Share-Based Payments (Tables)

12 Months Ended

Dec. 31, 2019

Share-Based Payments

Schedule of allocation of share-based compensation expense

	Year ended December 31,
(in thousands)	2017		2018		2019
Research and development	$	2,128	$	1,406	$	2,138
Selling, general and administrative		3,604		3,748		7,610
Total	$	5,732	$	5,154	$	9,748

SOP 2015

Share-Based Payments

Summary of information regarding stock option awards

	2017		2018		2019
		Weighted		Weighted		Weighted
		average		average		average
		exercise		exercise		exercise	Aggregate
		price in		price in		price in	intrinsic
Stock Option Plan 2015	Options	$ per share	Options	$ per share	Options	$ per share	value
Outstanding as of January 1	1,794,360	7.83	3,044,899	8.35	2,842,913	8.34
Granted	1,458,300	9.02	—	—	—	—
Exercised	—	—	—	—	—	—
Forfeited	(207,761)	8.60	(201,986)	8.41	(552,319)	8.40
Outstanding as of December 31,	3,044,899	8.35	2,842,913	8.34	2,290,594	8.33	$	—
Vested and exercisable as of December 31,	989,656	7.68	1,844,590	8.10	1,984,911	8.20	$	—

Summary of assumptions used for valuation of options

Input parameters	2017
Expected volatility	55.6% ‑ 62.0%
Expected term of options	6.1 years
Risk-free interest rate	1.9% ‑ 2.1%
Expected dividend yield	—

2017 Share Incentive Plan

Share-Based Payments

Summary of information regarding stock option awards

	2017		2018		2019
		Weighted		Weighted		Weighted
		average		average		average
		exercise		exercise		exercise	Aggregate
		price in $		price in $		price in $	intrinsic
2017 Plan	Options	per share	Options	per share	Options	per share	value
Outstanding as of January 1	—	—	294,100	6.92	2,398,425	5.41
Granted	294,100	6.92	2,199,225	5.27	2,463,300	1.95
Exercised	—	—	—	—	—	—
Forfeited	—	—	(94,900)	6.75	(439,061)	4.79
Outstanding as of December 31,	294,100	6.92	2,398,425	5.41	4,422,664	3.55	—
Vested and exercisable as of December 31,	—	—	119,287	6.88	1,120,280	5.53	—

Summary of assumptions used for valuation of options

Input parameters	2017	2018	2019
Range of expected volatility	59.5% ‑ 63.0%	59.8% - 61.4%	61.4% - 63.1%
Expected term of options (in years)	6	6.1	6.0
Range of risk-free interest rate	1.9% ‑ 2.3%	2.6% - 3.0%	1.9% - 2.6%
Dividend yield	—	–	—

Summary of information regarding restricted stock awards

	2018		2019
		weighted		weighted
		average fair		average fair
2017 Plan	RSUs	value per share	RSUs	value per share
Outstanding as of January 1	—	—	1,222,100	3.31
Granted	1,241,450	3.36	479,000	1.90
Vested and issued	—	—	(657,581)	3.18
Forfeited	(19,350)	6.47	(141,833)	2.79
Outstanding as of December 31	1,222,100	3.31	901,686	3.69

2019 Inducement Plan

Share-Based Payments

Summary of information regarding stock option awards

		Weighted
		average
		exercise		Aggregate
		price in $		intrinsic
2019 Plan	Options	per share		value
Outstanding as of January 1, 2019	—	—
Granted	703,150	2.22
Exercised	—	—
Expired
Forfeited	(97,500)	2.69
Outstanding as of December 31, 2019	605,650	2.14	$	—
Vested and exercisable as of December 31, 2019	—	—	$	—

Summary of assumptions used for valuation of options

Input parameters
Range of expected volatility	61.6% - 63.7%
Expected term of options (in years)	6.1
Range of risk-free interest rate	1.4% - 2.3%
Dividend yield	—

Inducement Awards Outside of the 2019 Inducement Plan

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	—