Organization and Basis of Presentation	9 Months Ended
Sep. 30, 2025
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Description of Business Plus Therapeutics, Inc. (the “Company”) is a clinical-stage pharmaceutical company focused on the development, manufacture and commercialization of complex and innovative treatments for patients battling cancer and other life-threatening diseases. CNSide Diagnostics, LLC is a wholly owned subsidiary of Plus Therapeutics, Inc. that develops and commercializes proprietary laboratory-developed tests, such as the CNSide™ Test, designed to identify tumor cells that have metastasized to the central nervous system in patients with carcinomas and melanomas. Basis of Presentation The accompanying unaudited condensed consolidated financial statements for the three and nine months ended September 30, 2025 and 2024 have been prepared in accordance with accounting principles generally accepted in the United States of America ("US GAAP") for interim financial information. Accordingly, they do not include all of the information and footnotes required by US GAAP for annual financial statements. The condensed consolidated balance sheet at December 31, 2024 has been derived from the audited consolidated financial statements at December 31, 2024, but does not include all of the information and footnotes required by US GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the financial position and results of operations of the Company have been included. Operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025.

Organization and Basis of Presentation

9 Months Ended

Sep. 30, 2025

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Organization and Basis of Presentation

Description of Business

Plus Therapeutics, Inc. (the “Company”) is a clinical-stage pharmaceutical company focused on the development, manufacture and commercialization of complex and innovative treatments for patients battling cancer and other life-threatening diseases. CNSide Diagnostics, LLC is a wholly owned subsidiary of Plus Therapeutics, Inc. that develops and commercializes proprietary laboratory-developed tests, such as the CNSide™ Test, designed to identify tumor cells that have metastasized to the central nervous system in patients with carcinomas and melanomas.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements for the three and nine months ended September 30, 2025 and 2024 have been prepared in accordance with accounting principles generally accepted in the United States of America ("US GAAP") for interim financial information. Accordingly, they do not include all of the information and footnotes required by US GAAP for annual financial statements. The condensed consolidated balance sheet at December 31, 2024 has been derived from the audited consolidated financial statements at December 31, 2024, but does not include all of the information and footnotes required by US GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the financial position and results of operations of the Company have been included. Operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025.