Stock-Based Compensation and Employee Stock Purchase Program (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Summary of Activity Under Stock Incentive Plans

The following is a summary of stock option information and weighted average exercise prices under the Company’s stock incentive plans (in thousands, except share data and price per share):

	Shares Subject to Outstanding Options			Weighted- Average Exercise Price Per Share		Aggregate Intrinsic Value
Outstanding — Balance at December 31, 2021		1,422,195		$	5.28	$	—
Options granted		326,108			0.91
Options exercised		—			—
Options forfeited		(31,366	)		3.13
Options expired		(7,385	)		15.07
Outstanding — Balance at March 31, 2022		1,709,552		$	4.44	$	161,253
Vested and expected to vest — March 31, 2022		1,518,077		$	4.77	$	118,914
Exercisable — March 31, 2022		777,274		$	7.24	$	—

Weighted-Average Fair Value Assumption of Stock Option Awards

The fair value of stock option awards was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumption:

	Three Months Ended March 31,
	2022			2021
Expected term (years)		6.08			6.03
Expected volatility		120	%		121	%
Risk-free interest rate		1.68	%		0.62	%
Dividend yield		—			—