INCOME TAXES - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets
Operating lease liability	$ 420	$ 541
Stock-based compensation	6,606	3,788
License fee	594	630
Net operating loss carryforwards	79,429	49,094
Research and development tax credits	14,940	9,037
Other	1,352	689
Total Deferred Tax Assets	103,341	63,779
Valuation Allowance	(102,932)	(63,246)
Net Deferred Tax Assets	409	533
Deferred Tax Liabilities
Right of Use Asset	(409)	(533)
Net Deferred Tax Liabilities	(409)	(533)
Net deferred tax asset (liability)	$ 0	$ 0