BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 97,194	$ 81,053
Receivables	44	21
Prepaid expenses and other current assets	27,892	23,810
Total current assets	125,130	104,884
Property and equipment, net	1,062	843
Deposits	128	128
Other non-current assets	493	493
Total assets	126,813	106,348
Current liabilities:
Accounts payable	81	156
Accrued expenses	9,354	9,109
Deferred revenue - current portion	6,389	6,389
Deferred rent - current portion	164	155
Total current liabilities	15,988	15,809
Deferred revenue, net of current portion	38,333	41,528
Deferred rent, net of current portion	52	126
Derivative liabilities	2,480	862
Total liabilities	56,853	58,325
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; 141,962,789 and 132,376,670 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	142	132
Additional paid-in capital - common stock	622,052	580,567
Accumulated deficit	(686,468)	(657,997)
Total stockholders' deficit	(64,274)	(77,298)
Total liabilities and stockholders' deficit	126,813	106,348
Series 1 Preferred Stock
Current liabilities:
Series 1 preferred stock, $1,200 stated value; 250,000 designated; 112,713 and 106,184 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively; liquidation value of $135.3 million and $127.4 million at June 30, 2017 and December 31, 2016, respectively	$ 134,234	$ 125,321