Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net loss	$ (55,020)	$ (45,968)
Reconciliation of net loss to net cash used in operating activities:
Depreciation	399	282
Stock-based compensation	10,364	7,849
Amortization of premiums on investment securities, net	(4,248)	(497)
Non-cash lease expense	28	49
Other		4
Change in operating assets and liabilities:
Prepaid expense and other assets	1,151	(2,922)
Accounts payable and other liabilities	1,564	4,977
Net cash used in operating activities	(45,762)	(36,226)
Cash flows from investing activities
Purchases of investment securities	(150,550)	(251,990)
Proceeds from maturities of investment securities	197,760	32,650
Proceeds from sale of asset		39
Purchases of property and equipment	(229)	(630)
Net cash provided by (used in) investing activities	46,981	(219,931)
Cash flows from financing activities
Issuance of common stock through employee stock purchase plan	206	225
Proceeds from the exercise of stock options	17	307
Payment of deferred issuance costs		(427)
Net cash provided by (used in) financing activities	223	105
Net increase (decrease) in cash and cash equivalents	1,442	(256,052)
Cash and cash equivalents at beginning of period	26,500	298,569
Cash and cash equivalents at end of period	$ 27,942	42,517
Supplemental disclosures
Initial recognition of right-of-use asset and operating lease liability		590
Deferred financing costs in accrued expenses		75
Purchases of property and equipment included in accounts payable and accrued expenses		$ 59