• Iomab-B and Actimab-A are the only targeted radiotherapies in for acute myeloid leukemia addressing different parts of the patient journey
• Improved survival demonstrated with both Iomab-B and Actimab-A in patients with high-risk acute myeloid leukemia including those with a TP53 mutation and prior venetoclax treatment
• Novel linker technology supports Actinium's Antibody Radiation Conjugate pipeline expansion in solid tumor indications

NEW YORK, May 13, 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 five abstracts have been accepted for presentation at the 2024 Society of Nuclear Medicine & Molecular Imaging (SNMMI) Annual Meeting being held June 8 – 11, 2024, in Toronto, Canada. The abstracts will feature results from the Phase 3 SIERRA trial of Iomab-B, a CD45 targeting ARC with the Iodine-131 payload, intended for conditioning to prepare patients for a potentially curative bone marrow transplant (BMT) and results from a Phase 1b trial of Actimab-A, a CD33 targeting ARC with the Actinium-225 payload, in combination with the chemotherapy regimen CLAG-M.  Iomab-B and Actimab-A are the only targeted radiotherapies in development for patients with relapsed/refractory acute myeloid leukemia (r/r AML), a blood cancer that is highly sensitive to radiation. In addition, an abstract detailing proprietary linker technology applicable for solid tumor targeting ARCs developed by Actinium will be presented for the first time.

Sandesh Seth, Actinium's Chairman and CEO, said, "Our presence at this year's SNMMI showcases the breadth of Actinium's capabilities and leadership in the development of Antibody Radiation Conjugates. We look forward to highlighting the potential for targeted radiotherapy in blood cancers to the nuclear medicine community, which represents a significant expansion opportunity for the field. The data from Iomab-B and Actimab-A that will be presented at SNMMI demonstrate the potential of targeted radiation to treat patients with high-risk, difficult-to-treat r/r AML, including the ability overcome mutations such as TP53 and those who have had extensive prior therapies."

Actinium's SNMMI presentations are detailed below:

• Safety and Dosimetric Analysis of Lintuzumab-Ac225 in Combination with Intensive CLAG-M Chemotherapy in Patients with Relapsed/Refractory AML
• Exploratory Analysis of Bone Marrow Dosimetry from the Randomized Phase 3 SIERRA Trial of Iomab-B (131I-apamistamab) Prior to HCT in Relapsed/Refractory Acute Myeloid Leukemia
• Survival Outcomes and Dosimetric Analysis of Iomab-B (131I-apamistamab) Followed by Allogeneic Hematopoietic Cell Transplant for Patients with TP53 Mutated Relapsed/Refractory AML
• Mathematical Modeling of Exposure Measurements Following High-Dose Targeted Therapy Using 131I-apamistamab: Analysis From the Large Multicenter Phase III SIERRA Trial
• Evaluation of novel DOTA-based linkers for improved targeted radiotherapy delivery to solid tumors

About the SNMMI Annual Meeting

The SNMMI Annual Meeting is recognized as the premier educational, scientific, research, and networking event in nuclear medicine and molecular imaging. The four-day event, taking place each June, provides physicians, technologists, pharmacists, laboratory professionals, and scientists with an in-depth view of the latest research and development in the field as well as providing insights into practical applications for the clinic.

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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