title: Identification of emerging FLT3 ITD-positive clones during clinical remission and kinetics of disease relapse in acute myeloid leukaemia with mutated nucleophosmin.
abstract: FLT3 internal tandem duplication (ITD) mutations are frequently detected at diagnosis in cytogenetically normal acute myeloid leukaemia (CN-AML) and predict unfavourable outcome. FLT3 ITD is an unstable aberration and may be lost or acquired at relapse. Recent whole genome sequencing studies have suggested that FLT3 ITD(+)ve AML relapse may evolve from small subclones undetectable at diagnosis by routine polymerase chain reaction (PCR). We developed a patient-specific real-time quantitative-PCR (RQ-PCR) to implement FLT3 ITD detection in six AML patients whose blasts carried wild-type FLT3 at diagnosis and who relapsed with FLT3 ITD by routine PCR. Patient-specific forward primers were designed after cloning and sequencing the FLT3 ITD in each case. The assay allowed retrospective detection of FLT3 ITD in diagnostic samples of 4/6 cases and to establish the kinetics of clonal evolution preceding relapse. After conventional chemotherapy, all patients had early relapse despite having been classified as NPM1(+)ve/FLT3 ITD(-)ve at presentation, with shorter remissions being observed in four patients re-classified as FLT3 ITD(+)ve by the new assay. Notably, FLT3 ITD clone became detectable by conventional PCR in three patients tested during remission after initial treatment. Our data underscore the need of identifying low FLT3 ITD levels, which are probably associated with relapse in otherwise good prognosis CN-AML.
authors.affiliation: Department of Biopathology, University of Tor Vergata, Rome, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Ottone
authors.forename: Serena
authors.initials: S
authors.lastname: Zaza
authors.forename: Mariadomenica
authors.initials: M
authors.lastname: Divona
authors.forename: Syed Khizer
authors.initials: SK
authors.lastname: Hasan
authors.forename: Serena
authors.initials: S
authors.lastname: Lavorgna
authors.forename: Serena
authors.initials: S
authors.lastname: Laterza
authors.forename: Laura
authors.initials: L
authors.lastname: Cicconi
authors.forename: Paola
authors.initials: P
authors.lastname: Panetta
authors.forename: Jonny
authors.initials: J
authors.lastname: Di Giandomenico
authors.forename: Michela
authors.initials: M
authors.lastname: Cittadini
authors.forename: Claudia
authors.initials: C
authors.lastname: Ciardi
authors.forename: Enrico
authors.initials: E
authors.lastname: Montefusco
authors.forename: Annibale
authors.initials: A
authors.lastname: Franchi
authors.forename: Luciana
authors.initials: L
authors.lastname: Annino
authors.forename: Adriano
authors.initials: A
authors.lastname: Venditti
authors.forename: Sergio
authors.initials: S
authors.lastname: Amadori
authors.forename: Francesco
authors.initials: F
authors.lastname: Lo-Coco
mesh_terms: D000328:Adult; D005260:Female; D018628:Gene Dosage; D020440:Gene Duplication; D006801:Humans; D060828:Induction Chemotherapy; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D000090243:Nucleophosmin; D012008:Recurrence; D012189:Retrospective Studies; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics*
chemical_list: C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D051941:fms-Like Tyrosine Kinase 3