Condensed Consolidated Statements of Operations and Other Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating expenses:
Research and development		$ 6,801	$ 5,415	$ 20,160	$ 13,959
General and administrative		5,978	5,945	18,907	18,898
Reverse merger related expenses					594
Total operating expenses		12,779	11,360	39,067	33,451
Loss from operations		(12,779)	(11,360)	(39,067)	(33,451)
Other expense (income), net		96	(199)	174	(293)
Net loss		(12,875)	(11,161)	(39,241)	(33,158)
Other Comprehensive Loss:
Net loss		(12,875)	(11,161)	(39,241)	(33,158)
Unrealized gain (loss) from available-for-sale securities		(12)		12
Comprehensive loss		$ (12,887)	$ (11,161)	$ (39,229)	$ (33,158)
Basic and diluted net loss per share		$ (0.32)	$ (0.32)	$ (1.05)	$ (1.05)
Weighted average number of common shares in computing basic and diluted net loss per share	[1]	39,944,324	35,005,979	37,394,310	31,485,067

[1] The following potentially dilutive securities have been excluded from the computation of diluted weighted average shares outstanding as their effect would be anti-dilutive: Nine months ended September 30, 2019 2018 Options to purchase common stock 4,797,040 3,611,400 Restricted stock units 508,228 767,743 Warrants 323,894 347,241 Total potential common stock equivalents 5,629,162 4,726,384