Condensed Statements of Operations And Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 6,476	$ 5,849	$ 12,789	$ 12,049
General and administrative	1,795	1,107	3,305	2,157
Total operating expenses	8,271	6,956	16,094	14,206
Loss from operations	(8,271)	(6,956)	(16,094)	(14,206)
Other income (expense), net:
Interest income	6	59	28	116
Change in fair value of convertible loan notes	(83)		(83)
Total other income (expense), net	(77)	59	(55)	116
Net loss and comprehensive loss	(8,348)	(6,897)	(16,149)	(14,090)
Net loss	(8,348)	(6,897)	(16,149)	(14,090)
Accretion of issuance costs on redeemable convertible preferred stock	(429)	(33)	(456)	(51)
Accrued dividends on redeemable convertible preferred stock	(2,187)	(1,476)	(3,957)	(2,728)
Net loss attributable to common stockholders	$ (10,964)	$ (8,406)	$ (20,562)	$ (16,869)
Weighted-average common shares outstanding—basic and diluted	1,488,489	1,429,484	1,488,489	1,413,935
Net loss per share attributable to common stockholders—basic and diluted	$ (7.37)	$ (5.88)	$ (13.81)	$ (11.93)