Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Summary of Option Activity under 2018 Plan, 2013 Plan and 2010 Plan

A summary of option activity under the 2018 Plan, 2013 Plan, and 2010 Plan for the three months ended March 31, 2019, is as follows:

Year-to-Date Activity	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (in millions)
Options outstanding at December 31, 2018		781,725		$	16.34		9.0
Granted		430,150		$	28.15
Cancelled/forfeited		(60,000	)	$	22.18
Options outstanding at March 31, 2019		1,151,875		$	18.77		9.4	$	6.8
Options exercisable at March 31, 2019		251,135		$	8.29		8.2	$	4.5

Summary of Restricted Stock Units Activity under 2018 Plan

A summary of restricted stock units activity under the 2018 Plan for the three months ended March 31, 2019, is as follows:

Year-to-Date Activity	Number of Shares		Weighted Average Grant Date Fair Value Per Share		Aggregate Intrinsic Value (in millions)
Non-vested outstanding at December 31, 2018		—		—
Granted		15,000	$	23.60
Non-vested outstanding at March 31, 2019		15,000	$	23.60	$	0.4

Summary of Stock-Based Compensation Expense

The amount of stock-based compensation expense recorded to research and development and to general and administrative is detailed in table below:

	Three Months Ended March 31,
	2019		2018
Stock-based compensation
Research and development	$	369,941	$	152,735
General and administrative		301,986		99,639
	$	671,927	$	252,374