TAT-10: Efficacy of Actinium-225-labeled Anti-CD33 Antibody in Acute Myeloid Leukemia Correlates with Peripheral Blast Count

Kanazawa, Japan (UroToday.com) This study was conducted in two phases. Phase one had 18 relapsed and refractory acute myeloid leukemia (AML) patients. Patients were treated with a single infusion of Actimab-A, the company’s name for Ac-225 conjugated to the anti-CD33 monoclonal antibody lintuzumab. Doses ranged from 18.5 to 148 kBq/kg and post analysis determined a maximum dose of 111 kBq/kg. In the second trial (18 newly diagnosed patients), were treated with two equal doses at 14 days and 21 days. Total doses ranged from 37 to 148 kB/kq.

When analyzing subgroups, no significant differences in efficacy were observed with respect to age, disease characteristics, bone marrow blast percentage, dose fractionization, or previous treatment. A significant correlation was observed with peripheral blood blast counts. In 19 patients with peripheral blood counts < 200/microliter, 8 responded (i.e., achieved one category of complete recovery as defined in advance).  The correlation remained even when the endpoint was relaxed to included additional patients who had > 50% reduction in bone marrow blasts.

Presented By: Mark Berger from Actinium Pharmaceuticals, Inc.

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.