In an open-label phase II study, pyrotinib plus capecitabine had significantly longer progression-free survival (PFS) (18.1 months vs. 7.0 months, P<0.001) and higher objective response rate (ORR) (78.5% vs. 57.1%, P<0.05) than lapatinib plus capecitabine in patients with HER2-positive breast cancer (13). Here, ERBB2 is linked to breast cancer.