Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Cash flows used in operating activities:
Net loss	$ (17,585)	$ (7,669)	$ (7,669)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of future tranche right liability		3,482	3,482
Depreciation and amortization	49	12
Share‑based compensation	2,368	231
Deferred rent	(15)	444
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(978)	31
Prepaid research and development	(5,595)	2,925
Accounts payable	331	(47)
Accrued expenses	(426)	377
Net cash used in operating activities	(21,851)	(214)
Cash flows used in investing activities:
Purchases of property and equipment	(99)	(884)
Net cash used in investing activities	(99)	(884)
Cash flows provided by financing activities:
Proceeds from issuance of common stock upon initial public offering	229,904
Proceeds from early exercise stock options	44	176
Net cash provided by financing activities	229,904	20,157
Net increase in cash and cash equivalents	207,954	19,059
Cash and cash equivalents at beginning of year	158,874	24,861	24,861
Cash and cash equivalents at end of year	366,828	43,920	$ 158,874
Supplemental disclosure of non‑cash investing and financing activities:
Deferred offering costs in accrued expenses and other current liabilities	70
Deferred offering costs in accounts payable	1,571
Reclassification of deferred offering costs paid in a prior period	763
Property and equipment in accounts payable		134
Vesting of early exercise option awards	$ 32	13
Series A-1 Convertible Preferred Stock
Cash flows provided by financing activities:
Proceeds from Issuance of Convertible Preferred Stock		$ 19,981