Provided are methods and compositions, for treating prostate cancer by administering to a patient in need thereof a therapeutically effective amount of a PARP inhibitor, e.g., niraparib; a therapeutically effective amount of a CYP17 inhibitor, e.g., abiraterone acetate, and a therapeutically effective amount of a glucocorticoid, e.g., prednisone.Se proporcionan metodos y composiciones para tratar el cancer de prostata al administrar a un paciente en necesidad de este una cantidad terapeuticamente eficaz de un inhibidor de PARP, p. ej., niraparib; una cantidad terapeuticamente eficaz de un inhibidor de CYP17, p. ej., acetato de abiraterona, y una cantidad terapeuticamente eficaz de un glucocorticoide, p. ej., prednisona.