Actinium Pharmaceuticals to Showcase ATNM-400's First-in-Human Clinical Data in Prostate Cancer and Preclinical Results in Lung Cancer Supporting Pan-Tumor Potential Today at EANM 2026

• First-in-human Phase 1 presentation to feature ATNM-400 clinical data in metastatic castration-resistant prostate cancer, advancing a differentiated approach beyond PSMA
• Preclinical presentation to feature ATNM-400 studies in KRAS- and ALK-driven non-small cell lung cancer, exploring its potential across molecular subtypes
• ATNM-400's HER3-targeted alpha radiotherapy approach offers pan-cancer potential, with development as a monotherapy and in combination with established treatments across multiple solid tumors

NEW YORK, Oct. 19, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in differentiated targeted radiotherapies with the potential to transform cancer treatment, today reminded investors and the scientific community that clinical and preclinical data for ATNM-400 will be presented today at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM), being held October 17–21, 2026, in Vienna, Austria.

The clinical oral presentation will feature early data from the ongoing first-in-human Phase 1 dose-escalation study of ATNM-400 in metastatic castration-resistant prostate cancer (mCRPC). It will describe evaluation of the Zirconium-89-labeled imaging counterpart, including safety, biodistribution, dosimetry and serial PET assessment of tumor uptake and clearance, to inform development and dosing of Actinium-225-labeled ATNM-400.

The preclinical oral presentation will feature studies of ATNM-400 in KRAS- and ALK-driven non-small cell lung cancer (NSCLC) models, including evaluation as monotherapy and in combination with KRAS or ALK inhibitors. The presentation builds on earlier EGFR-mutant research and will discuss the rationale for mutation-agnostic development across lung cancer subtypes.

ATNM-400 is an investigational, first-in-class Actinium-225 antibody radioconjugate targeting HER3. The program is being developed to expand targeted radiotherapy beyond PSMA in prostate cancer and explore its potential across multiple solid tumors, as a monotherapy and in combination with established treatments.

EANM 2026 Presentation Details

Both sessions: Monday, October 19, 2026, 4:45–6:15 p.m. CEST (10:45 a.m.–12:15 p.m. EDT).

Clinical prostate cancer presentation | OP-525
First-in-human Phase 1 study of ATNM-400 in mCRPC
Session 1111: Theranostics Track: Prostate Cancer Therapy II | Hall G1

Preclinical lung cancer presentation | EPS-149
ATNM-400 in KRAS- and ALK-driven NSCLC models
Session 1109: Translational Imaging and Therapy | Hall G2

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 HER3, an antigen distinct from PSMA, and is in a first-in-human Phase 1 study in metastatic castration-resistant prostate cancer (mCRPC), with preclinical development across multiple solid tumor indications. 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: [email protected]

SOURCE Actinium Pharmaceuticals, Inc.