• New data underscoring the potential of ATNM-400 as a first-in-class Ac-225 radioconjugate with broad pan-tumor efficacy across multiple solid tumor models
   
• Actimab-A demonstrates mutation-agnostic efficacy and a novel mechanism that enhances response to standard AML therapies
   
• Multiple data catalysts for ATNM-400 and Actimab-A in 2026; and posters for each to be presented on April 21, 2026 at AACR 2026 in San Diego, CA

NEW YORK, April 6, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, today announced the publication of two abstracts that will be presented at the American Association for Cancer Research (AACR) Annual Meeting 2026, taking place April 17–22, 2026, in San Diego, California.

The Company will present previously undisclosed data demonstrating the expanding potential of its Ac-225 radiotherapy platform across both solid tumors and hematologic malignancies. Both presentations will occur on April 21, 2026 in the session Radiopharmaceutical Platforms for Theranostic Precision Oncology.

Sandesh Seth, Actinium's Chairman and CEO, said, "These new data further validate the strength and versatility of our Ac-225 radiotherapy platform. ATNM-400 continues to show compelling pan-tumor activity, including activity in tumors resistant to current targeted therapies, supporting its potential as a first-in-class asset in large solid tumor indications. In parallel, Actimab-A's newly identified mechanism of transcriptional reprogramming provides important insight into its mutation-agnostic activity and ability to enhance standard-of-care therapies. Together, these findings reinforce our strategy to build a differentiated pipeline with multiple value-driving opportunities."

ATNM-400 AACR 2026 Presentation Details

Poster Number: 5824

Session: Radiopharmaceutical Platforms for Theranostic Precision Oncology

Date & Time: April 21, 2026 – 2:00 PM – 5:00 PM PT | Poster Section 16, Board #18

Actimab-A AACR 2026 Presentation Details

Poster Number: 5827

Session: Radiopharmaceutical Platforms for Theranostic Precision Oncology

Date & Time: April 21, 2026 – 2:00 PM – 5:00 PM PT | Poster Section 16, Board #21

About Actinium Pharmaceuticals, Inc.

Actinium is a pioneer in targeted radiotherapies designed to improve outcomes for patients with cancer. The company employs a biology-driven approach to develop differentiated radiopharmaceuticals for solid tumors and hematologic malignancies. Its mission is to transform cancer treatment through innovative radioconjugates that maximize therapeutic efficacy while minimizing toxicity to healthy tissue by combining expertise in tumor biology, translational medicine, and radiochemistry. Since inception, Actinium has focused on developing innovative radiotherapies. Its pipeline reflects this strategy across three areas: (1) solid tumor therapeutics including ATNM-400 and Actimab-A with pan-tumor potential; (2) Actimab-A as a therapeutic backbone for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in collaboration with the National Cancer Institute (NCI); and (3) targeted conditioning agents including Iomab-B for bone marrow transplant and Iomab-ACT for cell and gene therapy conditioning. ATNM-400 targets a novel antigen distinct from PSMA and has demonstrated preclinical activity across metastatic castration-resistant prostate cancer (mCRPC), non-small cell lung cancer (NSCLC), and breast cancer. Actimab-A has shown improved survival in relapsed/refractory AML with CLAG-M and is advancing toward a Phase 2/3 trial, with additional development ongoing through a CRADA with the NCI. Actinium is also advancing preclinical solid tumor programs and holds ~250 patents and patent applications, including intellectual property related to cyclotron-based production of Ac-225. For more information, please visit 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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SOURCE Actinium Pharmaceuticals, Inc.