Why Is Actinium Pharmaceuticals Stock Rising Today?

The Actinium-225 (Ac-225) antibody radioconjugate demonstrated strong anti-tumor activity across multiple breast cancer models.

Actinium Pharmaceuticals, Inc. (ATNM) stock was in the spotlight on Friday after the company announced promising new preclinical findings for its novel radiotherapy, ATNM-400, at the 2025 San Antonio Breast Cancer Symposium (SABCS). 

The Actinium-225 (Ac-225) antibody radioconjugate demonstrated strong anti-tumor activity across multiple breast cancer models, including hormone receptor–positive (HR+), triple-negative (TNBC), and treatment-resistant tumors.

ATNM-400’s Broad Potential

The company’s latest research shows ATNM-400 achieving substantial tumor-growth suppression with minimal side effects in preclinical studies. 

The therapy targets a validated antigen overexpressed in breast cancer and other solid tumors, such as Prostate Cancer and Non-Small Cell Lung Cancer (NSCLC), positioning ATNM-400 as a potential pan-tumor radiotherapy solution.

Following the update, Actinium’s stock traded over 3% higher in Friday’s premarket. 

Get updates to this developing story directly on Stocktwits.<