Rearrangements of ATP5L-KMT2A in acute lymphoblastic leukaemia

Recent genomic studies have identified a wide range of novel genetic alterations that have substantially increased our knowledge of the biology of B- and T-progenitor acute lymphoblastic leukaemia (B-ALL, T-ALL) and defined new subtypes with prognostic and therapeutic relevance.1-4 Thanks to the use of transcriptome sequencing approaches, new cryptic fusion transcripts have been described, such as the ATP5L-KMT2A gene fusion, described by Gestrich et al. in a 14-month-old patient with aggressive B-ALL.5 ATP5L or ATP5MG (ATP Synthase Membrane Subunit G) catalyzes ATP synthesis during oxidative phosphorylation.6 This protein has recently been reported to interact with a SARS-CoV-2 protein.7 The histone lysine [K]-methyl transferase 2A (KMT2A) gene is a transcriptional coactivator that plays an essential role in regulating gene expression during early development and haematopoiesis. It is frequently rearranged to over 135 translocation partner genes in acute leukaemias.8 ATP5L is a novel KMT2A fusion partner not detectable by fluorescent in situ hybridization (FISH) or karyotype, due to the closeness of the two genes on chromosome 11q23. The Cleveland Medical Centre team found a reciprocal out-of-frame ATP5L-KMT2A rearrangement that juxtaposes the ATP5L exon 1 to the KMT2A exon 2, with the insertion of an extra nucleotide (G) at the fusion site.5 We sequenced leukaemic cells from eight adult ALL patients (two T-ALL, five B-ALL Philadelphia negative (Ph−) and one B-ALL Ph+; Table I) by a 199 gene RNA-sequencing panel (RNA-seq; Pan-Heme FusionPlex, ArcherDx Inc., Boulder, CO, USA).The study was supported by European Union Seventh Framework Programme (FP7/2007-2013) (GA 306242-NGS-PTL) and Associazione Italiana Leucemie (AIL)

The synergistic efficacy of Chk1/Chk2 inhibitors and doxorubicin in the treatment of acute lymphoblastic leukemia

none11nononeAndrea Ghelli Luserna di Rora, Ilaria Iacobucci, Enrica Imbrogno, Enrico Derenzini, Anna Ferrari, Valentina Robustelli, Viviana Guadagnuolo, Cristina Papayannidis, Maria Chiara Abbenante, Sandro Grilli, Giovanni MartinelliAndrea Ghelli Luserna di Rora, Ilaria Iacobucci, Enrica Imbrogno, Enrico Derenzini, Anna Ferrari, Valentina Robustelli, Viviana Guadagnuolo, Cristina Papayannidis, Maria Chiara Abbenante, Sandro Grilli, Giovanni Martinell

Therapeutic implications of intratumor heterogeneity for TP53 mutational status in Burkitt lymphoma

Therapeutic implications of intra-tumor heterogeneity are still undefined. In this study we report a genetic and functional analysis aimed at defining the mechanisms of chemoresistance in a 43-year old woman affected by stage IVB Burkitt lymphoma with bulky abdominal masses and peritoneal effusion. The patient, despite a transient initial response to chemotherapy with reduction of the bulky masses, rapidly progressed and died of her disease. Targeted TP53 sequencing found that the bulky mass was wild-type whereas peritoneal fluid cells harbored a R282W mutation. Functional studies on TP53 mutant cells demonstrated an impaired p53-mediated response, resistance to ex vivo doxorubicin administration, overexpression of DNA damage response (DDR) activation markers and high sensitivity to pharmacologic DDR inhibition. These findings suggest that intra-tumor heterogeneity for TP53 mutational status may occur in MYC-driven cancers, and that DDR inhibitors could be effective in targeting hidden TP53 mutant clones in tumors characterized by genomic instability and prone to intra-tumor heterogeneity