INCOME TAXES - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets (liabilities):
Net operating loss carryforwards	$ 24,059	$ 9,512
Research and development tax credits	2,477	1,014
Operating lease liabilities	2,147	0
Accruals and other	680	280
Stock-based compensation	1,434	196
Total deferred tax assets	30,797	11,002
Valuation Allowance	(28,709)	(10,995)
Subtotal	2,088	7
Right-of-use assets	(2,063)	0
Net fixed assets	(25)	(7)
Net deferred tax assets	$ 0	$ 0