Stock-Based Awards (Tables)

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Valuation Assumptions of Stock Options Granted

The assumptions that the Company used to determine the grant-date fair value of the stock options granted to employees and directors during the six months ended June 30, 2020 and 2019 were as follows, presented on a weighted average basis:

	Six Months Ended June 30, 2020			Six Months Ended June 30, 2019
Risk-free interest rate		1.03	%		2.53	%
Expected term (in years)		6.3			6.3
Expected volatility		76.0	%		76.0	%
Expected dividend yield		0	%		0	%

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity since January 1, 2020:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding at December 31, 2019		3,320,706		$	3.87		7.4	$	—
Granted		1,771,000			0.72
Exercised		—			0.00
Canceled		(401,754	)		6.54
Forfeited		—			0.00
Outstanding at June 30, 2020		4,689,952		$	2.45		8.5	$	—
Options exercisable at June 30, 2020		1,879,181		$	3.68		7.6	$	—
Options vested and expected to vest at June 30, 2020		4,587,708		$	2.48		8.5	$	—
Options exercisable at December 31, 2019		1,415,900		$	5.56		5.2	$	—
Options vested and expected to vest at December 31, 2019		3,264,851		$	3.89		7.4	$	—

Summary of Restricted Stock Unit Activity

On April 15, 2019, the Company granted restricted stock units under the 2017 Plan. The following table summarizes the Company’s restricted stock unit activity during the six months ended June 30, 2020:

				Weighted-Average
				Grant Date
	Units			per Unit
Outstanding, non-vested at December 31, 2019		50,000		$	1.75
Issued		—			—
Vested		(40,000	)	$	1.75
Canceled/forfeited		—			—
Outstanding, non-vested at June 30, 2020		10,000		$	1.75

Summary of Stock Based Compensation Expense

The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its statements of operations and comprehensive loss:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development expenses	$	200	$	112	$	349	$	193
General and administrative expenses		360		348		716		830
	$	560	$	460	$	1,065	$	1,023