Amivantamab-VMJM

- 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 - ATNM-400 demonstrates efficacy across prostate cancer, non-small cell lung cancer (NSCLC), and breast cancer - three of the largest oncology indications - with potential as monotherapy, in combination, or as an alternative therapy NEW YORK, Nov. 4, 2025 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) ("Actinium" or the "Company"), a leader in the development of differentiated targeted radiotherapies, announced today that new preclinical data for its lead antibody radioconjugate program, ATNM‑400, will be presented at the 2025 San Antonio Breast Cancer Symposium (SABCS) taking place December 10‑14, 2025 in San Antonio, Texas. Title: Anti‑tumor activity of ATNM‑400, a first‑in‑class Actinium‑225 antibody radioconjugate, in tamoxifen and trastuzumab resistant breast cancer models Abstract Number: 2069 Presentation Number: PS4‑04‑26 Date/Time: Thursday, December 11, 2025, 5:00 PM–6:30 PM CT Session: Poster Session 4 The ATNM-400 data presentation at SABCS follows prostate cancer data presentations at the American Association for Cancer Research (AACR) annual meeting and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) annual meeting, NSCLC data was presented at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics, from which key findings are summarized below. ATNM ‑ 400: Program and Multi-Indication Opportunity Overview ATNM-400 is a first-in-class antibody-radioconjugate powered by Actinium-225 (Ac-225), designed to deliver potent alpha-particle radiation directly to tumor cells. The therapy's high linear energy transfer (LET) enables precise tumor cell killing with minimal off-target exposure, while its target - a disease-driving protein linked to resistance and poor prognosis - is overexpressed across multiple solid tumors, including prostate, lung, and breast cancers. Preclinical studies show ATNM-400 delivers best-in-class efficacy, overcomes resistance to, and synergizes with, standard-of-care therapies, supporting broad development as a monotherapy, combination, or treatment alternative across multiple solid tumors. Prostate Cancer Data Highlights Superior efficacy and durability vs 177Lu-PSMA-617 (active agent in Pluvicto®), 225Ac-PSMA-617, and ARPI enzalutamide (active agent in Xtandi®), with durable tumor control beyond 100 days. Improved overall survival compared to 177Lu-PSMA-617 and enzalutamide. Overcomes resistance to these standard-of-care agents, showing sustained tumor control and survival benefit in 177Lu-PSMA-617 and enzalutamide resistant prostate cancer models. Synergy with ARPI therapy as the ATNM-400 target is upregulated after enzalutamide; combination achieved complete tumor regression in 40% of animals. PSMA-independent activity enables treatment of patient populations not eligible for or progressing on 177Lu-PSMA-617. NSCLC Data Highlights 3–5x greater tumor growth inhibition vs. front-line osimertinib (Tagrisso®, AstraZeneca) and EGFR tyrosine kinase inhibitor (TKI), second-line Dato-DXd (Datroway®, AstraZeneca/Daiichi Sankyo) a Trop-2 ADC, and third-line amivantamab (Rybrevant®, Johnson & Johnson) an EGFR-cMET bispecific. Combined 2024 sales of these agents exceeded $7B. Target upregulation following EGFR inhibition; ATNM-400 + osimertinib achieved complete tumor regression in 100% of tumor-bearing animals demonstrating synergy of the combination. Clinical rationale for combination supported by a study that showed EBRT or external-beam radiotherapy + osimertinib improved PFS to 32.2 months vs. 20 months with osimertinib alone (Sampath et al.1, Lancet eClinicalMedicine, 2025). ATNM-400 has the potential to deliver precision targeted, powerful alpha radiation via Ac-225 which on a per-cell basis is ~4–8x more biologically lethal than diffuse, low-energy EBRT beams. Clinically, this may translate to higher response rates, lower toxicity, and entry into previously untreatable market segments when osimertinib is combined with EBRT. ATNM-400 Data Afford Development Opportunities in High-Value, Unmet Need Indications The data package for ATNM‑400 across breast cancer, prostate cancer and NSCLC underscores Actinium's intention to demonstrate the potential for this radiotherapy candidate to address unmet