Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Payments (Tables)

Stock-Based Payments (Tables)

9 Months Ended

Sep. 30, 2018

Summary of status of stock options and changes during the period

A summary of the status of stock options as of December 31, 2017 and September 30, 2018 and changes during the nine months ended September 30, 2018 is presented below:


					Aggregate
		Weighted		Remaining	Intrinsic
		Average		Contractual	Value
	Shares	Exercise Price		Life (in years)	(in thousands)
Outstanding at December 31, 2017	2,846,668	$	9.25	8.2	$	5,713
Granted	1,358,552		10.90
Exercised	(103,153)		4.73
Cancelled	(390,917)		10.95
Outstanding at September 30, 2018	3,711,150	$	9.80	8.1	$	9,358
Exercisable at September 30, 2018	1,354,815	$	7.50	6.7	$	6,505

Schedule of weighted-average assumptions used in Black-Scholes option-pricing model

The fair value of each stock option granted was estimated on the date of grant using the Black-Scholes option-pricing model based on the following weighted-average assumptions:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Weighted-average risk-free interest rate	2.87	%	2.04	%	2.49	%	2.03	%
Expected dividend yield	-	%	-	%	-	%	-	%
Expected option term (in years)	6.08		6.08		6.03		6.01
Volatility	89.71	%	90.84	%	90.34	%	87.22	%

Summary of stock-based compensation expense for stock options granted to employee and non-employees

The following table summarizes the stock-based compensation expense for stock options and restricted common stock granted to employees and non-employees recorded in the Company’s condensed consolidated statements of operations:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Research and development	$	550	$	443	$	1,785	$	1,221
General and administrative		987		665		3,192		1,927
Total stock-based compensation expense	$	1,537	$	1,108	$	4,977	$	3,148