Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating activities
Net loss	$ (73,790)	$ (120,717)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,927	709
Stock-based compensation	16,946	15,764
Non-cash research and development expenses		9,281
Non-cash lease expense	660	1,127
Accretion of discount on marketable debt securities	(4,788)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	2,532	(3,381)
Accounts payable	(3,507)	(8,328)
Accrued expenses and other current liabilities	(14,097)	11,951
Operating lease liabilities	2,410	4,259
Deferred revenue	998
Net cash used in operating activities	(70,709)	(89,335)
Investing activities
Cash acquired in acquisition of Apexigen, Inc.	6,660
Redemption of marketable debt securities	92,048
Purchase of marketable debt securities	(196,831)
Purchase of property and equipment	(6,726)	(6,399)
Net cash used in investing activities	(104,849)	(6,399)
Financing activities
Proceeds from shares issued under ATM, net of commission	6,122
Tax withholding payments related to net settlement of restricted common stock	(445)
Proceeds from the exercise of stock options	120	183
Proceeds from the sale of stock under employee stock purchase plan	132
Net cash provided by financing activities	5,929	183
Net decrease in cash, cash equivalents, and restricted cash	(169,629)	(95,551)
Cash, cash equivalents and restricted cash at beginning of year	180,765	276,316
Cash, cash equivalents and restricted cash at end of period	11,136	180,765
Supplemental cash flow information:
Cash received for interest	2,419	2,166
Cash paid for taxes	48	17
Noncash operating, investing and financing activities:
Shares, warrants, and replacement stock options and restricted stock units issued for acquisition of Apexigen, Inc.	10,732
Property and equipment in accounts payable and accrued expenses	237	4,479
Operating lease right-of-use assets obtained in exchange for operating lease liabilities		14,497
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	9,664	179,293
Restricted cash	1,472	1,472
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	11,136	$ 180,765
Pfizer License Agreement
Noncash operating, investing and financing activities:
Issuance of common stock to Pfizer Inc.	$ 5,000