Stock-Based Awards (Tables)

12 Months Ended

Dec. 31, 2019

Stock-Based Awards

Schedule of Assumptions Used to Determine Fair Value of Stock Options Granted to Employees and Directors Presented on Weighted Average Basis

	Year Ended
	December 31,
	2019		2018		2017
Risk-free interest rate	2.25	%	2.65	%	2.00	%
Expected term (in years)	6		6		6
Expected volatility	87	%	102	%	102	%
Expected dividend yield	—	%	—	%	—	%

Schedule of Stock Option Activity

				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
	Shares Issuable	Exercise		Contractual	Intrinsic
	Under Options	Price		Term	Value
				(In years)
Outstanding as of December 31, 2018	5,230,831	$	8.67	7.5	$	654
Granted	3,985,025		4.06
Exercised	(28,583)		2.72
Forfeited	(1,266,856)		6.84
Outstanding as of December 31, 2019	7,920,417	$	6.67	7.6	$	704
Options vested and expected to vest as of December 31, 2019	7,065,332	$	6.96	7.3	$	—
Options exercisable as of December 31, 2019	3,790,742	$	8.67	6.0	$	651

Schedule of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock

	Year Ended December 31,
	2019		2018		2017
Research and development	$	2,312	$	2,557	$	2,584
Selling and marketing		1,013		449		633
General and administrative		5,434		4,477		4,104
	$	8,759	$	7,483	$	7,321