Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 6,832	$ 72
Operating expenses:
Research and development	12,349	33,975
General and administrative	11,317	12,860
Total operating expenses	23,666	46,835
Loss from operations	(16,834)	(46,763)
Other income (expense):
Interest and other income	374	459
Interest and other expense	(2,131)	(2,343)
Loss before income taxes	(18,591)	(48,647)
Income tax expense	(1)	(62)
Net loss and comprehensive net loss	$ (18,592)	$ (48,709)
Net loss per share - basic and diluted (in dollars per share)	$ (1.08)	$ (5.59)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	17,260,176	8,718,563
Revenue under collaborations
Revenues:
Total revenues	$ 6,832	$ 72