Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 22,570	$ 23,059
Prepaid expenses and other	450	333
Total current assets	23,020	23,392
Property and equipment, net	581	213
Other assets	243	481
Other assets-equipment funding (note 9(c ))	6,763	6,763
Total assets	30,607	30,849
Current liabilities:
Current portion of long-term debt	378	8,412
Accounts payable	800	1,967
Accrued expenses	1,995	2,018
Total current liabilities	3,173	12,397
Other long-term liabilities	83
Long-term debt	8,102	5,481
Warrant liability	16,236
Total liabilities	27,594	17,878
Commitments (note 9)
Stockholders' equity:
Preferred stock, $0.001 par value; authorized 10,000,000 shares; issued and outstanding 8,804 and 0 at December 31, 2012 and December 31, 2011, respectively (liquidation value of $17,608 at December 31, 2012)	7,255
Common stock, $0.001 par value; authorized 90,000,000 shares; issued and outstanding 20,023,949 and 14,748,582 shares at December 31, 2012 and December 31, 2011, respectively	20	15
Additional paid-in capital	136,506	115,940
Deficit accumulated during the development stage	(140,768)	(102,984)
Total stockholders' equity	3,013	12,971
Total liabilities and stockholders' equity	$ 30,607	$ 30,849