CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (32,711)	$ (17,850)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	753	228
Loss on disposal of property and equipment	153	7
Stock-based compensation expense	1,068	227
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(449)	(1,902)
Other non-current assets	(1,923)	(544)
Accounts payable	311	709
Accrued expenses and other current liabilities	2,138	221
Deferred rent	339	(42)
Net cash used in operating activities	(30,321)	(18,946)
Cash flows from investing activities:
Purchases of property and equipment	(3,258)	(874)
Sale of property and equipment		7
Net cash used in investing activities	(3,258)	(867)
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	115,831	49,842
Proceeds from exercise of stock options	347	84
Proceeds from the early exercise of stock options	528	14
Net cash provided by financing activities	116,706	49,940
Net increase in cash and cash equivalents	83,127	30,127
Cash and cash equivalents at beginning of period	39,045	16,844
Cash and cash equivalents at end of period	122,172	46,971
Supplemental cash flow disclosures:
Deferred financing costs in accounts payable and accrued expenses	505
Purchases of property and equipment included in accounts payable and accrued expenses	832	616
Vesting of restricted stock subject to repurchase		1
Vesting of options early exercised subject to repurchase	$ 195	$ 8