As of June 30, 2022, the Company had 1,909,837 shares of its common stock available for future issuance under its stock incentive plan.

The Company’s stock options generally vest over 48 months with 25% vesting after one year followed by ratable monthly vesting over the remaining three years and have a contractual term of 10 years. The weighted-average assumptions used principally in determining the fair value of options granted were as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Fair value of common stock	$	4.37		$	23.38		$	8.30		$	22.66
Expected term (in years)		5.6			6.1			6.0			6.0
Expected volatility		79.8	%		79.7	%		78.4	%		79.7	%
Risk-free interest rate		3.4	%		1.1	%		1.8	%		0.8	%
Dividend yield		—			—			—			—

During the six months ended June 30, 2022 and 2021, the Company granted stock options to purchase 1,948,264 shares and 478,434 shares of its common stock, respectively, with a weighted-average grant-date fair value of $5.65 and $15.40 per share, respectively. As of June 30, 2022, total unrecognized compensation expense related to stock options was $17.3 million, which is expected to be recognized over a weighted-average period of 2.58 years.

As of June 30, 2022, options for 138,052 shares of Company common stock with a weighted average exercise price of $2.02 were exercised and unvested. The underlying proceeds from the unvested exercises of $0.3 million is recorded in other current liabilities on the condensed consolidated balance sheet.

During the six months ended June 30, 2022, the Company granted 1,040,500 restricted stock units with a weighted average grant date fair value of $6.00 per share. As of June 30, 2022, total unrecognized compensation expense related to restricted stock units was $6.1 million, which is expected to be recognized over a weighted-average period of 0.98 years. The Company did not grant any restricted stock units during the six months ended June 30, 2021.

Stock-based compensation expense was allocated as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2022		2021		2022		2021
Research and development	$	909	$	542	$	1,705	$	991
General and administrative		832		525		1,782		967
Total stock-based compensation expense	$	1,741	$	1,067	$	3,487	$	1,958