Perspective Therapeutics, Inc. (NYSE American: CATX) announced a clinical trial collaboration and supply agreement with Merck (NYSE: MRK) to evaluate a combination of Perspective's targeted alpha-particle therapy [212Pb]PSV359 with Merck's anti-PD-1 therapy Keytruda (pembrolizumab) in patients with FAP-α positive solid tumors.

The combination will be assessed under an amendment to Perspective's ongoing Phase 1/2a study of [212Pb]PSV359 in patients with certain types of non-small cell lung cancer and colorectal cancer that express fibroblast activation protein alpha, or FAP-α. The study has completed enrollment in its first three monotherapy dose cohorts. Perspective is sponsoring the study, and Merck is providing pembrolizumab at no cost.

Markus Puhlmann, Perspective's Chief Medical Officer, said the company aims "to evaluate whether this approach can reshape the tumor environment and potentially improve treatment outcomes for patients with advanced FAP-α-positive solid tumors."

PSV359 was designed to target and deliver the isotope 212Pb to tumor sites expressing FAP-α. According to the company's press release, FAP-α is expressed in the majority of epithelial cancers and has been associated with poor prognosis in several solid tumor types, including non-small cell lung cancer, colorectal cancer, and pancreatic cancer.

Perspective is conducting a multi-center, open-label, dose-finding and dose-expansion study of [212Pb]PSV359 in patients with advanced solid tumors. The primary objective of the dose-finding phase is to assess safety and tolerability of various doses to determine a recommended Phase 2 dose.