Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Payments (Tables)

Stock-Based Payments (Tables)

6 Months Ended

Jun. 30, 2016

Summary of status of stock options and changes during the period

A summary of the status of stock options as of December 31, 2015 and June 30, 2016 and changes during the six months ended June 30, 2016 is presented below:


					Aggregate
		Weighted		Remaining	Intrinsic
		Average		Contractual	Value
	Shares	Exercise Price		Life (in years)	(in thousands)
Outstanding at December 31, 2015	2,226,698	$	3.83	8.8	$	11,185
Granted	190,051		9.58
Exercised	(239,006)		1.49
Cancelled	(148,341)		3.18
Outstanding at June 30, 2016	2,029,402	$	4.69	8.5	$	27,316
Exercisable June 30, 2016	500,633	$	1.60	7.4	$	8,286
Vested and expected to vest at June 30, 2016	2,029,402	$	4.69	8.5	$	27,316

Summary of status of unvested restricted common stock and changes during the period

A summary of the status of unvested restricted common stock as of December 31, 2015, June 30, 2016 and changes during the six months ended June 30, 2016 is presented below:


		Weighted
		Average Grant
	Shares	Date Fair Value
Unvested at December 31, 2015	256,881	$	0.38
Vested	(82,664)		0.39
Repurchased	(73,334)		0.38
Unvested at June 30, 2016	100,883		0.42

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 June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Weighted-average risk-free interest rate	1.54	%	1.97	%	1.44	%	1.78	%
Expected dividend yield	0	%	0	%	0	%	0	%
Expected option term	6.08		6.08		6.08		6.08
Volatility	85.56	%	81.88	%	85.53	%	82.78	%

Summary of stock-based compensation expense for stock options and restricted common stock

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 statements of operations:


	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Research and development	$	929	$	535	$	1,489	$	997
General and administrative		219		78		321		127
Total stock-based compensation expense	$	1,148	$	613	$	1,810	$	1,124