needs in high‑value cancer segments. Data from preclinical studies thus far show ATNM-400 delivers best-in-class efficacy, overcomes resistance to, and synergizes with, standard-of-care therapies, supporting broad development as a monotherapy, combination, or treatment alternative across solid tumors. Key development opportunities based on the data include: Breast Cancer: Potential in hormone‑resistant (tamoxifen) and HER2‑resistant (trastuzumab) patients, which represents a significant therapeutic opportunity with the HER2-targeted therapy Herceptin® (Roche and biosimilars) generating approximately $4.0 billion in sales in 2024. Prostate Cancer: Broad use potential as a monotherapy, combination, or follow-on to ARPIs and PSMA radioligands; opportunity in the $10 billion ARPI market and Pluvicto non-responders or relapses who on balance might be expected to outnumber the patients treated with Pluvicto which generated $1.7 billion in revenue over the last twelve months. Non-Small Cell lung Cancer: Superior anti-tumor activity compared to the leading first, second and third-Line approved EGFR mutant therapies that generated sales of over $7.0 billion in 2024 and mechanistic synergy with first-line therapy osimertinib, which accounted for approximately $6.6 billion in sales in 2024. Sandesh Seth, Chairman and CEO of Actinium Pharmaceuticals, commented, "We're excited to present ATNM-400's breast cancer data at SABCS which expands our demonstration of its potential across multiple solid tumors. The strong single-agent efficacy of ATNM-400 and its ability to overcome resistance when coupled with enzalutamide (Xtandi®) in prostate cancer and osimertinib (TAGRISSO®) in lung cancer showcases Actinium's capability for innovation by exploiting the power of a radiotherapeutic directed to a target linked to resistance and poor prognosis. We believe that this program has the potential to meaningfully improve outcomes for patients with difficult-to-treat cancers and look forward to the data at SABCS". About ATNM-400 ATNM-400 is a highly innovative, first-in-class, and multi-indication Actinium-225 (Ac-225) targeted radiotherapy candidate in development for prostate cancer, non-small cell lung cancer (NSCLC) and breast cancer. ATNM-400 is highly differentiated in prostate cancer as it targets a distinct non-PSMA protein strongly implicated in prostate cancer disease biology including progression and treatment resistance. Unlike 177Lu-PSMA-617, the active agent in Pluvicto® and the majority of radiotherapies under development, which rely on PSMA targeting, ATNM-400 is designed to maintain efficacy in low-PSMA or high-PSMA resistant disease, a major unmet clinical need as up to 30% of patients do not respond to PSMA radioligand therapies and up to 60% of patients have at least one PSMA-negative tumor lesion. Ac-225 delivers high-linear-energy-transfer alpha particles that induce irreparable double-strand DNA breaks, offering superior potency over beta emitters like Lutetium-177 (177Lu), and has a shorter tissue path length that may reduce off-target toxicity. The receptor specifically targeted by ATNM-400 continues to be expressed at a high level even after androgen receptor inhibitor (ARPI) and ATNM-400 has shown to overcome resistance to the ARPI therapy enzalutamide and work synergistically in combination with enhanced tumor control including complete tumor regression. In NSCLC, ATNM-400 has shown superior efficacy compared to approved first, second- and third-line EGFR therapies including small molecules, antibody drug conjugates and bispecific antibodies that is synergistic with osimertinib, an EGFR tyrosine kinase inhibitor (TKI) that is a standard of care therapy approved for treatment of patients in the frontline setting and is also able to overcome osimertinib resistance. Prostate cancer is the most commonly diagnosed cancer in men, with ~1.5 million new cases globally and over 313,000 expected in the U.S. in 2025. While early-stage disease is typically managed with surgery, radiation, and ARPI therapy, up to 20% of cases progress to mCRPC - a lethal stage with limited treatment options. Targeted radiotherapy is a growing field in prostate cancer, dominated by PSMA-targeting agents like Pluvicto®, which had sales of