Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the stock option activity during the three months ended March 31, 2020:

	Stock Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding, January 1, 2020		5,335,850		$	2.60		6.23	$	2,866
Granted		702,000			0.52
Exercised		—			—
Expired/cancelled		(1,265,890	)		4.27
Outstanding, March 31, 2020		4,771,960		$	1.85		7.21	$	20,920
Expected to vest, March 31, 2020		2,897,757		$	1.51		9.08	$	20,920
Options exercisable, March 31, 2020		1,874,203		$	2.39		4.31		—

Summary of Recognized Compensation Cost Related to Employee and Non-employee Stock-Based Compensation Activity

The Company recognized the following compensation cost related to employee and non-employee stock-based compensation activity for the periods presented:

	Three Months Ended March 31,
	2020		2019
Research and development	$	131,678	$	159,331
General and administrative		195,789		462,354
Total	$	327,467	$	621,685

Stock Options Valuation Assumptions

The calculation was based on the following assumptions.

	Three Months Ended March 31,
	2020		2019
Expected term (years)		6.08		5.70
Risk-free interest rate	0.59%		2.49%
Expected volatility	67.33%		65.62%
Expected dividend yield	0%		0%