Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2021

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, 2021, 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, 2020		1,240,354		$	11.16		7.8
Granted		485,000		$	3.83
Cancelled/forfeited		(18,879	)	$	20.37
Options outstanding at March 31, 2021		1,706,475		$	8.98		8.3		0.1
Options exercisable at March 31, 2021		744,714		$	11.57		7.3		—

Summary of Stock-Based Compensation Expense

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

	Three Months Ended March 31,
	2021		2020
Stock-based compensation
Research and development	$	168,045	$	262,457
General and administrative		391,391		404,881
	$	559,436	$	667,338