title: Deciphering KRAS and NRAS mutated clone dynamics in MLL-AF4 paediatric leukaemia by ultra deep sequencing analysis.
abstract: To induce and sustain the leukaemogenic process, MLL-AF4+ leukaemia seems to require very few genetic alterations in addition to the fusion gene itself. Studies of infant and paediatric patients with MLL-AF4+ B cell precursor acute lymphoblastic leukaemia (BCP-ALL) have reported mutations in KRAS and NRAS with incidences ranging from 25 to 50%. Whereas previous studies employed Sanger sequencing, here we used next generation amplicon deep sequencing for in depth evaluation of RAS mutations in 36 paediatric patients at diagnosis of MLL-AF4+ leukaemia. RAS mutations including those in small sub-clones were detected in 63.9% of patients. Furthermore, the mutational analysis of 17 paired samples at diagnosis and relapse revealed complex RAS clone dynamics and showed that the mutated clones present at relapse were almost all originated from clones that were already detectable at diagnosis and survived to the initial therapy. Finally, we showed that mutated patients were indeed characterized by a RAS related signature at both transcriptional and protein levels and that the targeting of the RAS pathway could be of beneficial for treatment of MLL-AF4+ BCP-ALL clones carrying somatic RAS mutations.
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Trentin
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bresolin
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Giarin
authors.affiliation: Centro Ricerca Tettamanti, Department of Paediatrics, University of Milano Bicocca, Fondazione MBBM, Monza, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Bardini
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Serafin
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Accordi
authors.affiliation: Department of Experimental Medicine, University of Genoa, Genoa, Italy.|IRCCS AOU San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Fais
authors.affiliation: Department of Experimental Medicine, University of Genoa, Genoa, Italy.
authors.forename: Claudya
authors.initials: C
authors.lastname: Tenca
authors.affiliation: Centro Ricerca Tettamanti, Department of Paediatrics, University of Milano Bicocca, Fondazione MBBM, Monza, Italy.|Biostatistics Center, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: De Lorenzo
authors.affiliation: Biostatistics Center, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Valsecchi
authors.affiliation: Centro Ricerca Tettamanti, Department of Paediatrics, University of Milano Bicocca, Fondazione MBBM, Monza, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cazzaniga
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Geertruy Te
authors.initials: GT
authors.lastname: Kronnie
authors.affiliation: Department of Woman and Child Health, University of Padua, Via Giustiniani 3, 35128 Padua, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Basso
mesh_terms: D005260:Female; D020558:GTP Phosphohydrolases / Q000235:genetics* / Q000378:metabolism; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007938:Leukemia / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D051788:Myeloid-Lymphoid Leukemia Protein; D015514:Oncogene Proteins, Fusion; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism
chemical_list: C117307:KRAS protein, human; C113855:MLL-AF4 fusion protein, human; D008565:Membrane Proteins; D015514:Oncogene Proteins, Fusion; D051788:Myeloid-Lymphoid Leukemia Protein; D020558:GTP Phosphohydrolases; C579846:NRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)