ERBB2 and breast cancer: Furthermore, the phase III DESTINY-Breast02 study that compared T-DXd to treatment of physician choice in patients with HER2-positive metastatic BC who have received prior T-DM1, confirmed the greater efficacy of T-DXd also in later lines of treatment, with a median PFS of 17.8 months compared to 6.9 months with standard of care (HR 0.36, 95% CI 0.28–0.45).