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Stock-based compensation (Tables)
 3 Months Ended
Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]  
Schedule of Stock Option Activity Under Plan A summary of stock option activity is as follows:
Number
of Shares		Weighted-
Average
Exercise Price
Outstanding at January 1, 202310,051,283 $9.84 
Granted2,530,740 $6.07 
Exercised(8,826)$3.80 
Cancelled(273,670)$10.08 
Outstanding at March 31, 202312,299,527 $9.07 
Exercisable at March 31, 20235,902,352 $9.51 
Schedule of Restricted Stock Activity A summary of the RSU activity is as follows:
Number of Shares
Unvested at January 1, 20231,870,791 
Granted2,023,466 
Vested(372,291)
Forfeited(74,579)
Unvested at March 31, 20233,447,387 
Schedule of Stock-Based Compensation Expense by Award Type The following table presents stock-based compensation expense by award type included within the Company’s condensed consolidated statements of operations and comprehensive loss:
Three Months Ended March 31,
(in thousands)20232022
Stock options$4,219 $4,118 
Restricted stock units1,893 1,209 
Employee stock purchase plan295 158 
Stock-based compensation expense included in total operating expenses$6,407 $5,485 
Schedule of Stock-Based Compensation Expense as Reflected in the Company's Condensed Consolidated Statements of Operations and Comprehensive Loss The following table presents stock-based compensation expense as reflected in the Company’s condensed consolidated statements of operations and comprehensive loss:
Three Months Ended March 31,
(in thousands)20232022
Research and development$3,332 $2,933 
General and administrative3,075 2,552 
Stock-based compensation expense included in total operating expenses$6,407 $5,485 
Schedule of Weighted Average Assumptions for Estimating Fair Value of Option Awards The fair value of each option award is estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions:
Three Months Ended
March 31,
20232022
Risk-free interest rate3.6 %1.6 %
Expected dividend yield— %— %
Expected term (years)6.076.04
Expected stock price volatility99 %87 %