Plus Therapeutics Completes Dosing in Cohort 4 of ReSPECT-LM Phase 1 Clinical Trial of Rhenium (¹⁸⁶Re) Obisbemeda in Leptomeningeal Metastases
Wednesday, October 11, 2023
Plus Therapeutics, Inc. (Nasdaq: PSTV) (the “Company”), a clinical-stage pharmaceutical company developing targeted radiotherapeutics with advanced platform technologies for central nervous system cancers, today announced it has completed dosing in Cohort 4 of the ReSPECT-LM Phase 1/2a dose escalation clinical trial of rhenium (186Re) obisbemeda for the treatment of leptomeningeal metastases (LM) from solid tumors. In addition, the Company has completed the transfer of proprietary materials, protocols, and equipment from Biocept under the terms of the recently announced expanded agreement for CNSide, a cerebrospinal fluid (CSF)-based tumor cell capture and enumeration assay being utilized in the ReSPECT-LM clinical trial.
“The speed at which we are enrolling in the ReSPECT-LM trial reflects multiple factors, including the increasing number of patients diagnosed with LM, the lack of good therapeutic options and growing enthusiasm for the trial,” said Marc H. Hedrick M.D., President and Chief Executive Officer of Plus Therapeutics. “Furthermore, significant updates on both the ReSPECT-LM and ReSPECT-GBM studies are planned for November 15-19, 2023 at the Society for Neuro-Oncology (SNO) Annual Meeting.”
Phase 1, Part A of the ReSPECT-LM trial (Cohorts 1-3) is complete and demonstrated an average 53% reduction in CNSide tumor cell counts at Day 28 post-treatment in 10 patients receiving a single administration of rhenium (186Re) obisbemeda. The FDA has approved continued dose escalation and expansion into Part B (Cohorts 4-7). Completion of dosing in Cohort 4 was the fastest enrollment of all the Cohorts to date. There have been no observed dose limiting toxicities with radiation doses of up to 44.10 millicuries. The Company plans to initiate dosing in Cohort 5 this quarter, pending Data Safety Monitoring Board (DSMB) approval. After the update at the SNO meeting in November, the Company anticipates additional data releases in 2024.
The CNSide assay has potential as: an LM diagnostic assay, a surrogate endpoint in clinical trials for CNS cancers such as LM, and as a disease monitoring biomarker assay in the management of patients undergoing radiotherapy for LM. The acquired materials and protocols from Biocept help ensure Plus’ access to the CNSide assay in the ongoing ReSPECT-LM Phase 1 clinical trial with rhenium (186Re) obisbemeda. Plus Therapeutics retains its option, solely at the Company’s discretion, to acquire an exclusive field of use license on the CNSide assay in return for a $1.0 million payment, if exercised prior to January 1, 2025.
About Plus Therapeutics
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 for patients. Combining image-guided local beta radiation and targeted drug delivery approaches, the Company is advancing a pipeline of product candidates with lead programs in recurrent glioblastoma (GBM) and leptomeningeal metastases (LM). The Company has built a robust supply chain through strategic partnerships that enable the development, manufacturing and future potential commercialization of its products.
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Corey Davis, Ph.D.
LifeSci Advisors
(212) 215-2577
cdavis@lifesciadvisors.com
