ATNM-400 / Actinium - LARVOL DELTA

Anti-tumor activity of ATNM-400, a first-in-class Actinium-225 antibody radioconjugate, in tamoxifen and trastuzumab resistant breast cancer models (SABCS 2025) - "Abstract is embargoed at this time."

Preclinical • Breast Cancer • Oncology • Solid Tumor

ATNM-400, a first-in-class Actinium-225 antibody radioconjugate, demonstrates potent anti-tumor activity and overcomes resistance to enzalutamide and 177Lu-PSMA-617 in prostate cancer models (PCF 2025) - "We hypothesized that ATNM-400 would provide superior efficacy compared to current options and overcome resistance to AR inhibitors (enzalutamide) and PSMA-directed radioligands (177Lu-PSMA-617 or 225Ac-PSMA-617). ATNM-400 showed robust and durable anti-tumor efficacy and a favorable safety profile in preclinical PCa models. These findings support ATNM-400 as a next-generation Actinium-225 therapy - with potential as 1) Monotherapy in CRPC (pre-177Lu-PSMA-617), 2) Combination therapy with AR pathway inhibitors, or 3) Sequential therapy after ARPI or 177Lu-PSMA-617 failure. ATNM-400 holds promise to address critical gaps in mCRPC treatment landscape."

Preclinical • Castration-Resistant Prostate Cancer • Genito-urinary Cancer • Oncology • Prostate Cancer • Solid Tumor • FOLH1

Actinium Pharmaceuticals, Inc. to Highlight ATNM-400 Data in Hormone-Resistant and HER2-Resistant Breast Cancer at the 2025 San Antonio Breast Cancer Symposium, Expanding Pan-Tumor Profile Across Three Solid Tumor Indications (PRNewswire) - "New preclinical data to show anti-tumor activity of ATNM-400 in hormone-resistant and HER2-resistant breast cancer, addressing the need for new treatment options beyond tamoxifen and trastuzumab."

Preclinical • HER2 Breast Cancer • Hormone Receptor Breast Cancer

Actinium Announces Superior Anti-Tumor Activity of ATNM-400 in Lung Cancer Compared to the Leading First, Second and Third-Line Approved EGFR Mutant Therapies and Mechanistic Synergy with Osimertinib at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics (Actinium Pharmaceuticals Press Release) - "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."

Preclinical • Non Small Cell Lung Cancer

ATNM-400, a first-in-class Actinium-225 antibody radioconjugate, demonstrates potent anti-tumor activity and overcomes osimertinib resistance in lung cancer models (AACR-NCI-EORTC 2025) - "ATNM-400 shows strong anti-tumor efficacy and favorable tolerability across multiple LC subtypes, including Osi resistant models. These findings support further development of ATNM-400 as a novel therapeutic approach for LC patients with limited options following TKI therapy failure- both as monotherapy and in rational combination regimens or post-resistance to TKI."

Preclinical • Lung Cancer • Non Small Cell Lung Cancer • Oncology • Solid Tumor • CDKN2A • HER-2 • KRAS • TP53

Actinium Pharmaceuticals Presents New Data Demonstrating Potent and Durable Efficacy of ATNM-400, a First-in-Class Multi-Tumor Actinium-225 Radiotherapy, at the 32nd Annual Prostate Cancer Foundation Scientific Retreat (PRNewswire) - "ATNM-400 demonstrated superior and 5-times more durable anti-tumor efficacy extending to 100 days compared to approximately 20 days with enzalutamide alone...ATNM-400 overcame 177Lu-PSMA-617 resistance with approximately 5-times long tumor control and 2-times longer overall survival in tumor bearing animals...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; The expression of the ATNM-400 antigen target was not altered post-177Lu-PSMA-617; 22Rv1 cell lines are low-PSMA expressing and LNCaP cell lines are high-PSMA expressing."

