Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Stock-Based Compensation

Summary of Company's stock option activity

				Weighted Average
	Number of Shares	Weighted Average Exercise Price		Remaining Contractual Life (Years)	Aggregate Intrinsic Value (a)
Outstanding at December 31, 2015	1,748,877	$	15.04	9.38	$	8,224,947
Granted	877,640	$	31.41
Exercised	33,625	$	6.50
Cancelled or forfeited	25,875	$	18.17
Outstanding at September 30, 2016	2,567,017	$	20.51	8.95	$	54,745,699
Exercisable at September 30, 2016	635,347	$	13.54
Exercisable and expected to vest at September 30, 2016	2,502,817	$	21.17	8.98	$	50,563,537

(a)The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in-the-money at September 30, 2016 and December 31, 2015.

Summary of aggregate stock-based compensation recorded in the consolidated statements of operations and comprehensive loss

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2016		2015		2016		2015
Research and development	$	2,006,547	$	359,881	$	14,757,305	$	411,257
General and administrative	2,616,534		1,488,743		7,253,252		2,308,445
	$	4,623,081	1,848,624		$	22,010,557	$	2,719,702

Summary of Company's grant date fair value and assumptions used in determining fair value of stock options

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2016		2015		2016		2015
Expected volatility	97.82	%	80.80	%	92.46	%	80.80	%
Risk-free interest rate	1.10	%	1.89	%	1.42	%	1.89	%
Expected terms (in years)	6.08		6.08		6.08		6.08
Expected dividend yield	0.00	%	0.00	%	0.00	%	0.00	%

Summary of Company's restricted stock units activity

		Weighted
		Average
		Grant Date
	Number	Fair Value
	of Shares	Per Share
Outstanding at December 31, 2015	—	$	—
Granted	57,500	34.90
Vested	—	—
Forfeited and cancelled	—	—
Outstanding at September 30, 2016	57,500	$	34.90