Efficacy and safety of 40 mg osimertinib administered every other day for non‐small cell lung cancer harboring an epidermal growth factor receptor mutation: A single‐center retrospective cohort study

Abstract Osimertinib is a first‐line or adjuvant therapy for non‐small cell lung cancer (NSCLC) harboring an epidermal growth factor receptor (EGFR) mutation. However, owing to the adverse events associated with treatment, certain patients cannot maintain a daily regimen of 80 or 40 mg. In this study, we examined the efficacy of 40 mg of osimertinib administered every other day. In this single‐center, retrospective study, we evaluated patients with NSCLC harboring an EGFR mutation in whom treatment was initiated with 40 mg osimertinib every other day at our institution between May 2016 and June 2023. The major outcome was the duration of administering 40 mg osimertinib every other day. Six patients with NSCLC were evaluated. The median duration of 40 mg osimertinib intake every other day was 12.6 months. Four of the six patients weighed below 50 kg, and four experienced weight loss. Additionally, four of the six patients had severe renal impairment upon receiving 40 mg osimertinib every other day. Thus, our findings suggest the efficacy of administering 40 mg osimertinib every other day in patients with low bodyweight, weight loss, or severe renal impairment.