Convertible Preferred Stock and Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2022

Summary of Stock Option Activities

A summary of the Company’s stock option activities during the nine months ended September 30, 2022 is as follows:

		Weighted-		Weighted-
		Average		Average	Aggregate
		Exercise		Remaining	Intrinsic
		Price Per		Contract Term	Value
	Total Options	Share		(in years)	(in millions)
Outstanding as of December 31, 2021	1,734,696	$	8.50	8.8	$	7.6
Granted	1,170,928	$	8.04
Exercised	(31,152)	$	4.26
Forfeited or cancelled	(244,214)	$	10.39
Outstanding as of September 30, 2022	2,630,258	$	8.17	8.6	$	1.4
Vested and expected to vest as of September 30, 2022	2,630,258	$	8.17	8.6	$	1.4
Vested and exercisable as of September 30, 2022	905,005	$	6.51	7.7	$	0.8

Summary of Stock-Based Compensation Expense Recognized

The Company recognized stock-based compensation expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Research and development	$	728	$	683	$	2,821	$	1,452
General and administrative		204		179		770		368
Total stock-based compensation expense	$	932	$	862	$	3,591	$	1,820

Weighted-Average Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option Grants

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

	Three Months Ended September 30,		Nine Months Ended September 30,
	2022	2021	2022	2021
Risk-free interest rate	3.24%	0.90%	1.60% - 3.24%	0.80% - 1.12%
Expected volatility	103.3%	115.5%	88.1% - 112.1%	115.3% -118.7%
Expected term (in years)	6.1	6.1	5.3 - 6.1	5.0 - 6.1
Expected dividend yield	0%	0%	0%	0%

Schedule of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance consist of the following:

	September 30, 2022	December 31, 2021
Stock options	2,630,258	1,734,696
Restricted stock units	9,289	—
Reserved for future equity award grants	3,056,959	2,933,930
Reserved for future ESPP issuances	466,585	259,689
Total	6,163,091	4,928,315

Restricted Stock Units (RSU)

Summary of Restricted Stock Units Activities

		Weighted-		Aggregate
	Total	Average		Intrinsic
	Restricted	Grant Date		Value
	Stock Units	Fair Values		(in millions)
Outstanding as of December 31, 2021	—	$	—	$	—
Granted	9,289	$	6.25
Vested	—	$	—
Forfeited or cancelled	—	$	—
Outstanding as of September 30, 2022	9,289	$	6.25	$	—

Employee Stock Purchase Plan

Weighted-Average Assumptions Used in Black-Scholes Option Pricing Model to Determine Fair Value of Stock Option Grants

The weighted average assumptions used in the Black-Scholes option pricing model to estimate the fair value of purchase rights granted under the ESPP were as follows:

	Nine Months Ended September 30,
	2022	2021
Risk-free interest rate	0.1%	0.1%
Expected volatility	143.2%	127.8%
Expected term (in years)	1.9	1.4
Expected dividend yield	0%	0%