In the phase III DESTINY-Breast03 clinical trial, T-DXd conferred a significant improvement in progression-free survival (PFS), ORR and intracranial response rate compared with T-DM1 in 82 patients with HER2-positive breast cancer and stable brain metastases at baseline; the overall intracranial response rate was 63.8% for T-DXd compared with 33.3% for T-DM1 with the percentage of patients who achieved a complete intracranial response being 27.8% and 2.8%, respectively [14]. Here, ERBB2 is linked to breast cancer.