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
CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS
Alliance revenue	$ 323	$ 20	$ 918	$ 59
Operating expenses:
Research and development	9,393	7,454	28,817	25,134
General and administrative	3,907	4,030	11,601	11,688
Total operating expenses	13,300	11,484	40,418	36,822
Loss from operations	(12,977)	(11,464)	(39,500)	(36,763)
Other income (expense):
Interest income	90	123	320	239
Interest expense	(19)	(27)	(63)	(81)
Foreign currency exchange gain (loss)	3	3	32	40
Net loss	$ (12,903)	$ (11,365)	$ (39,211)	$ (36,565)
Basic and diluted net loss per common share (Note 13)	$ (0.10)	$ (0.10)	$ (0.32)	$ (0.32)
Shares used in computing basic and diluted net loss per common share	121,389	118,248	121,332	113,821
Net loss	$ (12,903)	$ (11,365)	$ (39,211)	$ (36,565)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	13	50	133	(10)
Comprehensive loss	$ (12,890)	$ (11,315)	$ (39,078)	$ (36,575)