Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property and Equipment
Property and equipment, gross	$ 4,899	$ 4,703
Less: accumulated depreciation and amortization	(4,546)	(4,252)
Property and equipment, net	353	451
Laboratory equipment
Property and Equipment
Property and equipment, gross	2,673	2,477
Computer equipment and purchased software
Property and Equipment
Property and equipment, gross	142	142
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 2,084	$ 2,084

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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