Share-based compensation (Tables)

9 Months Ended

Sep. 30, 2018

Share-based compensation

Schedule of share-based compensation expense by classification included in consolidated statements of operations and comprehensive loss

	Three months ended September 30,				Nine months ended September 30,
	2018		2017		2018		2017
	in thousands
Research and development	$	895	$	1,131	$	2,694	$	2,612
Selling, general and administrative		1,724		1,316		4,657		3,366
Total	$	2,619	$	2,447	$	7,351	$	5,978

Schedule of share-based compensation expense

	Three months ended September 30,				Nine months ended September 30,
	2018		2017		2018		2017
	in thousands
Award type
Share options	$	1,160	$	638	$	3,315	$	2,347
Restricted share units (“RSUs”)		667		728		1,953		1,960
Performance share units (“PSUs”)		792		1,081		2,083		1,671
Total	$	2,619	$	2,447	$	7,351	$	5,978

Schedule of unrecognized compensation cost related to unvested awards

			Weighted-average
	Unrecognized		remaining
	compensation		period for
	costs		recognition
Award type	in thousands		in years
Share options	$	15,651	3.29
Restricted share units		4,994	1.15
Performance share units		5,472	1.84
Total	$	26,117	2.58

Schedule of weighted-average assumptions for fair value of option issued

	Three months ended September 30,		Nine months ended September 30,
Assumptions	2018	2017	2018	2017
Expected volatility	80%	80%	80%	75%-80%
Expected terms (in years)	10 years	10 years	10 years	10 years
Risk-free interest rate	3.10%	2.40% - 2.48%	2.67% - 3.10%	2.40% - 2.81%
Expected dividends	0%	0%	0%	0%

Summary of RSUs activity

		RSU
			Weighted average
			grant-date fair
	Number of shares		value
Non-vested at December 31, 2017		683,663	$	6.38
Granted		262,599	$	23.61
Vested		(276,833)	$	5.99
Forfeited		(189,708)	$	8.00
Non-vested at September 30, 2018		479,721	$	15.40
Total weighted average grant date fair value of RSUs granted during the period (in millions)			$	6.2
Granted to directors and officers during the period (shares, $ in millions)		133,808	$	3.3

Summary of PSUs activity

		PSU
			Weighted average
			grant-date fair
	Number of shares		value
Non-vested at December 31, 2017		511,074	$	16.73
Granted		—	$	—
Vested		(68,115)	$	15.79
Forfeited		(73,068)	$	18.85
Non-vested at September 30, 2018		369,891	$	16.74
PSUs awarded but not yet earned		117,197	$	36.39
Total non-vested and discretionary PSUs		487,088	$	21.47
Total weighted average grant date fair value of PSUs awarded during the period (in millions)			$	4.3

2014 Plan

Share-based compensation

Summary of option activity

		Weighted average
	Options	exercise price
Outstanding at December 31, 2017	2,456,433	$	10.06
Granted	906,582	$	26.05
Forfeited	(266,222)	$	13.18
Expired	(9,915)	$	13.49
Exercised	(379,340)	$	11.42
Outstanding at September 30, 2018	2,707,538	$	14.91
Fully vested and exercisable at September 30, 2018	977,409	$	11.03
Outstanding and expected to vest at September 30, 2018	1,730,129	$	17.10
Total weighted average grant date fair value of options issued during the period (in $ millions)		$	15.8
Granted to directors and officers during the period (options, $ in millions)	315,156	$	4.7
Proceeds from option sales (in $ millions)		$	4.6