Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating expenses:
Research and development	$ 12,913	$ 7,405	$ 30,032	$ 22,607
General and administrative	3,138	2,778	10,736	9,207
Total operating expenses	16,051	10,183	40,768	31,814
Loss from operations	(16,051)	(10,183)	(40,768)	(31,814)
Other income, net	479	225	1,333	506
Loss before provision for (benefit from) income taxes, net	(15,572)	(9,958)	(39,435)	(31,308)
Provision for (benefit from) income taxes, net	(5)	37	(383)	108
Net loss	$ (15,567)	$ (9,995)	$ (39,052)	$ (31,416)
Net loss per common share, basic and diluted	$ (0.21)	$ (0.19)	$ (0.56)	$ (0.64)
Weighted-average shares used in computing net loss per common share, basic and diluted	74,347,489	52,268,443	69,517,119	49,080,049