Active relapsed or refractoryAML patients 65+ years receiving an Iomab-B led Bone MarrowTransplant (BMT) achieved significant improvement in survival at one and two years compared to control arm patients none of whom survived even one year

Unprecedented 100%BMT access and engraftment in evaluable patients receiving a therapeutic dose of Iomab-B despite high leukemia burden and multiple lines of prior treatment

Iomab-B has also demonstrated improved outcomes in patients with high-risk features including a TP53 mutation

Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a leader in the development of targeted radiotherapies, reported new analyses from the positive Phase 3 SIERRA trial of Iomab-B in oral presentations at the at the 2024 Tandem Meetings | Transplantation & Cellular Therapy (TCT) Meetings of ASTCT(R)(American Society for Transplantation and Cellular Therapy and CIBMTR(R) (Center for International Blood and Marrow Transplant Research). The presentations reported unprecedented 100% access to potentially curative bone marrow transplant (BMT) and engraftment in evaluable patients with active relapsed or refractory acute myeloid leukemia (r/r AML) and improved long-term survival outcomes greater than 2 years in patients age 65 or older. Patients with r/r AML age 65 and older who also have multiple comorbidities and high-risk cytogenetics have a poor prognosis are seldom offered BMT in current practice due to poor tolerance to induction and conditioning regimens and dismal outcomes. The SIERRA results presented at TCT demonstrate Iomab-B's ability to overcome multiple high-risk features including a TP53 genetic mutation, advanced age and treatment resistant disease. The two oral presentations at this year's TCT mark a total of ten oral presentations of the SIERRA results at various leading transplant, hematology and nuclear medicine conferences in the USA and Europe.

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Dr. Rajneesh Nath, Chief, Stem Cell Transplant, Cellular Therapy and Leukemia at Banner MD Anderson Cancer Center, said, "BMT physicians are eager to have treatment options for patients age 65 or older especially with high-risk factors like those enrolled in SIERRA study as this rapidly growing patient segment continues to have highly restrictive access to BMT due to poor outcomes. The SIERRA results show that Iomab-B targeted conditioning is well tolerated even in these patients with advanced age and multiple-comorbidities, providing access to potentially curative transplant for a substantially greater number of patients compared to the control arm. Patients receiving Iomab-B had significantly higher rates of complete remission as well as durable complete remission compared to the control arm. Most importantly, Iomab-B produced improved long-term survival outcomes as only the patients receiving Iomab-B achieved 1-year and 2-year survival. Iomab-B represents an important advancement in transplant conditioning and has the potential to address a significant unmet patient need."

Response Rates in Patients Age 65 and Above by Treatment Group

Iomab-B Crossover Control Arm (N=28) (N=17) (N=9) Achieved CR or CRp 19 (67.9%) 9 (52.9%) 3 (33.3%) Achieved durable CR 5 (17.9%) 1 (5.9%) 0 (0.0%)

Overall Survival in Patients Age 65 and Above by Treatment Received

Iomab-B & Crossover Control Arm (N=45) (N=9) 1-year survival 20.1% 0.0% 2-year survival 11.5% 0.0%

Sandesh Seth, Actinium's Chairman and CEO, added, "SIERRA was a first of its kind trial to use targeted radiotherapy conditioning to enable potentially curative BMT in patients who are not typically considered for transplant in current practice. Importantly, SIERRA demonstrated superior outcomes with an Iomab-B led BMT to current standard of care in the control arm that included approved therapies targeting FLT3 and IDH mutations and venetoclax, a BCL-2 inhibitor. We are incredibly excited that Iomab-B led BMT improved outcomes across all major patient segments including patients with advanced age and comorbidities, treatment resistant disease and high-risk features including TP53 mutations, which are mostly associated with dismal outcomes. We also are highly encouraged by the strong continued receptivity for Iomab-B data from the SIERRA trial by key medical and scientific communities both in US and Europe and focused on making Iomab-B available to patients globally as quickly as possible."

About the TCT Tandem Meetings

The Tandem Meetings ITransplantation & Cellular Therapy Meetings of ASTCT and CIBMTR are the combined annual meetings of theAmerican Society for Transplantation and Cellular Therapy (ASTCT)and the Center for International Blood & Marrow Transplant Research (CIBMTR). Administrators, clinicians, data manager/ clinical research professionals, fellows-in-training, investigators, laboratory technicians, MD/PhDs, nurses, nurse practitioners, pharmacists, physician assistants, and other allied health professional attendees benefit from a full scientific program that addresses the most timely issues in hematopoietic cell transplantation and cellular therapy.

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 220 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.

Investors:investorrelations@actiniumpharma.com

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