GNF-7, a novel FLT3 inhibitor, overcomes drug resistance for the treatment of FLT3‑ITD acute myeloid leukemia

Abstract

Abstract Background Acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation accounts for a large proportion of AML patients and diagnosed with dismay prognosis. Although the prognosis of FLT3-ITD AML has been greatly improved, the drug resistance frequently occurred in the treatment of FLT3 target drugs. GNF-7, a multitargeted kinase inhibitor, which provided a novel therapeutic strategy for overriding leukemia. In this study, we explored the antitumor activity of GNF-7 against FLT3-ITD and clinically-relevant drug resistance in FLT3 mutant AML. Methods Growth inhibitory assays were performed in AML cell lines and Ba/F3 cells expressing various FLT3 mutants to evaluate the antitumor activity of GNF-7 in vitro. Western blotting was used to examine the activity of FLT3 and its downstream pathways. Molecular docking was performed to predict the binding sites of FLT3 to GNF-7. The survival benefit of GNF-7 in vivo was assessed in mouse models of transformed Ba/F3 cells harboring FLT3-ITD and FLT3-ITD/F691L mutation. Primary patient samples and a patient-derived xenograft (PDX) model were also used to determine the efficacy of GNF-7. Results GNF-7 inhibited the cell proliferation of Ba/F3 cells expressing FLT3-ITD and exhibited potently anti-leukemia activity on primary FLT3-ITD AML samples. Moreover, GNF-7 could bind to FLT3 protein and inhibit the phosphorylation of downstream effectors in the FLT3 signaling pathways. In vitro and in vivo studies showed that GNF-7 exhibited a potent inhibitory activity against FLT3-ITD/F691L that confers resistant to quizartinib (AC220) or gilteritinib. Importantly, GNF-7 showed potent cytotoxic effect on leukemic stem cells, significantly extend the survival of PDX model and exhibited similar therapy effect compared with gilteritinib. Conclusions Our results show that GNF-7 is a potent FLT3-ITD inhibitor and may become a promising lead compound applied for treating some of the clinically drug resistant patients.