Stock-Based Compensation (Tables)

6 Months Ended

Jun. 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	599,740	$	29.40
Exercised	—	$	—
Cancelled or forfeited	—	$	—
Outstanding at June 30, 2016	2,348,617	$	18.70	9.09	$	46,569,629
Exercisable at June 30, 2016	389,060	$	9.74
Exercisable and expected to vest at June 30, 2016	2,285,137	$	19.16	9.10	$	44,312,789

(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 June 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				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Research and development	$	1,291,273	$	8,434	$	12,750,758	$	51,376
General and administrative	2,553,513		767,414		4,636,718		819,702
	$	3,844,786	775,848		$	17,387,476	$	871,078

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

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Expected volatility	90.00	%	77.80	%	90.00	%	77.80	%
Risk-free interest rate	1.57	%	2.01	%	1.57	%	2.01	%
Expected terms (in years)	6.08		6.08		6.08		6.08
Expected dividend yield	0.00	%	0.00	%	0.00	%	0.00	%