Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Total revenue	$ 4,799,000	$ 3,063,000	$ 13,625,000	$ 12,329,000
Operating expenses:
Research and development	15,510,000	18,675,000	51,916,000	58,223,000
General and administrative	8,683,000	9,149,000	25,845,000	27,021,000
Loss on impairment of intangible assets	5,006,000		5,006,000
Amortization of intangible assets	138,000	144,000	417,000	443,000
Total operating expenses	29,337,000	27,968,000	83,184,000	85,687,000
Loss from operations	(24,538,000)	(24,905,000)	(69,559,000)	(73,358,000)
Interest income	1,366,000	1,353,000	4,334,000	3,892,000
Other (loss) income, net	(32,000)	21,000	(54,000)	(15,000)
Loss before income tax	(23,204,000)	(23,531,000)	(65,279,000)	(69,481,000)
Income tax benefit	2,252,000	385,000	2,322,000	444,000
Net loss	$ (20,952,000)	$ (23,146,000)	$ (62,957,000)	$ (69,037,000)
Net loss per common share, basic and diluted	$ (0.26)	$ (0.29)	$ (0.79)	$ (0.88)
Shares used in computing net loss per common share, basic and diluted	80,232,739	79,086,841	79,940,155	78,607,180
Collaboration and license revenue
Revenue:
Total revenue	$ 4,799,000	$ 3,063,000	$ 13,625,000	$ 12,329,000