Trastuzumab deruxtecan has proven outstanding efficacy in both HER2 positive and HER2 low breast cancers in the metastatic setting [21,23] and is tested in the adjuvant and neoadjuvant setting (DESTINY-Breast05, NCT04622319; DESTINY-Breast11, NCT05113251; ADAPTHER-IV, NCT05704829; NCT04553770; SHAMROCK, NCT05710666; EXTEND, NCT06548178). Here, ERBB2 is linked to breast carcinoma.