STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 10,163	$ 9,419
General and administrative	3,106	2,886
Total operating expenses	13,269	12,305
Loss from operations	(13,269)	(12,305)
Interest income and other expense, net	334	662
Net loss	$ (12,935)	$ (11,643)
Net loss per share, basic and diluted (in dollars per share)	$ (0.44)	$ (0.40)
Shares used to compute net loss per share, basic and diluted (in shares)	29,411,233	29,292,135
Other comprehensive loss:
Unrealized gain on marketable securities	$ 14	$ 45
Comprehensive loss	$ (12,921)	$ (11,598)

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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The net result for the period of deducting operating expenses from operating revenues.

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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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