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

Core Insights - Actinium Pharmaceuticals has presented promising preclinical results for ATNM-400, a novel targeted radiotherapy for prostate cancer, indicating its potential as a transformative treatment option for patients with unmet clinical needs following Pluvicto therapy [1][7] Group 1: Efficacy and Mechanism - ATNM-400 demonstrated a 99.8% tumor growth inhibition with a single 40 µCi/kg dose in prostate cancer models, outperforming Pluvicto [1][6] - In vivo studies showed a statistically significant (p < 0.0001) reduction in tumor volume in 22Rv1 prostate cancer models, highlighting its transformative therapeutic potential [2][5] - The drug exhibited robust antitumor activity in mice with Pluvicto-resistant tumors, administered 14 days post-Pluvicto treatment [3][6] Group 2: Targeting and Safety - ATNM-400 targets a distinct non-PSMA receptor that is highly expressed in metastatic castration-resistant prostate cancer (mCRPC), maintaining expression levels even after Pluvicto treatment [4][7] - The Ac-225 isotope used in ATNM-400 is more potent than Lu-177, capable of causing lethal double-stranded DNA breaks, and has a shorter path length, potentially resulting in fewer off-target effects [4][10] - ATNM-400 was well tolerated in studies, showing no apparent toxicities and efficient clearance from essential organs [10] Group 3: Market Context and Future Outlook - Pluvicto, marketed by Novartis, generated sales of $1.39 billion in 2024, indicating a significant market for prostate cancer therapies [1] - The company anticipates increased demand for therapies addressing patients who progress after Pluvicto, especially following its recent approval in earlier treatment settings [7] - Actinium is committed to advancing ATNM-400's development, with additional data expected later this year [7]