Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2022

Equity [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity during the six months ended June 30, 2022:

	Shares Subject to Options			Weighted- Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Options outstanding at December 31, 2021		3,947,025		$	4.58
Granted		2,094,800		$	3.67
Exercised		-		$	-
Forfeitures and cancellations		(738,000	)	$	5.04
Options outstanding at June 30, 2022		5,303,825		$	4.16		8.30	$	-
Options exercisable at June 30, 2022		2,048,297		$	4.20		6.62	$	-

Summary of Non-cash Stock-based Compensation Expense

The non-cash stock-based compensation expense for all stock awards, net of forfeitures recognized as they occur, that was recognized in the condensed consolidated statements of operations is as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	397	$	462	$	942	$	936
General and administrative		905		602		1,658		1,172
Total	$	1,302	$	1,064	$	2,600	$	2,108

Summary of Reserved Shares of Common Stock for Future Issuance

Common stock reserved for future issuance at June 30, 2022 is as follows:

	June 30,		December 31,
	2022		2021
Stock options issued and outstanding		5,303,825		3,947,025
Warrants for common stock		1,366,141		1,366,141
Awards available under the 2018 Equity Incentive Plan		583,007		467,024
Employee stock purchase plan		988,028		769,658
Total		8,241,001		6,549,848