Randomized, Double‐blind, Phase 3 Study of Tucatinib or Placebo in Combination With Ado‐trastuzumab Emtansine (T‐DM1) for Subjects With Unresectable Locally advanced or Metastatic HER2+ Breast Cancer (HER2CLIMB‐02). This evidence concerns the gene ERBB2 and breast carcinoma.