Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 11,728	$ 8,785	$ 21,865	$ 17,119
General and administrative	3,479	4,178	6,844	7,598
Total operating expenses	15,207	12,963	28,709	24,717
Loss from operations	(15,207)	(12,963)	(28,709)	(24,717)
Other income, net	348	582	673	854
Loss before provision for (benefit from) income taxes, net	(14,859)	(12,381)	(28,036)	(23,863)
Provision for (benefit from) income taxes, net	19	(421)	(126)	(378)
Net loss	$ (14,878)	$ (11,960)	$ (27,910)	$ (23,485)
Net loss per common share, basic and diluted	$ (0.20)	$ (0.16)	$ (0.37)	$ (0.35)
Weighted-average shares used in computing net loss per common share, basic and diluted	74,688,283	74,320,415	74,587,350	67,061,904

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