title: Biological characteristics and prognosis of adult acute myeloid leukemia with internal tandem duplications in the Flt3 gene.
abstract: Internal tandem duplications of the FIt3 gene (FIt3/ITDs) are present in about 18% of all AML cases and are therefore one of the most frequent somatic gene mutations in AML. Little is known about the role of FIt3/ITDs in leukemogenesis or their clinical relevance. In this study we compared 18 samples with FIt3/ITDs and 63 AML samples without these mutations with respect to clinical prognosis, cytokine responsiveness, progenitor cell content and repopulation in the NOD/SCID mouse. We found that in patients with a mutation CR rates are reduced (P=0.03) and relapse rates are increased (P=0.01), indicating the prognostic importance of FIt3/ITDs. This is also emphasized by the finding that in patients under the age of 60 years, as well as in older patients the event-free survival was more unfavorable for the mutant patients (P=0.003 and P=0.03, respectively). At diagnosis FIt3/ITD and non-mutant AML bone marrow samples did not differ in their progenitor/stem cell frequencies. Cobblestone area forming cell (CAFC) subsets showed a similar frequency distribution in mutant and non-mutant samples. In 7-day liquid cultures, FIt3/ITD samples showed a reduced growth in response to a variety of myeloid growth factors. In contrast, FIt3/ITD samples displayed a higher ability to engraft the NOD/SCID bone marrow with leukemic cells. Together these data show that the FIt3/ITD represents an important diagnostic marker for patient prognosis, and that the presence of these mutations is associated with altered proliferative ability of progenitors in vivo and in vitro.
authors.affiliation: Dept of Haematology, Erasmus University, Rotterdam, The Netherlands.
authors.forename: W J
authors.initials: WJ
authors.lastname: Rombouts
authors.forename: I
authors.initials: I
authors.lastname: Blokland
authors.forename: B
authors.initials: B
authors.lastname: Löwenberg
authors.forename: R E
authors.initials: RE
authors.lastname: Ploemacher
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000627:therapeutic use; D001853:Bone Marrow / Q000473:pathology; D002452:Cell Count; D002455:Cell Division / Q000235:genetics; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D020440:Gene Duplication; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000473:pathology; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D015993:Life Tables; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics*; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000473:pathology; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D016019:Survival Analysis; D016896:Treatment Outcome; D014410:Tumor Stem Cell Assay; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; C497970:FLT3 protein, human; C497971:Flt3 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3