Plus Therapeutics Provides US Launch Update for its CNSide® Diagnostic

CNSide available for the state of Texas in August 2025 Initial commercial focus on NCI-Designated Cancer Centers and large private healthcare systems Company will expand testing services and broaden regional availability over the next 12 months HOUSTON, July 31, 2025 (GLOBE NEWSWIRE) -- Plus Therapeutics, Inc. (Nasdaq: PSTV) (the “Company”), a clinical-stage pharmaceutical company developing targeted radiotherapeutics with advanced platform technologies for central nervous system (CNS) cancers, announces that its wholly-owned subsidiary, CNSide Diagnostics, LLC (“CNSide”) will make CNSide cerebrospinal fluid (CSF) assay platform and testing services commercially available in Texas in August 2025. Initial commercial focus will be on National Cancer Institute (NCI) Designated Cancer Centers, which treat the highest number of patients at risk for leptomeningeal metastases (LM) and previously used CNSide. These institutions and provider networks include the University of Texas - Southwestern, MD Anderson Cancer Center, Mays Cancer Center, Baylor Scott & White Health, and Texas Oncology. “The CNSide assay is an invaluable diagnostic tool, relevant in providing important guidance in monitoring patient disease progression and in helping define patient treatment,” said Michael Youssef, M.D., Assistant Professor in the Department of Neurology and the Department of Hematology and Oncology at UT Southwestern Medical Center. “Having been a prior user of the CNSide assay, I look forward to the relaunch of this important patient management tool by CNSide.” Patients with LM or at risk for LM should consult with their providers and either contact one of the institutions or provider networks listed above or visit the CNSide website for further information. Physicians, providers, hospitals or clinics interested in CNSide should contact CNSide through our website. CNSide is a Comprehensive Diagnostic PlatformThe CNSide testing platform is a proprietary, laboratory-developed program designed to identify tumor cells that have metastasized to the central nervous system in patients with carcinomas and melanomas who are at risk of developing cancer of the central nervous system (CNS). CNS metastases are an epidemic affecting as many as 30% of adult cancer patients and affect the highly protected CNS space. Once the CNS is affected, diagnosis and treatment are difficult and as a result, approximately half of patients with CSF metastases instead receive just palliative care or hospice. The comprehensive CNSide CSF Assay is a highly sensitive tool that diagnoses, monitors, and guides treatment, demonstrating significant advantages over the current standard of care. The superior clinical utility of CNSide has been shown in 9 peer-reviewed publications, a completed clinical trial, and has been validated in the market through real-world use. More than 11,000 CNSide tests have been performed at over 200 U.S. cancer institutions since 2020, delivering high sensitivity (92%) and specificity (95%), while influencing treatment decisions in over 90% of cases. By comparison, CSF cytology, the current standard of care for CNS Mets diagnosis, was originally developed over a century ago and offers suboptimal test sensitivity leading to missed or delayed diagnosis and treatment. About LM Leptomeningeal metastases (LM) are a rare but severe complication of advanced cancer, affecting the fluid-lined structures of the central nervous system. LM occurs in approximately 5% of patients with metastatic cancer, with breast cancer, lung cancer, and melanoma being the most common sources. Median survival is typically 2-6 months, and effective treatment options are limited, highlighting the urgent need for novel therapies. About CNSide Diagnostic, LLC CNSide Diagnostics, LLC is a wholly owned subsidiary of Plus Therapeutics, Inc. that develops and commercializes proprietary laboratory-developed tests, such as CNSide, designed to identify tumor cells that have metastasized to the central nervous system in patients with carcinomas and melanomas. The CNSide® CSF Assay Platform enables quantitative analysis and molecular characterization of tumor cells and circulating tumor DNA in the cerebrospinal fluid that inform and improve the management of patients with leptomeningeal metastases. About Plus TherapeuticsHeadquartered in Houston, Texas, Plus Therapeutics, Inc. is a clinical-stage pharmaceutical company developing targeted radiotherapeutics for difficult-to-treat cancers of the central nervous system with the potential to enhance clinical outcomes. Combining image-guided local beta radiation and targeted drug delivery approaches, the Company is advancing a pipeline of product candidates with lead programs in leptomeningeal metastases (LM) and recurrent glioblastoma (GBM). The Company has built a supply chain through strategic partnerships that enable the development, manufacturing, and future potential commercialization of its products. For more information, visit https://www.plustherapeutics.com. Forward-Looking StatementsThis press release contains statements that may be deemed “forward-looking statements” within the meaning of U.S. securities laws, including statements regarding clinical trials, expected operations and upcoming developments. All statements in this press release other than statements of historical fact are forward-looking statements. These forward-looking statements may be identified by future verbs, as well as terms such as “expect” “potential,” “anticipating,” “planning” and similar expressions or the negatives thereof. Such statements are based upon certain assumptions and assessments made by management in light of their experience and their perception of historical trends, current conditions, expected future developments and other factors they believe to be appropriate. These statements include, without limitation, statements regarding the potential market for the CNSide CSF Assay, the timing in which the CNSide CSF Assay is commercially launched and commercialization is expanded, revenue and corporate profitability expectations including support reimbursements and payments for the CNSide CSF Assay, the development and utility of the CNSide CSF Assay and expectations as to the Company’s future performance, including the next steps in developing the Company’s product candidates. The forward-looking statements included in this press release could differ materially from those expressed or implied by these forward-looking statements because of risks, uncertainties, and other factors that include, but are not limited to, the following: the Company’s ability to maintain the listing of its common stock on Nasdaq; risks related to a halt in trading or delisting of the Company’s common stock on Nasdaq; Medicare and private payors may not provide coverage and reimbursement or may breach, rescind or modify their contracts or reimbursement policies or delay payments; the risk that our products and services may not perform as expected; the early stage of the Company’s product candidates and therapies; the results of the Company’s research and development activities, including uncertainties relating to the clinical trials of its product candidates and therapies; the Company’s liquidity and capital resources and its ability to raise additional cash; the outcome of the Company’s partnering/licensing efforts, risks associated with laws or regulatory requirements applicable to it; market conditions, product performance, litigation or potential litigation, and competition within the cancer diagnostics and therapeutics field; ability to develop and protect proprietary intellectual property or obtain licenses to intellectual property developed by others on commercially reasonable and competitive terms; challenges associated with radiotherapeutic manufacturing, production and distribution capabilities necessary to support the Company’s clinical trials and any commercial level product demand; and material security breach or cybersecurity attack affecting the Company’s operations or property. This list of risks, uncertainties, and other factors is not complete. Plus Therapeutics discusses some of these matters more fully, as well as certain risk factors that could affect Plus Therapeutics’ business, financial condition, results of operations, and prospects, in its reports filed with the SEC, including Plus Therapeutics’ annual report on Form 10-K for the fiscal year ended December 31, 2024, quarterly reports on Form 10-Q, and current reports on Form 8-K. These filings are available for review through the SEC’s website at www.sec.gov. Any or all forward-looking statements Plus Therapeutics makes may turn out to be wrong and can be affected by inaccurate assumptions Plus Therapeutics might make or by known or unknown risks, uncertainties, and other factors, including those identified in this press release. Accordingly, you should not place undue reliance on the forward-looking statements made in this press release, which speak only as of its date. The Company assumes no responsibility to update or revise any forward-looking statements to reflect events, trends or circumstances after the date they are made unless the Company has an obligation under U.S. federal securities laws to do so. Investor ContactCORE IRinvestor@plustherapeutics.com

Plus Therapeutics Provides US Launch Update for its CNSide® Diagnostic

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