Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Stock Option Activity

A summary of stock option activity was as follows (in thousands, except weighted-average exercise price and contractual term amounts):

	Options Outstanding
	Number of Shares Underlying Outstanding Options			Weighted- Average Exercise  Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding — December 31, 2021		416		$	123.57
Options granted		157		$	8.27
Options cancelled		(86	)	$	98.78
Outstanding — June 30, 2022		487		$	90.74		7.01	$	—
Exercisable — June 30, 2022		275		$	132.11		5.35	$	—

Summary of Restricted Stock Unit Activity

A summary of restricted stock unit activity was as follows (in thousands, except weighted-average grant-date fair value and contractual term amounts):

	Stock Awards (PSUs and RSUs)
	Shares			Weighted- Average Grant-Date Fair Value		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding — December 31, 2021		35		$	57.24
RSUs — Awarded		1		$	10.15
PSUs and RSUs — Vested		(17	)	$	59.32
PSUs and RSUs — Cancelled		(4	)	$	56.94
Outstanding — June 30, 2022		15		$	52.67		1.64	$	37

2010 Equity Incentive Plan, 2014 Equity Incentive Plan, 2018 Inducement Plan and 2014 Employee Stock Purchase Plan

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Stock Based Compensation Expense

Total stock-based compensation expense related to the Company’s 2010 Equity Incentive Plan, 2014 Equity Incentive Plan, 2018 Inducement Plan, and the 2014 Employee Stock Purchase Plan was as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	456	$	1,588	$	954	$	2,868
General and administrative		519		1,056		1,201		2,471
Total stock-based compensation	$	975	$	2,644	$	2,155	$	5,339