FLT3-ITD Induces CMTM6 and Enhances Immune Escape in Acute Myeloid Leukemia.

FLT3-ITD Driven CMTM6 Expression Contributes to Immune Escape of Acute Myeloid Leukemia

Cytoplasmic localization of phosphorylated STAT5 in human acute myeloid leukemia is inversely correlated with Flt3-ITD

Cage Transcriptome Analysis Reveals BCL2A1 Upregulation in FLT3-ITD/D835 Dual Mutated AML Cells Harboring Complex Co-Mutations

AXL Inhibitor ONO-9330547 Suppresses PLK1 Gene and Protein Expression and Effectively Induces Growth Arrest and Apoptosis in FLT3 ITD Acute Myeloid Leukemia Cells

It is not clear how Fms-like tyrosine kinase 3-internal tandem duplications (FLT3-ITD) regulates checkpoint kinase 1 (CHK1) in acute myeloid leukemia (AML). In this study, we investigated the regulatory effect of FLT3-ITD on CHK1. Our results showed that CHK1 was highly expressed in FLT3-ITD positive AML. The overall survival rate and disease-free survival rate of AML patients with high CHK1 level were lower than those of patients with low CHK1 level. Mechanistically, FLT3-ITD recruited p300 to the CHK1 promoter and subsequently acetylated H3K27, thereby enhancing the transcription of CHK1. Interfering with the expression of CHK1 significantly inhibited the cell proliferation and induced cell apoptosis in FLT3-ITD positive MV4-11 cells. In addition, CHK1 knockdown promoted the sensitivity of MV4-11 cells to the epigenetic inhibitors JQ1 and C646. This study discovers a new therapeutic target for FLT3-ITD + AML and provided evidence for the combination of epigenetic inhibitors for AML treatment.

Prognostic Impact of <i>NPM1</i> and <i>FLT3</i>-ITD Mutations in Patients Treated with Non-Intensive Regimens: A Pethema Registry Study

Clinical Activity, Pharmacokinetics, and Pharmacodynamics of Sorafenib In Pediatric Acute Myeloid Leukemia.

Single Cell Network Profiling (SCNP) Functionally Characterizes FLT3 Pathway Deregulation in Non-M3 Acute Myeloid Leukemia (AML) and Provides Prognostic Value Independent From Mutational Status

Multi-kinase inhibitor sorafenib showed dramatic effects in acute myeloid leukemia (AML) cells harboring fms-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation. However, FLT3-ITD mutation only occurs in 25% of AML cases. The therapeutic effects of sorafenib in AML patients without FLT3-ITD are still in need of further investigation. A young AML patient with central nervous system (CNS) relapse was treated with sorafenib combined with chemotherapy. Another patient with refractory AML arising form chronic myelomonocytic leukemia (CMML) was treated with sorafenib monotherapy. Spinal and cranial magnetic resonance imaging (MRI), minimal residual disease (MRD) and peripheral blood cell count were monitored to evaluate disease status. The patient with CNS relapse exhibited significant shrink of tumor volume. The other patient with refractory AML achieved hematological improvements. These two cases suggested that sorafenib might be utilized as a potent salvage therapy for some refractory/relapsed AML patients without the FLT3-ITD mutation.

ITD-Flt3 Enhances Migration of Hematopoietic Cells through Aberrant CXCR4 Signaling Pathways Overlapping but Functionally Distinct From SDF1/CXCR4 Signaling Axis in Normal Hematopoietic Cells.

SM09419, a Novel, Small-Molecule CDC-like Kinase (CLK) Inhibitor, Demonstrates Strong Inhibition of the Wnt Signaling Pathway and Antitumor Effects in FMS-like Tyrosine Kinase 3 (FLT3)-Mutant Acute Myeloid Leukemia Models

