Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 35,583	$ 44,711
Inventory, net	0	27
Prepaid expenses and other current assets	576	821
Total current assets	36,159	45,559
Property and equipment, net	1,665	1,637
Restricted cash	225	225
Other assets	73	78
Total assets	38,122	47,499
Current Liabilities:
Accounts payable	702	350
Accrued expenses	7,224	6,116
Deferred revenue	0	43
Common stock warrant liability	1,289	1,258
Equipment loans, current portion	42	62
Total current liabilities	9,257	7,829
Long-term debt, $30,000 net of discount of $9,143 at March 31, 2015 and $9,698 at December 31, 2014	20,857	20,302
Other liabilities	196	169
Total liabilities	30,310	28,300
Stockholders' Equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.001 par value; 250,000,000 shares authorized; 85,769,392 and 85,607,806 shares issued at March 31, 2015 and December 31, 2014, respectively; 85,748,500 and 85,586,914 shares outstanding at March 31, 2015 and December 31, 2014, respectively	86	86
Additional paid-in capital	546,967	546,175
Accumulated deficit	(536,187)	(524,008)
Treasury stock (at cost); 20,892 shares	(3,054)	(3,054)
Total stockholders' equity	7,812	19,199
Total liabilities & stockholders' equity	$ 38,122	$ 47,499