CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 9,419	$ 12,103
General and administrative	2,886	2,541
Total operating expenses	12,305	14,644
Loss from operations	(12,305)	(14,644)
Interest income and other expense, net	662	343
Net loss	$ (11,643)	$ (14,301)
Net loss per share, basic and diluted (in dollars per share)	$ (0.40)	$ (0.63)
Shares used to compute net loss per share, basic and diluted (in shares)	29,292,135	22,580,620
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	$ 45	$ (2)
Comprehensive loss	$ (11,598)	$ (14,303)

Amount of interest income and other expense netted together.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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