Actinium Pharmaceuticals Inc. (NYSE American: ATNM)

Actinium Pharmaceuticals Inc. (NYSE American: ATNM) is a pioneering biotechnology company focused on the development of targeted radiotherapies that aim to deliver precision treatment for hematologic malignancies. The company’s platform centers around harnessing the power of Actinium-225 (Ac-225), an alpha-emitting radioisotope, to create potent therapies that selectively destroy cancer cells while sparing healthy tissue. Actinium’s lead candidate, Actimab-A, targets the CD33 protein and is being positioned as a foundational therapy for acute myeloid leukemia (AML) and other myeloid disorders.

Driven by a vision to transform the treatment paradigm in oncology, Actinium is advancing radiotherapy innovations that are mutation-agnostic and capable of synergizing with both traditional and novel therapies. The company’s approach is centered on building value through strategic research partnerships, clinical collaborations, and regulatory engagement to unlock new therapeutic options for patients with limited alternatives.

Actinium’s mission is to significantly improve patient survival and quality of life through highly targeted therapies with the potential to overcome resistance and relapse. By innovating at the intersection of nuclear medicine and immuno-oncology, the company is working to redefine the future of cancer care.

The company is headquartered in New York, New York.

Pipeline

Actimab-A

Actimab-A is Actinium’s lead clinical-stage asset, currently in development for relapsed and refractory AML. The drug leverages a CD33-targeting monoclonal antibody linked to Ac-225, delivering cytotoxic alpha radiation directly to cancer cells. In clinical studies, Actimab-A combined with CLAG-M chemotherapy has demonstrated high complete remission (CR) rates and measurable residual disease (MRD) negativity, with promising survival outcomes. It is being advanced to a pivotal Phase 2/3 trial. Additionally, under a Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute, Actimab-A will be evaluated in combination with Venetoclax and ASTX-727 for newly diagnosed AML patients.

Actimab-A (Pan-Tumor Immunotherapy)

Actimab-A is also being developed as a potential pan-tumor agent by depleting immunosuppressive myeloid-derived suppressor cells (MDSCs), enhancing the effectiveness of checkpoint inhibitors such as KEYTRUDA® and OPDIVO®. This expansion could open significant new indications across solid tumors.

Iomab-ACT

Iomab-ACT is a conditioning agent designed to improve outcomes and expand access for patients undergoing cell and gene therapies. Its use in pre-conditioning may enhance tolerability and increase eligibility for patients in need of curative treatment.

Iomab-B

Iomab-B is a late-stage induction and conditioning agent intended for patients with relapsed or refractory AML who are undergoing bone marrow transplantation. Actinium is seeking a strategic partner to support potential U.S. commercialization.

Preclinical Programs

Actinium is also advancing several preclinical candidates focused on solid tumors, extending the utility of its alpha-targeted radiotherapy platform into broader oncology markets.

Technology

Actinium’s technology is centered on leveraging the unique properties of the isotope Actinium-225 (Ac-225), a potent alpha-emitter capable of delivering highly targeted and lethal radiation to cancer cells. Its high linear energy transfer (LET) and short path length allow for effective cell killing with minimal impact on surrounding healthy tissue. This precision makes Ac-225 an attractive payload for targeted radiotherapy.

The company’s innovation platform, known as Antibody Warhead Enabling (AWE) Technology, is designed to optimize the development and application of targeted radiotherapies using Ac-225. AWE integrates Actinium’s proprietary linkers, conjugation methods, and radioisotope expertise to enhance the therapeutic profile of Ac-225-based agents. This includes improving targeting, stability, and manufacturing scalability across hematologic and solid tumor indications.

Actinium also holds key capabilities in Ac-225 production and processing, including multiple supply agreements and patents covering cyclotron-based production. This infrastructure supports Actinium’s current programs and provides strategic flexibility to scale clinical and commercial supply of Ac-225.

Market Opportunity

Actinium is focused on addressing critical gaps in the treatment of hematologic malignancies, particularly acute myeloid leukemia, where survival rates remain low and existing therapies often fall short. The company’s lead product candidate targets relapsed and refractory AML, a patient group with significant unmet need and limited therapeutic options.

With additional pipeline programs aimed at improving outcomes for patients undergoing bone marrow transplants or receiving cell and gene therapies, Actinium’s portfolio is strategically positioned at the intersection of several evolving treatment modalities. The company’s expansion into pan-tumor applications could further diversify its addressable market as interest in combining radiotherapies with immuno-oncology agents continues to rise.

Leadership Team

Sandesh Seth, Chairman and Chief Executive Officer, brings over 25 years of experience across investment banking, equity research, and the pharmaceutical industry. He previously held roles at Pfizer, Cowen & Co., and Bear Stearns, and holds several patents related to radiopharmaceuticals.

Steve O’Loughlin, Chief Financial Officer, joined Actinium in 2015 and has held finance and corporate development roles across life sciences firms, with prior experience in investment banking and publicly traded biotech companies.

Avinash Desai, M.D., Chief Medical Officer, is a veteran in hematology and oncology, having led development and medical affairs programs at GSK, Eli Lilly, Janssen, and Sanofi, contributing to several approved oncology therapies.

Jenny Hsieh, Chief Strategy Officer, has nearly two decades of healthcare strategy experience. She helped lead Immunomedics through its $21 billion acquisition by Gilead following the FDA approval of Trodelvy®.