The present Invention relates to a monoclonal antibody or Antigen binding Fragment of blocking CTLA4 Binding to B7. It also relates to a Nucleic Acid Molecule, AN EXPRESSION vector, host Cell, a method of preparing a Pharmaceutical Composition and a Kit.This Antibody is useful in the treatment of cancer such as prostate cancer, bladder cancer, colorectal cancer, among othersLa presente invencion se refiere a un anticuerpo monoclonal o fragmento de union a antigeno del mismo que bloquea la union de CTLA4 a B7. Tambien se refiere a una molecula de acido nucleico, un vector de expresion, una celula hospedera, un metodo de preparacion, un kit y una composicion farmaceutica. Dicho anticuerpo es util en el tratamiento del cancer tal como cancer de prostata, cancer de vejiga, cancer colorrectal, entre otros
