A randomized, multicenter, 2-arm, open-label phase 2 trial comparing RC48 (2.0 mg/kg Q2W) with capecitabine plus lapatinib in trastuzumab pretreated patients with advanced HER2-positive breast cancer is currently recruiting in Chinese trial centers (clinicaltrials.gov identifier: NCT02881138). This evidence concerns the gene ERBB2 and breast cancer.