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The Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) news page on Stock Titan aggregates company announcements, scientific conference updates and regulatory disclosures related to its Actinium-225 targeted radiotherapy programs. Actinium regularly issues press releases detailing preclinical and clinical data, corporate events and participation in oncology meetings, offering investors and observers insight into the evolution of its pipeline.
Recent news has focused heavily on ATNM-400, the company’s first-in-class, multi-indication Ac-225 antibody radioconjugate. Actinium has reported preclinical data for ATNM-400 in metastatic castration-resistant prostate cancer, non-small cell lung cancer (NSCLC) and breast cancer, including models resistant to standard-of-care therapies such as enzalutamide, 177Lu-PSMA-617, osimertinib, tamoxifen and trastuzumab. Releases describe superior tumor growth inhibition versus several approved agents, durable tumor control, and synergistic effects when ATNM-400 is combined with ARPIs or EGFR inhibitors.
News items also cover Actimab-A, a CD33-targeting Ac-225 therapeutic for acute myeloid leukemia, including its planned pivotal Phase 2/3 trial and a Cooperative Research and Development Agreement with the National Cancer Institute. Additional updates describe Iomab-ACT and Iomab-B in conditioning for bone marrow transplant and cell or gene therapies, as well as Actinium’s broader research efforts in solid tumors.
Visitors to this page can review earnings‑independent scientific updates, conference abstracts and corporate communications that outline Actinium’s development strategy, preclinical results and governance milestones such as annual meeting outcomes. For anyone tracking ATNM as an oncology development story, this news feed provides a centralized view of how the company portrays progress across its Ac‑225 radiotherapy platform.
Actinium Pharmaceuticals (NYSE: ATNM) presented preclinical AACR 2026 data showing ATNM-400, an Ac-225 radioconjugate, with pan-tumor activity in prostate, EGFR-mutant lung, and HER2+ breast cancer models.
Data show efficacy in low/negative PSMA prostate models, superior activity versus several approved ADCs and targeted agents, durable control post-treatment in breast models, and no in vivo toxicities at therapeutic doses.
Actinium (NYSE:ATNM) presented AACR 2026 data showing that Actimab-A (lintuzumab-Ac225) drives mutation-agnostic anti-leukemic activity via transcriptional reprogramming, shifting AML cells from proliferation toward differentiation and apoptosis. Combinations with revumenib, gilteritinib, and azacitidine enhanced in vivo killing across models and primary patient samples, independent of FLT3, NPM1, KMT2A, IDH1/2, or TP53 status. Prior clinical work in >150 AML patients showed a manageable safety profile and supports Actimab-A as a universal combination backbone across AML treatment settings.
Actinium Pharmaceuticals (NYSE: ATNM) announced two AACR 2026 abstracts to be presented April 21, 2026, highlighting new preclinical data for ATNM-400 and a differentiated mechanism for Actimab-A. ATNM-400 shows pan-tumor Ac-225 radioconjugate activity; Actimab-A shows mutation-agnostic transcriptional reprogramming that may enhance AML therapy response. Posters: ATNM-400 #5824 and Actimab-A #5827 in session Radiopharmaceutical Platforms for Theranostic Precision Oncology, April 21, 2:00–5:00 PM PT, Poster Section 16.
Actinium Pharmaceuticals (NYSE American: ATNM) will present two abstracts at the AACR Annual Meeting 2026 in San Diego on April 21, 2026, within the Experimental and Molecular Therapeutics category.
Abstract details (titles and full text) will be publicly available March 17, 2026 at 4:30 PM ET via the AACR Online Program Planner. Presentations focus on ATNM-400 and Actimab-A programs and radiopharmaceutical theranostic platforms using Ac-225.
Actinium Pharmaceuticals (NYSE: ATNM) presented preclinical data for ATNM-400, an Actinium-225 antibody radioconjugate, at SABCS 2025 showing potent anti-tumor activity across HR+, TNBC, and tamoxifen- and trastuzumab-resistant breast cancer models.
Key findings include significant tumor-growth inhibition in HR+ and TNBC models, increased target expression and enhanced cytotoxicity in treatment-resistant models, combination-induced tumor regression in a trastuzumab-resistant model, sustained tumor uptake through 144 hours, and rapid clearance from normal organs suggesting a differentiated tolerability profile.
Actinium Pharmaceuticals (NYSE: ATNM) will present preclinical data for ATNM-400, a first-in-class Actinium-225 antibody radioconjugate, showing potent anti-tumor activity in triple-negative breast cancer (TNBC) and efficacy in models resistant to tamoxifen and trastuzumab. Data include tumor growth inhibition exceeding 100% at higher doses, elevated target expression in resistant lines, combination activity with standard agents, and a favorable tolerability profile in xenograft models. The program also showed activity in metastatic castrate-resistant prostate cancer and non-small cell lung cancer. The presentation is scheduled for December 11, 2025 at 5:00 PM CT at the San Antonio Breast Cancer Symposium.
Actinium Pharmaceuticals (NYSE: ATNM) is prioritizing ATNM-400, an Ac-225 alpha-emitter pan-tumor candidate, alongside clinical assets Actimab-A and Iomab-ACT as it targets the growing targeted radiotherapy market. Actinium lists ~250 issued and pending patents and reports preclinical data showing ATNM-400 produced superior tumor control versus 177Lu-PSMA-617 and achieved 40% complete tumor regressions in combination with enzalutamide in animal models. The company disclosed a competitive and regulatory backdrop including a Novartis objection letter (Aug 2025) and noted market context where RLT is estimated at $25–$30B and Pluvicto sales reached about $1.4B in early 2025.
Actinium Pharmaceuticals (NYSE:ATNM) announced that preclinical data for its lead Ac-225 antibody radioconjugate ATNM-400 will be presented at the 2025 San Antonio Breast Cancer Symposium on Dec 11, 2025 (Poster PS4-04-26).
Data show anti-tumor activity of ATNM-400 in tamoxifen- and trastuzumab-resistant breast cancer models and confirm efficacy signals across prostate cancer and NSCLC, including durable tumor control beyond 100 days, complete regressions in combination models (prostate 40%, NSCLC 100%), and synergy with enzalutamide and osimertinib. The company frames ATNM-400 as a multi-indication candidate targeting major oncology markets.
Actinium Pharmaceuticals (NYSE American: ATNM) announced that Sandesh Seth, Chairman and CEO will participate in the Stephens Biotechnology Virtual Fireside Chat on November 4, 2025 from 10:30–11:20 am ET. Company management will be available for one-on-one investor meetings during the virtual event. Investors or advisors seeking to join meetings or request more information should contact their Stephens representative.
Actinium (NYSE AMERICAN: ATNM) on Oct 27, 2025 announced preclinical ATNM-400 NSCLC data showing 3–5x greater tumor growth inhibition versus frontline osimertinib, second-line Dato-DXd and third-line amivantamab in EGFR‑mutant models. Combination with osimertinib produced 100% complete tumor regression in treated animals, with synergy linked to increased ATNM-400 target antigen expression after EGFR inhibition. The release frames ATNM-400 as a first‑in‑class Ac‑225 antibody radioconjugate with potential across first–third line settings and cites ~$7B 2024 sales for approved EGFR‑mutant therapies (osimertinib $6.6B) to illustrate market opportunity.