Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (108,057)	$ (75,347)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	386	217
Stock-based compensation	12,474	3,461
Issuance of PIK interest debt	130
Amortization of debt discount	3,088	904
Change in fair value of warrant liabilities		(95)
Other	722	158
Changes in operating assets and liabilities:
Prepaid expenses and other current assets (includes the change in related party amounts of $82, and $0, respectively)	3,177	11,034
Accounts payable and accrued expenses (includes the change in related party amounts of $1,251 and $238, respectively)	(9,629)	7,661
Accrued clinical trial expenses	(9,506)	10,845
Accrued interest	(98)	146
Operating right-of-use asset and lease liabilities	75	(272)
Other long-term assets	43	(200)
Net cash used in operating activities	(107,195)	(41,488)
Cash flows from investing activities
Cash paid for property, plant and equipment	(228)	(916)
Net cash used in investing activities	(228)	(916)
Cash flows from financing activities
Proceeds from issuance of common stock from exercise of stock options	1,781
Repayment of long-term debt	(54,125)
Net proceeds from issuance of long-term debt	96,889	25,000
Net cash provided by financing activities	44,545	25,000
Net (decrease) in cash and cash equivalents	(62,878)	(17,404)
Cash and cash equivalents – beginning of period	287,496	243,765
Cash and cash equivalents – end of period	224,618	226,361
Supplemental disclosure of cash flow information
Interest paid	2,920	2,235
Supplemental disclosure of noncash investing and financing activities
Issuance of common stock warrants in connection with long-term debt	1,290
Property and equipment purchases included in accounts payable and accrued liabilities	9	39
Final interest payment fee	7,500	2,063
Settlement of ESPP liability in common stock	819
Settlement of 401(k) liability in common stock	$ 903
Operating lease liabilities arising from obtaining right-of-use assets		1,396
Conversion of Lender Warrants into equity		$ 318