The current invention refers to a monoclonal antibody or the anti-virus part of the alliance, which blocks carbon tetrachloride alliance 4 to B7. He also mentioned a nucleic acid molecule, an expression vector, a hospitera cell, a preparation method, a toolkit and a pharmacosynthesis. This antibody is useful in the treatment of cancer, such as prostate cancer, bladder cancer, rectal cancer and so on.La 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
