Plus Therapeutics to Present Data from Two Studies Supporting the Treatment of Leptomeningeal Metastases with Rhenium-186 Nanoliposome

AUSTIN, Texas, Aug. 11, 2021 (GLOBE NEWSWIRE) — Plus Therapeutics, Inc. (Nasdaq: PSTV) (the “Company”), a clinical-stage pharmaceutical company developing innovative, targeted therapies for rare and difficult to treat cancers, today announced it will present data from one planned clinical trial and one completed preclinical study evaluating its lead investigational drug, Rhenium-186 Nanoliposome (¹⁸⁶RNL), for the treatment of leptomeningeal metastases (LM). The data will be presented at the Third Annual Conference on Brain Metastases hosted by the Society for Neuro-Oncology (SNO), being held virtually August 19-20, 2021.

Data from both studies will be presented as electronic posters (ePosters) by Andrew J. Brenner, M.D., Ph.D., Associate Professor of Medicine, Neurology, and Neurosurgery at The University of Texas, and principal investigator, and will be viewable to meeting attendees beginning at the start of the conference on Thursday, August 19 at 11:00 am EDT. The accepted abstracts are currently available in the Neuro-Oncology Advances Journal. Details of both are as follows:

LMD-13: “ReSPECT™-LM: Maximum tolerated dose, safety, and efficacy of intraventricular Rhenium-186 Nanoliposome (¹⁸⁶RNL) for leptomeningeal metastases”
Data from the ongoing U.S. multi-center ReSPECT-GBM Phase 1 dose-finding clinical trial in adults with recurrent glioblastoma (NCT01906385) demonstrate that the mean absorbed dose of ¹⁸⁶RNL to the tumor when coverage was 75% or greater (n=10) was 392 Gy (CI 306 – 478). Thus far, the therapy has been well tolerated with one possible treatment-related serious adverse event, cerebral edema, that resolved after steroid treatment.

In addition, this abstract details a proposed two-part clinical trial for patients with leptomeningeal metastases (LM). Part 1 will enroll up to 21 subjects to characterize the safety and tolerability of a single dose of ¹⁸⁶RNL administered intraventricularly via an Ommaya reservoir and identify a maximum tolerated dose (MTD) / maximum feasible dose (MFD) for future studies, and Part 2 will independently evaluate ¹⁸⁶RNL in two different cohorts. Cohort A will enroll up to 20 subjects with a diagnosis of LM from primary breast cancer. Cohort B will enroll up to 20 subjects with a diagnosis of LM from primary non-small cell lung cancer. The primary endpoint is to estimate the anti-tumor activity of ¹⁸⁶RNL as a single agent. The full abstract can be found here: https://academic.oup.com/noa/article/3/Supplement_3/iii10/6345010.

LMD-14: “Preclinical safety and activity of intraventricular Rhenium-186 Nanoliposome (¹⁸⁶RNL) for leptomeningeal metastases”
As part of this preclinical safety and activity study, researchers concluded that the intraventricular delivery of ¹⁸⁶RNL is well tolerated and improves animal survival at two weeks in a rat model of LM. The full abstract can be found here: https://academic.oup.com/noa/article/3/Supplement_3/iii10/6345068.

Copies of each poster will be made available under the Presentations tab of the Investors section of the Company’s website when presentations go live at www.plustherapeutics.com.

LM are a rare but typically fatal complication of advanced cancer that affects the fluid-lined structures of the central nervous system and are diagnosed in approximately five percent of patients with metastatic cancer. With survival measured in weeks to months, novel approaches are needed that can both improve quality and quantity of life. ¹⁸⁶RNL permits the selective delivery of beta-emitting radiation of high specific activity directly to the tumor.

About Plus Therapeutics, Inc.

Plus Therapeutics (Nasdaq: PSTV) is a clinical-stage pharmaceutical company whose radiotherapeutic portfolio is concentrated on nanoliposome-encapsulated radionuclides for several cancer targets. Central to the Company’s drug development is a unique nanotechnology platform designed to reformulate, deliver and commercialize multiple drugs targeting rare cancers and other diseases. The platform is designed to facilitate new delivery approaches and/or formulations of safe and effective, injectable drugs, potentially enhancing the safety, efficacy and convenience for patients and healthcare providers. More information may be found at PlusTherapeutics.com and ReSPECT-Trials.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 “will,” “believe,” “plan,” “can,” “enable,” “design,” “intend,” “potential,” “expect,” “estimate,” “project,” “prospect,” “target,” “focus,” “anticipate,” “could,” “should,” 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 design and potential of the Plus Therapeutics portfolio to reformulate, deliver and commercialize multiple novel, proprietary drugs targeting rare cancers and other diseases and to facilitate new delivery approaches and/or formulations of safe and effective, injectable drugs; the potential of the Company’s in-licensed portfolio of investigational drugs; the Company’s intent to advance its CNS oncology portfolio through the clinical development process; the ability of RNL to safely, effectively and conveniently deliver a very high dose of radiation directly into the brain tumor; anticipated benefits of strategic collaborations and license agreements, intellectual property, FDA approval process and government regulation; and the Company’s anticipated milestones and events, including with respect to additional sites, enrollment, pivotal trial planning, IND process, and clinical phase plans for RNL, pipeline expansion through additional drug development candidates, and partnership discussions for RNL, DocePLUS and DoxoPLUS; and future development and/or expansion of its product candidates and therapies in its markets.   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 risk that the Company is not able to successfully develop product candidates that can leverage the FDA’s accelerated regulatory pathways; the early stage of the Company’s product candidates and therapies, the results of its research and development activities, including uncertainties relating to the clinical trials of its product candidates and therapies; the Company’s history of losses; the Company’s need for, and ability to raise, additional cash or obtain other sources of funding in the immediate future; the Company’s ability to: (a) obtain and maintain regulatory approvals, (b) continue as a going concern, (c) remain listed on the Nasdaq Capital Market, (d) to obtain or maintain sufficient levels of reimbursement for its tests, and (d) to repay or refinance some or all of its outstanding indebtedness; the outcome of the Company’s partnering/licensing efforts; market and economic conditions; the impact of the COVID-19 pandemic on the Company and the effectiveness of the efforts it has taken or may take in the future in response thereto; 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.

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