title: The potential of clofarabine in MLL-rearranged infant acute lymphoblastic leukaemia.
abstract: MLL-rearranged acute lymphoblastic leukaemia (ALL) in infants is the most difficult-to-treat type of childhood ALL, displaying a chemotherapy-resistant phenotype, and unique histone modifications, gene expression signatures and DNA methylation patterns. MLL-rearranged infant ALL responds remarkably well to nucleoside analogue drugs in vitro, such as cytarabine and cladribine, and to the demethylating agents decitabine and zebularine as measured by cytotoxicity assays. These observations led to the inclusion of cytarabine into the treatment regimens currently used for infants with ALL. However, survival chances for infants with MLL-rearranged ALL do still not exceed 30-40%. Here we explored the in vitro potential of the novel nucleoside analogue clofarabine for MLL-rearranged infant ALL. Therefore we used both cell line models as well as primary patient cells. Compared with other nucleoside analogues, clofarabine effectively targeted primary MLL-rearranged infant ALL cells at the lowest concentrations, with median LC50 values of ∼25 nM. Interestingly, clofarabine displayed synergistic cytotoxic effects in combination with cytarabine. Furthermore, at concentrations of 5-10nM clofarabine induced demethylation of the promoter region of the tumour suppressor gene FHIT (Fragile Histidine Triad), a gene typically hypermethylated in MLL-rearranged ALL. Demethylation of the FHIT promoter region was accompanied by subtle re-expression of this gene both at the mRNA and protein level. We conclude that clofarabine is an interesting candidate for further studies in MLL-rearranged ALL in infants.
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus MC - Sophia Children's Hospital Rotterdam, Wytemaweg 80, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands. Electronic address: dominiquestumpel@hotmail.com.
authors.forename: Dominique J P M
authors.initials: DJ
authors.lastname: Stumpel
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus MC - Sophia Children's Hospital Rotterdam, Wytemaweg 80, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands. Electronic address: p.schneider@erasmusmc.nl.
authors.forename: Pauline
authors.initials: P
authors.lastname: Schneider
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus MC - Sophia Children's Hospital Rotterdam, Wytemaweg 80, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands; Princess Maxima Center for Pediatric Oncology, Lundlaan 6, Utrecht, The Netherlands. Electronic address: r.pieters@prinsesmaximacentrum.nl.
authors.forename: Rob
authors.initials: R
authors.lastname: Pieters
authors.affiliation: Department of Pediatric Oncology/Hematology, Erasmus MC - Sophia Children's Hospital Rotterdam, Wytemaweg 80, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands. Electronic address: r.stam@erasmusmc.nl.
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Stam
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000235:genetics / Q000378:metabolism; D000227:Adenine Nucleotides / Q000494:pharmacology*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001087:Arabinonucleosides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000077866:Clofarabine; D003561:Cytarabine / Q000494:pharmacology; D019175:DNA Methylation; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D015321:Gene Rearrangement; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics*; D006801:Humans; D007223:Infant; D020128:Inhibitory Concentration 50; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014407:Tumor Cells, Cultured; D000099170:Bis(5'-adenosyl)triphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D000227:Adenine Nucleotides; D000964:Antimetabolites, Antineoplastic; D001087:Arabinonucleosides; D000077866:Clofarabine; D003561:Cytarabine; D011495:Histone-Lysine N-Methyltransferase; D051788:Myeloid-Lymphoid Leukemia Protein; D009363:Neoplasm Proteins; D000099170:Bis(5'-adenosyl)triphosphatase; C497422:KMT2A protein, human
keywords: Clofarabine; Epigenetic; Infant ALL; MLL; Paediatric leukaemia