Preclinical Efficacy of a PSMA-Targeted Actinium-225 Conjugate (225Ac-Macropa-Pelgifatamab): A Targeted Alpha Therapy for Prostate Cancer.

Purpose: Initially, prostate cancer responds to hormone therapy, but eventually resistance develops. Beta emitter-based prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy is approved for the treatment of metastatic castration-resistant prostate cancer. Here we introduce a targeted alpha therapy (TAT) consisting of the PSMA antibody pelgifatamab covalently linked to a macropa chelator and labeled with actinium-225 and compare its efficacy and tolerability with other TATs.

Tumor growth inhibition and immune system activation following treatment with thorium-227 conjugates and PD-1 check-point inhibition in the MC-38 murine model.

Targeted thorium-227 conjugates comprise the combination of a monoclonal antibody with specificity for a tumor cell antigen and a 3,2-HOPO chelator enabling complexation of thorium-227 (Th-227). The radiolabeled conjugate functions as an effective delivery system of alpha-particle radiation to the surface of the tumor cell inducing difficult to repair complex DNA damage and cell death. In addition, the mechanism of action of targeted alpha therapy (TAT) appears to involve a significant component linked to stimulation of the immune system.

TAK1-inhibitors did not reduce disease burden in a Vκ*MYC model of multiple myeloma.

Objective: Multiple myeloma is a haematological malignancy characterized by proliferation of monoclonal plasma cells in the bone marrow. Development of resistance and minimal residual disease remain challenging in the treatment of multiple myeloma. Transforming growth factor-β activated kinase 1 (TAK1) has recently gained attention as a potential drug target in multiple myeloma.

Zr-3,2-HOPO-Mesothelin Antibody PET Imaging Reflects Tumor Uptake of Mesothelin-Targeted Th-Conjugate Therapy in Mice.

The mesothelin (MSLN)-targeted Th conjugate is a novel α-therapy developed to treat MSLN-overexpressing cancers. We radiolabeled the same antibody-chelator conjugate with Zr to evaluate whether PET imaging with Zr-MSLN matches Th-MSLN tumor uptake, biodistribution, and antitumor activity. Serial PET imaging with protein doses of 4, 20, or 40 μg of Zr-MSLN and Zr-control was performed up to 168 h after tracer injection in human tumor-bearing nude mice with high (HT29-MSLN) and low (BxPc3) MSLN expression.