Actinium Pharmaceuticals

ATNM

Market cap $43.1M

Presentation to include new data in triple-negative disease, a breast cancer subtype with poor outcomes and limited viable treatment options ATNM-400 overcomes HER2 therapy resistance and represents a novel targeted radiotherapy with the potential to avoid off-target toxicities including ILD that constrains other therapeutic modalities such as antibody drug conjugates ATNM-400 has demonstrated the potential to overcome resistance to first-line tamoxifen endocrine therapy Data to be presented on December 11, 2025 at 5:00 PM CT NEW YORK , Dec. 1, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM), a leader in the development of differentiated targeted radiotherapies, today announced compelling preclinical data for ATNM-400, a first-in-class Actinium-225 (AC-225) antibody radioconjugate, in hormone receptor positive (HR+), HER2 positive (HER2+) and triple-negative breast cancer (TNBC) that will be presented at the San Antonio Breast Cancer Symposium (SABCS) being held December 10‑14, 2025 in San Antonio, Texas. The data demonstrates significant anti-tumor activity in breast cancer models resistant to standard-of-care therapies including endocrine therapy tamoxifen and HER2-targeted therapy trastuzumab (Herceptin, Roche) as well as potent tumor growth inhibition in TNBC models.

Vancouver, Kelowna, and Delta, British Columbia--(Newsfile Corp. - November 17, 2025) - Investorideas.com, a go-to investing platform covering biotech and pharma stocks issues a snapshot looking at the radiotherapy cancer market, featuring Actinium Pharmaceuticals, Inc. (NYSE American: ATNM), a pioneer in the development of differentiated, targeted radiotherapies intended to meaningfully improve outcomes for patients with advanced cancers. Actinium is deploying its technologies, capabilities and intellectual property with approximately 250 issued and pending patents worldwide, to develop next-generation radiotherapies focused on solid tumors, hematology and conditioning for cellular therapies.

-  ATNM-400 exhibits superior efficacy with 3-5x greater tumor growth inhibition compared to front line therapy osimertinib (EGFR TKI TAGRISSO®), second line therapy Dato-DXd (Trop-2 ADC DATROWAY®) and third line therapy amivantamab (EGFR-cMET bispecific RYBREVANT®) -  Combination of ATNM-400 and osimertinib resulted in complete tumor regression in 100% of tumor bearing animals; synergistic mechanism supported by increased ATNM-400 target antigen expression after EGFR inhibition with osimertinib -  Improved progression free survival has been demonstrated clinically with the combination of osimertinib and external beam radiotherapy providing strong rationale for a combination with targeted alpha-therapy -  Data validates the multi-tumor potential of ATNM-400 in multiple disease and treatment settings that support several blockbuster drugs NEW YORK , Oct. 27, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of differentiated targeted radiotherapies, today announced the presentation of the first ever preclinical data of ATNM-400 in non-small cell lung cancer (NSCLC). ATNM-400 a novel, multi-indication first-in-class antibody radioconjugate armed with the potent alpha-emitter Actinium-225 (Ac-225) is Actinium's lead solid tumor program, which is also being studied in prostate cancer.

- ATNM-400 targets a novel, non-PSMA antigen implicated in disease biology withcontinued expression following androgen receptor pathway inhibitor (ARPI) therapy and 177Lu-PSMA-617 therapy, enabling potent activity independent of PSMA expression - ATNM-400 demonstrated superior efficacy over PSMA-targeted radioligand therapy(177Lu-PSMA-617 and 225Ac-PSMA-617) with enhanced tumor control and prolonged survival in low-PSMA and treatment-resistant models - Demonstrated durable anti-tumor responses, exceeding those achieved with the ARPI enzalutamide - Combination of ATNM-400 with enzalutamide achieved complete tumor regressionin 40% of prostate cancer-bearing animals, demonstrating strong mechanistic synergy with AR pathway inhibition NEW YORK , Oct. 24, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of differentiated targeted radiotherapies, today highlighted new preclinical data for ATNM-400, its novel, first-in-class antibody radioconjugate armed with the potent alpha-emitter Actinium-225 (Ac-225) at the 32nd Annual Prostate Cancer Foundation (PCF) Scientific Retreat being held October 23 – 25, 2025 in Carlsbad, CA.  ATNM-400, which targets a non-PSMA antigen associated with prostate cancer progression and treatment resistance, demonstrated superior tumor control and improved overall survival compared with the active agents in key standard-of-care therapies including enzalutamide (the active agent in Xtandi®, Astellas/Pfizer) and 177Lu-PSMA-617 (the active agent in Pluvicto®, Novartis), as well as 225Ac-PSMA-617 across multiple preclinical prostate cancer models.

ATNM-400 is advancing as a first-in-class, multi-tumor Actinium-225 radiotherapy candidate with activity across prostate and lung cancers, two of the largest cancer indications globally New preclinical findings demonstrate ATNM-400 overcomes resistance to the EGFR inhibitor osimertinib in EGFR-mutated NSCLC, addressing a major unmet clinical need NEW YORK , Oct. 13, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM), a leader in the development of differentiated targeted radiotherapies, today announced that the first-ever preclinical data from its ATNM-400 program in non-small cell lung cancer (NSCLC) has been accepted for presentation at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics being held October 22 – 26, 2025, at the Hynes Convention Center in Boston, Massachusetts. ATNM-400 is a highly innovative, first-in-class, Actinium-225 (Ac-225) antibody radioconjugate with preclinical data in both prostate cancer and NSCLC.

