Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Product sales	$ 0	$ 42	$ 7	$ 70
Grant revenue	75	1,051	259	1,054
Total revenues	75	1,093	266	1,124
Expenses:
Cost of product sales	0	731	929	1,512
Research and development	7,129	6,858	14,211	12,448
Selling, general and administrative	3,383	4,446	6,736	8,869
Total expenses	10,512	12,035	21,876	22,829
Operating loss	(10,437)	(10,942)	(21,610)	(21,705)
Change in fair value of common stock warrant liability	469	1,448	438	1,826
Other income / (expense):
Interest and other income	1	2	234	4
Interest and other expense	(1,359)	(1,131)	(2,567)	(2,224)
Other income / (expense), net	(1,358)	(1,129)	(2,333)	(2,220)
Net loss	$ (11,326)	$ (10,623)	$ (23,505)	$ (22,099)
Net loss per common share
Basic (in dollars per share)	$ (0.13)	$ (0.12)	$ (0.27)	$ (0.26)
Diluted (in dollars per share)	$ (0.13)	$ (0.14)	$ (0.27)	$ (0.28)
Weighted-average number of common shares outstanding
Basic (in shares)	85,753	85,061	85,671	84,766
Diluted (in shares)	85,753	85,882	85,671	86,111