Stockholders' Equity (Deficit) (Tables)

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Summary of Preferred Stock

As of December 31, 2019, preferred stock consisted of the following (in thousands, except per share data):

Series	Shares Authorized		Shares Issued and Outstanding		Per Share Original Issue Price and Conversion Price		Liquidation Preference		Carrying Value
Series A		4,367		4,350	$	2.2615	$	9,838	$	9,773
Series B		8,108		8,108		2.8269		22,922		22,814
Series C		25,580		24,809		4.2812		106,210		102,133
Total		38,055		37,267			$	138,970	$	134,720

Summary of Stock Option Activity

Stock option activity for employee and nonemployee awards and related information is as follows (options in thousands):

	Number			Weighted- Average Exercise Price
Outstanding at December 31, 2019		1,667		$	1.08
Granted		2,035			12.13
Exercised		(106	)		0.44
Forfeited		(51	)		1.24
Outstanding at September 30, 2020		3,545		$	7.44

Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option/Unit Grants

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock option/unit grants were as follows:

	Nine Months Ended September 30,
	2020	2019
Risk-free interest rate	0.3% - 1.5%	1.4% - 2.7%
Expected volatility	88% - 92%	84% - 88%
Expected term (in years)	5.4 - 6.1	2.0 - 5.5
Expected dividend yield	—%	—%

Schedule of Allocated Stock-based Compensation Expense

The allocation of stock-based compensation expense was as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development expense	$	565	$	6	$	850	$	22
General and administrative expense		731		16		1,582		33
Total stock-based compensation expense	$	1,296	$	22	$	2,432	$	55