Successful oral desensitization with osimertinib following osimertinib-induced fever and hepatotoxicity: a case report

Osimertinib is a standard second-line therapy for patients who develop EGFR Thr790Met resistance mutation after treatment with first-line epidermal growth factor receptor tyrosine kinase inhibitors. Although no other effective targeted treatment option exists for these patients, osimertinib might be permanently discontinued owing to the onset of severe drug-induced toxicities like hepatotoxicity. Herein, we report a case of successful oral desensitization with osimertinib after the patient developed osimertinib-induced fever and hepatotoxicity. In the present case report, a 62-year-old Japanese woman received osimertinib as the sixth-line therapy for non-small cell lung carcinoma harboring EGFR Thr790Met-mutation. After 15days of treatment, she developed general malaise. Although we reduced the drug at a lower dose, she again presented with high fever and elevated serum AST/ALT levels three days after re-initiating treatment. We then attempted oral desensitization with osimertinib over a two-week period. Thereafter, the patient continued osimertinib treatment for 6months without the recurrence of side effects. In conclusion, oral desensitization may be a useful method in treating hepatotoxicity and drug fever caused by osimertinib.