That targeted therapies against the same single molecular alteration can be effective across cancers, as shown, for instance, by the efficacy of anti-Her2 therapy in both gastric and breast cancers [7, 8] or the clinical benefit from inhibition of mutated cKIT in gastrointestinal stromal tumors (GIST) and melanoma or mastocytosis [9, 10]. This evidence concerns the gene ERBB2 and breast cancer.