Trastuzumab deruxtecan (Specialist drug)

Do not substitute trastuzumab deruxtecan for or with trastuzumab or ado-trastuzumab emtansine. Duration: post-neoadjuvant HER2-positive early breast cancer — 14 cycles unless disease recurrence or unacceptable toxicity; metastatic breast cancer, HER2-mutant NSCLC and HER2-positive (IHC 3+) solid tumours — until disease progression or unacceptable toxicity. HER2-positive locally advanced or metastatic gastric cancer: 6.4 mg/kg every 3 weeks until disease progression or unacceptable toxicity. HER2-positive first-line metastatic breast cancer in combination with pertuzumab: Cycle 1 Day 1 — 5.4 mg/kg followed by pertuzumab 840 mg (given 30 minutes after); subsequent cycles Day 1 — 5.4 mg/kg followed by pertuzumab 420 mg every 3 weeks, until disease progression or unacceptable toxicity. HER2-positive early breast cancer neoadjuvant (in sequence): 5.4 mg/kg every 3 weeks for 4 cycles, followed by the THP regimen for 4 cycles (a taxane concurrent with trastuzumab 6 mg/kg every 3 weeks and pertuzumab, initial dose 840 mg then 420 mg every 3 weeks). Premedication: the product is highly emetogenic, including delayed nausea and/or vomiting — administer prophylactic antiemetics per local institutional guidelines. Slow or interrupt the infusion rate if infusion-related symptoms develop; permanently discontinue for severe infusion reactions. Management of adverse reactions (ILD, neutropenia, thrombocytopenia or left ventricular dysfunction) may require temporary interruption, dose reduction or discontinuation. A higher incidence of Grade 1 and 2 ILD/pneumonitis has been observed in patients with moderate renal impairment (no dose adjustment is stated in the fetched label text). Paediatric population: safety and effectiveness have not been established in paediatric patients. No UK SPC posology was available in the fetched bundle — this draft is from US labelling (Enhertu) and must be verified against the UK SPC.