Plus Therapeutics Announces Presentation of ReSPECT-GBM Trial Dosimetery Data at the American Society for Radiation Oncology (ASTRO) 2021 Annual Meeting

Data demonstrated Rhenium-186 NanoLiposome (186RNL) provides sustained, localized radiation treatment for over eight days to the tumor with minimal whole brain and body radiation exposure

The analysis of 3D drug distribution and tumor response shows image monitoring is a predictive tool to evaluate delivery and treatment effectiveness

Compared to sealed source brachytherapy, 186RNL offers minimally invasive, convenient delivery

AUSTIN, Texas, Oct. 27, 2021 (GLOBE NEWSWIRE) -- Plus Therapeutics, Inc. (Nasdaq: PSTV) (the "Company"), a clinical-stage pharmaceutical company developing innovative, targeted radiotherapeutics for rare and difficult-to-treat cancers, today presented data at the American Society for Radiation Oncology (ASTRO) 2021 Annual Meeting indicating Rhenium-186 NanoLiposome (186RNL) delivered to patients with recurrent glioblastoma (GBM) through convection enhanced delivery results in predictable distribution and stable retention to the targeted tissues, providing days of sustained, localized radiation treatment to the tumor.

Data from the ePoster titled "Image-guided Rhenium-186 NanoLiposome (186RNL) brachytherapy in the treatment of recurrent glioblastoma: technique, image analysis, dosimetry, and monitoring" demonstrated the following:

  • Mean locoregional retention in the brain volume at the end of infusion (85.9% ± 17.1% ID, n=18) and at eight days post-infusion (46.6% ± 16.7% ID, n=17).
  • Following dose escalation, the mean radiation absorbed dose in the two most recent cohorts to the tumor volume was 354.7 ± 144.0 Gy, to the whole brain was 1.32 ± 1.06 Gy, and to the whole body was 0.16 ± 0.04 Gy (n=6), establishing evidence of a high radiation absorbed dose to the tumor with minimal brain and whole body radiation exposure.

"We're very encouraged by this latest data supporting investigational 186RNL for the treatment of recurrent glioblastoma, specifically underscoring its potential to effectively treat difficult to reach brain tumors, without harming surrounding tissue," said John Floyd, M.D., University of Texas Health Science Center San Antonio, study investigator, and presenter of the ePoster. "Coupled with state-of-the-art imaging technology tools, treatment with 186RNL has shown to be highly precise, which may give reassurance to patients living with recurrent glioblastoma and advance understanding of convection therapy and targeted radiation for healthcare providers treating this unforgiving disease."

In addition, the analysis shows image monitoring can provide a predictive tool to evaluate therapy delivery and treatment effectiveness. In this study, up to four catheters showed to have effectively enhanced locoregional drug distribution and tumor volume coverage, supporting that the 3D dose distribution calculation leads to convenient dose and therapy evaluation, and application of additional therapy for better tumor control.

"This presentation documents the potential safety and utility of locoregional radiotherapeutic delivery to the brain or any organ or tissue in the body," said Marc Hedrick, M.D., President and Chief Executive Officer of Plus Therapeutics. "We are committed to further investigating the potential of 186RNL in hopes of offering a novel treatment to patients in need of minimally invasive and convenient therapeutic options for recurrent GBM and other difficult to treat cancers. This new data builds on existing evidence and reinforces the clinical promise of providing precise, targeted radiotherapeutics for cancer."

186RNL is under investigation as a potentially safe, effective and convenient way to deliver a very high dose of radiation, possibly over 20 times greater than traditional external beam radiation therapy. This trial is supported by the U.S. National Institutes of Health/National Cancer Institute at three trial sites in the U.S., including UT Health Science Center San Antonio, UT Southwestern Medical Center Dallas and UT MD Anderson Cancer Center Houston.

The U.S. Food and Drug Administration has granted both Orphan Drug designation and Fast Track designation to 186RNL for the treatment of patients with GBM. Additional details about the ReSPECT™ trial are available at clinicaltrials.gov (NCT01906385).

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

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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