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Stock-Based Compensation (Tables)
12 Months Ended
Dec. 31, 2022
Stock-Based Compensation  
Summary of stock option activity

Options Outstanding and Exercisable

Weighted

Weighted

Average

Aggregate

Average

Remaining

Intrinsic

Number of

Exercise

Contractual

Value(1)

    

Shares

    

Price

    

Life (Years)

    

(in thousands)

Outstanding as of January 1, 2021

3,112,376

$

16.95

8.2

$

10,810

Granted

 

2,020,718

$

10.89

 

 

Exercised

(105,731)

$

1.62

Forfeitures

(481,569)

$

21.33

Outstanding as of December 31, 2021

 

4,545,794

$

14.15

 

8.1

$

2,860

Granted

1,739,350

$

5.34

Exercised

(50,420)

$

1.32

Forfeitures

(972,545)

$

13.77

Outstanding as of December 31, 2022

5,262,179

$

11.44

7.6

$

115

Exercisable as of December 31, 2022

 

2,790,206

$

12.97

 

6.6

$

115

(1)The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that were in the money at December 31, 2022 and 2021.
Summary of stock based compensation expense recorded

December 31, 

(in thousands)

2022

    

2021

Research and development

$

3,056

$

4,081

General and administrative

 

6,452

 

6,207

Total stock-based compensation expense

$

9,508

$

10,288

Summary of assumptions used in the Black Scholes option pricing model for stock options granted

Year Ended

December 31, 

    

2022

    

2021

Expected term

 

5.5 - 6.1

years 

5.3 - 6.1

years 

Expected volatility

 

79.7 - 81.4

%

79.7

%

Risk free interest rate

 

1.8 - 4.2

%

0.8 - 1.4

%

Expected dividend yield

 

%

%