Pediatric AML primary samples with FLT3/ITD mutations are preferentially killed by FLT3 inhibition.

Pediatric acute myelogenous leukemia (AML) has a poor prognosis, and novel therapies are needed. The FLT3 tyrosine kinase represents a promising target in pediatric AML. FLT3 is constitutively activated either by an internal tandem duplication (ITD) or by a point mutation (PM) in 17% to 24% of pediatric AML cases. Autocrine stimulation of wild-type (WT) FLT3 by coexpressed FLT3 ligand (FL) occurs in many other cases. FLT3/ITD mutations confer a particularly poor prognosis in pediatric AML patients. Inhibitors of FLT3 are being tested in adult AML patients, with promising preliminary results. In this study, cytotoxicity and apoptosis assays were performed on 44 diagnostic pediatric AML blast samples (14 FLT3/WT, 15 FLT3/ITD, 15 FLT3/PM) using CEP-701, a potent and selective FLT3 inhibitor. Pronounced cytotoxicity and induction of apoptosis were observed in a higher percentage of FLT3/ITD samples (93%) than FLT3/PM (27%) or FLT3/WT (29%). The cytotoxicity was greatest in samples with a high FLT3/ITD mutant-to-wild-type allelic ratio. The addition of FL enhanced the survival and augmented the sensitivity to FLT3 inhibition for the CEP-701-responsive subset of FLT3/WT and FLT3/PM samples. Clinical testing of FLT3 inhibitors as molecularly targeted agents for the improvement of outcome of pediatric AML patients is warranted.

[1]  H. Kantarjian,et al.  Single-agent CEP-701, a novel FLT3 inhibitor, shows biologic and clinical activity in patients with relapsed or refractory acute myeloid leukemia. , 2004, Blood.

[2]  D. Small,et al.  FLT3 inhibitors: a paradigm for the development of targeted therapeutics for paediatric cancer. , 2004, European journal of cancer.

[3]  D. Hicklin,et al.  FLT3 ligand causes autocrine signaling in acute myeloid leukemia cells. , 2004, Blood.

[4]  S. Feig,et al.  Pilot study of idarubicin-based intensive-timing induction therapy for children with previously untreated acute myeloid leukemia: Children's Cancer Group Study 2941. , 2004, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[5]  M. Levis,et al.  Novel FLT3 tyrosine kinase inhibitors , 2003, Expert opinion on investigational drugs.

[6]  J. Radich,et al.  FLT3 internal tandem duplication in 234 children with acute myeloid leukemia: prognostic significance and relation to cellular drug resistance. , 2003, Blood.

[7]  J. Radich,et al.  The role of FLT3 in haematopoietic malignancies , 2003, Nature Reviews Cancer.

[8]  M. Levis,et al.  FLT3: ITDoes matter in leukemia , 2003, Leukemia.

[9]  I. Bernstein,et al.  Activating mutations of RTK/ras signal transduction pathway in pediatric acute myeloid leukemia. , 2003, Blood.

[10]  M. Heinrich,et al.  SU11248 is a novel FLT3 tyrosine kinase inhibitor with potent activity in vitro and in vivo. , 2003, Blood.

[11]  W. Hiddemann,et al.  The protein tyrosine kinase inhibitor SU5614 inhibits FLT3 and induces growth arrest and apoptosis in AML-derived cell lines expressing a constitutively activated FLT3. , 2003, Blood.

[12]  M. Valsecchi,et al.  FLT3 internal tandem duplication in childhood acute myeloid leukaemia: association with hyperleucocytosis in acute promyelocytic leukaemia , 2003, British journal of haematology.

[13]  Ø. Bruserud,et al.  Flt3-mediated signaling in human acute myelogenous leukemia (AML) blasts: a functional characterization of Flt3-ligand effects in AML cell populations with and without genetic Flt3 abnormalities. , 2003, Haematologica.

[14]  G. Mcmahon,et al.  SU5416 and SU5614 inhibit kinase activity of wild-type and mutant FLT3 receptor tyrosine kinase. , 2002, Blood.

[15]  J. Griffin,et al.  The roles of FLT3 in hematopoiesis and leukemia. , 2002, Blood.

[16]  R. Arceci,et al.  What is the optimal therapy for childhood AML? , 2002, Oncology.

[17]  R. Arceci.  Progress and controversies in the treatment of pediatric acute myelogenous leukemia , 2002, Current opinion in hematology.

[18]  D. Liang,et al.  Clinical relevance of internal tandem duplication of the FLT3 gene in childhood acute myeloid leukemia , 2002, Cancer.

[19]  G. Ehninger,et al.  Analysis of Flt3-activating Mutations in 979 Patients with Acute Myelogenous Leukemia: Association with Fab Subtypes and Identification of Subgroups with Poor Prognosis , 2022 .

[20]  Doriano Fabbro,et al.  Inhibition of mutant FLT3 receptors in leukemia cells by the small molecule tyrosine kinase inhibitor PKC412. , 2002, Cancer cell.

[21]  Donna Neuberg,et al.  CT53518, a novel selective FLT3 antagonist for the treatment of acute myelogenous leukemia (AML). , 2002, Cancer cell.

[22]  B. Smith,et al.  A FLT3-targeted tyrosine kinase inhibitor is cytotoxic to leukemia cells in vitro and in vivo. , 2002, Blood.

[23]  T. Naoe,et al.  Mechanism of constitutive activation of FLT3 with internal tandem duplication in the juxtamembrane domain , 2002, Oncogene.

[24]  D. Fabbro,et al.  Inhibition of mutant FLT 3 receptors in leukemia cells by the small molecule tyrosine kinase inhibitor PKC 412 , 2002 .

