The present disclosure relates to an antigen specific binding domain which binds to RON (Macrophage Stimulating Protein Receptor or Recepteur d'Origine Nantais). The disclosure also extends to chimeric antigen receptors (and a cell expressing the same), antibody molecules (including full length antibodies and fragments thereof, as well as antibody conjugates) containing the antigen binding domains disclosed herein. Also disclosed herein are pharmaceutical compositions comprising the cells, antibody molecules as disclosed herein. The present disclosure also refers to the use of the antigen binding domains, the chimeric antigen receptors, the antibody molecules and the pharmaceutical compositions disclosed herein in therapy, more particularly in treating cancer. Also disclosed herein are radiolabelled antibody conjugates comprising the antigen binding domains as disclosed, and their use in methods of treatment or diagnosis.