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Stock-Based Compensation (Tables)
3 Months Ended
Mar. 31, 2024
Summary of Assumptions Used in Black-Scholes Option Pricing Model

Three Months Ended

March 31, 

    

2024

    

2023

    

Risk-free interest rate

 

4.12%

3.62% - 4.22%

 

Expected volatility

 

89.6%

76.3% - 81.3%

 

Expected dividend yield

 

0%

0%

 

Expected life of employee and Board options (in years)

 

6.25

6.25

 

Summary of Stock Option Activity

Weighted

Number of

Average Exercise

    

Shares

    

 Price

    

Outstanding, December 31, 2023

 

7,897,647

$

12.99

 

Granted

 

1,875,125

 

0.99

 

Exercised

 

 

 

Forfeited

 

(679,165)

 

10.87

 

Expired

 

(277,075)

 

13.36

 

Outstanding, March 31, 2024

 

8,816,532

$

10.59

Options exercisable, March 31, 2024

 

4,827,562

Employees And Non-Employee Members Of Board Of Directors [Member]  
Summary of Restricted Stock Unit Activity

Weighted

Number of

Average Grant

    

Units

    

Date Fair Value

Outstanding, December 31, 2023

 

566,324

$

9.27

Awarded

 

 

Vested and released

 

(186,375)

 

11.04

Forfeited

 

(129,682)

 

10.57

Outstanding, March 31, 2024

 

250,267

$

7.28

Restricted stock units exercisable (vested and deferred), March 31, 2024

 

Employee Stock Option [Member]  
Summary of Compensation Expense Recognized

Three Months Ended

March 31, 

    

2024

    

2023

    

Research and development

$

504

$

1,480

General and administrative

 

1,229

 

1,241

Total stock option expense

$

1,733

$

2,721

Restricted Stock Units [Member]  
Summary of Compensation Expense Recognized

Three Months Ended

March 31, 

    

2024

    

2023

Research and development

 

$

255

 

$

179

General and administrative

1,357

453

Total restricted stock unit expense

 

$

1,612

 

$

632