Plus Therapeutics Presents Positive Interim ReSPECT-LM Phase 1 Data for Leptomeningeal Metastases at 2024 SNO/ASCO CNS Metastases Conference

Plus Therapeutics Inc.
Plus Therapeutics Inc.

In This Article:

Respect-LM dosing shows continued feasibility and safety of up to 44 mCi of intrathecal Rhenium (186Re) Obisbemeda

High absorbed radiation doses, mean circulating tumor cell reductions, and median overall survival of 12 months continue to show clinical promise

AUSTIN, Texas, Aug. 12, 2024 (GLOBE NEWSWIRE) -- Plus Therapeutics, Inc. (Nasdaq: PSTV) (“Plus” or the “Company”), a clinical-stage pharmaceutical company developing targeted radiotherapeutics with advanced platform technologies for central nervous system (CNS) cancers, presented data in a podium presentation updating the progress of its ReSPECT-LM clinical trial of Rhenium (186Re) Obisbemeda (Rhenium Nanoliposome, 186RNL) in leptomeningeal disease (LM). The data were presented at the 2024 Society for NeuroOncology (SNO)/American Society for Clinical Oncology (ASCO) CNS Metastases Conference August 8-10, 2024 in Denver, Colorado.

The presentation, titled, “Phase 1 Dose Escalation of Rhenium (186Re) Obisbemeda (Rhenium Nanoliposome, 186RNL) for the Treatment of Leptomeningeal Metastases (LM): Ongoing Clinical Study Update for Initial Safety and Feasibility,” provided a safety and efficacy update on the single dose trial for the first 4 cohorts (n = 16 patients). The trial is currently enrolling in Cohort 5. The study was presented by Andrew Brenner, M.D., Ph.D., Professor and Kolitz/Zachry Endowed Chair Neuro-Oncology Research; Co-Leader, Experimental and Developmental Therapeutics Program, University of Texas Health, San Antonio.

Key ReSPECT-LM highlights through Cohort 4:

  • 16 patients were treated: 8 patients had a breast cancer primary diagnosis, 4 patients had a lung cancer primary diagnosis, and 4 patients had a mix of other primary cancers

  • There were no dose limiting toxicities through cohort 4 and the maximum tolerated dose or maximum feasible dose was not reached

  • We observed a linear increase in absorbed radiation dose to the spinal fluid and ventricles and cranial subarachnoid space over 4 cohorts

  • In cohort 4, the mean average absorbed radiation dose to the ventricles and cranial subarachnoid space was 156 Gy vs. 1 Gy to the spleen

  • The majority of adverse events (AEs) across all 4 cohorts were mild or moderate and unrelated or unlikely related to the study drug

  • There was a mean reduction of CSF circulating tumor cells (CTCs) of 53% at 28 days post treatment vs. baseline (CTCs only performed on only Cohorts 1-3 as testing was commercially unavailable during Cohort 4)

  • Median overall survival for Cohorts 1-4 was 12 months with 8 of 16 patients alive at the time of analysis