Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Cash flows from operating activities:
Net loss	$ (101,320)	$ (68,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense related to issuance of options and employee stock purchase plan	8,384	2,961
Depreciation and amortization expense	3,227	1,327
Gain on disposal of property and equipment	0	(206)
Loss on debt extinguishment	1,233	222
Change in fair value of preferred stock warrant liability	0	69
Noncash lease expense	4,288	4,201
Noncash interest expense	318	238
Amortization (accretion) of premium/discount on marketable securities	179	(1)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,814)	(4,670)
Collaboration receivable	(300,000)	0
Accounts payable	135	474
Accrued expenses and other liabilities	2,653	3,194
Operating lease liabilities	(4,010)	15,135
Deferred revenue	336,477	14,570
Net cash used in operating activities	(50,250)	(31,286)
Cash flows from investing activities:
Purchases of property and equipment	(3,313)	(16,183)
Proceeds from sale of property and equipment	0	250
Purchases of marketable securities	(99,984)	(92,981)
Proceeds from maturities of marketable securities	139,470	0
Net cash provided by (used in) investing activities	36,173	(108,914)
Cash flows from financing activities:
Proceeds from stock purchase agreement	42,205	0
Proceeds from initial public offering, net of underwriting discounts, commissions and offering costs	0	122,121
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	89,861
Proceeds from issuance of common stock upon exercise of stock options	1,418	1,221
Proceeds from issuance of notes payable, net of issuance costs	0	19,800
Repayments of notes payable	(21,205)	(15,530)
Net cash provided by financing activities	22,418	217,473
Net increase in cash, cash equivalents and restricted cash	8,341	77,273
Cash, cash equivalents and restricted cash at beginning of period	94,528	17,255
Cash, cash equivalents and restricted cash at end of period	102,869	94,528
Supplemental cash flow information:
Cash paid for interest	1,716	660
Supplemental disclosure of noncash investing and financing information:
Purchases of property and equipment included in accounts payable, accrued expenses and other liabilities	295	2,400
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	101,136	92,795
Restricted cash (current and non-current)	1,733	1,733
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	102,869	94,528
Conversion of Redeemable Convertible stock
Supplemental disclosure of noncash investing and financing information:
Conversion of stock, amount converted	0	176,405
Conversion of Warrant Liability to Equity
Supplemental disclosure of noncash investing and financing information:
Conversion of stock, amount converted	0	114
Conversion of Notes Payable in to Warrants
Supplemental disclosure of noncash investing and financing information:
Issuance of warrants in connection with notes payable	$ 0	$ 188