SEATTLE, June 10, 2024 (GLOBE NEWSWIRE) — Perspective Therapeutics, Inc. (“Perspective” or “the Company”) (NYSE AMERICAN: CATX), a radiopharmaceutical company that is pioneering advanced treatment applications for cancers throughout the body, today announced six updates featuring the Company’s alpha-particle radiopharmaceuticals at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2024 Annual Meeting, that was held on June 8-11, 2024, in Toronto Canada.

“We are pleased with the accrual of additional data supporting the continued development of our proprietary alpha-particle therapies. The data presentations highlight a favorable safety profile and potential benefits of our lead clinical candidates, [²¹²Pb]VMT-α-NET and [²¹²Pb]VMT01, and demonstrate the potential for FAP targeting using our novel PSV-359,” said Thijs Spoor, Perspective Therapeutics’ CEO. “We are grateful to our colleagues, collaborators and patients for their commitment to advancing our lead-based radiopharmaceuticals that have the potential to improve the lives of patients with intractable tumors.”

VMT-α-NET:

Presentation One: A Phase I/IIa of [²¹²Pb]VMT-α-NET Targeted Alpha-Particle Therapy for Advanced SSTR2 Positive Neuroendocrine Tumors

Summary: This presentation outlines the design of an open-label, multi-center phase I/IIa clinical trial (NCT05636618) evaluating the safety, tolerability, pharmacokinetics, and efficacy of [²¹²Pb]VMT-α-NET in peptide receptor radionuclide therapy (“PRRT”)-naïve patients with unresectable or metastatic somatostatin receptor type 2 (“SSTR2”)-positive neuroendocrine tumors (“NETs”). This clinical trial aims to establish the recommended phase 2 dose and overall therapeutic potential of [²¹²Pb]VMT-α-NET. Updates on this trial as of March 7, 2024 were provided during the Company’s investor update on March 18, 2024 and are accessible on the events page of the Company’s website. In conjunction with the Phase 0 imaging study as discussed below, this clinical trial will inform the recommended Phase 2 dose of [²¹²Pb]VMT-α-NET.

Presenter: Vikas Prasad, MD PhD, Associate Professor of Radiology, Washington University School of Medicine in St. Louis

Presentation Two: Optimal imaging timepoint for diagnostic performance of ²⁰³Pb-VMT-α-NET SPECT/CT in neuroendocrine tumors

Summary: The purpose of this Phase 0 (NCT05111509) imaging trial is to evaluate the optimal imaging timepoint(s) for diagnostic/dosimetric performance of [²⁰³Pb]-VMT-α-NET in neuroendocrine tumors. Investigators analyzed 48 lesions across nine patients and the results showed that tumor uptake of [²⁰³Pb]-VMT-α-NET peaked at approximately four hours post-injection, with 98% of maximum uptake observed at one hour. The results suggest that imaging with [²⁰³Pb]VMT-α-NET at 4 hours post-injection has the best overall diagnostic performance, followed closely by imaging at 1 hour.

Presenter: Sanchay Jain, MD, Research Fellow, University of Iowa

Presentation Three: [²¹²Pb]VMT-α-NET Targeted Alpha Therapy in Metastatic Neuroendocrine Tumors: First in Human study on Safety and Efficacy

Summary: This is an investigator sponsored, exploratory first-in-human use of [²¹²Pb]VMT-α-NET in adult patients with histologically confirmed metastatic NETs and medullary thyroid carcinomas in a compassionate setting in India. The investigator reported updated safety and anti-tumor activity of [²¹²Pb]VMT-α-NET administered at 2.5 MBq/kg every 8 weeks in 13 patients as of data cut-off date of May 31, 2024. All patients received prior treatments, eight of whom received prior PRRT treatment. Six patients remain eligible for further treatments as of the data cut-off date.

The investigator concluded that the toxicity profile suggests the potential for dose escalation to achieve optimal treatment responses.   Confirmed tumor response per RECIST 1.1 was reported to be observed in eight of the thirteen patients, while unconfirmed responses were observed in two additional patients who eventually had progressive disease and died. Median progression free survival (PFS) was reported to be 16.4 months (95% confidence interval: 3.5 to NA). The investigator also reported higher absorbed doses in the tumors compared to select other tissues.

