Actinium Pharmaceuticals (NYSE American: ATNM) has announced compelling preclinical data for ATNM-400, a first-in-class Actinium-225 (AC-225) antibody radioconjugate, in hormone receptor positive (HR+), HER2 positive (HER2+) and triple-negative breast cancer (TNBC) that will be presented at the San Antonio Breast Cancer Symposium (SABCS) on December 11, 2025, in San Antonio, Texas.
According to Actinium, the data demonstrate significant anti-tumor activity in breast cancer models resistant to standard-of-care therapies including endocrine therapy tamoxifen and HER2-targeted therapy trastuzumab as well as potent tumor growth inhibition in TNBC models.
The data highlight ATNM-400’s potential to address critical unmet needs in patients who have exhausted treatment options following endocrine therapy or HER2-targeted therapy failure. These data add to ATNM-400’s robust preclinical data package that also encompasses metastatic castrate-resistant prostate cancer (mCRPC) and non-small cell lung cancer (NSCLC).
