Plus Therapeutics Highlights ReSPECT-LM Clinical Trial Results at 40th SITC Annual Meeting, Melanoma Research Foundation Brain Metastases Summit 4.0

Rhea-AI Summary

Plus Therapeutics (Nasdaq: PSTV) will present ReSPECT-LM clinical trial results at the 40th SITC Annual Meeting and MRF Brain Metastases Summit on November 9, 2025.

Phase 1 single-dose escalation data reported at SNO/ASCO 2025 showed clinical benefit rate >75% across three outcome measures, RNA sequencing and circulating tumor cell reductions consistent with tumor cell death, and no dose-limiting toxicities up to the recommended Phase 2 dose of 44.1 mCi. REYOBIQ has received FDA Fast Track and Orphan Drug designations and enrollment in the ReSPECT-LM Dose Optimization Trial is ongoing.

Positive

• Clinical benefit rate >75% in Phase 1 single-dose escalation
• No dose-limiting toxicities up to 44.1 mCi recommended Phase 2 dose
• RNA sequencing and CTC reductions consistent with tumor cell death
• REYOBIQ granted FDA Fast Track and Orphan Drug designations

Negative

• Data are from a Phase 1 single-dose escalation trial (early-stage evidence)
• ReSPECT-LM Dose Optimization Trial is still enrolling (results pending)

Insights

Clinical Development Strategist

Early ReSPECT-LM data show a > 75% clinical benefit signal, no dose-limiting toxicities, and regulatory fast-track momentum.

Plus Therapeutics presented Phase 1 single-dose escalation results for REYOBIQ in the ReSPECT-LM program showing a clinical benefit rate above 75% across three outcome measures, RNA sequencing and circulating tumor cell reductions consistent with tumor cell death, and no dose-limiting toxicities up to the recommended Phase 2 dose of 44.1 mCi. These facts indicate an early efficacy signal coupled with a tolerable safety profile in a patient population with no approved therapies.

Key dependencies include confirmation of efficacy in the ongoing Dose Optimization Trial and durability of response beyond the initial measures reported. The FDA Fast Track and Orphan Drug Designations are procedural advantages but do not guarantee approval. Safety monitoring as dose escalates and larger cohort reproducibility remain critical risks.

Watch enrollment progress and readouts from the ReSPECT-LM Dose Optimization Trial and any formal efficacy endpoints in 2026-era updates, plus any regulatory interactions or pivotal trial designs announced after the ongoing trial. Near-term milestones include the presentation at the SITC/MRF session on Nov 9, 2025 and subsequent published datasets; those will determine whether the early signal holds in broader cohorts.

Leptomeningeal metastases disease session features novel treatments in the horizon, REYOBIQ™ and ReSPECT-LM, and future directions and needs

HOUSTON, Nov. 06, 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 its participation at the 40^th Society for Immunotherapy of Cancer (SITC) Annual Meeting, Melanoma Research Foundation (MRF) Brain Metastases Summit 4.0 on November 9, 2025 in Alexandria, VA. Dr. Andrew Brenner, M.D., Ph.D., Professor of Medicine in the Division of Hematology and Oncology at The University of Texas Health Science Center at San Antonio will highlight the Company’s REYOBIQ and ReSPECT-LM clinical trial results in the session on leptomeningeal metastases (LM) disease.

Recall, at the 2025 SNO/ASCO CNS Metastases conference in August, ReSPECT-LM Phase 1 single dose escalation trial data showed:

• REYOBIQ produced a clinical benefit rate of over 75% in 3 clinically relevant outcome measures
• RNA sequencing and circulating tumor cell reduction consistent with tumor cell death
• No dose limiting toxicities were observed with an overall favorable safety profile up to and including the recommended phase 2 dose of 44.1 mCi
  

“Given the growing incidence and unmet need, with no approved therapies for LM, we are encouraged by the continued interest in the ReSPECT-LM data, which demonstrated excellent tolerance of REYOBIQ at much higher doses than current standard, which we believe supports its broad therapeutic range,” said Dr. Brenner. “REYOBIQ has been granted FDA Fast Track and Orphan Drug Designation, with enrollment in the ReSPECT-LM Dose Optimization Trial ongoing.”

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 REYOBIQ™ (rhenium Re186 obisbemeda)
REYOBIQ (rhenium Re186 obisbemeda) is a novel injectable radiotherapy specifically formulated to deliver direct targeted high dose radiation in CNS tumors in a safe, effective, and convenient manner to optimize patient outcomes. REYOBIQ has the potential to reduce off target risks and improve outcomes for CNS cancer patients, versus currently approved therapies, with a more targeted and potent radiation dose. Rhenium-186 is an ideal radioisotope for CNS therapeutic applications due to its short half-life, beta energy for destroying cancerous tissue, and gamma energy for real-time imaging. REYOBIQ is being evaluated for the treatment of recurrent glioblastoma, leptomeningeal metastases, and pediatric brain cancer in the ReSPECT-GBM, ReSPECT-LM, and ReSPECT-PBC clinical trials. ReSPECT-GBM is supported by an award from the National Cancer Institute (NCI), part of the U.S. National Institutes of Health (NIH), and ReSPECT-LM is funded by a three-year $17.6M grant by the Cancer Prevention & Research Institute of Texas (CPRIT). The Company’s ReSPECT-PBC clinical trial for pediatric brain cancer is supported by a $3 million grant from the U.S. Department of Defense’s Peer Reviewed Cancer Research Program.

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 of the cerebrospinal fluid that informs and improves the management of patients with leptomeningeal metastases.

About Plus Therapeutics
Headquartered 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 Statements
This 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.

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 Contact
CORE IR
investor@plustherapeutics.com

FAQ

What ReSPECT-LM results will Plus Therapeutics present on November 9, 2025 for PSTV?

Plus will highlight Phase 1 single-dose escalation data showing a clinical benefit rate >75%, RNA sequencing and CTC reductions, and safety up to 44.1 mCi.

What safety profile did REYOBIQ show in the ReSPECT-LM Phase 1 trial for PSTV?

No dose-limiting toxicities were observed and an overall favorable safety profile was reported through the recommended Phase 2 dose of 44.1 mCi.

Has REYOBIQ received any FDA designations relevant to PSTV and ReSPECT-LM?

Yes, REYOBIQ has been granted both FDA Fast Track and Orphan Drug designations.

What is the current status of the ReSPECT-LM trials for PSTV?

Enrollment in the ReSPECT-LM Dose Optimization Trial is ongoing.

How definitive are the ReSPECT-LM efficacy results reported for PSTV?

The efficacy metrics come from a Phase 1 single-dose escalation trial and are considered early-stage evidence pending further trial results.