A novel approach for relapsed/refractory FLT3mut+ acute myeloid leukaemia: synergistic effect of the combination of bispecific FLT3scFv/NKG2D-CAR T cells and gilteritinib

Mol Cancer. 2022 Mar 4;21(1):66. doi: 10.1186/s12943-022-01541-9.

Abstract

Background: Patients with relapsed/refractory acute myeloid leukaemia (AML) with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) have limited treatment options and poor prognosis. Therefore, novel treatment modalities are needed. Since high expression of natural killer group 2 member D ligands (NKG2DLs) can be induced by FLT3 inhibitors, we constructed dual-target FLT3 single-chain fragment variable (scFv)/NKG2D-chimeric antigen receptor (CAR) T cells, and explored whether FLT3 inhibitors combined with FLT3scFv/NKG2D-CAR T cells could have synergistic anti-leukaemia effects.

Methods: FLT3scFv and NKG2D expression in CAR T cells, FLT3 and NKG2DL expression in AML cells, and the in vitro cytotoxicity of combining CAR T cells with gilteritinib were assessed by flow cytometry. The therapeutic effect was evaluated in a xenograft mouse model established by injection of MOLM-13 cells. Mechanisms underlying the gilteritinib-induced NKG2DL upregulation were investigated using siRNA, ChIP-QPCR and luciferase assays.

Results: The FLT3scFv/NKG2D-CAR T cells specifically lysed AML cells both in vitro and in the xenograft mouse model. The efficacy of FLT3scFv/NKG2D-CAR T cells was improved by gilteritinib-pretreatment. The noncanonical NF-κB2/Rel B signalling pathway was found to mediate gilteritinib-induced NKG2DL upregulation in AML cells.

Conclusions: Bispecific FLT3scFv/NKG2D-CAR T cells can effectively eradicate AML cells. The FLT3 inhibitor gilteritinib can synergistically improve this effect by upregulating NF-κB2-dependent NKG2DL expression in AML cells.

Keywords: Acute myeloid leukaemia; Chimeric antigen receptor (CAR); FLT3 inhibitor; FMS-like tyrosine kinase 3 (FLT3); Gilteritinib; Immunotherapy; Natural killer group 2 member D (NKG2D).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aniline Compounds / pharmacology
  • Animals
  • Disease Models, Animal
  • Humans
  • Leukemia, Myeloid, Acute* / genetics
  • Mice
  • Mutation
  • NF-kappa B p52 Subunit / genetics
  • NK Cell Lectin-Like Receptor Subfamily K* / genetics
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Pyrazines
  • T-Lymphocytes / metabolism
  • fms-Like Tyrosine Kinase 3 / genetics
  • fms-Like Tyrosine Kinase 3 / metabolism
  • fms-Like Tyrosine Kinase 3 / therapeutic use

Substances

  • Aniline Compounds
  • NF-kappa B p52 Subunit
  • NK Cell Lectin-Like Receptor Subfamily K
  • Protein Kinase Inhibitors
  • Pyrazines
  • gilteritinib
  • FLT3 protein, human
  • fms-Like Tyrosine Kinase 3