Plus Therapeutics Successfully Treats First Patient in Cohort 8 of ReSPECT-GBM Phase 1/2a Trial

Rhea-AI Summary

Plus Therapeutics (PSTV) has successfully treated the first patient in Cohort 8 of its ReSPECT-GBM Phase 1/2a trial for rhenium (186Re) obisbemeda in recurrent glioblastoma. The trial has treated 25 patients without dose-limiting toxicities. Cohort 8 is now enrolling with a dose of 41.5 mCi, allowing treatment of larger tumors. The Phase 2 trial has treated five patients with a lower dose of 22.3 mCi. So far, safety and efficacy signals from the trials are promising, with no treatment-emergent toxicities noted. The FDA has granted Orphan Drug and Fast Track designations for this investigational therapy.

Positive

• First patient in Cohort 8 treated successfully.
• No dose-limiting toxicities observed in 25 patients.
• Promising safety and efficacy signals from treated patients.
• FDA granted Orphan Drug and Fast Track designations.

Negative

• None.

Company also enrolling ReSPECT-GBM Phase 2 trial

Presentation of data from Phase 1/2a and Phase 2 trials planned in 2023

AUSTIN, Texas, March 28, 2023 (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 cancers, today announced the first patient in Cohort eight of the ReSPECT-GBM Phase 1/2a dose escalation clinical trial evaluating the Company’s lead investigational targeted radiotherapeutic, rhenium (¹⁸⁶Re) obisbemeda, in recurrent glioblastoma (GBM) has been successfully treated.

The dose escalation phase of the trial has now treated 25 patients with no dose-limiting toxicities observed through 7 completed dosing cohorts. Cohort 8 is now enrolling using 41.5 millicuries (mCi) administered dose rhenium (¹⁸⁶Re) obisbemeda with an infused volume of 16.34 milliliters (mL) which allows the treatment of large and morphologically complex tumors.

In parallel, the Company has treated five patients to date with rhenium (¹⁸⁶Re) obisbemeda in the Phase 2 trial in recurrent GBM administering a dose of 22.3 mCi and 8.8 mL in small- to medium-sized tumors.

“Taken together, the safety and efficacy signals observed thus far in 30 treated recurrent GBM patients are very promising,” said Norman La France, M.D., President and Chief Medical Officer of Plus Therapeutics. “We remain on track in 2023 to continue to dose escalate to the yet unreached maximal tolerated dose, expand the number of clinical trial sites and present data from the Phase 1/2a and 2 trials in the second half of 2023.”

Thus far, no treatment emergent dose-limiting toxicities have been observed in either trial. The absorbed radiation doses from the 30 patients treated to date have resulted in an absorbed dose of up to 740 gray to the tumor.

The U.S. Food and Drug Administration granted both Orphan Drug designation and Fast Track designation to rhenium (¹⁸⁶Re) obisbemeda for the treatment of GBM. More information about the ReSPECT-GBM trial may be found at ReSPECT-Trials.com and ClinicalTrials.gov (NCT01906385).

About Rhenium (¹⁸⁶Re) obisbemeda
Rhenium (¹⁸⁶Re) obisbemeda is a novel injectable radiotherapy specifically formulated to deliver highly targeted high dose radiation in CNS tumors in a safe, effective and convenient manner to optimize patient outcomes. Rhenium (¹⁸⁶Re) obisbemeda has the potential to reduce risks and improve outcomes for CNS cancer patients, versus currently approved therapies, with a more targeted and potent radiation dose. Rhenium is an ideal radioisotope for CNS therapeutic applications due to its short half-life, beta energy for destroying cancerous tissue and gamma energy for live imaging.

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. Plus Therapeutics is led by an experienced and dedicated leadership team and has operations in key cancer clinical development hubs including Austin and San Antonio, Texas. For more information, visit https://plustherapeutics.com/.

Cautionary Statement Regarding Forward-Looking Statements
This press release contains statements that may be deemed “forward-looking statements” within the meaning of U.S. securities laws. 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 “designed to,” “will,” “can,” “potential,” “focus,” “preparing,” “next steps,” “possibly,” 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. These statements include, without limitation, statements regarding the following: the potential promise of ¹⁸⁶Re including the ability of ¹⁸⁶Re to safely and effectively deliver radiation directly to the tumor at high doses; expectations as to the Company’s future performance including the next steps in developing the Company’s current assets; the Company’s clinical trials including statements regarding the timing and characteristics of the ReSPECT-GBM and ReSPECT-LM clinical trials; possible negative effects of ¹⁸⁶Re; the continued evaluation of ¹⁸⁶Re including through evaluations in additional patient cohorts; and the intended functions of the Company’s platform and expected benefits from such functions.

The forward-looking statements included in this press release are subject to a number of risks and uncertainties that may cause actual results to differ materially from those discussed in such forward-looking statements. These risks and uncertainties include, but are not limited to: the Company’s actual results may differ, including materially, from those anticipated in these forward-looking statements as a result of various factors, including, but not limited to, the following: 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, among others; and additional risks described under the heading “Risk Factors” in the Company’s Securities and Exchange Commission filings, including in the Company’s annual and quarterly reports. There may be events in the future that the Company is unable to predict, or over which it has no control, and its business, financial condition, results of operations and prospects may change in the future. 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
Peter Vozzo
ICR Westwicke
(443) 377-4767
Peter.Vozzo@westwicke.com

Media Contact
Terri Clevenger
ICR Westwicke
(203) 856-4326
Terri.Clevenger@westwicke.com

FAQ

What is the ReSPECT-GBM trial for Plus Therapeutics (PSTV)?

The ReSPECT-GBM trial is a clinical study evaluating the efficacy and safety of rhenium (186Re) obisbemeda for treating recurrent glioblastoma.

What are the recent developments in Plus Therapeutics' (PSTV) clinical trials?

Recently, Plus Therapeutics announced the treatment of the first patient in Cohort 8 of the Phase 1/2a trial, with 25 patients treated to date without dose-limiting toxicities.

What designations has the FDA granted to rhenium (186Re) obisbemeda?

The FDA has granted Orphan Drug designation and Fast Track designation to rhenium (186Re) obisbemeda for the treatment of recurrent glioblastoma.

How does rhenium (186Re) obisbemeda work in treating CNS tumors?

Rhenium (186Re) obisbemeda delivers targeted high-dose radiation specifically to CNS tumors, optimizing treatment effectiveness and patient outcomes.

When can we expect data presentations for Plus Therapeutics' trials?

Data presentations from the Phase 1/2a and Phase 2 trials are planned for the second half of 2023.