Benzinga | Nov 18, 2021 08:05AM EST

Plus Therapeutics Highlights Presentation Of Data From ReSPECT-GBM Phase 1 Clinical Trial At 2021 Society For Neuro-Oncology Annual Meeting

Latest interim analysis shows Rhenium-186 NanoLiposome (186RNL) well-tolerated without dose-limiting toxicities

Mean and median overall survival in patients receiving absorbed dose greater than 100 Gy is 453.8 days and 330 days, respectively, with seven patients remaining alive

AUSTIN, Texas, Nov. 18, 2021 (GLOBE NEWSWIRE) -- Plus Therapeutics, Inc. (Nasdaq: PSTV) (the "Company"), a U.S. clinical-stage pharmaceutical company developing innovative, targeted radiotherapeutics for rare and difficult-to-treat cancers, today released positive interim data on its lead investigational drug, Rhenium-186 NanoLiposome (186RNL), from the first-in-man Phase 1 ReSPECT(tm)-GBM clinical trial in patients with recurrent glioblastoma (GBM) at the 2021 Society for Neuro-Oncology Annual Meeting and Education Day being held in Boston, Massachusetts.

According to the interim data, 186RNL delivered via convection enhanced delivery (CED) is well-tolerated with favorable overall survival in adult patients at higher absorbed radiation doses (greater than 100 Gy). A positive correlation was observed between overall survival and higher absorbed radiation doses (greater than 100 Gy).

The poster, titled "Safety and Feasibility of Rhenium-186 NanoLiposome (186RNL) in Recurrent Glioma: the ReSPECT(tm) Phase 1 Trial," outlines data from the ReSPECTTM-GBM trial, substantially funded by the U.S. National Institutes of Health/National Cancer Institute, which has thus far evaluated 22 adult patients with recurrent GBM across seven cohorts of increasing dose, treated over a six year period.

"In the ReSPECTTM trial thus far, 186RNL has been well-tolerated without dose-limiting toxicities and we believe further clinical investigation of relative efficacy is warranted," said Andrew J. Brenner, M.D., Ph.D., Professor of Medicine, Neurology, and Neurosurgery at The University of Texas Health Science Center at San Antonio and principal investigator of the ReSPECT(tm)-GBM clinical trial. "The open label, dose escalation trial was not designed to show efficacy but the trends observed between overall survival and key delivery parameters such as therapeutic radiation dose to the tumor are promising."

Key findings include the following:

* No delivery failures were observed and an average absorbed dose of 267.5 Gy (range 8.9-740Gy) of radiation was delivered to the tumor.

* No dose limiting toxicities or adverse events (AEs) with the outcome of death, or discontinuations due to AEs have been observed.

* Of 22 total subjects with recurrent GBM treated with 186RNL, seven patients remain alive and mean and median overall survival (OS) is currently 336.6 days and 231.5 days, respectively.

* In the subset of 13 patients receiving greater than 100 Gy absorbed radiation, seven patients remain alive and mean and median OS is currently at 453.8 days and 330 days respectively.

* No patients remain alive in the cohort of 9 patients receiving less than 100 Gy absorbed radiation and mean and median OS is 167.3 days and 156 days respectively.

* In 10 treated patients in cohorts five through seven, 13.4 millicuries or more of radiation was delivered and 80% received greater than 100 Gy average absorbed dose of radiation to the tumor.

"Our team is pleased with the clinical performance and the potential promise of 186RNL in patients with this devastating disease," said Marc Hedrick, M.D., President and Chief Executive Officer of Plus Therapeutics. "In particular, the observation that we may be able to reliably and precisely deliver a significant therapeutic dose of radiation greater than 100 Gy and potentially influence survival is a positive development. We look forward to completing key drug scale-up activities and proceed to FDA discussions regarding CMC and next clinical steps in early 2022."

For a more detailed discussion of the ReSPECT-GBM trial data, please join the Plus Therapeutics hosted webinar on Thursday, November 18, 2021, 4:00 to 5:00 p.m. ET (details below).

A copy of the poster will be available under the Presentations tab of the Investors section of the Company's website at https://ir.plustherapeutics.com.