Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (75,347)	$ (157,125)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	217	2
Stock-based compensation	3,461	66
Amortization of debt discount	904	243
Acquired in-process research and development		78,897
Change in fair value of warrant liabilities (includes related party amounts of $0 and $59,031, respectively)	(95)	59,060
Change in fair value of convertible promissory notes (includes related party amounts of $0 and $1,053, respectively)		4,928
Other	158
Changes in operating assets and liabilities:
Prepaid expenses and other current assets (includes the change in related party amounts of $0, and $17, respectively)	11,034	(3,147)
Accounts payable and accrued expenses (includes the change in related party amounts of $238, and $186, respectively)	18,506	1,603
Accrued interest (includes the change in related party amounts of $0 and $483, respectively)	146	2,347
Operating right-of-use asset and lease liabilities	(272)
Other long-term assets	(200)
Net cash used in operating activities	(41,488)	(13,126)
Cash flows from investing activities
Cash paid for purchased in-process research and development		(25,118)
Cash paid for property, plant and equipment	(916)	(26)
Net cash used in investing activities	(916)	(25,144)
Cash flows from financing activities
Proceeds from initial public offering, net of issuance costs		(1,299)
Proceeds from issuance of convertible promissory notes		88,324
Net proceeds from issuance of long-term debt	25,000	24,850
Net cash provided by financing activities	25,000	111,875
Net (decrease) increase in cash and cash equivalents	(17,404)	73,605
Cash and cash equivalents – beginning of period	243,765	879
Cash and cash equivalents – end of period	226,361	74,484
Supplemental disclosure of cash flow information
Interest paid	2,235	549
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	39
Final interest payment fee	2,063	2,063
Operating lease liabilities arising from obtaining right-of-use assets	1,396
Unpaid initial public offering costs		714
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
Lender Warrants
Supplemental disclosure of noncash investing and financing activities
Conversion of Lender Warrants into equity	$ 318