Maintenance Treatment With Gilteritinib Suppresses Post-transplant Relapse in Relapse/Refractory FLT3-Mutated Acute...

The FLT3 inhibitor, gilteritinib, has been widely used in patients with relapsed or refractory (R/R) FLT3-mutated acute myeloid leukemia (AML). However, its tolerability and effectiveness after allogeneic hematopoietic stem cell transplantation (HSCT) are not well known outside of clinical trials. Therefore, we performed nationwide surveillance in Japan. We used data from the national registry for patients receiving transplants, including R/R FLT3-mutated AML patients treated with gilteritinib before and/or after HSCT. Post-HSCT administration dosage and safety were summarized, and outcomes, including relapse-free survival (RFS) were investigated. We also used the historical cohort of HSCT before the approval of gilteritinib. Among R/R FLT3-mutated AML patients, 120 were treated with gilteritinib before and/or after allo-HSCT, and maintenance treatment was performed in 55 patients. The median initiation day was Day 47 after allo-HSCT (range, 23-379), with a median starting dose of 80 mg (range, 40-120 mg). Serious adverse events leading to gilteritinib dose reduction or temporary discontinuation were observed in 52.7% of these cases. The 3-year RFS was 46.8% and patients treated with post-HSCT gilteritinib had significantly better RFS (58.8%) than those without it (36.4%) (P < .001). Survival data in the historical cohort were similar to that of those who did not resume gilteritinib. In the subgroup analysis, post-HSCT gilteritinib showed an RFS benefit in cord blood transplantation (79.4% vs. 26.1%, P < .001) but not in bone marrow or peripheral blood stem cell transplantation. This Japanese real-world study supports the tolerability and effectiveness of post-HSCT gilteritinib in R/R FLT3-mutated AML.