	$	(587	)	$	(1,122,440	)	$	437,755

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three and six months ended June 30, 2022 (in thousands, except share data):

	Convertible Preferred Stock				Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares		Amount		Shares		Amount		Capital		Gain (Loss)			Deficit			Equity
Balance at December 31, 2021		2,794,549	$	3		95,726,962	$	96	$	1,448,584	$	(762	)	$	(769,083	)	$	678,838
Exercise of stock options, net of issuance costs		—		—		398,415		—		3,001		—			—			3,001
Issuance of common stock upon vesting of restricted stock units		—		—		412,707		1		—		—			—			1
Stock-based compensation		—		—	—			—		19,331		—			—			19,331
Unrealized loss on investments		—		—		—		—		—		(2,088	)		—			(2,088	)
Net loss		—		—		—		—		—		—			(65,690	)		(65,690	)
Balance at March 31, 2022		2,794,549	$	3		96,538,084	$	97	$	1,470,916	$	(2,850	)	$	(834,773	)	$	633,393
Exercise of stock options, net of issuance costs		—		—		251,486		—		3,184		—			—			3,184
Issuance of common stock upon vesting of restricted stock units		—		—		73,227		—		—		—			—			—
Stock-based compensation		—		—		—		—		20,542		—			—			20,542
Unrealized loss on investments		—		—		—		—		—		(531	)		—			(531	)
Net loss		—		—		—		—		—		—			(76,105	)		(76,105	)
Balance at June 30, 2022		2,794,549	$	3		96,862,797	$	97	$	1,494,642	$	(3,381	)	$	(910,878	)	$	580,483