[25]  D. Campana,et al.  Childhood acute lymphoblastic leukaemia--current status and future perspectives. , 2001, The Lancet. Oncology.

[26]  M. Caligiuri,et al.  Absence of the wild-type allele predicts poor prognosis in adult de novo acute myeloid leukemia with normal cytogenetics and the internal tandem duplication of FLT3: a cancer and leukemia group B study. , 2001, Cancer research.

[27]  B. Smith,et al.  A FLT3 tyrosine kinase inhibitor is selectively cytotoxic to acute myeloid leukemia blasts harboring FLT3 internal tandem duplication mutations. , 2001, Blood.

[28]  J. Reilly,et al.  Identification of novel FLT‐3 Asp835 mutations in adult acute myeloid leukaemia , 2001, British journal of haematology.

[29]  T. Naoe,et al.  Activating mutation of D835 within the activation loop of FLT3 in human hematologic malignancies. , 2001, Blood.

[30]  I. Bernstein,et al.  Prevalence and prognostic significance of Flt3 internal tandem duplication in pediatric acute myeloid leukemia. , 2001, Blood.

[31]  H. Broxmeyer,et al.  Flt3 ligand induces tyrosine phosphorylation of gab1 and gab2 and their association with shp-2, grb2, and PI3 kinase. , 2000, Biochemical and biophysical research communications.

[32]  W. Leonard,et al.  Essential Role of Signal Transducer and Activator of Transcription (Stat)5a but Not Stat5b for Flt3-Dependent Signaling , 2000, The Journal of experimental medicine.

[33]  T. Naoe,et al.  Tandem-duplicated Flt3 constitutively activates STAT5 and MAP kinase and introduces autonomous cell growth in IL-3-dependent cell lines , 2000, Oncogene.

[34]  早川 文彦.  Tandem-duplicated Flt3 constitutively activates STAT5 and MAP kinase and introduces autonomous cell growth in IL-3-dependent cell lines , 2000 .

[35]  K. Horibe,et al.  Prognostic value of internal tandem duplication of the FLT3 gene in childhood acute myelogenous leukemia. , 1999, Medical and pediatric oncology.

[36]  Wan Ariffin Bin Abdullah,et al.  Med Pediatr Oncol , 1999 .

[37]  Y. Hayashi,et al.  Tandem duplication of the FLT3 gene is found in acute lymphoblastic leukaemia as well as acute myeloid leukaemia but not in myelodysplastic syndrome or juvenile chronic myelogenous leukaemia in children , 1999, British journal of haematology.

[38]  H. Broxmeyer,et al.  Flt3 signaling involves tyrosyl‐phosphorylation of SHP‐2 and SHIP and their association with Grb2 and Shc in Baf3/Flt3 cells , 1999, Journal of leukocyte biology.

[39]  H. Broxmeyer,et al.  p85 subunit of PI3 kinase does not bind to human Flt3 receptor, but associates with SHP2, SHIP, and a tyrosine-phosphorylated 100-kDa protein in Flt3 ligand-stimulated hematopoietic cells. , 1999, Biochemical and biophysical research communications.

[40]  M. Taniwaki,et al.  Internal tandem duplication of the FLT3 gene and clinical evaluation in childhood acute myeloid leukemia , 1999, Leukemia.

[41]  H. Saito,et al.  Internal tandem duplication of the FLT3 gene is a novel modality of elongation mutation which causes constitutive activation of the product , 1998, Leukemia.

[42]  D. Birnbaum,et al.  FLT3 signaling in hematopoietic cells involves CBL, SHC and an unknown P115 as prominent tyrosine-phosphorylated substrates , 1998, Leukemia.

[43]  S. Feig,et al.  Feasibility, toxicity, and biologic response of interleukin-2 after consolidation chemotherapy for acute myelogenous leukemia: a report from the Children's Cancer Group. , 1998, Journal of Clinical Oncology.

[44]  H. Kaneko,et al.  Internal tandem duplication of the flt3 gene found in acute myeloid leukemia. , 1996, Leukemia.

[45]  S. Braun,et al.  Flt3-ligand production by human bone marrow stromal cells. , 1996, Leukemia.

[46]  H. Drexler,et al.  Expression of FLT3 receptor and response to FLT3 ligand by leukemic cells. , 1996, Leukemia.

[47]  D. Birnbaum,et al.  Human FLT3/FLK2 receptor tyrosine kinase is expressed at the surface of normal and malignant hematopoietic cells. , 1996, Leukemia.

[48]  M. Borowitz,et al.  Expression of the hematopoietic growth factor receptor FLT3 (STK-1/Flk2) in human leukemias. , 1996, Blood.

[49]  D. Birnbaum,et al.  Expression and signal transduction of the FLT3 tyrosine kinase receptor. , 1996, Acta haematologica.

[50]  D. Birnbaum,et al.  Expression of FLT3 receptor and FLT3-ligand in human leukemia-lymphoma cell lines. , 1995, Leukemia.

[51]  P. D. Vries,et al.  Expression of the flt3 receptor and its ligand on hematopoietic cells. , 1995, Leukemia.

[52]  D. Birnbaum,et al.  Expression of the FMS/KIT-like gene FLT3 in human acute leukemias of the myeloid and lymphoid lineages. , 1992, Blood.

[53]  D. Gerlier,et al.  Use of MTT colorimetric assay to measure cell activation. , 1986, Journal of immunological methods.

[54]  J. Peto,et al.  Asymptotically Efficient Rank Invariant Test Procedures , 1972 .

[55]  E. Kaplan,et al.  Nonparametric Estimation from Incomplete Observations , 1958 .