ACCOUNTS PAYABLE AND ACCRUED EXPENSES - Summary of accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accounts payable	$ 988	$ 710
Accrued payroll	1,109	1,856
Accrued outsourced pre-clinical and clinical fees	4,455	5,461
Accrued professional fees	413	363
Other accrued expenses	296	310
Accounts payable and accrued expenses, Total	$ 7,261	$ 8,700