Share-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Share-Based Compensation

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
	March 31,
	2018		2017
General and administrative	$	711	$	569
Research and development		309		267
Total share-based compensation	$	1,020	$	836

Schedule of weighted-average assumptions, option-pricing model

The weighted‑average assumptions used in the Black‑Scholes option‑pricing model are as follows:

	Three Months Ended
	March 31,
	2018		2017
Expected stock price volatility	66.5	%	65.1	%
Expected life of options (years)	5.8		6.1
Expected dividend yield	0	%	0	%
Risk free interest rate	2.5	%	2.1	%