Preclinical • Prostate Cancer

Actinium to Present ATNM-400 Preclinical Data Highlighting Durable Tumor Control and Ability to Overcome Resistance to Standard-of-Care Prostate Cancer Therapies at the 32nd Annual Prostate Cancer Foundation Scientific Retreat (PRNewswire)

Preclinical • Castration-Resistant Prostate Cancer

Actinium Pharmaceuticals to Unveil the Multi-Tumor Potential of ATNM-400, a First-in-Class Actinium-225 Radiotherapy, with Data in Non-Small Cell Lung Cancer at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics (PRNewswire) - "Preclinical data to be presented at AACR-NCI-EORTC conference demonstrate that ATNM-400 exerts potent anti-tumor activity in EGFR-mutant NSCLC models and is capable of overcoming resistance to osimertinib and is furthermore synergistic in combination osimertinib."

Preclinical • Non Small Cell Lung Cancer

Actinium Presents Data Supporting Paradigm Changing Potential of ATNM-400 in Prostate Cancer Demonstrating Its Superior Efficacy and Improved Survival in Treatment Resistant Tumor Models versus Pluvicto and ARPI Therapy, and Also Enhanced Efficacy in Combination with ARPI Therapy at the 4th Annual Targeted Radiopharmaceuticals Summit (PRNewswire) - "Unlike PSMA-targeted agents that primarily serve as imaging and targeting tools, the ATNM-400 target is directly implicated in tumor progression, survival signaling, and resistance to androgen receptor (AR) pathway inhibitor (ARPI) therapy...The ATNM-400 antibody showed sustained tumor uptake up to 216 hours with rapid clearance from normal tissues; ATNM-400 is more efficacious than Pluvicto (Lu-177-PSMA-617) with potent tumor control; ATNM-400 demonstrated significant in vitro tumor cell killing when used in combination with AR-targeting agents, such as enzalutamide...Actinium highlighted that follow-up continues to further evaluate the durability of ATNM-400's anti-tumor efficacy in prostate cancer with additional data expected in the second half of 2025."

Preclinical • Prostate Cancer

First-in-class Actinium-225 (Ac-225) antibody radioconjugate ATNM-400 exhibits potent anti-tumor activity in preclinical solid tumor models (SNMMI 2025) - "Pluvicto® (lutetium Lu 177 vipivotide tetraxetan) and Lutathera® (lutetium Lu 177 dotatate), both FDA-approved beta-emitting therapies, have demonstrated efficacy in metastatic prostate cancer and gastroenteropancreatic neuroendocrine tumors, respectively, highlighting the potential of TR in addressing unmet clinical needs. ATNM-400 demonstrated robust anti-tumor efficacy in multiple preclinical models of solid tumors, supporting its potential as a novel therapeutic option for patients with limited treatment options or resistant to current targeted therapies. These findings underscore the promise of ATNM-400 for clinical translation and its role in addressing unmet needs in cancer therapy."

Preclinical • Breast Cancer • Endocrine Cancer • Genito-urinary Cancer • Lung Cancer • Neuroendocrine Tumor • Oncology • Pancreatic Cancer • Prostate Cancer • Solid Tumor

First-in-class Actinium-225 (Ac-225) antibody radioconjugate ATNM-400 exhibits potent anti-tumor activity in preclinical solid tumor models (SNMMI 2025) - "Pluvicto® (lutetium Lu 177 vipivotide tetraxetan) and Lutathera® (lutetium Lu 177 dotatate), both FDA-approved beta-emitting therapies, have demonstrated efficacy in metastatic prostate cancer and gastroenteropancreatic neuroendocrine tumors, respectively, highlighting the potential of TR in addressing unmet clinical needs. ATNM-400 demonstrated robust anti-tumor efficacy in multiple preclinical models of solid tumors, supporting its potential as a novel therapeutic option for patients with limited treatment options or resistant to current targeted therapies. These findings underscore the promise of ATNM-400 for clinical translation and its role in addressing unmet needs in cancer therapy."

