A new FLT3 inhibitor with two cases: the gilteritinib experience.

Introduction: In acute myeloid leukemia (AML), a heterogeneous group of leukemias, there are various factors to determine prognosis. Among these prognostic factors, cytogenetic results are increasing in importance day by day. FLT3 mutations are among the most common molecular abnormalities in AML, patients with recurrent or refractory (R/R) AML with this mutation have a low response rate to salvage therapy. Gilteritinib has activity against FLT3, ALK and AXL. This article shall present two cases, for which Gilteritinib was used, a new FLT3 inhibitor, and the results of the treatment. Case 1: A 52-year-old female patient presented to the emergency clinic with weakness and fever. In initial biochemical analysis, leukocyte was 104000/mm³. Peripheral smear contained diffuse myeloid blastoid cells, peripheral blood flow cytometry also supported the AML M0-1 phenotype. The bone marrow biopsy aspiration performed on the 14^th day of induction "3+7" treatment, contained diffuse blastic infiltrate and supported refractory disease. In addition to the FLAG-IDA salvage regimen, 120 mg/day Gilteritinib was also started. Bone marrow aspiration performed on the 28^th day of salvage therapy was compatible with remission. Case 2: 53 years old male patient with also no comorbidity other than known hypertension. In the initial biochemical analysis of the patient, leukocyte was 156000/mm³, platelet 58000/mm³ and hemoglobin 7.6 g/dl. Peripheral blood flow cytometry supported the AML M5 phenotype, whose peripheral smear showed diffuse monoblastoid cells. On the 14^th day of the patient's 3+7 induction treatment, the control bone marrow aspiration showed diffuse blast infiltration and was considered refractory, FLAG-IDA salvage therapy with again 120 mg/day Gilteritinib per oral were started. On the 28^th day, control bone marrow aspiration was evaluated as remission.

Discussion and conclusion: Unlike other FLT 3 inhibitors, Gilteritinib has been shown to be a highly effective agent in R/R AML with FLT3 mutations. Being the first data to be reported from Turkey, we think it would be quite guiding the titular.