On December 4, 2025 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, reported three positive clinical data update presentations at the World Federation of Neuro-Oncology Societies/Society for Neuro-Oncology (WFNOS/SNO) Annual Meeting, November 19-23, 2025 in Honolulu, Hawaii. The World Federation of Neuro-Oncology Societies (WFNOS) and Society for Neuro-Oncology (SNO) advance research, education, and clinical care for patients with tumors of the central nervous system.

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"Real world clinical experience with REYOBIQ in both primary and metastatic CNS cancers continues to show a promising safety profile and signs of efficacy," said Marc H. Hedrick, M.D., Plus Therapeutics President and Chief Executive Officer. "This expanding clinical data set around REYOBIQ coupled with substantial progress bringing our CNSide diagnostic portfolio to market provides our team at Plus with growing confidence that we can achieve our goal of materially improving survival rates for patients with CNS cancers."

KEY HIGHLIGHTS:

Phase 1 Multicenter Study of Multiple Doses of Rhenium (186Re) Obisbemeda (Reyobiq) for Leptomeningeal Metastases: Rationale, Design, and Preliminary Cohort 1 Data

Overview:

Completed ReSPECT-LM single dose trial showed REYOBIQ was well-tolerated up to a maximum tolerated dose of 66mCi, with a recommended phase 2 dose of 44.1 mCi, and absorbed doses delivered of >300 Gy observed
ReSPECT-LM open label, multidose Phase 1/2 trial initiated to identify maximum tolerated dose across varying dosing intervals and to characterize efficacy of multiple doses at optimal dose selected by assessing response using CNSide CSF tumor cell enumeration test

Response:

Enrollment in Cohort 1 has begun with delivery of 13.2 mCi at 3 intervals
Three patients enrolled as of data cutoff: one patient has received all doses without dose limiting toxicity

Next Steps:

Phase 1b/2a dose optimization trial is enrolling with the ultimate goal of improving outcomes for LM patients

Phase 1/2 ReSPECT-GBM Trial of Rhenium (186Re) Obisbemeda in Recurrent Glioblastoma: Safety and Efficacy from the Phase 1 and Update on Phase 2

Overview:

Phase 1 dose-escalation study completed, with patients dosed from 1.0 mCi to 41.5 mCi, achieving a maximum absorbed tumor dose of 739.5 Gy. Dose 22.3 mCi was selected as the recommended Phase 2 dose due to its favorable safety profile
Ongoing Phase 2 study has enrolled 24 of planned 34 patients as of data cutoff; study continues to evaluate safety and efficacy at the Phase 2 recommended dose

Safety:

Across all patients treated in both Phase 1 and 2, most treatment-related adverse events were Grade 1 or 2, including lymphopenia (7.9%), cognitive disorder (7.0%), and headache (7.0%), with no treatment-related deaths or study discontinuations due to serious adverse reactions (SARs)

Response:

Efficacy data from Phase 1 cohorts 1 to 6 showed a median overall survival of 17 months for patients receiving ≥100 Gy, compared to 6 months for those receiving <100 Gy, surpassing historical bevacizumab monotherapy outcomes
SPECT/CT imaging continues to confirm high tumor-specific radiation retention, with minimal systemic exposure

Next Steps:

Phase 2 continues to enroll
REYOBIQ has demonstrated promising safety and efficacy profile, supporting continued investigation as a novel therapeutic for recurrent GBM

Assessment of rhenium-186 obisbemeda (186RNL) therapy for recurrent glioblastoma (rGBM) using MRI and SPECT imaging biomarkers

Overview:

Phase 1 ReSPECT-GBM showed promising improvements in overall survival
REYOBIQ efficacy also evaluated using MRI and SPECT imaging biomarkers

Response:

REYOBIQ dose positively correlates with treatment coverage ratio, time to peak, and progression free survival; negatively correlates with mean transit time and tumor volume
Based on a Wilcoxon Signed Rank test on 23 patients receiving REYOBIQ, untreated tumor volume was significantly increased relative to treated tumor volume. Overall survival negatively associated with tumor volume

Conclusion:

MRI combined with SPECT imaging biomarkers effectively evaluate REYOBIQ in recurrent GBM treatment, guiding patient specific planning

Plus Therapeutics and its wholly owned subsidiary, CNSide Diagnostics focused on central nervous system metastases management, each hosted a booth at the WFNOS/SNO Annual Meeting exhibit hall.

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.

(Press release, Plus Therapeutics, DEC 4, 2025, View Source [SID1234661129])