Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Schedule of share-based compensation expense

Share-based compensation expense was included in general and administrative and research and development expenses as follows in the accompanying condensed statements of comprehensive loss (in thousands):



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
		2018		2017		2018		2017
General and administrative	$	861	$	420	$	2,008	$	3,673
Research and development		766		316		1,548		862
Total share-based compensation	$	1,627	$	736	$	3,556	$	4,535

Schedule of weighted-average assumptions, option-pricing model

The weighted‑average assumptions used in the Black‑Scholes option‑pricing and Monte Carlo simulation models are as follows:


	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2018	2017	2018	2017

Expected stock price volatility	—	66.5%	66.3%	65.8%
Expected life of options (years)	—	6.1	5.8	5.9
Expected dividend yield	—	0%	0%	0%
Risk free interest rate	—	2.0%	2.7%	2.0%