Presenter: Ishita B. Sen, DNB, Director and Head of the Department of Nuclear Medicine & Molecular Imaging at Fortis Memorial Research Institute (FMRI), Gurgaon

Presentation Four: ²¹²Pb-VMT-α-NET αPRRT planning based on ²⁰³Pb-VMT-α-NET predictive dosimetry

Summary: Investigators applied patient-specific dosimetry in a Phase 0 imaging trial (NCT05111509) of [²⁰³Pb]VMT-a-NET, and in the first cohort of a Phase I absorbed dose escalation study (NCT06148636) of [²¹²Pb]VMT-α-NET. Ten patients with β-PRRT-relapsed or refractory GEP-NETs received [²⁰³Pb]VMT-α-NET (5 mCi) followed by sequential blood sampling, planar imaging, and qSPECT/CT imaging at 1h, 4h, 24h, and 48h post-administration. Three of ten patients received amino acid infusions while seven patients did not receive amino acids.

The dosimetry showed that the average renal doses for patients who received amino acids was 0.46±0.20 Gy/mCi, as compared to 0.56±0.16 Gy/mCi for patient who did not receive amino acids; the difference was not statistically significant. For the three patients who received [²¹²Pb]VMT-α-NET treatment, based upon their individual dosimetry results, they were prescribed 5.3, 7.3, and 13.3 mCi cumulative activity (delivered over 2 cycles), respectively, to reach the cohort target renal dose of 3.5 Gy. Higher levels of targeted renal absorbed doses are in the protocol for subsequent cohorts.

Presenter: Stephen A. Graves, PhD Assistant Professor of Radiology-Division of Nuclear Medicine, University of Iowa

VMT01:

Presentation Five: Low-dose [²¹²Pb]VMT01 targeted alpha-particle therapy cooperates with immune checkpoint inhibitors to induce robust tumor responses in a heterogeneous melanoma model in mice

Summary: Melanoma tumors, even within a single individual, are known to be very heterogenous with respect to growth rates, radiosensitivity, mutational profiles and melanocortin receptor 1 (“MC1R”) expression. In pre-clinical studies, the authors assessed the effect of a single dose of [²¹²Pb]VMT01, an α-targeted radionuclide therapy (α-TRT) targeting MC1R, in combination with dual immune checkpoint inhibitors (“ICIs”) in diverse murine melanoma models with MC1R expression levels of high (B16-F10), mid (YUMM-D3) and low (YUMMwt). Overall, tumor radiation dosimetry and the anti-tumor effect of [²¹²Pb]VMT01 with and without ICIs correlated with MC1R expression level. Strong cooperative anti-tumor effect between [²¹²Pb]VMT01 α-TRT and ICIs was observed in single and heterogeneous murine melanoma allograft models. This work is foundational to understanding how tumor dosimetry correlates to melanoma anti-tumor responses to mono and combination therapy with [²¹²Pb]VMT01 and immune checkpoint inhibitors.

Presenter: Sam Rodman, PhD, Research Scientist, Perspective Therapeutics

Presentation Six: De novo discovery and preclinical evaluation of cyclic radiopeptide [^203/212Pb]-PSV-359 targeting human fibroblast activation protein for alpha-particle radiotherapy in cancers

Summary: Researchers presented a novel cyclic peptide targeting human fibroblast activation protein (“hFAP”), which was discovered by Perspective Therapeutics via phage display methods. FAP is a protein abundantly expressed in certain cancer cell as well as cancer-associated fibroblasts in tumor lesions and involved in promoting disease progression. The peptide was conjugated to a lead (Pb)-specific chelator via a molecular linker to form a novel construct, PSV-359. The purpose of this study was to evaluate the in vitro and in vivo performance of [^203/212Pb]PSV-359 in preclinical xenograft models. PSV-359 demonstrated superior binding affinity and specificity against hFAP (Kd=1.8 nM, Ki=0.4 nM) and remained stable in serum for 96 hours. Overall, strong anti-tumor clinical activity of [²¹²Pb]PSV-359 was found in both HT1080-hFAP (FAP on cancer cells) and U87MG (FAP in stromal tissues) xenograft models.

Presenter: Brianna S. Cagle, PhD, Research Scientist, Perspective Therapeutics

About Perspective Therapeutics, Inc. 
Perspective Therapeutics, Inc., is a radiopharmaceutical development company that is pioneering advanced treatment applications for cancers throughout the body. The Company has proprietary technology that utilizes the alpha emitting isotope ²¹²Pb to deliver powerful radiation specifically to cancer cells via specialized targeting peptides. The Company is also developing complementary imaging diagnostics that incorporate the same targeting peptides, which provide the opportunity to personalize treatment and optimize patient outcomes. This “theranostic” approach enables the ability to see the specific tumor and then treat it to potentially improve efficacy and minimize toxicity.

