Besilesomab er et monoklonalt antistof, dvs. en proteintype, hvis form bevirker, at det genkender og binder sig til en bestemt struktur, der kaldes et antigen, og findes på visse celler i organismen.
Besilesomab is a monoclonal antibody (a type of protein that has been designed to recognise and bind to a specific structure called an antigen, that may be found on certain cells in the body).