Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Fair Value of Stock Options Issued to Employees

The fair value of stock option issued to employees was estimated at the date of grant using Black-Scholes with the following weighted-average assumptions:

	For the Year Ended December 31,
	2018			2017
Expected volatility		92.14	%		89.17	%
Expected term (years)		6.07		5.84
Risk-free interest rate		2.86	%		1.95	%
Expected dividend yield		0.00	%		0.00	%

Schedule of Information Related to Stock Options Outstanding

A summary of stock option activities under the Plans is presented below:

	Number of Stock Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Year)		Weighted- Average Intrinsic Value
Outstanding, January 1, 2018		60,618		$	128.23		4.45	$	-
Granted		339,619			4.63
Exercised		(9,541	)		2.40			$	-
Forfeited or expired		(37,422	)		145.58
Outstanding, December 31, 2018		353,274		$	10.97		6.04	$	-
Exercisable, December 31, 2018		15,278		$	106.08		5.29	$	-
Expected to vest, December 31, 2018		337,996		$	6.67		6.07	$	-

Summary of Restricted Stock Activity

A summary of restricted stock activities is presented below:

	Shares			Weighted- average Grant Date Fair Value		Restricted Stock Repurchase Liability
Unvested, January 1, 2018		781		$	310.80	$	315
Vested		(284	)		310.80		(116	)
Granted		322,907			3.59		—
Unvested, December 31, 2018		323,404		$	4.06	$	199

Schedule of Stock-based Compensation Expense

Stock-based compensation expense is classified in the accompanying consolidated statements of operations and comprehensive loss for the years ended December 31, 2018 and 2017 as follows:

	For the Year Ended December 31,
	2018		2017
Research and development	$	319,354	$	327,610
General and administrative		453,894		1,115,882
Total	$	773,248	$	1,443,492