BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 40,404	$ 70,946
Receivables	663	19
Prepaid expenses and other current assets	11,926	19,818
Total current assets	52,993	90,783
Property and equipment, net	1,332	1,211
Deposits	128	128
Other non-current assets	21,930	13,484
Total assets	76,383	105,606
Current liabilities:
Accounts payable	588	4,417
Accrued expenses	8,663	9,909
Contract liability - current portion		6,389
Deferred rent - current portion	63	141
Total current liabilities	9,314	20,856
Contract liability, net of current portion	49,513	35,139
Deferred rent, net of current portion	5	1
Derivative liabilities	2,358	2,424
Total liabilities	61,190	58,420
Commitments and contingencies (Note 6)
Preferred stock, $0.001 par value, 30,000,000 shares authorized
Stockholders' deficit:
Common stock, $0.001 par value; 250,000,000 shares authorized; 142,379,770 and 142,658,037 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	142	143
Additional paid-in capital	609,247	615,493
Accumulated deficit	(748,624)	(712,442)
Total stockholders' deficit	(139,235)	(96,806)
Total liabilities and stockholders' deficit	76,383	105,606
Series 1 Preferred Stock
Current liabilities:
Series 1 preferred stock, $1,200 stated value; 250,000 designated; 127,002 and 119,644 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively; liquidation value of $152.4 million and $143.6 million at June 30, 2018 and December 31, 2017, respectively	$ 154,428	$ 143,992