Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Stock-Based Compensation

Summary of stock option activity under the Company's Equity Incentive Plans

		Weighted
		Average		Weighted	Aggregate
		Exercise Price		Average Remaining	Intrinsic
	Options	Per Share		Life in Years	Value
Outstanding at December 31, 2016	53,228	$	4.93	7.00	$	213
Granted	2,220,858	$	12.51
Exercised	(3,506)	$	5.55
Forfeited	(12,959)	$	5.78
Outstanding at December 31, 2017	2,257,621	$	12.38	8.66	$	68
Granted	599,050	$	6.68
Exercised	(2,478)	$	5.56
Forfeited	(92,281)	$	7.89
Outstanding at December 31, 2018	2,761,912	$	11.30	8.01	$	—
Options exercisable at December 31, 2018	1,599,633	$	13.90	7.40	$	—
Options vested and expected to vest at December 31, 2018	2,761,912	$	11.30	8.01	$	—

Schedule of assumptions used to determine grant-date fair value of stock options

	Year Ended		Year Ended
	December 31,		December 31,
	2018		2017
Expected volatility	66.94	%	68.70	%
Weighted average risk-free interest rate	2.80	%	2.10	%
Expected dividend yield	0.00	%	0.00	%
Expected term (in years)	6.95		6.6

Schedule of stock-based compensation expense classified in the consolidated statements of operations

	Year Ended
	December 31,
	2018		2017
Research and development	$	625	$	1,834
General and administrative		2,844		3,766
Total	$	3,469	$	5,600