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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

Key Takeaway: Actinium Pharmaceuticals presented promising preclinical data for ATNM-400 at the 32nd Annual Prostate Cancer Foundation Scientific Retreat. This first-in-class radiotherapy targets a novel antigen and demonstrated superior efficacy compared to PSMA-targeted therapies. Notably, ATNM-400 achieved complete tumor regression in a significant percentage of animal models, showcasing its potential in treating resistant prostate cancer.
Price reaction · baseline $1.58 (2025-10-24T13:29:00.000Z) · hit during market hours · 1 other ATNM headline(s) in the window, move may be shared
day 0 close
+5.7%
day 1
-3.2%
day 3 · peak
-7.6%

Market Sentiment Analysis

POSITIVE FACTORS

  • ATNM-400 shows superior efficacy over existing therapies.
  • Demonstrated durable anti-tumor responses exceeding enzalutamide.
  • Achieved complete tumor regression in 40% of tested models.

BiopharmaWatch Analysis

From our catalyst data and publicly available data · not financial advice
Cash runway
~21 mo
Low dilution risk
Lead asset
131I-apamistamab
Phase 3 · Acute Leukemia

Full Press Release Details

- ATNM-400 targets a novel, non-PSMA antigen implicated in disease biology withcontinued expression following androgen receptor pathway inhibitor (ARPI) therapyand 177Lu-PSMA-617 therapy, enabling potent activity independent of PSMAexpression
- ATNM-400 demonstrated superior efficacy over PSMA-targeted radioligand therapy(177Lu-PSMA-617 and 225Ac-PSMA-617) with enhanced tumor control andprolonged survival in low-PSMA and treatment-resistant models
- Demonstrated durable anti-tumor responses, exceeding those achieved withthe ARPI enzalutamide
- Combination of ATNM-400 with enzalutamide achieved complete tumor regressionin 40% of prostate cancer-bearing animals, demonstrating strong mechanisticsynergy with AR pathway inhibition

NEW YORK,Oct. 24, 2025/PRNewswire/ --Actinium Pharmaceuticals, Inc.(NYSE AMERICAN: ATNM) (Actinium or the Company), a pioneer in the development of differentiated targeted radiotherapies, today highlighted new preclinical data for ATNM-400, its novel, first-in-class antibody radioconjugate armed with the potent alpha-emitter Actinium-225 (Ac-225) at the 32ndAnnual Prostate Cancer Foundation (PCF) Scientific Retreat being held October 23 – 25, 2025 in Carlsbad, CA.

Frequently Asked Questions

What is ATNM-400?

ATNM-400 is a first-in-class antibody radioconjugate using Actinium-225 for targeted radiotherapy.

How does ATNM-400 compare to PSMA-targeted therapies?

ATNM-400 demonstrated superior efficacy and enhanced tumor control over PSMA-targeted therapies.

What were the results of combining ATNM-400 with enzalutamide?

The combination achieved complete tumor regression in 40% of prostate cancer-bearing animals.

Where was the data on ATNM-400 presented?

The data was presented at the 32nd Annual Prostate Cancer Foundation Scientific Retreat.

Last updated: Oct 24, 2025