EQUITY INCENTIVE PLANS - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Number of Shares
Outstanding, beginning balance (in shares)	8,296,091
Options granted (in shares)	2,005,700
Options exercised (in shares)	0
Options canceled (in shares)	(1,109,875)
Outstanding, ending balance (in shares)	9,191,916	8,296,091
Vested and expected to vest (in shares)	9,191,916
Exercisable (in shares)	5,177,319
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 3.21
Options granted (in dollars per share)	0.80
Options exercised (in dollars per share)	0
Options canceled (in dollars per share)	3.11
Outstanding, ending balance (in dollars per share)	2.70	$ 3.21
Vested and expected to vest (in dollars per share)	2.70
Exercisable (in dollars per share)	$ 3.54
Weighted Average Remaining Contractual Life in Years
Outstanding	7 years 10 days	6 years 3 months 21 days
Vested and expected to vest	7 years 10 days
Exercisable	5 years 9 months 14 days
Total Aggregate Intrinsic Value (in thousands)
Outstanding	$ 0	$ 0
Vested and expected to vest	0
Exercisable	$ 0