Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Total revenues	$ 6,778	$ 18
Operating expenses:
Research and development	5,983	11,828
General and administrative	3,533	3,773
Total operating expenses	9,516	15,601
Loss from operations	(2,738)	(15,583)
Other income (expense):
Interest and other income	56	164
Interest and other expense	(578)	(605)
Loss before income taxes	(3,260)	(16,024)
Income tax expense	0	(1)
Net loss	(3,260)	(16,025)
Other comprehensive loss:
Unrealized gain on short-term investments, net	0	7
Comprehensive loss	$ (3,260)	$ (16,018)
Net loss per share, basic and diluted (in dollars per share)	$ (0.31)	$ (1.85)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	10,379,830	8,668,695
Revenue under strategic alliances and collaborations
Revenues:
Total revenues	$ 6,778	$ 18