Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Stockholders' Equity

Schedule of share-based compensation expense recognized

The estimated grant-date fair value of the Company’s stock-based awards is amortized on a straight-line basis over the awards’ service periods. Stock-based compensation expense recognized was as follows (in thousands):

	Three Months Ended March 31,
	2020		2019
Research and development	$	209	$	232
General and administrative		682		522
Total stock-based compensation	$	891	$	754

Summary of stock option activity

	Options Outstanding
				Weighted
				Average
		Weighted		Remaining
		Average		Contractual
	Number of	Exercise		Term
	Shares	Price		(in years)
Balance, December 31, 2019	7,568,304	$	3.40	7.01
Granted	230,000		0.80
Exercised	—		—
Forfeited/Cancelled	(207,874)		(3.69)
Balance, March 31, 2020	7,590,430	$	3.32	6.94
Vested or expected to vest at March 31, 2020	7,590,430	$	3.32	6.94
Exercisable at March 31, 2020	4,812,040	$	4.23	6.03

Schedule of weighted-average assumptions:

	March 31,
	2020		2019
Expected term of options (in years)	6.3		6.3
Risk-free interest rate	1.5	%	2.5	%
Expected volatility	95.4	%	75.4	%
Dividend yield	—	%	—	%

Schedule of changes in the status of non-vested RSU

		Weighted
		Average
	Number of	Grant Date
	Awards	Fair Value
Non-vested at December 31, 2019	2,945,585	$	0.73
Granted	250,000		0.79
Vested	—		—
Forfeited	(118,400)		0.70
Non-vested at March 31, 2020	3,077,185	$	0.73

Schedule of shares available to be granted under equity incentive plans

At March 31, 2020, the Company has the following shares available to be granted under its equity incentive plans:

		Inducement
	2013 Plan	Plan
Available at December 31, 2019	4,394,301	205,000
Authorized	3,768,550	—
Granted	(480,000)	—
Forfeited/Cancelled	302,524	23,750
Available at March 31, 2020	7,985,375	228,750

Schedule of shares of common stock reserved/available

At March 31, 2020, the Company has reserved the following shares of common stock for issuance:

Stock options outstanding under 2013 Plan	7,319,180
Restricted stock units outstanding under 2013 Plan	3,077,185
Shares reserved for future issuance under 2013 Plan	7,985,375
Stock options outstanding under Inducement Plan	271,250
Shares reserved for future issuance under Inducement Plan	228,750
Shares reserved for future issuance under 2013 Employee Stock Purchase Plan	225,806
Warrants outstanding	623,091
Total shares of common stock reserved for future issuance	19,730,637