ERBB2 and breast cancer: Results of the final overall survival analysis showed that tucatinib plus trastuzumab and capecitabine significantly prolonged OS, both in all 291 patients with brain metastases (21.6 vs. 12.5 months) and in 174 patients with active brain metastases (21.4 vs. 11.8 months) [56], which provides convincing evidence for the use of TKIs in patients with HER2‐positive breast cancer and brain metastases.