Trastuzumab deruxtecan is a new type of drug called an antibody-drug conjugate that is used to treat advanced breast cancer that overexpresses the HER2 receptor.[1] When combined with pertuzumab, it shows better efficacy in both early and advanced stages of HER2-positive breast cancer.[2] In phase III clinical trials (DESTINY Breast 03), trastuzumab deruxtecan demonstrated impressive results, including higher response rates (70% vs. 29%) and increased progression-free time (29.0 months vs. 7.2 months) compared with standard therapy.[5] The drug is given intravenously at a dose of 5.4 mg/kg every three weeks, often in combination with pertuzumab 420 mg.[4][5] The most common side effects are gastrointestinal and hematological, while an increased frequency of interstitial lung disease has also been observed, but is usually manageable with corticosteroids.[1] This preparation represents a promising new treatment option and may change the approach to the treatment of HER2-positive metastatic breast cancer.[1]