CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
REVENUE:
Product Development and Licensing Agreements	$ 493	$ 377	$ 1,551	$ 1,053
Contracts and Grants	1,727	649	3,362	2,636
Total Revenue	2,220	1,026	4,913	3,689
OPERATING EXPENSE:
Research and Development	25,009	24,656	78,168	76,271
General and Administrative	6,950	8,487	24,049	22,761
Amortization of Acquired Intangible Assets	254	254	760	760
Total Operating Expense	32,213	33,397	102,977	99,792
Operating Loss	(29,993)	(32,371)	(98,064)	(96,103)
Investment and Other Income, Net	395	391	1,841	1,590
Net Loss	$ (29,598)	$ (31,980)	$ (96,223)	$ (94,513)
Basic and Diluted Net Loss Per Common Share (in dollars per share) (Note 3)	$ (0.29)	$ (0.32)	$ (0.97)	$ (0.98)
Shares Used in Calculating Basic and Diluted Net Loss per Share (in shares) (Note 3)	100,672	98,568	99,398	96,518
COMPREHENSIVE LOSS:
Net Loss	$ (29,598)	$ (31,980)	$ (96,223)	$ (94,513)
Other Comprehensive (Loss) Income:
Foreign Currency Translation Adjustments				15
Unrealized Gain (Loss) on Marketable Securities	(113)	124	303	(45)
Comprehensive Loss	$ (29,711)	$ (31,856)	$ (95,920)	$ (94,543)