Actinium Pharmaceuticals, Inc.

Company overview

Actinium Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing targeted radiopharmaceutical therapeutics for oncology. The company focuses on biology-driven radiopharmaceuticals with multi-indication potential across solid tumors and hematologic malignancies. Its strategy includes vertically integrated capabilities—from isotope production to final drug product—and a platform that targets antigens beyond conventional radiotherapy targets.

What the company does

• Develops alpha-emitter–based targeted radiotherapies with a biology-driven target selection approach.
• Pursues first-in-class or differentiated radiopharmaceuticals with multi-indication potential.
• Maintains end-to-end capabilities, including isotope supply, radioconjugate design, preclinical and translational work, and clinical development.
• Plans to build an internal cGMP radiopharmaceutical manufacturing facility (expected operational in 2H 2026) to support clinical and commercial supply, while maintaining a network of external manufacturers and isotope suppliers for trials.

Pipeline and programs

• ATNM-400: Solid tumor program targeting a novel non-PSMA antigen with pan-tumor potential (prostate cancer, NSCLC, breast cancer). Preclinical data indicate activity across multiple tumor types and potential for combination therapy.
• Actimab-A (lintuzumab-Ac-225): CD33-targeted radioconjugate designed to deplete CD33+ MDSCs in the tumor microenvironment to enhance checkpoint inhibitor efficacy. In hematology, developed as backbone therapy for AML/MDS; in solid tumors, evaluated in combination with PD-1 inhibitors in a basket approach.
• Iomab-B (apamistamab-I-131): CD45-targeted conditioning agent to enable bone marrow transplant in relapsed/refractory AML patients who are ineligible for traditional conditioning.
• Iomab-ACT: CD45-targeted conditioning for cell and gene therapies (commercial and experimental CAR-T, allogeneic transplant, and gene therapies); intended as a universal conditioning agent.

Clinical progress and partnerships

• Actimab-A and Iomab-B are Phase 2/3–ready assets with validation across more than 15 clinical trials involving over 500 patients.
• Iomab-B SIERRA trial (Phase 3) in elderly relapsed AML met its primary endpoint (dCR) but did not meet the OS endpoint in the intent-to-treat population. The FDA required an additional randomized head-to-head trial and a dose-optimization study for Iomab-B; the company is seeking a strategic U.S. partner to conduct these studies.
• Iomab-ACT has three active trials for conditioning in commercial CAR-T, experimental CAR-T, and sickle cell disease transplant conditioning.
• Actimab-A development includes a Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute (NCI) to support AML/MDS and additional oncology combinations.

Commercialization and partnerships

• The company is pursuing strategic partnerships to advance late-stage hematology programs (Actimab-A and Iomab-B) and to support global pivotal trials.
• The NCI CRADA supports cost-effective development while the company retains commercial rights in certain territories.

Manufacturing and supply chain

• Internal cGMP radiopharmaceutical manufacturing facility in New York expected to be commissioned in 2H 2026.
• Proprietary cyclotron-based Ac-225 production technology intended to provide high-purity Ac-225 and reliable isotope supply at scale, with potential partnership opportunities for Ac-225 production.
• Established end-to-end supply chain: multiple isotope suppliers, contract manufacturing organizations (CMOs), and a distribution network to about 50 leading cancer centers.
• Historically sourced isotopes such as Ac-225 and I-131 from DOE and other suppliers; exploring additional production routes (linear accelerator, cyclotron) to scale supply.

Intellectual property

• Patent portfolio of approximately 250 issued patents and applications covering composition of matter, methods of use, manufacturing, and platform technologies related to Actimab-A, Iomab-B, Iomab-ACT, ATNM-400, and radiochemistry/conjugation technologies.
• Orphan drug designations for Iomab-B and Actimab-A in the U.S. and EU, providing associated market exclusivities if approvals are obtained.

People and facilities

• As of March 25, 2026: 25 full-time employees.
  • 12 hold Ph.D. or M.D. degrees.
  • 21 work in research and development and clinical development.
• Corporate headquarters: 100 Park Avenue, New York, NY; lease through 2027 with annual rent of approximately $0.636 million and a collateral letter of credit of about $0.335 million.
• Additional lab and manufacturing space leased at Albert Einstein College of Medicine, Bronx, NY (lab lease ends August 2026) and a manufacturing space lease through 2030.

Financial profile

• No commercial product revenue to date.
• Net loss of $33.9 million in 2025 and $38.2 million in 2024.
• Accumulated deficit of approximately $409.7 million as of December 31, 2025 (compared to about $375.8 million as of December 31, 2024).
• Existing resources are sufficient to fund planned operations for more than 12 months from the report date.
• The company notes limited access to capital markets and may need strategic collaborations or licensing arrangements; future financings could be dilutive and terms may be unfavorable.

Customers and market presence

• Distribution and clinical trial network includes approximately 50 leading hospitals and treatment centers.
• Approximately 24 clinical trial sites associated with SIERRA and related programs.
• More than 500 patients treated across the company’s trials to date (across 15+ clinical trials).

Summary

Actinium is a clinical-stage, pre-revenue company developing targeted alpha-emitter radiopharmaceuticals for hematology and solid tumors, alongside a conditioning platform for cell and gene therapies. The company maintains integrated development and manufacturing plans, an extensive intellectual property portfolio, and active partnerships to advance late-stage programs.