-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

4989 Excellent Outcome Following Maintenance Therapy with Gilteritinib after Allogeneic Hematopoietic Stem Cell Transplantation for FLT3-Mutated Acute Myeloid Leukemia Even in Non-Remission Status

Program: Oral and Poster Abstracts
Session: 732. Allogeneic Transplantation: Disease Response and Comparative Treatment Studies: Poster III
Hematology Disease Topics & Pathways:
Research, Acute Myeloid Malignancies, AML, Diseases, Therapies, Myeloid Malignancies, Biological Processes, Technology and Procedures, Study Population, Human
Monday, December 11, 2023, 6:00 PM-8:00 PM

Aya Nishida, MD1*, Otoya Watanabe, MD1*, Daisuke Kaji, MD, PhD1*, Yuki Taya, MD, PhD1*, Shinsuke Takagi, MD, PhD1*, Hisashi Yamamoto, MD, PhD1*, Go Yamamoto, MD, PhD1*, Yuki Asano-Mori2, Atsushi Wake, MD, PhD3 and Naoyuki Uchida, MD, PhD1

1Department of Hematology, Toranomon Hospital, Tokyo, Japan
2Department of Transfusion Medicine, Toranomon Hospital, Tokyo, Japan
3Department of Hematology, Toranomon Hospital Kajigaya, Kanagawa, Japan

[Background] FMS-like tyrosine kinase 3 (FLT3) mutation has been shown to be a poor prognostic factor for recurrence and overall survival in AML. In recent years, various FLT3 inhibitors have been successively developed and reported to improve the prognosis of FLT3-mutated AML. However, relapse after allogeneic stem cell transplantation(allo-HSCT) remains high, and strategies to improve prognosis are desired. Clinical trials have been conducted using FLT3 inhibitors as maintenance therapy allo-HSCT to reduce the relapse rate and some efficacy has been reported, but real-world data on maintenance therapy with gilteritinib for FLT3-mutated AML after allo-HSCT are limited, especially after cord blood transplantation (CBT).

[Objective and method] To assess the efficacy, safety, clinical features and outcome of gilteritinib maintenance after allo-HSCT for FLT3-mutated AML, we retrospectively analyzed patients underwent allo-HSCT, most of which are CBT for FLT3-mutated AML from April 2019 to October 2022.

[Result] During the study period, 46 patients received allo-HSCT for FLT3-mutated AML in our institute. The median follow-up day of survivors was 649 (115-1149). The median age of the patients was 55 years (range, 20-75). Twenty-seven patients had de novo AML, 16 had AML with myelodysplasia related changes, and 3 had therapy related AML. One had favorable karyotype, 37 had intermediate, and 6 had adverse. Thirty-six patients received myeloablative pretransplant conditionings (MAC), and 10 received reduced intensity conditionings (RIC). All but 9 were in in non-remission at HSCT. The majority, 40, had used unrelated cord blood, 3 did unrelated bone marrow, 2 did unrelated peripheral blood, and 1 did related peripheral blood as grafts. Twenty-eight patients received gilteritinib maintenance therapy after HSCT, whereas 18 did not. Between the 2 groups, the patient characteristics, AML status, and HSCT procedures were well balanced. At 2 years after HSCT, overall survival (OS), disease free survival (DFS), relapse rate (RR), and non-relapse mortality (NRM) of whole studied population were 65.0%, 56.3%, 27.0%, and 21.1%, respectively. Patients with gilteritinib maintenance showed significantly superior OS and DFS to those without gilteritinib maintenance (2-year OS; 84.2% vs 35.7%, P = 0.0030, 2-year DFS; 71.4% vs 30.4%, P = 0.0036)(Figure 1A, 1B). RR and NRM tended to be lower in patients with gilteritinib maintenance than those without (2-year RR; 41.4% vs 18.1%, P = 0.1350, 2-year NRM; 34.4% vs 11.9%, P = 0.0548). Even if in non-remission status at HSCT, 23 patients with gilteritinib maintenance showed excellent outcome with 2-year OS 81.6%, DFS 70.9%, RR 21.2%, and NRM13.9%. A subanalysis of the four groups by with or without gilteritinib maintenance and by pretreatment conditioning intensity showed that patients who received MAC and gilteritinib maintenance had the most superior 2-year OS 94.1%.

[Conclusion] Our data indicated that following maintenance therapy with gilteritinib after allo-HSCT could overcome the poor prognosis of FLT3-mutated AML even for those in non-remission status, despite the profound chemo-resistant character of FLT3-mutated AML.

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH