Perspective Therapeutics Partners with Merck to Evaluate Combination Therapy for Solid Tumors

SEATTLE, Sept. 14, 2026 /CourierPR/ -- Perspective Therapeutics, a radiopharmaceutical development company, has announced a significant collaboration with Merck, the global health care company, to evaluate the potential of combining their targeted alpha-particle therapy, [212Pb]PSV359, with Keytruda® (pembrolizumab), an anti-PD-1 therapy. This partnership aims to explore the efficacy of this combination in treating patients with certain solid tumors that express fibroblast activation protein alpha (FAP-α).

The collaboration is an amendment to an ongoing Phase 1/2a study of [212Pb]PSV359 in patients with non-small cell lung cancer and colorectal cancer, both of which express FAP-α. The study, which has completed enrollment in the first three monotherapy dose cohorts, will now evaluate the combination therapy. Perspective Therapeutics is sponsoring the study, while Merck is providing Keytruda® at no cost.

FAP-α, a protein abundantly expressed on the surface of cancer-associated fibroblasts (CAFs) in the stroma, a part of the tumor microenvironment, is associated with a majority of solid tumors. Higher FAP-α expression has been linked to poor prognosis in various solid tumors, including non-small cell lung cancer, colorectal cancer, pancreatic cancer, stomach cancer, mesothelioma, head and neck cancer, esophageal cancer, and ovarian cancer. The combination of targeted radiopharmaceutical treatment with an established immune checkpoint inhibitor aims to reshape the tumor environment and potentially improve treatment outcomes for patients with advanced FAP-α-positive solid tumors.

PSV359, designed to target and deliver 212Pb to tumor sites expressing FAP-α, is a key component of this study. The targeting moiety may also be radiolabeled with 203Pb or 68Ga to detect FAP-α expression in individual patients. Preclinical imaging and therapy results suggest that 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.

The multi-center, open-label study is designed to assess the safety and tolerability of various doses 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 is to determine the recommended Phase 2 dose for the expansion phase, where anti-tumor activities may be an additional primary outcome measure.

Perspective Therapeutics, Inc., a radiopharmaceutical development company, is advancing a portfolio of clinical-stage programs in the U.S., including bamzireotide navoxetan (VMT-α-NET, neuroendocrine tumors), lapemelanotide zapixetar (VMT01, melanoma), and PSV359 (solid tumors). The company is also expanding its regional finished drug product candidate supply network, enabled by its proprietary 224Ra/212Pb generator platform, to support the delivery of patient-ready drug product candidates for clinical trials and, if approved, commercial operations.

The collaboration with Merck underscores Perspective's commitment to developing innovative treatments for cancers throughout the body. By combining targeted radiopharmaceutical treatment with an established immune checkpoint inhibitor, the company aims to reshape the tumor environment and potentially improve treatment outcomes for patients with advanced FAP-α-positive solid tumors.