Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of expenses relating to employee and non-employee stock-based awards

The Company’s results of operations include expenses relating to stock‑based awards as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Research and development	$	3,103	$	2,919	$	2,692
General and administrative		4,245		4,216		3,537
Total	$	7,348	$	7,135	$	6,229

Employee stock options

Schedule of fair value of share-based awards to employees was estimated using Black Scholes model

	Year Ended December 31,
	2019		2018		2017
Risk-free interest rate	1.9	%	2.8	%	2.1	%
Expected volatility	82.1	%	82.7	%	91.4	%
Expected term (in years)	6.0		6.0		6.0
Expected dividend yield	0	%	0	%	0	%