Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 6,438	$ 11,848
General and administrative	8,816	9,524
Total operating expenses	15,254	21,372
Loss from operations	(15,254)	(21,372)
Other income:
Investment income	262	436
Other income, net		207
Total other income	262	643
Net loss and net loss attributable to common stockholders	(14,992)	(20,729)
Foreign currency translation adjustment	(2)	(1)
Unrealized gain on available-for-sale investments		20
Comprehensive loss	$ (14,994)	$ (20,710)
Net loss per share attributable to common stockholders - basic and diluted (in dollars per share)	$ (30.15)	$ (45.80)
Weighted-average common shares outstanding used in net loss per share attributable to common stockholders - basic and diluted (in shares)	497,275	452,555