Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Operating expenses:
Research and development	$ 4,239	$ 4,519	$ 9,486	$ 9,917
General and administrative	2,397	2,400	4,789	4,763
Total operating expenses	6,636	6,919	14,275	14,680
Loss from operations	(6,636)	(6,919)	(14,275)	(14,680)
Other income (expense):
Interest expense	(33)	(127)	(90)	(276)
Interest and investment income	43	44	75	83
Other income, net	147	28	159	23
Total other income (expense), net	157	(55)	144	(170)
Net loss	$ (6,479)	$ (6,974)	$ (14,131)	$ (14,850)
Net loss per share - basic and diluted (in dollars per share)	$ (0.20)	$ (0.32)	$ (0.48)	$ (0.73)
Weighted-average common shares outstanding used in net loss per share - basic and diluted (in shares)	32,728,771	21,796,194	29,659,358	20,452,200

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