Actinium Pharmaceuticals Announces Oral and Poster Presentations at EANM 2026 Highlighting Broad Antitumor Activity of ATNM-400 Across Lung, Colorectal and Ovarian Cancer Models

Actinium Pharmaceuticals (ATNM) announced three EANM presentations reporting preclinical ATNM-400 activity in lung, colorectal and ovarian cancer models.

Rhea-AI Summary

Actinium Pharmaceuticals (ATNM) announced three EANM presentations reporting preclinical ATNM-400 activity in lung, colorectal and ovarian cancer models. The presentations comprise an oral presentation and two e-posters at the congress in Vienna, October 17–21, 2026.

In non-small cell lung cancer models, ATNM-400 showed activity alone and enhanced activity with KRAS or ALK inhibitors, including in resistant models. Colorectal studies showed activity alone in SW620 models and enhanced activity with bevacizumab plus oxaliplatin in HCT15 models. Ovarian studies showed durable activity alone, including in bevacizumab-resistant tumors. Actinium said the findings support development of ATNM-400 alone and in combinations across solid tumors, complementing ongoing clinical development in metastatic castration-resistant prostate cancer.

Positive

• Minor pointATNM-400 showed preclinical lung cancer activity alone and enhanced activity with KRAS or ALK inhibitors, including resistant models.
• Minor pointColorectal models showed ATNM-400 activity alone in SW620 and enhanced activity with bevacizumab plus oxaliplatin in HCT15.
• Minor pointOvarian cancer models showed durable ATNM-400 monotherapy activity, including in bevacizumab-resistant tumors.
• Minor point. Forward-looking: it has not happened yet and may not happen.Actinium's development strategy includes ATNM-400 alone and with established therapies across solid tumors.

Negative

• None.

Historical Context

1 past event · Latest: Jun 03

1 event

1. Jun 03

   Preclinical data

   24h Move

   -4.9%

   Earlier ATNM-400 NSCLC work reported KRAS/EGFR model activity and combination efficacy.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

nsclc, actinium-225, xenografts, mcrpc

4 terms

nsclc medical

"non-small cell lung cancer (NSCLC)"

NSCLC stands for non-small cell lung cancer, which is the most common type of lung cancer. It develops in the lungs and can spread to other parts of the body, making it serious but often treatable if caught early. Understanding NSCLC helps people recognize the importance of lung health and early detection.

actinium-225 medical

"first-in-class Actinium-225 (²²⁵Ac) radiotherapy"

Actinium-225 is a rare, radioactive form of the metal actinium used as a microscopic radiation source in some cancer treatments; it emits very strong, short-range radiation that can destroy diseased cells when attached to a carrier drug. Investors pay attention because supply is limited and production is complex, so shortages or cost changes can directly affect the development, manufacturing and valuation of companies pursuing therapies that rely on this scarce medical “fuel.”

xenografts medical

"monotherapy activity in SW620 xenografts"

Xenografts are tissues or tumors taken from one species and implanted into another—most commonly human tumor samples grown in mice to study disease and test treatments. For investors, they matter because results from these models help drug developers decide which therapies are likely to work or cause harm, influencing project timelines, clinical trial choices and the perceived value of a biotech program; think of them as a dress rehearsal for human trials.

mcrpc medical

"metastatic castration-resistant prostate cancer (mCRPC)"

mCRPC stands for metastatic castration‑resistant prostate cancer, a form of prostate cancer that has spread beyond the prostate and keeps progressing despite treatments that lower male hormones. It matters to investors because this stage is harder to treat, drives demand for new therapies, and often involves large, expensive clinical trials and regulatory decisions that can strongly influence a drug maker’s future revenue and stock value—think of it as a stubborn problem that creates both medical need and commercial opportunity.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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• Oral presentation to highlight ATNM-400 antitumor activity across KRAS- and ALK-driven NSCLC models, building on earlier EGFR-mutant findings and supporting mutation-agnostic development
  
  
• Colorectal cancer data demonstrate ATNM-400's potential to enhance responses to standard-of-care therapies
  
  
• Ovarian cancer data demonstrate the durable antitumor activity of ATNM-400, including in treatment-resistant models
  
  
• Collectively, the findings support the broad potential of ATNM-400 as a differentiated targeted radiotherapy across multiple large solid tumor indications, both as monotherapy and in combination with existing treatments

NEW YORK, Oct. 16, 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 announced three presentations, including an oral presentation and two e-posters, highlighting preclinical data supporting ATNM-400's broad potential at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM), October 17–21, 2026, in Vienna, Austria.

