Prognostic Significance of Fms-Like Tyrosine Kinase 3 Internal Tandem Duplication Mutation in Non-Transplant Adult Patients with Acute Myeloblastic Leukemia: A Systematic Review and Meta-Analysis

FLT3 inhibition by olverembatinib (HQP1351) downregulates MCL-1 and synergizes with BCL-2 inhibitor lisaftoclax (APG-2575) in preclinical models of FLT3-ITD mutant acute myeloid leukemia

Introduction

FLT3-ITD mutations occur in approximately 25% of patients with acute myeloid leukemia (AML) and are associated with poor prognosis. Despite initial efficacy, short duration of response and high relapse rates limit clinical use of selective FLT3 inhibitors. Combination approaches with other targeted therapies may achieve better clinical outcomes.

Materials and methods

Anti-leukemic activity of multikinase inhibitor olverembatinib (HQP1351), alone or in combination with BCL-2 inhibitor lisaftoclax (APG-2575), was evaluated in FLT3-ITD mutant AML cell lines in vitro and in vivo. A patient-derived FLT3-ITD mutant AML xenograft model was also used to assess the anti-leukemic activity of this combination.

Results

HQP1351 potently induced apoptosis and inhibited FLT3 signaling in FLT3-ITD mutant AML cell lines MV-4-11 and MOLM-13. HQP1351 monotherapy also significantly suppressed growth of FLT3-ITD mutant AML xenograft tumors and prolonged survival of tumor-bearing mice. HQP1351 and APG-2575 synergistically induced apoptosis in FLT3-ITD mutant AML cells and suppressed growth of MV-4–11 xenograft tumors. Combination therapy improved survival of tumor bearing-mice in a systemic MOLM-13 model and showed synergistic anti-leukemic effects in a patient-derived FLT3-ITD mutant AML xenograft model. Mechanistically, HQP1351 downregulated expression of myeloid-cell leukemia 1 (MCL-1) by suppressing FLT3-STAT5 (signal transducer and activator of transcription 5) signaling and thus enhanced APG-2575-induced apoptosis in FLT3-ITD mutant AML cells.

Conclusions

FLT3 inhibition by HQP1351 downregulates MCL-1 and synergizes with BCL-2 inhibitor APG-2575 to potentiate cellular apoptosis in FLT3-ITD mutant AML. Our findings provide a scientific rationale for further clinical investigation of HQP1351 combined with APG-2575 in patients with FLT3-ITD mutant AML.

FLT3-ITD Mutation and FLT3 Ligand Plasma Level Were Not Associated with One-Year Survival of Indonesian Acute Myeloid Leukemia Patients

OBJECTIVE

To analyze the association of FLT3-ITD mutation and FLT3 ligand plasma level with one-year survival of Indonesian acute myeloid leukemia (AML) patients.

METHODS

A prospective cohort study was conducted to determine the association between FLT-3-ITD mutation and FLT3 ligand plasma level with one-year survival of Indonesian AML patients. In the study, a total of 51 AML patients were obtained from two tertiary hospitals in Indonesia from year 2018 to 2020. Inclusion criteria were de novo AML male and female patients aged ≥18 years old. Exclusion criteria were prior myelodysplastic syndrome and patients that refused to participate in the study. FLT3-ITD genotype of patients was then analyzed using PCR method while FLT3 ligand plasma level was measured using ELISA method. Patients were then followed-up for 1 year or until death occurred with survival as the measured outcome. Association between independent and dependent variable were analyzed by cox regression proportional hazard.

RESULTS

Eleven patients (21.5%) in this study had FLT3-ITD mutation. The median age of AML patients was 45 (18-71) years, and the median blast percentage was 50% (5-87%). After one-year follow-up, 33 (64.7%) patients had died. The median survival of AML patients was 6 months. Univariate analysis showed no association between FLT3-ITD mutation status (HR: 1.051 ; 95% CI: 0.483-2.286; P: 0.901) and FLT3 ligand plasma level (HR: 0.798; 95% CI: 0.347-1.837; p= 0.596), and age (HR: 1.283; 95% CI: 0.575-2.862; p= 0.542) with one-year survival of AML patients, but multivariate analysis showed association between GFR with one-year survival of AML patients in this cohort (HR: 4.053; 95% CI: 1.469-11.183; p= 0.007).

CONCLUSION

One-year survival of AML patients in Indonesia is not affected by FLT3-ITD mutation and FLT3 ligand plasma level. However, GFR showed association with one-year survival of AML patient in this cohort study.