Therapeutic Efficacy of a Bivalent Inhibitor of Prostate-Specific Membrane Antigen Labeled with 67Cu.

Radionuclide therapy targeting prostate-specific membrane antigen (PSMA) is promising for prostate cancer. We previously reported a ligand, 64Cu-CuSarbisPSMA, featuring 2 lysine-ureido-glutamate groups. Here, we report the therapeutic potential of 67Cu-CuSarbisPSMA. Methods: Growth of PSMA-positive xenografts was evaluated after treatment with 67Cu-CuSarbisPSMA or 177Lu-LuPSMA imaging and therapy (I&T). Results: At 13 d after injection, tumor growth was similarly inhibited by the 2 tracers in a dose-dependent manner. Survival was comparable after single (30 MBq) or fractionated (2 × 15 MBq, 2 wk apart) administrations. Conclusion:67Cu-CuSarbisPSMA is efficacious in a PSMA-expressing model of prostate cancer.