SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss per Share (Details) - shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Antidilutive securities excluded from calculation of net loss per share	20,151,036	18,769,495
Stock option
Antidilutive securities excluded from calculation of net loss per share	14,519,506	14,537,031
Employee Stock Purchase Plan
Antidilutive securities excluded from calculation of net loss per share	193,194	39,766
Restricted stock units
Antidilutive securities excluded from calculation of net loss per share	2,499,178	1,253,540
Series A Convertible Preferred Stock
Antidilutive securities excluded from calculation of net loss per share	97,000	97,000
Series B Convertible Preferred Stock
Antidilutive securities excluded from calculation of net loss per share	2,842,158	2,842,158