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Stock-Based Compensation (Tables)
9 Months Ended
Sep. 30, 2024
Summary of Assumptions Used in Black-Scholes Option Pricing Model

Three Months Ended

Nine Months Ended

September 30, 

September 30, 

    

2024

    

2023

    

    

2024

    

2023

    

Risk-free interest rate

 

N/A

4.20%

 

4.12% - 4.34%

3.38% - 4.22%

 

Expected volatility

 

N/A

80.8%

 

89.6% - 89.8%

76.3% - 81.3%

 

Expected dividend yield

 

N/A

0%

 

0%

0%

 

Expected life of employee and Board options (in years)

 

N/A

6.25

 

 

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

 

3,045,125

 

0.86

 

Exercised

 

 

 

Forfeited

 

(3,311,296)

 

5.08

 

Expired

 

(3,371,914)

 

14.92

 

Outstanding, September 30, 2024

 

4,259,562

$

8.95

Options exercisable, September 30, 2024

 

2,284,882

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

Weighted

Number of

Average Grant

    

Units

    

Date Fair Value

Outstanding, December 31, 2023

 

566,324

$

9.27

Awarded

 

903,883

 

0.66

Vested and released

 

(365,935)

 

7.81

Forfeited

 

(136,348)

 

10.57

Outstanding, September 30, 2024

 

967,924

$

1.60

Restricted stock units exercisable (vested and deferred), September 30, 2024

 

Employee Stock Option  
Summary of Compensation Expense Recognized

Three Months Ended

Nine Months Ended

September 30, 

September 30, 

    

2024

    

2023

    

2024

    

2023

    

Research and development

$

16

$

1,387

$

795

$

4,314

General and administrative

 

1,120

 

1,447

 

3,494

 

4,122

Total stock option expense

$

1,136

$

2,834

$

4,289

$

8,436

Restricted Stock Units  
Summary of Compensation Expense Recognized

Three Months Ended

Nine Months Ended

September 30, 

September 30,

    

2024

2023

2024

2023

Research and development

 

$

$

90

$

249

$

385

General and administrative

353

410

2,036

1,308

Total restricted stock unit expense

 

$

353

$

500

$

2,285

$

1,693