Stock-Based Awards (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [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, 2022 and 2021 were as follows, presented on a weighted average basis:

	Six Months Ended June 30, 2022		Six Months Ended June 30, 2021
Risk-free interest rate	2.46%		0.96%
Expected term (in years)		5.9		6.2
Expected volatility	94.2%		91.0%
Expected dividend yield	0%		0%

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity since January 1, 2022:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Term in Years		Aggregate Intrinsic Value
Outstanding at December 31, 2021		9,375,497		$	1.79		8.5	$	4
Granted		3,148,500			0.46
Exercised		—			0.00
Canceled, forfeited or expired		(1,401,565	)		1.02
Outstanding at June 30, 2022		11,122,432		$	1.51		8.2	$	—
Options exercisable at June 30, 2022		5,099,852		$	2.21		7.0	$	—
Options vested and expected to vest at June 30, 2022		10,902,956		$	2.21		8.1	$	—

Summary of Restricted Stock Unit Activity

The following table summarizes the Company’s restricted stock activity since January 1, 2022:

				Weighted-Average
	Number of			Grant Date Fair Value
	Units			per Unit
Outstanding, non-vested at December 31, 2021		—		$	—
Issued		250,000			0.39
Vested		(250,000	)		0.39
Canceled/forfeited		—			—
Outstanding, non-vested at June 30, 2022		—			—

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,
	2022		2021		2022		2021
Research and development expenses	$	178	$	103	$	321	$	202
General and administrative expenses		350		258		896		791
Total Stock Based Compensation	$	528	$	361	$	1,217	$	993