Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity since December 31, 2014:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding as of December 31, 2014		1,104,172		$	0.53		9.7	$	67
Granted		1,938,705		$	4.06
Exercised		(12,572	)	$	0.38
Cancelled or forfeited		(8,981	)	$	0.38
Outstanding as of September 30, 2015		3,021,324		$	2.80		9.4	$	22,359
Options vested and expected to vest as of September 30, 2015		3,021,324		$	2.80		9.4	$	22,359
Options exercisable as of September 30, 2015		311,081		$	1.24		9.0	$	2,788

Summary of Restricted Common Stock Activity

The following table summarizes the Company’s restricted common stock activity:

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested restricted common stock at December 31, 2014		210,287		$	0.53
Issued		35,788		$	3.57
Vested		(72,067	)	$	1.37
Unvested restricted common stock at September 30, 2015		174,008		$	0.86

Summary of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock

Stock-based compensation expense related to stock options and restricted common stock was classified in the condensed statements of operations and comprehensive loss as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2015		2014		2015		2014
Research and development	$	318	$	14	$	487	$	32
General and administrative		232		9		399		17
	$	550	$	23	$	886	$	49