v3.23.1
Stock-based Compensation (Tables)
12 Months Ended
Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]  
Summary of Stock Option Activity

The following table summarizes stock option activity for the years ended December 31, 2022 and 2021:

 

   Number of Options   Weighted-Average Exercise Price   Weighted-Average Remaining Contractual Term (Years)   Aggregate Intrinsic Value 
Outstanding — January 1, 2021   144,962   $64.20    8.75   $60 
Granted   58,039    27.79           
Forfeited or expired   (6,995)   83.78           
Outstanding — December 31, 2021   196,006   $52.72    8.12   $- 
Granted   125,487    6.40           
Forfeited or expired   (16,670)   143.95           
Outstanding — December 31, 2022   304,823    28.66    7.98   $- 
Exercisable — December 31, 2022   148,482   $44.39    7.23   $-  
Schedule of Calculation of Fair Value Assumptions

 

    Year ended December 31,  
    2022     2021  
Expected option life (years)     6.0       6.0  
Risk-free interest rate     2.06 %     0.64 %
Expected volatility     113.25 %     104.96 %
Expected dividend yield     - %     - %
Schedule of Stock-based Compensation Expenses

The following table presents total stock-based compensation expense for the years ended December 31, 2022 and 2021, respectively:

 

         
   Year ended December 31, 
   2022   2021 
Research and development  $254   $217 
General and administrative   860    941 
Total stock-based compensation expense  $1,114   $1,158