Condensed Statements of Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating expenses:
General and administrative	$ 2,364,000	$ 2,050,000	$ 7,025,000	$ 8,951,000
Research and development	3,542,000	6,489,000	12,479,000	17,606,000
Total operating expenses	5,906,000	8,539,000	19,504,000	26,557,000
Loss from operations	(5,906,000)	(8,539,000)	(19,504,000)	(26,557,000)
Interest expense, net	(172,000)	(132,000)	(476,000)	(107,000)
Other expense	(1,000)		(1,000)	(5,000)
Loss before income taxes	(6,079,000)	(8,671,000)	(19,981,000)	(26,669,000)
Provision (benefit) for income taxes	0	0	0	0
Net loss	(6,079,000)	(8,671,000)	(19,981,000)	(26,669,000)
Other comprehensive loss, net of tax	0	0	0	0
Comprehensive loss	$ (6,079,000)	$ (8,671,000)	$ (19,981,000)	$ (26,669,000)
Net loss per share:
Basic and diluted (Note 9)	$ (0.43)	$ (0.82)	$ (1.46)	$ (2.60)
Number of shares used in per share calculations:
Basic and diluted	14,259,691	10,623,601	13,650,556	10,253,437