CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 30,754	$ 76,793
Grant and incentive receivables	2,859	1,608
Restricted cash	101	0
Prepaid expenses and other current assets	1,366	1,129
Total current assets	35,080	79,530
Property and equipment, net	285	421
Restricted cash	539	355
Other assets	100	948
Total assets	36,004	81,254
Current liabilities:
Accounts payable	545	1,893
Accrued expenses	4,116	5,779
Unearned income	737	694
Loans payable, net of discount		2,314
Total current liabilities	5,398	10,680
Loan payable, net of discount and current portion	7,894	9,922
Unearned income	1,107	1,936
Other long-term liabilities	5	9
Total liabilities	14,404	22,547
Commitments and contingencies
Stockholders’ equity:
Common stock	15	15
Additional paid-in capital	156,630	150,830
Accumulated other comprehensive income	241	127
Accumulated deficit	(135,286)	(92,265)
Total stockholders' equity	21,600	58,707
Total liabilities and stockholders’ equity	$ 36,004	$ 81,254