The use of trastuzumab and pertuzumab in HER2-positive breast cancer is well-supported by the CLEOPATRA study, which demonstrated that dual-targeted therapy with trastuzumab and pertuzumab, in combination with chemotherapy, significantly improved progression-free survival (PFS) and overall survival (OS) in patients with HER2-positive breast cancer (7). The gene discussed is ERBB2; the disease is breast cancer.