CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 1,716	$ 1,520
Short-term investments	18,346	20,830
Grant and other receivables	715	1,934
Prepaid expenses and other current assets	494	416
Total current assets	21,271	24,700
Property and equipment, net	981	1,037
Restricted cash	679	679
Other assets	127	159
Total assets	23,058	26,575
Current liabilities:
Accounts payable	4,253	2,632
Accrued expenses	4,162	4,757
Deferred revenue	0	970
Current portion of notes payable, net of discount	2,485	0
Total current liabilities	10,900	8,359
Notes payable, net of current portion and discount	17,809	20,103
Deferred rent, net of current portion	6,605	4,644
Commitments and contingencies (Note 8)
Shareholders’ equity:
Preferred stock, par value $0.01 per share: Authorized shares-20,000,000 at June 30, 2013 (unaudited) and December 31, 2012; Issued and outstanding shares-none
Common stock, par value $0.01 per share: Authorized shares-150,000,000 at June 30, 2013 (unaudited) and December 31, 2012; Issued and outstanding shares-29,832,771 and 25,897,483 at June 30, 2013 (unaudited) and December 31, 2012, respectively	298	259
Additional paid-in capital	226,104	207,787
Accumulated deficit	(238,658)	(214,577)
Total shareholders’ deficit	(12,256)	(6,531)
Total liabilities and shareholders’ equity	$ 23,058	$ 26,575