Perspective Therapeutics Announces First Patients Dosed in New Cohorts of Two Ongoing Phase 1/2a Studies

Perspective Therapeutics Announces First Patients Dosed in New Cohorts of Two Ongoing Phase 1/2a Studies

May 18, 2026

SEATTLE, May 18, 2026 (GLOBE NEWSWIRE) -- Perspective Therapeutics, Inc. ("Perspective," the "Company," "we," "us," and "our") (NYSE AMERICAN: CATX), a radiopharmaceutical development company pioneering advanced treatments for cancers throughout the body, today announced that the first patients were dosed with [²¹²Pb]VMT-α-NET and [²¹²Pb]PSV359 in two new cohorts of Phase 1/2a studies in neuroendocrine tumors and solid tumors, respectively.

The first patient was treated with [²¹²Pb]VMT-α-NET in a fourth cohort of the Company's ongoing Phase 1/2a clinical trial of [²¹²Pb]VMT-α-NET in patients with unresectable or metastatic somatostatin receptor type 2 (SSTR2) expressing neuroendocrine tumors (NETs). This cohort explores optimizing a 20 mCi cumulative dose by front-loading, with 6.0 mCi in the first dose, 5.0 mCi in the second dose, 5.0 mCi in the third dose, and 4.0 mCi in the fourth dose. The design of this dosing regimen will help determine whether front-loading could change response kinetics and further improve response rate and tolerability at the same cumulative administered dose.

Additionally, the first patient was treated with [²¹²Pb]PSV359 in a third cohort of the Company's Phase 1/2a dose-finding trial to determine safety and preliminary anti-tumor activity of the radiopharmaceutical [²¹²Pb]PSV359 in patients with solid tumors that express fibroblast activation protein alpha (FAP-α). Cohort 3 was cleared to open following a safety monitoring committee review of safety data from Cohort 2. Patients in Cohort 3 are receiving up to four fixed administered doses of PSV359 at 6.0 mCi every eight weeks.

About [²¹²Pb]VMT-α-NET

Perspective designed [²¹²Pb]VMT-α-NET to target and deliver ²¹²Pb to tumor sites expressing somatostatin receptor type 2 (SSTR2). The Company is conducting a multi-center, open-label, dose-escalation, dose-expansion study (clinicaltrials.gov identifier NCT05636618) of [²¹²Pb]VMT-α-NET in patients with unresectable or metastatic SSTR2-positive neuroendocrine tumors who have not received prior radiopharmaceutical therapies (RPT).

Interim analysis with a data cut-off date of March 4, 2026 was previously presented at the American Association for Cancer Research Annual Meeting 2026 (AACR 2026) in April 2026, including efficacy data on half of the patients in Cohort 2 and both patients in Cohort 1. Initial efficacy data for the remaining patients in Cohort 2 and eight patients in Cohort 3 are pending, and submissions for presentations at additional medical conferences during 2026 are planned.

About PSV359

PSV359 was designed to target and deliver ²¹²Pb to tumor sites expressing FAP-α, associated with multiple highly prevalent solid tumors, with patients in need of additional treatment options. The targeting moiety may also be radiolabeled with ²⁰³Pb or ⁶⁸Ga (known as PSV377) to detect FAP-α expression in individual patients. Preclinical imaging and therapy as well as human imaging results suggest Perspective's proprietary targeting ligand has improved levels of target engagement and uptake in tumors, as well as reduced retention in healthy tissues, which may result in a desirable therapeutic index.

Perspective is conducting a multi-center, open-label, dose-finding and dose-expansion study (clinicaltrials.gov identifier NCT06710756) of [²¹²Pb]PSV359 in patients with advanced solid tumors that express FAP-α as determined by imaging with [²⁰³Pb]PSV359. The primary objective of the dose finding phase of the study is to assess the safety and tolerability of various doses of [²¹²Pb]PSV359 in order to determine the recommended Phase 2 dose to be used in the expansion phase of the study, where anti-tumor activities may be an additional primary outcome measure.

About Perspective Therapeutics, Inc.

Perspective Therapeutics, Inc. is a radiopharmaceutical development company pioneering advanced treatments for cancers throughout the body. The Company has proprietary technology that utilizes the alpha-generating isotope ²¹²Pb to deliver powerful radiation specifically to cancer cells via specialized targeting moieties. The Company is also developing complementary imaging techniques that incorporate the same targeting moieties, which provides the opportunity to personalize treatment and optimize patient outcomes. This "theranostic" approach enables visualization of the specific tumor and subsequent treatment, potentially improving efficacy and minimizing toxicity.

The Company is advancing a portfolio of clinical-stage programs in the U.S., including VMT-α-NET (neuroendocrine tumors), VMT01 (melanoma), and PSV359 (solid tumors).

The Company is expanding its regional finished drug product candidate supply network, enabled by its proprietary ²²⁴Ra/²¹²Pb generator platform used to manufacture clinical drug product candidates, to support the delivery of patient-ready drug product candidates for clinical trials and, if approved, commercial operations.

For more information, please visit the Company's website at https://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 clinical development plans and the expected timing for the release of additional data from its programs; the potential for a front-loading dosing regimen for [²¹²Pb]VMT-α-NET to change response kinetics and further improve response rate and tolerability at the same cumulative administered dose; the Company's expectation that certain characteristics of PSV359 identified in preclinical research and human imaging, such as preferential uptake and retention in the tumor, binding affinity to FAP-α and fast clearance from healthy tissues, may result in a desirable therapeutic index; the Company's plans to assess the safety and tolerability of various doses of [²¹²Pb]PSV359 to determine the recommended Phase 2 dose to be used in the expansion phase of the study, and its belief that anti-tumor activity may be an additional primary outcome measure of the expansion phase of the study; the Company's expectations regarding its interactions with regulatory agencies and the expected timing thereof; 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. Known risk factors include that the Company's preclinical development plans and clinical trials may be more costly or take longer to complete than anticipated, or may never be completed, or may not generate results that warrant future development of the tested product candidate; the Company may elect to change its strategy regarding its product candidates and clinical development activities; economic and market conditions may worsen; regulatory agencies may issue decisions that negatively impact the Company's product candidates and clinical development plans; and risks related to the sufficiency of the Company's cash resources for its future operating expenses and capital expenditures. A more complete discussion of the risks and uncertainties facing the Company appears under the heading "Risk Factors" in the Company's most recent Annual Report on Form 10-K 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.

Media and Investor Relations Contacts:

Perspective Therapeutics IR:
Annie J. Cheng, CFA
[email protected]

ENTENTE Network of Companies
Virginia Amann
[email protected]