Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (28,059,807)	$ (15,528,269)	$ (15,190,250)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11,126	8,316	7,932
Stock‑based compensation	1,345,722	329,184	395,440
Amortization of right of use lease asset	159,128
Foreign currency gain	(1,328,140)	(961,316)	(662,140)
Changes in operating assets and liabilities:
Prepaid expense and other current assets	(2,633,732)	(19,452)	4,041
Accounts payable	437,515	214,380	327,054
Accrued expenses and other liabilities	3,513,782	706,923	1,115,805
Lease liability	(154,301)
Net cash used in operating activities	(26,708,707)	(15,250,234)	(14,002,118)
Cash flows from investing activities:
Purchases of property and equipment	(30,901)	(3,702)
Net cash used in investing activities	(30,901)	(3,702)
Cash flows from financing activities:
Proceeds from the exercise of stock options	70,997	2,097
Proceeds from issuance of common stock in initial public offering, net	86,906,179
Net cash provided by financing activities	92,575,538	56,366,742	23,343,863
Increase in cash	65,835,930	41,112,806	9,341,745
Effect of exchange rate changes on cash	(1,422,992)	161,637	1,394,568
Cash and cash equivalents—beginning of year	65,675,931	24,401,488	13,665,175
Cash and cash equivalents—end of year	130,088,869	65,675,931	24,401,488
Series B convertible preferred stock
Cash flows from financing activities:
Proceeds from Issuance of Convertible Preferred Stock			$ 23,343,863
Series C convertible preferred stock
Cash flows from financing activities:
Proceeds from Issuance of Convertible Preferred Stock	$ 5,598,362	$ 56,364,645