#USA #New York #Prostate Cancer #Actinium Pharmaceuticals #ATNM-400

Groundbreaking Advances in Prostate Cancer Treatment

At the 32nd Annual Prostate Cancer Foundation (PCF) Scientific Retreat taking place from October 23 to 25, 2025, Actinium Pharmaceuticals, Inc. (NYSE: ATNM), a pioneer in targeted radiotherapies, revealed significant preclinical results for ATNM-400. This innovative treatment approach utilizes Actinium-225, a potent alpha-emitter, aimed at combating prostate cancer resistance by targeting a novel non-PSMA antigen. Unlike traditional therapies that rely on PSMA expression, ATNM-400 offers a new mechanism that allows for effective treatment even in patients who have low or undetectable PSMA levels.

Unparalleled Efficacy and Durability

The preclinical studies established that ATNM-400 exhibited superior efficacy compared to standard treatments like enzalutamide (Xtandi®) and various PSMA-targeted therapies. In particular, models resistant to enzalutamide showed five times more durable anti-tumor effects when treated with ATNM-400. In fact, complete tumor regression was witnessed in 40% of animal subjects when combining ATNM-400 with enzalutamide, highlighting its synergistic potential with existing androgen receptor pathway inhibitors (ARPI).

Moreover, studies involving 22Rv1 prostate cancer models, known for their resistance to 177Lu-PSMA-617, demonstrated that ATNM-400 not only improved overall survival rates but also ensured enduring therapeutic activity independently of PSMA expression levels. This is crucial, given that approximately 25-30% of mCRPC patients exhibit low or no PSMA expression, leaving them vulnerable with few remaining treatment options.

Addressing Prostate Cancer Challenges

Patients progressing to metastatic castration-resistant prostate cancer (mCRPC) face significant hurdles, and conventional therapies often fall short. By developing ATNM-400, Actinium aims to fill this critical gap in treatment options. The novel radiotherapy is designed to remain effective irrespective of a patient's PSMA levels, marking a transformative potential in a field dominated by PSMA-dependent therapies.

Expert Commentary on ATNM-400

Sandesh Seth, Chairman and CEO of Actinium Pharmaceuticals, emphasized the growing excitement around ATNM-400’s prospects, especially regarding its unique PSMA-independent targeting mechanism. He noted, "The combined precision of antibody targeting and the unmatched potency of Ac-225 highlights ATNM-400's potential to redefine treatment protocols for mCRPC patients."

This innovative therapy is not only being advanced for prostate cancer but is also being explored in treating non-small cell lung cancer (NSCLC). Early data suggest that ATNM-400 can even overcome resistance to the EGFR TKI osimertinib (TAGRISSO®), which is critical as lung cancer remains a leading cause of cancer fatalities in the U.S.

Future of ATNM-400

Moving forward, Actinium plans to leverage ATNM-400 in various therapeutic contexts, including:

• - Monotherapy for early-stage disease prior to using PSMA-targeted treatments.
• - Combination therapies with existing ARPIs to enhance treatment responses.
• - Sequential therapies for patients who relapse after PSMA-targeted or ARPI treatments.

In conclusion, the promising findings presented at the PCF Scientific Retreat underline ATNM-400’s potential to navigate around existing resistance mechanisms in prostate and potentially lung cancer. As the oncology landscape evolves, therapies like ATNM-400 that offer new paths forward are essential for improving patient outcomes in these challenging diseases.