Based on results from the phase 2 HER2CLIMB trial (19), the FDA approved tucatinib for use with trastuzumab and capecitabine in patients with unresectable or metastatic HER2+ BC, including those with brain metastases, who have been pretreated with at least 1 prior HER2-directed regimen in the metastatic setting (20). The gene discussed is ERBB2; the disease is breast cancer.