over $1.3 billion in 2024, yet up to 30% of patients either lack or have no PSMA expression and virtually all patients develop resistance to Pluvicto® within 1-year. In the U.S., 40,000–60,000 mCRPC patients annually progress after ARPI therapy with approximately 35% of patients progressing within 1-year. As a class, ARPI therapies had sales of over $10.0 billion in 2024 including enzalutamide (Xtandi®) that led the class with sales of over $5.9 billion in 2024, highlighting a significant unmet need. Lung cancer is the leading cause of cancer deaths and there are there are over 200,000 new cases expected in the U.S. in 2025 and over 2 million cases globally. NSCLC accounts for approximately 85% of all lung cancer cases. EGFR targeting therapies including front-line osimertinib (Tagrisso®, AstraZeneca) an EGFR tyrosine kinase inhibitor (TKI), second-line Dato-DXd (Datroway®, AstraZeneca/Daiichi Sankyo) a Trop-2 ADC, and third-line amivantamab (Rybrevant®, Johnson & Johnson) an EGFR-cMET bispecific had sales of approximately $7 billion in 2024 with the EGFR TKI Osimertinib (TAGRISSO®, AstraZeneca) generating sales of $6.6 billion in 2024. Breast cancer is the most diagnosed cancer among woman in the United States with approximately 316,950 women expected to be diagnosed with the disease in 2025 according to the National Cancer institute. It is estimated that approximately 200,000 women are living with metastatic breast cancer in 2025, which is expected to grow to 250,000 in 2030. Of those diagnosed, hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer accounts for 70-75% of breast cancer, representing the largest subtype. In this setting, tamoxifen and trastuzumab (Herceptin®, Roche and biosimilars) generated sales of approximately $4.0 billion in 2024. Across prostate cancer, NSCLC and breast cancer, ATNM-400 has demonstrated treatment paradigm changing potential in these indications, which have over 800,000 new cases in the U.S. alone. About Actinium Pharmaceuticals, Inc. Actinium is a pioneer in the development of targeted radiotherapies intended to meaningfully improve patient outcomes. ATNM-400, Actinium's lead product candidate, is a novel, first-in-class, and multi-indication Actinium-225 (Ac-225) in development for prostate cancer, non-small cell lung cancer (NSCLC) and breast cancer. The antigen specifically targeted by ATNM-400 is highly expressed in metastatic castration-resistant prostate cancer (mCRPC), contributes directly to disease progression, poorer survival outcomes, and continues to be expressed at a high level even after androgen receptor inhibitor (ARPI) and Pluvicto® treatment. ATNM-400 is supported by preclinical data demonstrating tumor-specific uptake, higher efficacy than androgen receptor inhibitor enzalutamide (Xtandi®) and 177Lu-PSMA-617 radiotherapy, the active agent in Pluvicto®, durable tumor control and potent efficacy in prostate cancer models resistant to both enzalutamide and 177Lu-PSMA-617. In addition, ATNM-400 has demonstrated synergy with enzalutamide. In NSCLC, ATNM-400 showed superior efficacy to EGFR targeting therapies including osimertinib (TARGRISSO®, AstraZeneca), Dato-DXd (DATROWAY®, AstraZeneca/Daiichi Sankyo) and amivantamab (RYBREVANT®, J&J) with synergistic activity in combination with osimertinib. In breast cancer, Actinium has been studied in hormone and HER-2 resistant settings with data to be presented at the San Antonio Breast Cancer Symposium in December 2025. The data generated to date with ATNM-400 supports its potential across treatment settings to be used either as a monotherapy, or in combination or sequenced with other therapies. Actinium's most advanced product candidate in development is Actimab-A, a CD33 targeting therapeutic, that is a potential backbone therapy for acute myeloid leukemia (AML) and other myeloid malignancies leveraging the mutation agnostic alpha-emitter radioisotope payload Actinium-225 (Ac-225). Actimab-A has demonstrated potential activity in relapsed and refractory acute myeloid leukemia (r/r AML) patients in combination with the chemotherapy CLAG-M including high rates of Complete Remissions (CR) and measurable residual disease (MRD) negativity leading to improved survival outcomes and is being advanced to a pivotal