• The SIERRA results demonstrate Iomab-B's ability to overcome the negative impact of a TP53 mutation in patients who otherwise would have limited treatment options and dismal prognosis
• -Represents the eleventh oral presentation of the Phase 3 SIERRA results demonstrating continued recognition of the high potential for Iomab-B led allogeneic bone marrow transplant by the bone marrow transplant community  

NEW YORK, April 1, 2024 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a leader in the development of Antibody Radiation Conjugates (ARCs) and other targeted radiotherapies, today announced that results from the Phase 3 SIERRA trial of Iomab-B in patients with a TP53 mutation have been accepted for oral presentation at the 50^th Annual meeting of the European Bone Marrow Transplant Society (EBMT) being held April 14 – 17, 2024, in Glasgow, Scotland. Iomab-B is a targeted radiotherapy conditioning agent comprised of an anti-CD45 monoclonal antibody and Iodine-131 radioisotope payload. The Phase 3 SIERRA trial enrolled 153 patients with active relapsed or refractory acute myeloid leukemia (r/r AML) and compared outcomes of patients receiving Iomab-B and a bone marrow transplant (BMT) to those of patients receiving physician's choice of care in the control arm. In total, 24% of patients (37/153) in the SIERRA trial had a TP53 mutation, which is associated with poor outcomes, and 27 of the TP53 positive patients received Iomab-B. Iomab-B met the primary endpoint of durable Complete Remission (dCR) in the SIERRA trial with high-statistical significance (p<0.0001) and 100% of patients receiving a therapeutic dose of Iomab-B achieved BMT access and engagement.

Dr. Hannah Choe, Assistant Professor of Medicine at Ohio State University and SIERRA trial investigator will present the SIERRA results. Details of the oral presentation are as follows:

Title: I-131-Apamistamab-Led Allogeneic Hematopoietic Cell Transplant Demonstrates Survival Benefit and Overcomes High-Risk TP53 Mutations in Patients with R/R AML

Date and Time: Wednesday, April 17, 2024, 12:39 PM GMT

Session: OS17-02

Location: Scottish Event Campus (SEC Centre)

Dr. Avinash Desai, Actinium's Chief Medical Officer, said, "In addition to demonstrating unprecedented 100% access to BMT in Iomab-B treated patients with active r/r AML and achieving the primary endpoint of dCR with high statistical significance, we are excited by the compelling outcomes in patients with a TP53 mutation in the SIERRA trial. We look forward to returning to EBMT and once again highlighting the positive results from the Phase 3 SIERRA trial to the European bone marrow transplant community. We are particularly focused on Europe as it represents the largest bone marrow transplant market performing 40% of the BMT transplants globally. We also look forward to continuing to work with our European, Middle East and North African commercial partner, Immedica Pharma Ab, to bring Iomab-B to patients globally."

About the EBMT Annual Meeting

The Annual Meeting of the EBMT is attended by more than 5,500 participants, including physicians, nurses, data managers, statisticians, quality managers, cell therapists, paediatricians, pharmacists, psychologists, psychiatrists and psychoanalysts, transplant coordinators, lab scientists, trainees, patients. This important congress ensures and encourages dialogues and information exchange, education and scientific productivity.

The full annual meeting program is available online at: https://ebmt2024.abstractserver.com/program/#/program/2/horizontal.

About Actinium Pharmaceuticals, Inc.

Actinium develops targeted radiotherapies to meaningfully improve survival for people who have failed existing oncology therapies. Advanced pipeline candidates Iomab-B (pre-BLA & MAA (EU)), an induction and conditioning agent prior to bone marrow transplant, and Actimab-A (National Cancer Institute CRADA pivotal development path), a therapeutic agent, have demonstrated potential to extend survival outcomes for people with relapsed and refractory acute myeloid leukemia. Actinium plans to advance Iomab-B for other blood cancers and next generation conditioning candidate Iomab-ACT to improve cell and gene therapy outcomes. Actinium holds more than 230 patents and patent applications including several patents related to the manufacture of the isotope Ac-225 in a cyclotron.

For more information, please visit: https://www.actiniumpharma.com/

Forward-Looking Statements

This press release may contain projections or other "forward-looking statements" within the meaning of the "safe-harbor" provisions of the private securities litigation reform act of 1995 regarding future events or the future financial performance of the Company which the Company undertakes no obligation to update. These statements are based on management's current expectations and are subject to risks and uncertainties that may cause actual results to differ materially from the anticipated or estimated future results, including the risks and uncertainties associated with preliminary study results varying from final results, estimates of potential markets for drugs under development, clinical trials, actions by the FDA and other governmental agencies, regulatory clearances, responses to regulatory matters, the market demand for and acceptance of Actinium's products and services, performance of clinical research organizations and other risks detailed from time to time in Actinium's filings with the Securities and Exchange Commission (the "SEC"), including without limitation its most recent annual report on form 10-K, subsequent quarterly reports on Forms 10-Q and Forms 8-K, each as amended and supplemented from time to time.

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