The approval of pertuzumab in the front-line treatment of advanced HER2+ breast cancer was established in the phase III CLEOPATRA trial which randomized approximately 800 women to either pertuzumab, trastuzumab, and docetaxel (THP) vs. placebo, trastuzumab, and docetaxel (TH) [20]. This evidence concerns the gene ERBB2 and breast cancer.