XML 31 R20.htm IDEA: XBRL DOCUMENT v3.22.1
Stock-Based Compensation (Tables)
3 Months Ended
Mar. 31, 2022
Share-based Payment Arrangement [Abstract]  
Stock-Based Compensation Expense
The following stock-based compensation expense was recognized for the periods indicated (in thousands):
Three Months Ended March 31,
20222021
Research and development$2,392 $2,727 
Selling, general and administrative2,882 2,559 
Total stock-based compensation expense$5,274 $5,286 
Valuation Assumptions Using the Black-Scholes Option-Pricing Model
The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions in the following table for options issued during the period indicated:
Three Months Ended March 31,
20222021
Expected dividend yield0%0%
Expected volatility
87.9% -88.3%
86.4% - 86.7%
Risk-free interest rate
1.5% - 2.4%
0.6% - 1.4%
Expected term5.95 years6.25 years
Schedule of Stock Options Roll Forward
The following table summarizes stock option activity during the three months ended March 31, 2022:
SharesWeighted-
Average
Exercise Price
Weighted-Average
Remaining
Contractual Term
(Years)
Aggregate
Intrinsic
Value
 (in thousands)
Outstanding, December 31, 20218,373,921 $21.47 6.6
Granted2,349,197 10.21 
Exercised(25,646)1.44 
Forfeited(157,197)16.51 
Expired(33,695)21.16 
Outstanding, March 31, 202210,506,580 $19.08 7.1$904 
As of March 31, 2022:
Exercisable5,853,827 $22.61 5.5898 
Vested and expected to vest9,693,151 $19.41 7.0903
Schedule of RSU Activity
The following table summarizes RSU activity during the three months ended March 31, 2022:
Shares
Weighted-Average
Grant Date Fair Value
Outstanding, December 31, 202121,500 $25.97 
Granted309,372 10.25 
Forfeited(5,428)10.15 
Outstanding, March 31, 2022325,444 11.29