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Stock-Based Compensation (Tables)
 12 Months Ended
Dec. 31, 2021
Share-based Payment Arrangement [Abstract]  
Schedule of Stock-based Compensation Expense for Options Granted Reflected in the Consolidated Statement of Operations and Comprehensive Loss Stock-based compensation expense for stock options and RSUs is reflected in the consolidated statements of operations and comprehensive loss as follows (in thousands):
Year ended December 31,
202120202019
General and administrative$4,909 $349 $363 
Research and development2,049 311 521 
Total$6,958 $660 $884 
Schedule of Weighted Average Assumptions Utilized in Fair Value Calculation
The assumptions utilized in the fair value calculation for stock options as of December 31, 2021, 2020, and 2019 were as follows:
Year ended December 31,
202120202019
Weighted average expected option term (years)6.06.06.0
Range of expected stock price volatility
109% – 116%
110% – 117%
89% – 110%
Weighted average expected stock price volatility111%112%109%
Range of risk-free interest rate
0.4% – 1.4%
0.3% – 1.7%
1.5% – 2.4%
Expected dividend rate0%0%0%
Schedule of Stock Option Activity The following table summarizes the stock option activity:
Number of SharesWeighted Average Exercise PriceWeighted Average Remaining Contractual Life (Years)Aggregate Intrinsic Value (In Thousands)
Options outstanding at December 31, 20204,224,433 $0.84 8.9$5,496 
Granted7,728,260 3.45 — 
Exercised(1,208,631)0.70 11,144 
Forfeited(657,895)4.79 1,277 
Options outstanding at December 31, 202110,086,167 $2.59 8.8$24,664 
Options exercisable at December 31, 20211,281,244 $2.92 8.1$2,990 
Schedule of Share-based Payment Arrangement, Restricted Stock Unit, Activity The following table summarizes the RSU activity:
Number of SharesWeighted-
Average
Grant-Date
Fair Value		Aggregate Intrinsic Value (In Thousands)
RSUs outstanding at December 31, 2020— $— $— 
Granted204,901 6.87 1,483 
Forfeited(13,090)8.05 108 
RSUs outstanding at December 31, 2021191,811 $6.79 $873