ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Contracted research services	$ 5,102	$ 434
Payroll and related expenses	3,729	1,182
Professional and consulting fees	1,603	984
Legal fees	199	299
Current portion of operating lease liability	1,047
Total accrued expenses	$ 11,680	$ 2,899
Current portion of operating lease liability, statement of financial position	us-gaap:accruedliabilitiescurrent