The study of Tucatinib vs. Placebo in Combination With Capecitabine and Trastuzumab in Patients With Advanced HER2 + Breast Cancer (HER2CLIMB trial)5, showed a benefit in terms of progression-free survival (PFS) and OS in patients who received tucatinib in combination with trastuzumab and capecitabine. This evidence concerns the gene ERBB2 and breast carcinoma.