ERBB2 and breast cancer: In phase 2, the DESTINY‐Breast01 trial explored the efficacy of T‐DXd for advanced HER2‐positive breast cancer patients who were heavily pre‐treated and already received T‐DM1; the median PFS was 16.4 months, with 60.9% of patients responding; interstitial lung disease needed extra attention and was observed in 13.6% of the patients.134