Profile of Trastuzumab Deruxtecan in the Management of Patients with HER2-Positive Unresectable or Metastatic Breast Cancer: An Evidence-Based Review

Trastuzumab deruxtecan is a novel antibody–drug conjugate for the treatment of advanced solid tumors, including breast cancer, which overexpress or have amplification of the human epidermal growth factor receptor 2 (HER2). The novel structure of this exciting new agent means that it can deliver a highly potent cytotoxic agent to HER2-expressing tissues resulting in selective killing of cancer cells. In phase I and II trials, trastuzumab deruxtecan has shown impressive response rates in heavily pretreated populations, including patients who had received prior treatment with trastuzumab emtansine, another highly active antibody–drug conjugate. The most common side effects are gastrointestinal and hematological. Importantly, a high rate of interstitial lung disease was seen in early trials, but this appears manageable in most patients with corticosteroids. In light of its efficacy, this promising new drug may change the treatment paradigm of HER2-positive breast cancer.