Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from Contract with Customer, Including Assessed Tax	$ 200,000	$ 265,000	$ 818,000	$ 3,690,000
Operating expenses:
Research and development	12,409,000	4,616,000	33,219,000	11,272,000
General and administrative	5,042,000	4,190,000	16,136,000	10,076,000
Restructuring costs	0	(952,000)	0	(849,000)
Total operating expenses	17,451,000	7,854,000	49,355,000	20,499,000
Operating loss	(17,251,000)	(7,589,000)	(48,537,000)	(16,809,000)
Other income and (expenses):
Interest income	26,000	5,000	58,000	69,000
Non-cash interest expense related to sale of future royalties	(337,000)	(464,000)	(1,137,000)	(1,401,000)
Foreign exchange loss, net	0	(11,000)	(1,000)	(13,000)
Loss before income taxes	(17,562,000)	(8,059,000)	(49,617,000)	(18,154,000)
Provision for income taxes	21,000	26,000	89,000	205,000
Net loss	$ (17,583,000)	$ (8,085,000)	$ (49,706,000)	$ (18,359,000)
Net loss per share - basic and diluted (in dollars per share)	$ (0.14)	$ (0.08)	$ (0.41)	$ (0.23)
Shares used to compute net loss per share - basic and diluted (in shares)	123,984,141	107,718,578	120,110,780	81,121,045
Comprehensive loss:
Net loss	$ (17,583,000)	$ (8,085,000)	$ (49,706,000)	$ (18,359,000)
Unrealized gains (losses) on available-for-sale investments	6,000	0	(3,000)	0
Comprehensive loss	(17,577,000)	(8,085,000)	(49,709,000)	(18,359,000)
Customer Service Contracts [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	2,000	13,000	193,000
Royalty [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	2,962,000
Non Cash Royalty Revenue [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 200,000	$ 263,000	$ 805,000	$ 535,000