Successful Alternate-day Osimertinib Administration with Desensitization Following Osimertinib-induced Hepatotoxicity and Neutropenia in a Case of EGFR-mutant Lung Cancer

Osimertinib is widely used in cases of non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) gene mutations, including Thr790 Met mutations. We herein report a case of successful desensitization therapy combined with alternate-day dosing after osimertinib-induced hepatotoxicity and neutropenia. A 67-year-old woman with recurrent EGFR-mutated NSCLC after surgery discontinued osimertinib due to hepatotoxicity. Following disease progression and detection of the Thr790 Met mutation after afatinib treatment, desensitization therapy with osimertinib was initiated at 0.1 mg/day. Grade 3 neutropenia developed during dose escalation. However, alternate-day dosing enabled continuation and escalation to the standard dose. Alternate-day dosing may mitigate adverse events during dose escalation.