Myeloid cell leukemia 1 (Mcl-1) is one of the key anti-apoptotic Bcl-2 family proteins that binds and neutralizes pro-apoptotic BIM, BAX and BAK at the mitochondrial outer membrane, preventing cytochrome c release and caspase activation. Selective upregulation of Mcl-1 functionally contributes to resistance of acute myeloid leukemias (AML) with FMS-like tyrosine kinase-3-internal tandem duplications (FLT3-ITD) to chemotherapy (Kasper S. et al. 2012, Blood Cancer J. 2:e60, doi:10.1038/bcj.2012.5). Here we show that a novel Mcl-1 inhibitor S63845 (Kotschy A. et al. 2016, Nature 538, 477-482), has synergistic proapoptotic activity in combination with FLT3-ITD kinase inhibitor midostaurin in pre-clinical models of AML. Our studies demonstrate that S63845 has potent single agent activity in AML cell lines and primary AML samples harboring FLT3-ITD with IC50 values in low nanomolar range. Co-targeting of Mcl-1 and FLT3-ITD with S63845 and midostaurin, respectively, significantly increased apoptosis in FLT3-ITD cells with caspase-3 activation and PARP cleavage occurring rapidly within 6 hours of treatment. Consistent with markedly reduced cell growth and viability, analysis of drug combinations efficacy using Bliss independence model revealed strong synergistic interactions between S63845 and midostaurin in FLT3-ITD cell lines and primary AML samples. Midostaurin caused de-phosphorylation of FLT3-ITD and its downstream targets such as STAT5, AKT and MAPK. This was accompanied by significant downregulation of MAPK-mediated phosphorylation of Mcl-1 at Thr163 required for Mcl-1 stability. Consequently, midostaurin reduced Mcl-1 protein levels, with no major changes in antiapoptotic Bcl-2 or Bcl-XL. Importantly, midostaurin increased expression of pro-apoptotic Bim, which could in turn bind and negate residual Mcl-1 pro-survival activity. Elevated Bim was sustained upon S63845 co-treatment, suggesting that Bim plays functional role in midostaurin/S63845-mediated lethality. Dynamic BH3 profiling showed that midostaurin primed FLT3-ITD cells to Mcl-1 and Bcl-2 inhibitors and facilitated general apoptosis priming in response to Bim peptide. Importantly, given that Mcl-1 is a major contributing factor to resistance of AML to Bcl-2 selective BH3-mimetic venetoclax, S63845/midostaurin treatment induced cell death in venetoclax-resistant FLT3-ITD mutants. In summary, S63845/midostaurin is highly synergistic in FLT3-ITD mutated AML cells including those resistant to venetoclax. In vivo experiments of tolerability and efficacy are ongoing and will be reported. Citation Format: Anna Skwarska, Qi Zhang, Shelley M. Herbrich, Natalia Baran, Ensar Halilovic, Peter Ruvolo, Vivian Ruvolo, Erick Morris, Andrew Wei, Donia Moujalled, Michael Andreff, Marina Konopleva. S63845, a novel BH3 mimetic Mcl-1 inhibitor synergizes with midostaurin to induce potent apoptosis in acute myeloid leukemia cells carrying FLT3-ITD mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 342.

Acute myeloid leukemia (AML) with normal cytogenetics represents approximately 40% to 50% of de novo AML. This heterogeneous AML subgroup constitutes the single largest cytogenetic group with an intermediate prognosis. Previous studies have suggested that the Fms-like tyrosine kinase-3 internal tandem duplication (FLT3/ITD) mutation-positive de novo AML may represent a distinctive subgroup of AML. We analyzed the clinical and pathologic features of 15 cases of de novo AML with normal cytogenetics and with the FLT3/ITD mutation. In comparison with patients with AML without the FLT3/ITD mutation, patients with FLT3/ITD+ AML are relatively younger, more often have marked peripheral leukocytosis with a higher number of circulating blasts at initial examination, more often have minimal differentiation morphologic features, more frequently have abnormal CD7 coexpression, and have poorer outcome. Close association of aberrant CD7 expression and FLT3/ITD mutation in the myeloblasts of FLT3/ITD+ AML suggests that FLT3/ITD- mediated leukemic transformation occurs in the more early stage of myeloid progenitor cells.

FLT3-ITD Has Developmental Context Specific Effects on Hematopoiesis and Myeloid Leukemogenesis

FLT3-ITD Activates Cytoplasmic Drosha-Dependent Non-Canonical Mechanisms of Mir-155 Biogenesis in Acute Myeloid Leukemia