Phase 2/3 trial. In addition, Actinium is engaged with the National Cancer Institute (NCI) under a Cooperative Research and Development Agreement (CRADA) for development of Actimab-A in AML and other myeloid malignancies. The first clinical trial under the CRADA will evaluate the triplet combination comprised of Actimab-A, Venetoclax (Abbvie/Roche) an oral Bcl-2 inhibitor and ASTX-727 (Taiho Oncology, an Otsuka holdings company) a novel oral hypomethylating agent (HMA) in frontline acute myeloid leukemia (AML) patients. Additionally, Actinium is developing Actimab-A as a potential pan tumor therapy in combination with PD-1 checkpoint inhibitors including KEYTRUDA® and OPDIVO® by depleting myeloid derived suppressor cells (MDSCs), which represents a potential multi-billion-dollar addressable market. Iomab-ACT, Actinium's next generation conditioning candidate, is being developed with the goal of improving patient access and outcomes for potentially curative cell and gene therapies. Iomab-B is an induction and conditioning agent prior to bone marrow transplant in patients with r/r AML, which Actinium is seeking a potential strategic partner for the U.S. In addition, the company's R&D efforts are primarily focused on advancing several preclinical programs for solid tumor indications. Actinium holds approximately 240 patents and patent applications including several patents related to the manufacture of the isotope Ac-225 in a cyclotron. For more information, please visit: Sources: Sampath et al. Osimertinib plus consolidative radiotherapy for advanced EGFR mutant non-small cell lung cancer: a multicenter, single-arm, phase 2 trial. The Lancet eClinicalMedicine, Volume 87, 103435. (25)00367-0/fulltext. 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. 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iStock, Denis_prof The company cut back in areas while investing in internal and external opportunities to offset the loss of exclusivity on a product that, until recently, accounted for 20% of innovative medicine sales. Johnson & Johnson has made a molehill out of a mountain. Facing the loss of exclusivity on a drug that accounted for 20% of innovative medicine sales in 2023, J&J has reshaped its business around other products and programs to leave analysts predicting a new era of growth for the company. The anticipated arrival of biosimilar versions of Stelara, J&J’s blockbuster autoimmune disease drug, has occupied analysts for years. J&J executives have fielded questions about their preparations since at least 2021, reflecting how important the anti-IL-12 and IL-23 antibody became to the company after sales of chronic inflammatory disease drug Remicade began to erode in the face of off-patent rivals. Stelara sales peaked at $10.9 billion in 2023. Biosimilar competition, first overseas and later in the U.S., caused sales to slip in 2024 and tumble further in 2025. Yet while sales of the drug fell 40% over the first nine months of 2025, J&J still grew global innovative medicine revenue by 5%. BioSpace , Annalee Armstrong Cutting and Investing The growth reflects J&J’s multi-year effort to adapt its business for a post-Stelara future. Some parts of the business have been sacrificed to enable investment in the most promising programs. In 2023, J&J axed clinical-phase programs targeting hepatitis B, HIV and respiratory syncytial virus and ended R&D at an infectious disease and vaccine site in the Netherlands. J&J CFO Joseph Wolk framed the infectious disease and vaccine changes in the context of Stelara at a Bernstein event in May; The company “probably had to cut some investment” to prepare for the entry of Stelara biosimilars, he said. J&J’s medtech business provides sales to offset slowdowns at the medicines unit but the company nonetheless had to pull back from some areas. “We still make choices. You saw last year we exited infectious diseases and vaccines. We still prioritize, but it gives us a lot more flexibility to manage for that long term and have the robust pipeline and the growth outlook we have for the balance of this decade,” Wolk said. As J&J pulled back from infectious diseases and vaccines, it invested in other areas to ensure new growth drivers were in place to ease the Stelara transition. At