Therapeutic Efficacy of a Bivalent Inhibitor of Prostate-Specific Membrane Antigen Labeled with <sup>67</sup>Cu
Lachlan E. McInnes, Carleen Cullinane, Peter Roselt, Susan Jackson, Benjamin J. Blyth, Ellen M. van Dam, Nicholas Zia, Matthew Harris, Rodney J. Hicks, Paul S. Donnelly
Abstract
Radionuclide therapy targeting prostate-specific membrane antigen (PSMA) is promising for prostate cancer. We previously reported a ligand, <sup>64</sup>Cu-CuSarbisPSMA, featuring 2 lysine-ureido-glutamate groups. Here, we report the therapeutic potential of <sup>67</sup>Cu-CuSarbisPSMA. <b>Methods:</b> Growth of PSMA-positive xenografts was evaluated after treatment with <sup>67</sup>Cu-CuSarbisPSMA or <sup>177</sup>Lu-LuPSMA imaging and therapy (I&T). <b>Results:</b> 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. <b>Conclusion:</b><sup>67</sup>Cu-CuSarbisPSMA is efficacious in a PSMA-expressing model of prostate cancer.