Combined Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (255,131)	$ (1,288)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8
Stock-based compensation	406
Amortization of debt discount	409
Acquired in-process research and development	78,897
Non-cash interest expense (includes related party amounts of $590 and 0, respectively)	2,605
Change in fair value of warrant liabilities (includes related party amounts of $96,278 and $0, respectively)	96,272
Change in fair value of convertible promissory notes (includes related party amounts of $10,941 and $50, respectively)	49,546	50
Changes in operating assets and liabilities:
Prepaid expenses and other current assets (includes related party amounts of $19, and $(19), respectively)	(11,813)	(23)
Accounts payable and accrued expenses (includes related party amounts of $460, and $47, respectively)	2,265	225
Accrued interest (includes related party amounts of $0 and $13, respectively)	156	13
Operating right-of-use asset and lease liabilities	51
Other long-term assets	(181)
Net cash used in operating activities	(36,510)	(1,023)
Cash flows from investing activities
Cash paid for purchased in-process research and development	(25,118)
Cash paid for property, plant and equipment	(132)
Net cash used in investing activities	(25,250)
Cash flows from financing activities
Proceeds from initial public offering, net of issuance costs	191,472
Proceeds from issuance of common stock		2
Proceeds from issuance of convertible promissory notes	88,324	1,900
Net proceeds from issuance of long-term debt	24,850
Net cash provided by financing activities	304,646	1,902
Net increase in cash and cash equivalents	242,886	879
Cash and cash equivalents – beginning of period	879
Cash and cash equivalents – end of period	243,765	$ 879
Supplemental disclosure of cash flow information
Interest paid	1,007
Supplemental disclosure of noncash investing and financing activities
Exchange of accrued interest for convertible promissory notes	27
Issuance of common stock warrants in connection with long-term debt	419
Property and equipment purchases included in accounts payable and accrued liabilities	339
Final interest payment fee	2,063
Operating lease liabilities arising from obtaining right-of-use assets	796
Conversion of convertible promissory notes and accrued interest into common shares	142,437
Takeda Warrants
Supplemental disclosure of noncash investing and financing activities
Conversion of Takeda Warrants into Equity	144,172
Takeda License
Supplemental disclosure of noncash investing and financing activities
Issuance of Takeda Warrants in connection with Takeda License	47,894
Issuance of common stock in connection with Takeda License	$ 5,885