Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Expenses
Research and development	$ 4,216	$ 1,525	$ 7,383	$ 3,045
General and administrative	1,674	924	3,202	1,681
Total operating expenses	5,890	2,449	10,585	4,726
Loss from operations	(5,890)	(2,449)	(10,585)	(4,726)
Other Expense
Interest and other income, net	542	173	1,126	300
Total interest and other income, net	542	173	1,126	300
Net loss	(5,348)	(2,276)	(9,459)	(4,426)
Unrealized gain (loss) on available-for-sale securities	2	(2)	16	(2)
Comprehensive loss	$ (5,346)	$ (2,278)	$ (9,443)	$ (4,428)
Net loss attributable to common stockholders per share: Basic and diluted	$ (0.37)	$ (0.22)	$ (0.65)	$ (0.43)
Weighted-average common shares outstanding: Basic and diluted	14,522,515	10,310,101	14,470,371	10,308,747