CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 22,238	$ 10,883
Operating expenses
Research and development	82,416	45,122
General and administrative	27,026	13,673
Total operating expenses	109,442	58,795
Loss from operations	(87,204)	(47,912)
Other income (expense), net:
Change in fair value of convertible notes payable	(9,758)
Interest expense	(182)
Interest income	4,267	1,875
Total other income (expense), net	(5,673)	1,875
Net loss and net loss attributable to common stockholders	$ (92,877)	$ (46,037)
Net loss per share attributable to common stockholders- basic and diluted	$ (2.21)	$ (2.92)
Weighted average shares of common stock outstanding- basic and diluted	41,991,162	15,775,541