CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 61,653	$ 146,470
Available-for-sale securities	50,097	49,897
Prepaid expenses and other current assets	3,305	3,836
Total Current Assets	115,055	200,203
Property and equipment, net	531	642
Security deposits	343	163
Total Assets	115,929	201,008
Current Liabilities:
Accounts payable	13,263	13,869
Accrued expenses	4,328	1,962
Interest payable on Senior Convertible Notes	1,988	2,500
Total Current Liabilities	19,579	18,331
Senior Convertible Notes, net of deferred financing costs of $7,769 and $12,336 as of December 31, 2015 and December 31, 2014, respectively	151,241	187,664
Derivative financial instruments, at estimated fair value-warrants	322	172
Total Liabilities	$ 171,142	$ 206,167
Commitments and contingencies (Note 9)
Stockholders' Deficit:
Preferred stock, Authorized 20,000,000 shares and none outstanding, at December 31, 2015 and December 31, 2014
Common stock, par value of $.0001 authorized 350,000,000 shares at December 31, 2015. Issued and outstanding 113,694,606 and 96,609,764 shares at December 31, 2015 and 2014, respectively	$ 11	$ 11
Additional paid-in capital	329,161	261,715
Accumulated deficit	(384,385)	(266,885)
Total Stockholders' Deficit	(55,213)	(5,159)
Total Liabilities and Stockholders' Deficit	$ 115,929	$ 201,008