The Company’s melanoma (VMT01) and neuroendocrine tumor (VMT-α-NET) programs have entered Phase 1/2a imaging and therapy trials for the treatment of metastatic melanoma and neuroendocrine tumors at several leading academic institutions. The Company has also developed a proprietary ²¹²Pb generator to secure key isotopes for clinical trial and commercial operations.

For more information, please visit the Company’s website at www.perspectivetherapeutics.com.

Safe Harbor Statement
This press release contains forward-looking statements within the meaning of the United States Private Securities Litigation Reform Act of 1995. Statements in this press release that are not statements of historical fact are forward-looking statements. Words such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “estimate,” “believe,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions are intended to identify forward-looking statements, though not all forward-looking statements contain these identifying words. Forward-looking statements in this press release include statements concerning, among other things, the Company’s ability to pioneer advanced treatment applications for cancers throughout the body; the Company’s belief that the data presentations highlight a favorable safety profile and potential benefits of its lead clinical candidates, [²¹²Pb]VMT-α-NET and [²¹²Pb]VMT01, and demonstrate the potential for FAP targeting using the Company’s novel PSV-359; the Company’s expectation that its colleagues, collaborators and patients will continue their commitment to advancing the Company’s lead-based radiopharmaceuticals that it believes has the potential to improve the lives of patients with intractable tumors; the Company’s ability to develop proprietary technology that utilizes the alpha emitting isotope ²¹²Pb to deliver powerful radiation specifically to cancer cells via specialized targeting peptides; the Company’s prediction that complementary imaging diagnostics that incorporate certain targeting peptides provide the opportunity to personalize treatment and optimize patient outcomes; the Company’s expectation that its “theranostic” approach enables the ability to see specific tumors and then treat it to potentially improve efficacy and minimize toxicity; the Company’s ability to develop a proprietary ²¹²Pb generator to secure key isotopes for clinical trial and commercial operations; the Company’s clinical development plans and the expected timing thereof; the expected timing for availability and release of data; expectations regarding the potential market opportunities for the Company’s product candidates; the potential functionality, capabilities, and benefits of the Company’s product candidates and the potential application of these product candidates for other disease indications; the Company’s expectations, beliefs, intentions, and strategies regarding the future; the Company’s intentions to improve important aspects of care in cancer treatment; and other statements that are not historical fact.

The Company may not actually achieve the plans, intentions or expectations disclosed in the forward-looking statements and you should not place undue reliance on the forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause the Company’s actual results to differ materially from the results described in or implied by the forward-looking statements, including, without limitation, the potential that regulatory authorities may not grant or may delay approval for the Company’s product candidates; uncertainties and delays relating to the design, enrollment, completion, and results of clinical trials; unanticipated costs and expenses; pre-clinical and early clinical trials may not be indicative of the results in later clinical trials; clinical trial results may not support regulatory approval or further development in a specified indication or at all; actions or advice of regulatory authorities may affect the design, initiation, timing, continuation and/or progress of clinical trials or result in the need for additional clinical trials; the Company’s ability to obtain and maintain regulatory approval for the Company’s product candidates; delays, interruptions or failures in the manufacture and supply of the Company’s product candidates; the size and growth potential of the markets for the Company’s product candidates, and the Company’s ability to service those markets; the Company’s cash and cash equivalents may not be sufficient to support its operating plan for as long as anticipated; the Company’s expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; the Company’s ability to obtain additional funding to support its clinical development programs; the availability or potential availability of alternative products or treatments for conditions targeted by the Company that could affect the availability or commercial potential of its product candidates; the ability of the Company to manage growth and successfully integrate its businesses; the Company’s ability to maintain its key employees; sufficient training and use of the Company’s products and product candidates; the market acceptance and recognition of the Company’s products and product candidates; the Company’s ability to maintain and enforce its intellectual property rights; the Company’s ability to maintain its therapeutic isotope supply agreement with the Department of Energy; the Company’s ability to continue to comply with the procedures and regulatory requirements mandated by the FDA for additional trials, Phase 1 and 2 approvals, Fast Track approvals, and 510(k) approval and reimbursement codes; and any changes in applicable laws and regulations. Other factors that may cause the Company’s actual results to differ materially from those expressed or implied in the forward-looking statements in this press release are described under the heading “Risk Factors” in the Company’s most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the “SEC”), in the Company’s other filings with the SEC, and in the Company’s future reports to be filed with the SEC and available at www.sec.gov. Forward-looking statements contained in this news release are made as of this date. Unless required to do so by law, we undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise.

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