Actinium Pharmaceuticals, Inc.

HER3‑targeted PET imaging demonstrated tumor uptake and retention, supporting ATNM‑400's potential to deliver sustained alpha radiation to tumors over a timeframe consistent with Actinium‑225's 10-day half‑life Initial three‑patient cohort completed the first dose level of 1.0 µCi/kg with no dose‑limiting toxicities, xerostomia or Grade 3/4 hematologic adverse events observed ATNM‑400 advanced to the second dose level of 1.5 µCi/kg, marking continued clinical progress for a first‑in‑class Actinium‑225 antibody radiotherapy with potential across the broad mCRPC population NEW YORK, Oct. 20, 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 encouraging initial clinical results from the first‑in‑human Phase 1 study of ATNM‑400 in metastatic castration‑resistant prostate cancer (mCRPC). The findings, presented in an oral presentation on October 19 at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM) in Vienna, Austria, showed a favorable initial safety profile at the first dose level and tumor uptake and retention with the HER3‑targeted imaging agent.

ATNM-400 demonstrated activity across EGFR-, KRAS- and ALK-driven lung cancer models, supporting mutation-agnostic development as monotherapy and in combination with established treatments In colorectal cancer, adding ATNM-400 to standard therapy increased tumor growth inhibition to 72% from 25% for oxaliplatin and bevacizumab in a poorly responsive model with moderate target expression In ovarian cancer, ATNM-400 achieved 93% tumor growth inhibition as monotherapy and retained activity following bevacizumab failure Three presentations expand the preclinical foundation for ATNM-400 as a potential pan-tumor treatment, complementing ongoing clinical development in prostate cancer NEW YORK, Oct. 20, 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 new preclinical results demonstrating the broad antitumor potential of ATNM-400 across non-small cell lung cancer (NSCLC), colorectal cancer and ovarian cancer models. The findings were presented in an oral presentation and two e-posters at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM), October 17–21, 2026, in Vienna, Austria.

First-in-human Phase 1 presentation to feature ATNM-400 clinical data in metastatic castration-resistant prostate cancer, advancing a differentiated approach beyond PSMA Preclinical presentation to feature ATNM-400 studies in KRAS- and ALK-driven non-small cell lung cancer, exploring its potential across molecular subtypes ATNM-400's HER3-targeted alpha radiotherapy approach offers pan-cancer potential, with development as a monotherapy and in combination with established treatments across multiple solid tumors NEW YORK, Oct. 19, 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 reminded investors and the scientific community that clinical and preclinical data for ATNM-400 will be presented today at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM), being held October 17–21, 2026, in Vienna, Austria. The clinical oral presentation will feature early data from the ongoing first-in-human Phase 1 dose-escalation study of ATNM-400 in metastatic castration-resistant prostate cancer (mCRPC).

NEW YORK, Oct. 16, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) ("Actinium" or the "Company"), a pioneer in the development of targeted radiotherapies, today announced inducement equity awards to Matt David, M.D., the Company's newly appointed Chief Financial Officer, and Sean Maenpaa, the Company's newly appointed Senior Vice President, Business Development.

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.

– Brings more than 20 years of oncology business development and commercial leadership, including senior roles across the radiopharmaceutical sector at Bayer, Clovis Oncology, Telix Pharmaceuticals and BWXT Medical – Will lead partnering, licensing and strategic transactions across Actinium's targeted radiotherapy pipeline NEW YORK, Oct. 16, 2026 /PRNewswire/ -- Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) ("Actinium" or the "Company"), a pioneer in the development of targeted radiotherapies, today announced the appointment of Sean Maenpaa as Senior Vice President, Business Development, effective October 12, 2026. Mr. Maenpaa will lead the Company's business development activities, including out-licensing, partnering and collaboration transactions, in-licensing opportunities, and broader corporate development strategy.