In total, 524 patients with HER2-positive advanced BC were randomized, and the primary endpoint of PFS was significantly improved with T-DXd compared to T-DM1 [PFS by BICR, HR 0.2840, 95% CI 0.2165 to 0.3727, P = 7.8 × 10−22(two-sided)], median PFS was not reached for T-DXd and was 6.8 months for T-DM1. This evidence concerns the gene ERBB2 and breast cancer.