[Successful treatment with gilteritinib for relapsed acute myeloid leukemia with FLT3-N676K mutation].

The patient was a 68-year-old woman, diagnosed with acute myelomonocytic leukemia with normal karyotype and FLT3-ITD-negative status in May 2019. She had achieved complete remission (CR) after "7+3" intensive induction chemotherapy and maintained CR by consolidation chemotherapy. However, she relapsed with swelling of the lips and gums in January 2020. She did not achieve CR by salvage chemotherapy with cytarabine-aclarubicin-G-CSF regimen. Comprehensive genomic analysis of leukemic cells revealed the presence of FLT3-N676K mutation, which was undetectable by companion diagnostics at the time. Complete remission with incomplete count recovery was obtained on day 28 after initiation of gilteritinib monotherapy, and the lip and gum swelling improved rapidly. However, she relapsed on day 106 after gilteritinib administration, and gilteritinib was discontinued. Genomic analysis at recurrence revealed NRAS mutation for the first time. Finally, the patient died of the uncontrolled primary disease. This is a case in which comprehensive gene mutation analysis was useful in determining a treatment strategy.