Stock Based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Key Assumptions Used for Black-Scholes Option-pricing Model to Estimate the Fair Value of Stock Options

The key assumptions used to apply this pricing model during the six months ended June 30, 2021 and 2020, were as follows:

	Six Months Ended June 30,
	2021			2020
Risk free interest rate		0.67	%		1.10	%
Expected term (in years)		6.07			6.06
Expected dividend yield		0	%		0	%
Expected volatility of underlying common stock		73	%		71	%

Summary of Stock Option Activity

The following table summarizes the stock option activity under the 2018 Plan:

	Stock Options			Weighted Average Exercise Price		Weighted Average Remaining Life (in Years)		Intrinsic Value (in thousands)
Outstanding January 1, 2021		1,445,427		$	2.62		8.74	$	3,799
Granted		1,272,770			7.25
Exercised		(108,656	)		2.18
Canceled		(118,377	)		2.45
Outstanding June 30, 2021		2,491,164		$	5.01		8.94	$	22,235
Options vested or expected to vest as of June 30, 2021		2,491,164		$	5.01		8.94	$	22,235
Stock options exercisable as of June 30, 2021		456,750		$	2.30		8.02	$	5,315

Summary of Restricted Common Stock Activity

A summary of the activity for the six months ended June 30, 2021 is as follows:

	Number of Shares			Weighted Average Grant Date Fair Value
Unvested restricted stock as of January 1, 2021		438,280		$	0.00
Vested		(175,305	)	$	0.00
Unvested restricted stock as of June 30, 2021		262,975		$	0.00

Summary of Stock-based Compensation Expense

Stock-based compensation expense was as follows (in thousands):

	Six Months Ended June 30,				Three Months Ended June 30,
	2021		2020		2021		2020
Research and development	$	356	$	111	$	205	$	62
General and administrative		491		125	$	298	$	64
	$	847	$	237	$	503	$	126