Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2023

Equity [Abstract]

Summary of Stock Based Compensation Expense

Stock-based compensation expense was recognized in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands):

	Three Months Ended March 31,
	2023		2022
Research and development	$	182	$	160
General and administrative		449		484
Total	$	631	$	644

Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model

The fair value of each award granted was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions:

	Three Months Ended March 31,
	2023	2022
Expected life (years)	6.0	6.0
Risk-free interest rate	3.5%-4.0%	1.7%
Volatility	98%-99%	88%
Dividend rate	—  %	—  %

Summary of Stock Option Transactions

The following table summarizes stock option transactions for the three months ended March 31, 2023 as issued under the 2014 Plan and the Inducement Plan:

	Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	Outstanding			Share		(in years)		(in thousands)
Balance at January 1, 2023		686,574		$	28.83		7.93
Options granted		240,000			2.37
Options exercised		—			—
Options canceled/forfeited		(249	)		2.80
Balance at March 31, 2023		926,325		$	21.98		8.21	$	—
Options exercisable at March 31, 2023		428,551		$	34.46		7.30	$	—
Options vested and expected to vest at March 31, 2023		903,367		$	20.61		8.28	$	—

Summary of Restricted Stock Unit Transactions

The following table summarizes restricted stock unit transactions for the three months ended March 31, 2023 as issued under the 2014 Plan:

	Number of Restricted Stock Units			Weighted- Average Grant-Date Fair Value per Share
Outstanding at January 1, 2023		19,068		$	57.75
Restricted stock units granted		-		$	0.00
Restricted stock units vested		(9,534	)	$	57.75
Restricted stock units canceled/forfeited		-		$	0.00
Outstanding at March 31, 2023		9,534		$	57.75