Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (21,220)	$ (27,142)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	347	384
Stock-based compensation expense	1,865	372
Change in fair value of redeemable convertible preferred stock warrant		179
Amortization of operating right-of-use assets	180
Net amortization of premiums on investments	151
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(557)	(951)
Other assets	(441)	(89)
Operating lease liabilities	(105)
Accounts payable	2,185	(723)
Accrued compensation	723	(65)
Accrued manufacturing expenses	2,525	13,159
Accrued expenses	1,142	1,245
Deferred rent and other long-term liabilities		(2)
Net cash used in operating activities	(13,205)	(13,633)
Cash flows from investing activities:
Purchases of property and equipment	(1,246)	(349)
Purchases of investments	(172,145)
Net cash used in investing activities	(173,391)	(349)
Cash flows from financing activities:
Payments of capital lease obligations		(60)
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		109,875
Proceeds from exercise of common stock options	487	49
Proceeds from issuance of common stock related to early exercised stock options		36
Payments of deferred offering costs		(103)
Net cash provided by financing activities	487	109,797
Effect of exchange rate changes on cash and cash equivalents	(281)
Net increase (decrease) in cash, cash equivalents and restricted cash	(186,390)	95,815
Cash, cash equivalents and restricted cash, beginning of period	386,200	58,976
Cash, cash equivalents and restricted cash, end of period	199,810	154,791
Supplemental disclosure of cash flow information:
Cash paid for interest		7
Supplemental disclosures of non-cash investing and financing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	$ 1,537	35
Issuance costs for initial public offering included in accounts payable and accrued expenses		$ 142