Condensed consolidated statements of operations and comprehensive loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses
Research and development	$ 8,456	$ 6,134	$ 24,708	$ 20,250
General and administrative	3,614	2,149	9,879	5,932
Total operating expenses	12,070	8,283	34,587	26,182
Other income, net (Note 6)	237	137	672	424
Net loss	$ (11,833)	$ (8,146)	$ (33,915)	$ (25,758)
Net loss per common stock - basic and diluted (Note 7)	$ (0.50)	$ (0.46)	$ (1.45)	$ (1.48)
Basic and diluted weighted average number of common stock outstanding	23,464,785	17,690,362	23,444,181	17,372,616
Comprehensive loss:
Net loss	$ (11,833)	$ (8,146)	$ (33,915)	$ (25,758)
Other comprehensive income (loss) - unrealized gain (loss) on available-for-sale securities	102	(80)	66	282
Comprehensive loss	$ (11,731)	$ (8,226)	$ (33,849)	$ (25,476)