Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (82,465,000)	$ (107,758,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8,624,000	5,805,000
Loss on disposal of property and equipment	55,000	0
Amortization of discount on investments, net	(659,000)	(163,000)
Impairment of intangible assets	0	4,254,000
Stock-based compensation	14,132,000	13,587,000
Gain on remeasurement of future royalty liability	0	(6,960,000)
Non-cash interest expense related to sale of future royalties	1,447,000	1,305,000
Non-cash revenue related to sale of future royalties	(737,000)	(151,000)
Change in operating assets and liabilities:
Accounts receivable	(2,988,000)	51,000
Prepaid expenses and other assets	3,561,000	(3,783,000)
Accounts payable	(2,444,000)	357,000
Deferred grant revenue	(2,000,000)	2,000,000
Accrued liabilities	(6,979,000)	(3,323,000)
Net cash used in operating activities	(70,453,000)	(94,779,000)
Cash flows from investing activities:
Purchase of property and equipment	(1,871,000)	(9,601,000)
Proceeds from sale of property and equipment	120,000	0
Purchases of investments	(27,497,000)	(55,014,000)
Proceeds from maturities of investments	73,200,000	44,200,000
Net cash provided by (used in) investing activities	43,952,000	(20,415,000)
Cash flows from financing activities:
Proceeds from issuance of common stock upon exercise of warrants	0	2,000
Proceeds from issuance of common stock upon exercise of stock options	17,000	223,000
Shares acquired to settle employee tax withholding liabilities	(366,000)	0
Proceeds from issuance of common stock under the employee stock purchase plan	562,000	0
Net cash provided by financing activities	15,243,000	17,462,000
Net decrease in cash, cash equivalents and restricted cash	(11,258,000)	(97,732,000)
Cash, cash equivalents and restricted cash at beginning of the period	46,013,000	143,745,000
Cash, cash equivalents and restricted cash at end of the period	34,755,000	46,013,000
Supplemental disclosure of non-cash investing and financing activity:
Operating lease liabilities arising from obtaining right-of-use assets	495,000	9,997,000
Acquisition of property and equipment included in accounts payable and accrued expenses	4,000	1,803,000
Cash and cash equivalents	34,755,000	44,013,000
Restricted cash	0	2,000,000
Cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows	34,755,000	46,013,000
Registered Direct Offering [Member]
Cash flows from financing activities:
Net proceeds from issuance of common stock	13,600,000	0
At-the-market Facility [Member]
Cash flows from financing activities:
Net proceeds from issuance of common stock	$ 1,430,000	$ 17,237,000