Initial insights into the interaction of antibodies radiolabeled with Lutetium-177 and Actinium-225 with tumor microenvironment in experimental human and canine osteosarcoma.

Background: Osteosarcoma (OS) is a prevalent primary bone cancer affecting both humans and canines. This study describes initial insights into the interaction of the human monoclonal antibody IF3 to an insulin-like growth factor 2 receptor (IGF2R) radiolabeled with either alpha-emitting Actinium-225 (Ac) or beta-emitting Lutetium-177 (Lu) radionuclides with the OS cells and tumor microenvironment (TME) in experimental human and canine OS.

Basic Procedures: SCID mice bearing canine Gracie or human OS-33 OS tumors were treated with Lu- or Ac-labeled IF3 antibody, sacrificed at 24, 72 or 168 h post-treatment and their tumors were analyzed by immunohistochemistry (IHC) for the presence of OS cells, various elements of TME as well as for the double DNA strand breaks with γH2AX and caspase 3 assays.