Actinium Reveals 67 Percent Overall Response Rate In Actimab-A Venetoclax Combination Trial

Actinium Pharmaceuticals, Inc. (ATNM) on Tuesday announced that first-in-human data from the first dose cohort of the Phase 1 portion of the Actimab-A venetoclax Phase 1/2 combination trial in patients with relapsed or refractory Acute Myeloid Leukemia or AML.

Actinium reported 67 percent overall response rate in the first cohort in Actimab-A Venetoclax combination trial. This Phase 1/2 trial is a multicenter, open label trial of Actimab-A (lintuzumab-Ac225) added to venetoclax for patients with CD33 positive R/R AML.

The data was presented at the 62nd American Society of Hematology or ASH annual meeting and highlighted results from the first three patients treated with the initial subtherapeutic dose level of 0.5 µCi/kg of Actimab-A and venetoclax.

The company noted that the 67 percent overall response rate includes one complete response in patient with TP53 mutation, and one partial response reported in patients with poor risk adverse cytogenetics with subtherapeutic dose of Actimab-A indicative of mechanistic synergy with venetoclax.

The enrolled patients had a median of 2 prior therapies and a median bone marrow blast percentage of 30 percent. All three patients had poor risk disease with adverse cytogenetics, and each patient had an additional high-risk marker.

“Particularly compelling is the complete response reported in a patient with complex mutations like TP53 with Actimab-A and venetoclax and the high MRD negativity rate with Actimab-A and CLAG-M. The results clearly demonstrate that a superior clinical effect without adding meaningful toxicity is achievable using Ac-225 ARC’s to precisely deliver powerful internal radiation and elicit a potentiating and synergistic treatment effect with chemotherapy and targeted agents,” said Sandesh Seth, Actinium’s Chairman and Chief Executive Officer.

Actinium added that a Phase 2 trial studying Actimab-A as a single agent produced a 69 percent overall response rate in older unfit patients with newly diagnosed AML.

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