Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (71,514)	$ (68,480)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,341	1,073
Stock-based compensation expense	7,571	3,499
Change in fair value of redeemable convertible preferred stock warrant		179
Amortization of operating right-of-use assets	910
Net amortization of premiums on investments	910
Loss on disposal of fixed assets	32	32
Asset impairment charges		267
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(16,306)	(1,040)
Other assets	(3,030)	33
Operating lease liabilities	(75)
Accounts payable	5,601	7,330
Accrued compensation	1,791	1,076
Accrued manufacturing expenses	(5,979)	18,763
Accrued expenses	8,448	1,416
Deferred rent and other long-term liabilities		(8)
Net cash used in operating activities	(70,300)	(35,860)
Cash flows from investing activities:
Purchases of property and equipment	(5,173)	(433)
Proceeds from sale of property and equipment		50
Purchases of investments	(295,279)
Maturities of investments	58,000
Sales of investments	30,062
Net cash used in investing activities	(212,390)	(383)
Cash flows from financing activities:
Payments of capital lease obligations		(61)
Proceeds from initial public offering, net of underwriters' commissions and discounts		267,375
Payment of issuance costs for initial public offering		(3,368)
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		109,879
Proceeds from exercise of common stock options	1,444	454
Proceeds from issuance of common stock related to at-the-market offering, net of issuance costs	7,108
Proceeds from issuance of common stock related to early exercised stock options		36
Proceeds from issuance of common stock under the Employee Stock Purchase Plan	490
Net cash provided by financing activities	9,042	374,315
Effect of exchange rate changes on cash and cash equivalents	363
Net (decrease) increase in cash, cash equivalents and restricted cash	(273,285)	338,072
Cash, cash equivalents and restricted cash, beginning of period	386,200	58,976
Cash, cash equivalents and restricted cash, end of period	112,915	397,048
Supplemental disclosure of cash flow information:
Cash paid for interest	7	7
Supplemental disclosures of non-cash investing and financing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	271	149
Conversion of convertible preferred stock into common stock		270,190
Issuance costs for initial public offering included in accounts payable and accrued expenses		$ 17
Stock issued for payment of accounts payable	10,000
Deferred offering costs included in accounts payable and accrued expenses	154
Proceeds from issuance of common stock through ATM facility not yet received	$ 5,011