The presentations feature ATNM-400, the Company's first-in-class Actinium-225 (²²⁵Ac) radiotherapy, in non-small cell lung cancer (NSCLC), colorectal cancer, and ovarian cancer models. Together, the studies demonstrate preclinical antitumor activity as monotherapy and enhanced activity in combination with standard-of-care agents, supporting both approaches to development across solid tumors. These findings further expand the preclinical evidence supporting ATNM-400's potential across multiple cancer indications, complementing its ongoing clinical development in metastatic castration-resistant prostate cancer (mCRPC).

In NSCLC, ATNM-400 demonstrated antitumor activity as monotherapy and enhanced activity in combination with KRAS or ALK inhibitors, including in resistant models. These findings extend earlier EGFR-mutant results and support mutation-agnostic development both as a standalone therapy and in combination with established treatments.

In colorectal cancer, ATNM-400 demonstrated monotherapy activity in SW620 xenografts and enhanced activity when combined with bevacizumab plus oxaliplatin in HCT15 xenografts, a model with moderate target expression and limited response to the standard-of-care combination. These findings support both monotherapy development and combinations aimed at improving outcomes in poorly responsive disease.

In ovarian cancer, ATNM-400 monotherapy produced durable antitumor activity, including in bevacizumab-refractory tumors. These findings support its potential as a standalone treatment in recurrent disease, with further evaluation of ATNM-400 alone and in combination with standard-of-care therapies extending this development strategy.

"These findings build a compelling preclinical foundation for ATNM-400's pan-cancer potential and our vision to expand targeted radiotherapy across major solid tumor indications," said Sandesh Seth, Actinium's Chairman and CEO. "The high prevalence of ATNM-400's target in NSCLC, coupled with activity in KRAS- and ALK-driven models that builds on our earlier EGFR-mutant findings, supports the potential to reach a broad lung cancer population regardless of oncogenic mutation. Encouraging results in colorectal and treatment-resistant ovarian cancer models further extend this opportunity into areas of significant unmet need. Together, these data support our strategy to develop ATNM-400 as both a standalone therapy and a combination partner for established treatments, with the potential to address multiple large patient populations."

ATNM-400 EANM 2026 Presentation Details

Abstract Title: ATNM-400 Elicits Durable Anti-tumor Responses in KRAS- and ALK-Driven NSCLC Models in a Mutation-Agnostic Manner
Abstract Number: EPS-149
Presentation Type: Oral presentation
Session: 1109 — Translational Imaging and Therapy
Session Date & Time: Monday, October 19, 2026, 4:45–6:15 p.m. CEST | Vienna, Austria
Location: Hall G2

Abstract Title: ATNM-400, a First-in-Class Actinium-225 Radioconjugate Improves Response to Standard-of-Care Therapeutics in Colorectal Cancer Models
Abstract Number: EP-0163
Presentation Type: e-Poster

Abstract Title: ATNM-400, a First-in-Class Actinium-225 Radioconjugate Triggers Durable Antitumor Responses in Ovarian Cancer Models
Abstract Number: EP-0176
Presentation Type: e-Poster

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.

FAQ

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What did Actinium's ATNM-400 studies at EANM 2026 show?

Preclinical studies showed ATNM-400 antitumor activity in lung, colorectal and ovarian cancer models. Lung and colorectal studies also showed enhanced activity with established treatments. Ovarian models showed durable activity with ATNM-400 alone, including in tumors resistant to bevacizumab.

What was distinctive about the colorectal cancer model used to test ATNM-400 combinations?

The HCT15 model had moderate target expression and limited response to bevacizumab plus oxaliplatin. Adding ATNM-400 enhanced activity in this model.