Plus Therapeutics Presents Preliminary Safety and Feasibility Data from ReSPECT-LM Clinical Trial at the European Association of Nuclear Medicine Congress

ReSPECT-LM Phase 1 clinical trial selected as TOP Trials Oral Presentation

Treatment was well tolerated without dose limiting toxicities and all patients showed a decrease in spinal fluid tumor cell counts

ReSPECT-GBM Phase 1 clinical data selected as Top-Rated Oral Presentation and inclusion in opening Highlights Lecture

AUSTIN, Texas, Oct. 19, 2022 (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, presented data from two ongoing clinical trials evaluating the Company’s lead investigational targeted radiotherapeutic, Rhenium-186 NanoLiposome (¹⁸⁶RNL), in leptomeningeal metastases (LM) and recurrent glioblastoma (GBM) at the 35^th Annual Congress of the European Association of Nuclear Medicine (EANM). The Company’s ReSPECT-GBM presentation was selected for inclusion in the opening Plenary Highlights Lecture, signaling significant clinical interest in the field.

“The findings presented at EANM indicate the potential for ¹⁸⁶RNL in patients diagnosed with leptomeningeal metastases,” said Norman LaFrance, M.D., Chief Medical Officer and Senior Vice President at Plus Therapeutics. “Combined with our Phase 1 data in recurrent glioblastoma, these presentations reinforce the tremendous potential of ¹⁸⁶RNL as a versatile radiotherapeutic treatment option for multiple CNS cancers.”

The TOP Trials Oral Presentation titled, Safety and Feasibility of Rhenium-186 Nanoliposome (¹⁸⁶RNL) in Leptomeningeal Metastases (LM) Phase 1 dose escalation Trial [OP-759], demonstrated:

• The ¹⁸⁶RNL dose administered through an intraventricular catheter at 6.6 mCi in 5.0 mL in Cohort 1 achieved absorbed doses of 18.7 to 29.0 Gray to the ventricles and cranial subarachnoid space, which was well tolerated with no treatment-related adverse events of greater than grade 1.
• All four patients treated to date in Cohorts 1 and 2 were observed to have prompt and complete ¹⁸⁶RNL distribution throughout the cerebrospinal fluid (CSF) subarachnoid space that was durable past 28 days and was well tolerated.
• All patients showed a decreased CSF cell count by microfluidic chamber assay after treatment, ranging from 46% to 92%.
• Cohort 2 in the ReSPECT-LM trial has commenced, with interim data from the first two patient cohorts expected by the end of 2022.
• This trial is supported by the recently announced $17.6 million grant by the Cancer Prevention & Research Institute of Texas (CPRIT).

The Top Rated Oral Presentation (TROP) titled, Safety and Feasibility of Rhenium-186 NanoLiposome (¹⁸⁶RNL) in Recurrent Glioma: the ReSPECT™ Phase 1/2a Trial [OP-542], reviewed data which indicate that:

• Direct administration of ¹⁸⁶RNL is safe in patients with recurrent GBM with no dose-limiting toxicities (DLT).
• There is a statistically significant overall survival benefit observed with ¹⁸⁶RNL radiation doses over 100 Gray. In 23 adult patients across eight cohorts of increasing dose and treated over a seven-year period, the improved median overall survival (OS) rates correlated with the absorbed tumor radiation dose.
• Patients receiving a therapeutic absorbed radiation dose (>100 Gray) had a median OS of 129.7 weeks (95% CI of 35.0-169.1) compared to those receiving a subtherapeutic absorbed radiation dose (<100 Gray) whose median OS was 22.3 weeks (95% CI of 6.4-45.3).
• The Company plans to initiate a National Institutes of Health (NIH)-funded Phase 2 study by the end of 2022 that will utilize cGMP ¹⁸⁶RNL and leverage a higher dose and volume that could potentially show a greater survival rate in patients with recurrent GBM.

Abstracts presented at the conference can be viewed here. A copy of the presentation is available under the Presentations tab of the Investors section of the Company’s website at https://ir.plustherapeutics.com.

About Plus Therapeutics

Plus Therapeutics, Inc. is a clinical-stage pharmaceutical company focused on the development, manufacture, and commercialization of complex and innovative treatments for patients battling cancer and other life-threatening diseases. Our proprietary nanotechnology platform is currently centered around the enhanced delivery of a variety of drugs using novel liposomal encapsulation technology. Liposomal encapsulation has been extensively explored and undergone significant technical and commercial advances since it was first developed. Our 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 “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 ¹⁸⁶RNL including the ability of ¹⁸⁶RNL 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 ¹⁸⁶RNL; the continued evaluation of ¹⁸⁶RNL 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.

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