Share-Based Payments (Tables)

12 Months Ended

Dec. 31, 2018

Share-Based Payments

Schedule of allocation of share-based compensation expense

	Year ended December 31,
(in thousands)	2016		2017		2018
Research and development	$	894	$	2,128	$	1,406
General and administrative		1,651		3,604		3,748
Total	$	2,545	$	5,732	$	5,154

SOP 2015

Share-Based Payments

Summary of information regarding stock option awards

	2016		2017		2018
	Weighted		Weighted		Weighted
	average		average		average
	exercise		exercise		exercise		Aggregate
	price in		price in		price in		intrinsic
Stock Option Plan 2015	$ per share	Options	$ per share	Options	$ per share	Options	value
Outstanding as of January 1	7.61	1,092,300	7.83	1,794,360	8.35	3,044,899
Granted	8.02	922,130	9.02	1,458,300	—	—
Exercised	7.21	(23,360)	—	—	—	—
Forfeited	7.64	(196,710)	8.60	(207,761)	8.41	(201,986)
Outstanding as of December 31	7.83	1,794,360	8.35	3,044,899	8.34	2,842,913	—
Vested and exercisable as of December 31	7.52	452,210	7.68	989,656	8.10	1,844,590	—

Summary of assumptions used for valuation of options

Input parameters	2016	2017
Expected volatility	59.8% - 67.2%	55.6% - 62.0%
Expected term of options	6.0 years	6.1 years
Risk-free interest rate	1.15% - 2.09%	1.89% - 2.10%
Expected dividend yield	–	–

2017 Share Incentive Plan

Share-Based Payments

Summary of information regarding stock option awards

	2017		2018
	Weighted		Weighted
	average		average
	exercise		exercise		Aggregate
	price in $		price in $		intrinsic
Stock Option Plan 2017	per share	Options	per share	Options	value
Outstanding as of January 1	—	—	6.92	294,100
Granted	6.92	294,100	5.27	2,199,225
Exercised	—	—	—	—
Forfeited	—	—	6.75	(94,900)
Outstanding as of December 31	6.92	294,100	5.41	2,398,425	—
Vested and exercisable as of December 31	—	—	6.88	119,287	—

Summary of assumptions used for valuation of options

Input parameters	2017	2018
Expected volatility	59.5% - 63.0%	59.8% - 61.4%
Expected term of options	6.0	6.1
Risk-free interest rate	1.93% - 2.27%	2.55% - 3.03%
Expected dividend yield	–	–

Inducement Awards

Share-Based Payments

Summary of assumptions used for valuation of options

Input parameters
Expected volatility	59.8	%
Expected term of options (in years)	6.1
Range of risk-free interest rate	2.9	%
Dividend yield	—