Preclinical • Breast Cancer • Endocrine Cancer • Genito-urinary Cancer • Lung Cancer • Neuroendocrine Tumor • Oncology • Pancreatic Cancer • Prostate Cancer • Solid Tumor

Actinium Highlights Expanded Data Set for ATNM-400 in Prostate Cancer Demonstrating Superior Efficacy to Enzalutamide and Ability to Overcome Resistance to ARPI Therapy and PSMA-Ac-225/Lu-177 Labelled Radiotherapy at the Society of Nuclear Medicine & Molecular Imaging Annual Meeting (PRNewswire) - "ATNM-400 shows consistent tumor uptake, rapid clearance from the blood and clearance from vital organs including intestines, liver, and kidneys...ATNM-400 exhibited potent killing of all Xtandi resistant prostate cancer cells that remained following treatment with Xtandi, with Xtandi only killing 50% of the resistant prostate cancer cells; ATNM-400 monotherapy and in combination with Xtandi had superior anti-tumor efficacy in vivo compared to Xtandi alone in a prostate cancer model; all treatments were well-tolerated with no change in body weight; ATNM-400 inhibited tumor growth of Xtandi resistant tumors whereas re-treatment with Pluvicto or additional enzalutamide did not....ATNM-400 was more potent than both Pluvicto (177Lu-PSMA-617) and 225Ac-PSMA-617 in prostate cancer cell killing."

Preclinical • Castration-Resistant Prostate Cancer • Prostate Cancer

Actinium Presents Data Showing ATNM-400 is More Efficacious than Pluvicto and is Highly Efficacious after Pluvicto Resistance in Prostate Cancer Tumor Models at the American Association for Cancer Research Annual Meeting (PRNewswire) - "In mice bearing Pluvicto-failed tumors, ATNM-400 was administered on day 14 following Pluvicto treatment, demonstrating robust antitumor activity and tumor growth inhibition in Pluvicto- resistant tumor models.; Expression of the target receptor for ATNM-400 persists following Pluvicto therapy and ATNM-400 demonstrates sustained tumor control after Pluvicto stops working; ATNM-400 demonstrated greater efficacy than Pluvicto in prostate cancer models with 99.8% tumor growth inhibition achieved with a single 40 µCi/kg dose of ATNM-400 supporting its potential to be offered as an alternative option; ATNM-400 internalizes rapidly, exhibiting potent cytotoxicity and prostate cancer cell killing via double strand DNA breaks that are produced by the Ac-225 alpha-particle emitting radionuclide payload of ATNM-400...'we look forward to validating the potential of this exciting radiotherapy candidate as we advance its development with additional data expected later this year.'"

Preclinical • Castration-Resistant Prostate Cancer • Prostate Cancer

ATNM-400 is a novel Actinium-225 antibody radioconjugate with strong efficacy in preclinical models of prostate cancer (AACR 2025) - "ATNM-400 showed strong anti-tumor efficacy and a favorable safety profile in preclinical PCa models. These results highlight ATNM-400's potential as a transformative therapeutic option for PCa patients with unmet clinical needs."

Preclinical • Castration-Resistant Prostate Cancer • Genito-urinary Cancer • Oncology • Prostate Cancer • Solid Tumor • FOLH1

Actinium Pharmaceuticals Provides Business Update After Presentation at Trump Mar-A-Lago Club Announcing Novel Non-PSMA Prostate Cancer Radiotherapy ATNM-400 and Outlining Revitalized Clinical Pipeline with 2025 Corporate Objectives (PRNewswire) - "Actinium Pharmaceuticals...provided a business update detailing recent achievements and anticipated milestones from its revitalized and expanding clinical pipeline. The update featured the unveiling of ATNM-400, Actinium's new Actinium-225 (Ac-225) solid tumor program, which is a novel, non-PSMA targeting, first-in-class radiotherapy for prostate cancer. Initial preclinical data from ATNM-400 will be presented at AACR on April 27, 2025....Pipeline Expansion into Prostate Cancer with ATNM-400, a first-in-class, non-PSMA targeting Ac-225 radiotherapy."

Preclinical • Prostate Cancer