Share-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-Based Compensation

Schedule of share option activity under the Plans

		Weighted
	Number of	Average
	Shares	Fair Value
Outstanding as of December 31, 2019	8,491,734	$	7.68
Granted	1,956,670	$	11.66
Exercised	(1,080,425)	$	3.01
Forfeited	(684,599)	$	11.30
Outstanding as of June 30, 2020	8,683,380	$	8.88
Options exercisable as of June 30, 2020	3,068,290	$	8.56
Options unvested as of June 30, 2020	5,615,090	$	10.02

Schedule of stock option valuation assumptions presented on weighted-average basis

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Risk-free interest rate	0.39	%	2.16	%	0.71	%	2.48	%
Expected term (in years)	5.99		5.97		6.18		6.18
Expected volatility	79.38	%	78.88	%	79.71	%	78.35	%
Expected dividend yield	—	%	—	%	—	%	—	%

Schedule of restricted share activity

		Weighted
		Average
	Number of	Grant Date
	Shares	Fair Value
Unvested RSUs as of December 31, 2019	328,296	$	12.93
Granted	5,211	$	17.79
Vested	—	$	—
Forfeited	(46,780)	$	12.93
Unvested RSUs as of June 30, 2020	286,727	$	13.01

Schedule of share-based compensation expense was classified in the consolidated statements of operations and comprehensive loss

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Research and development expenses	$	2,189	$	1,504	$	3,958	$	2,691
General and administrative expenses		2,662		1,960		5,102		3,666
	$	4,851	$	3,464	$	9,060	$	6,357