Maximum tumor uptake was observed after several hours and retained for several days—a good match to the Ac225 half life. Treatment doses of Ac225-PSMA-617 ranged from 50-200 kBq/kg and dose intervals from 2-4 months. Treatment failure (death or rising PSA) was observed at the lowest dose and severe xerostomia was the limiting factor at higher doses. Based on these data, a standard treatment of 100 kBq/kg every two months was chosen for the second trial.
Twenty eight patients were recruited for the second phase. Eight of these dropped out early (5 due to xerostomia, 3 due to early progression). Of the 20 patients who completed the standard treatment, 19 showed a PSA drop at 8 weeks. Four patients showed complete remission. Based on these results, Ac225-PSMA-617 is a very promising potential therapy for mCRPC patients, especially if ways could be found to ameliorate the side effects to the salivary glands.
Presented By: Alfred Morgenstern from European Commission, Joint Research Center, Directorate for Nuclear Safety and Security, Karlsruhe, Germany
Written By: William Carithers, Lawrence Berkeley National Laboratory
at the 10th International Symposium on Targeted Alpha Therapy (TAT-10) May 31 - June 1, 2017 - Kanazawa, Japan.