ACCOUNTS PAYABLE AND ACCRUED EXPENSES - Summary of accounts payable and accrued expenses (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Payables and Accruals [Abstract]
Accounts payable	$ 560	$ 226
Accrued payroll	2,872	2,768
Accrued outsourced pre-clinical and clinical fees	5,501	8,034
Accrued professional fees	641	379
Other accrued expenses	589	525
Accounts payable and accrued expenses, Total	$ 10,163	$ 11,932