Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Expenses
Research and development	$ 12,812	$ 7,820	$ 40,447	$ 21,882
General and administrative	4,864	1,875	10,919	4,807
Total expenses	17,676	9,695	51,366	26,689
Interest and other income (expense)
Other income	619	100	1,805	660
Interest income	1,189	23	2,328	112
Interest expense	(1)	(3)	(5)	(7)
Preferred stock warrant liability revaluation		(57)	(123)	(30)
Foreign exchange loss	(1)		(1)
Loss on disposal of property and equipment			(7)	(1)
Loss before income tax expense	(15,870)	(9,632)	(47,369)	(25,955)
Income tax expense	(1)		(2)	(1)
Net loss	$ (15,871)	$ (9,632)	$ (47,371)	$ (25,956)
Net loss per share, basic and diluted	$ (0.57)	$ (4.56)	$ (4.03)	$ (12.35)
Weighted-average shares used in computing net loss per share, basic and diluted	27,949,682	2,112,180	11,747,825	2,101,030