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Summary of Stock Option Activity (Detail)
6 Months Ended
Jun. 30, 2021
$ / shares
shares
Shares  
Beginning Balance | shares 3,987,575
Granted | shares 2,065,000
Exercised | shares (252,500)
Forfeited/Cancelled | shares (880,350)
Ending Balance | shares 4,919,725
Weighted Average Exercise Price  
Beginning Balance | $ / shares $ 4.29
Granted | $ / shares 2.20
Exercised | $ / shares 2.19
Forfeited/Cancelled | $ / shares 5.52
Ending Balance | $ / shares $ 3.30