-   ATNM-400 targets a highly differentiated, non-PSMA antigen associated with the development and progression of prostate cancer, exhibiting potent therapeutic activity independent of PSMA expression levels -   Extended follow-up in prostate cancer models demonstrated durable anti-tumor responses with ATNM-400, exceeding those achieved with the androgen receptor pathway inhibitor (ARPI), enzalutamide NEW YORK , Oct. 13, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of differentiated targeted radiotherapies, today announced that compelling preclinical data for ATNM-400, its novel, first-in-class antibody radioconjugate armed with the potent alpha-emitter Actinium-225 (Ac-225), has been accepted for presentation at the 32nd Annual Prostate Cancer Foundation (PCF) Scientific Retreat being held on October 23 – 25, 2025 in Carlsbad, CA. The presentation will highlight ATNM-400's ability to induce robust, durable anti-tumor activity in metastatic castration-resistant prostate cancer (mCRPC) models, including tumors resistant to standard-of-care therapies such as the androgen receptor pathway inhibitor (ARPI), enzalutamide (Xtandi®, Astellas/Pfizer) and the PSMA-targeted therapy, 177Lu-PSMA-617 (active agent in Pluvicto®, Novartis) as well as superior efficacy compared to 225Ac-PSMA-617.

Here is how Actinium Pharmaceuticals (ATNM) and Avadel (AVDL) have performed compared to their sector so far this year.

-     ATNM-400 demonstrates robust efficacy in prostate cancer tumor models with acquired resistance to Pluvicto ® and enzalutamide, follow-up continues -     ATNM-400 significantly improved survival compared to the approved prostate cancer treatment Pluvicto ®, the first blockbuster radiotherapy -     In combination with enzalutamide, an approved ARPI therapy, ATNM-400 produced enhanced efficacy with 40% of prostate cancer tumor-bearing animals achieving complete cures NEW YORK , July 31, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, today reported additional preclinical data supporting its ATNM-400 radiotherapy prostate cancer candidate at the 4th Annual Targeted Radiopharmaceuticals Summit (TRP) being held July 29 – 31, 2025 in San Diego, CA. ATNM-400 is a novel, first-in-class targeted radiotherapy designed to deliver potent Actinium-225 (Ac-225), an alpha-emitter radioisotope, to prostate cancer cells by targeting a non-Prostate Specific Membrane Antigen (PSMA), disease-driving protein overexpressed in advanced and treatment-resistant disease.

-  ATNM-400 shows; superior prostate cancer cell killing compared to androgen receptor inhibitor Xtandi® (enzalutamide), the ability to overcome Xtandi resistance, and activity in combination -  ATNM-400 is more efficacious than both Pluvicto® (177-Lu-PSMA-617) and Ac-225-PSMA-617 targeted radiotherapy in prostate cancer in vitro and in vivo models and overcome resistance in prostate cancer tumors that failed Pluvicto® therapy -  ATNM-400's target is highly differentiated from PSMA as it is implicated in disease biology, contributing to disease progression, faster progression to castration resistance and poorer survival outcomes with target expression reported following androgen receptor inhibitor and PSMA radiotherapy -  Data further supports ATNM-400's potential to address critical gaps in prostate cancer treatment as a monotherapy or in sequence with other therapeutic modalities NEW YORK , June 23, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, today reported new preclinical data from its first-in-class, non-PSMA targeting radiotherapy prostate cancer candidate ATNM-400, that leverages the potent alpha-particle emitter Actinium-225 (Ac-225) isotope, at the Society of Nuclear Medicine & Molecular Imaging (SNMMI) annual meeting being held June 21 st – 24th, 2025, in New Orleans, Louisiana. The data presented at SNMMI showed ATNM-400 has superior potency compared Xtandi® (enzalutamide) and is highly efficacious in Xtandi® resistant prostate models.

NEW YORK , June 10, 2025 /PRNewswire/ -- Kuehn Law, PLLC, a shareholder litigation law firm, is investigating whether certain officers and directors of Actinium Pharmaceuticals, Inc. (NYSE: ATNM)  breached their fiduciary duties to shareholders.  According to a federal securities lawsuit, Insiders at Actinium Pharmaceuticals caused the company to misrepresent or fail to disclose that (1) the Company's data from the Sierra Trial was unlikely to satisfy the FDA's guidelines for the acceptance and approval of Iomab-B BLA; (2) the additional analyses, including long-term follow-ups that purportedly demonstrated a trend towards improved Overall Survival that the Company provided to the FDA in an attempt to mitigate Sierra's poor OS data were unlikely to satisfy the FDA's guidelines for the acceptance and approval of Iomab-B BLA; (3) as a result, the FDA would likely refuse to review the Iomab-B BLA or, if it did consider that BLA, that the application in its current form was unlikely to be approved; and (4), as a result, positive statements about the Company's business, operations, and prospects were materially misleading and/or lacked a reasonable basis.