A recent real-world analysis evaluating T-DXd in HER2-positive breast cancer brain metastasis patients reported an intracranial objective response rate (iORR) of 59%, median intracranial progression-free survival (iPFS) of 15.6 months, and intracranial disease control rate (iDCR) of 94.9%, with a tolerable safety profile. The gene discussed is ERBB2; the disease is breast carcinoma.