Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Revenue from license agreement	$ 0	$ 0	$ 3,000	$ 0
Revenue from development agreement	77	0	138	0
Revenue from related party	0	400	0	2,163
Revenue from grants	271	0	271	0
Total revenues	348	400	3,409	2,163
Cost and expenses:
Research and development	7,032	13,703	27,178	44,322
General and administrative	4,601	8,033	16,207	21,551
(Gain) / loss on lease modification and termination	0	444	881	(1,669)
Total cost and expenses	11,633	22,180	44,266	64,204
Loss from operations	(11,285)	(21,780)	(40,857)	(62,041)
Sublease termination income, net	0	2,875	0	2,875
Interest and other income, net	(5)	93	(15)	592
Net loss	$ (11,290)	$ (18,812)	$ (40,872)	$ (58,574)
Net loss per share:
Basic and diluted net loss per share (in dollars per share)	$ (0.26)	$ (0.59)	$ (1.08)	$ (2.01)
Weighted average shares used in calculating:
Basic and diluted net loss per share (in shares)	43,291	32,096	37,730	29,196
Other comprehensive loss:
Net loss	$ (11,290)	$ (18,812)	$ (40,872)	$ (58,574)
Other comprehensive loss:
Foreign currency translation adjustment (loss) gain	(0)	3	1	(7)
Comprehensive loss	$ (11,290)	$ (18,809)	$ (40,871)	$ (58,581)