Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accounts payable—trade	$ 222	$ 424
Payroll and benefits	1,331	1,050
Research and development	182	323
Royalty fees due to unrelated parties	170	157
Accrued interest on notes payable	98	9
Consulting	29	152
Rent and utilities	85	77
Legal	45	57
Accrued withholding taxes	0	24
Other	197	150
Total accounts payable and accrued expenses	$ 2,359	$ 2,423