⁸⁹Zr-barecetamab-DFO

⁸⁹Zr-barecetamab-DFO (also known as 89Zr-ATNM-400) is an investigational, zirconium-89-labeled antibody radioconjugate developed by Actinium Pharmaceuticals. It serves as a diagnostic companion imaging agent (theranostic partner) to the therapeutic Actinium-225-labeled radioconjugate ATNM-400 (²²⁵Ac-barecetamab-DOTA). The agent consists of the fully human monoclonal antibody barecetamab (formerly ISU104), which targets human epidermal growth factor receptor 3 (HER3/ErbB3), conjugated to the chelator deferoxamine (DFO) and radiolabeled with the positron-emitting isotope zirconium-89 (⁸⁹Zr). ⁸⁹Zr-barecetamab-DFO is utilized in positron emission tomography (PET) imaging to visualize tumor uptake, assess biodistribution, and perform dosimetry, helping to select patients and optimize dosing for the therapeutic counterpart in solid tumors, including metastatic castration-resistant prostate cancer (mCRPC), non-small cell lung cancer (NSCLC), breast cancer, colorectal cancer, pancreatic cancer, and ovarian cancer.