J&J’s immunology unit, rising sales of Tremfya and Simponi are partly offsetting the decline of Stelara and the development of icotrokinra , JNJ-4804 and nipocalimab are laying the groundwork for a potential new-look portfolio. All three assets are in development for multiple indications, from plaque psoriasis to ulcerative colitis to psoriatic arthritis. The emergence of oncology as J&J’s tentpole business has allowed the company to weather a period of falling immunology sales. Five years ago, J&J reported nine-month oncology revenue of $8.9 billion. Oncology sales for the first nine months of 2025 were $18.5 billion. The growth reflects the blossoming of multiple myeloma drug Darzalex, plus product launches. Darzalex was a blockbuster in 2020, generating sales of $2.9 billion in just the first nine months of the year. It has grown significantly since then. The growth covers a period in which J&J launched a subcutaneous version of Darzalex and expanded the label. Sales hit $10.4 billion over the first nine months of 2025. J&J has also turned its prostate cancer drug Erleada, which was approved in 2019, into a multi-billion dollar a year product. The CAR T cell therapy Carvykti became J&J’s latest cancer blockbuster in the third quarter of 2025, when total sales for the year reached $1.3 billion. With sales of the bispecific antibodies Tecvayli, Talvey and Rybrevant still rising, and the bladder cancer drug Inlexzo new to the market, J&J is aiming to grow oncology revenues to $50 billion by 2030. The forecast was at least three times above the 2028 analyst consensus estimate when the company made the prediction in July, partly reflecting J&J’s belief that annual Inlexzo sales will exceed $5 billion. Guggenheim Securities analysts recently discussed Inlexzo’s prospects with a community urologist. J&J could face competition from CG Oncology’s oncolytic immunotherapy cretostimogene grenadenorepvec. The urologist told the analysts that the ability to keep Inlexzo at room temperature, the lack of biohazard requirements and the option to administer the drug at the office give J&J an advantage. “The speaker emphasized that in his community practice setting, practical convenience and logistical advantages would be the main determinants in choosing between the two products,” the analysts wrote in a note to investors. “As such, he envisions using Inlexzo in the large majority of his patients when both products are available in the future.” Deals Drive Growth Speaking on an earnings call in October, J&J CEO Joaquin Duato called Inlexzo an example of the company’s “outstanding business development model.” J&J acquired the asset through its 2019 takeover of Taris Biomedical. Wolk said on the earnings call that the company paid “a couple of hundred million dollars” for Taris, which was then in early clinical development. Duato said J&J has completed “more than 60 deals of this kind” in the past 18 months. J&J has struck the early-stage deals alongside bigger bets such as its $14.6 billion takeover of Intra-Cellular Therapies. The deal added the schizophrenia and bipolar depression drug Caplyta to J&J’s neuroscience portfolio. Caplyta generated $240 million in the third quarter, helping J&J grow neuroscience revenues despite sales of Concerta and Invega falling. Spravato is the other key product in J&J’s neuroscience portfolio. Sales grew more than 50% to near $1.2 billion over the first nine months of 2025. The drugs have established neuroscience as J&J’s third biggest innovative medicine unit after oncology and immunology. J&J’s pulmonary hypertension and cardiovascular units also have blockbuster drugs, giving the company a broad base to offset future challenges. The nature of the pharma industry means new challenges are inevitable. J&J is now receiving questions about potential price negotiations and patent expirations for Darzalex. Guggenheim analysts said they believe investors are “underappreciating Darzalex’s increased longevity and potentially improved economics,” but at some point J&J will need to adapt to pressure on its latest star drug. Having navigated the launches of Remicade and Stelara biosimilars over the past decade, the company has established a track record of managing such pressures and continuing to grow.