Biology of Leukaemias
Despite the impressive success in cure rates of approximately 80%, leukaemia is still one of the leading causes of death in childhood and adolescence. Moreover, a substantial proportion of surviving children experiences severe treatment-related side and late effects. Therefore, it is of paramount importance to further improve risk stratification, identify relapse-prone cases and to implement targeted therapies. To do this, we explore genome-wide alterations and study the molecular and cellular mechanisms that contribute to leukaemia development, drug resistance and relapses. Childhood acute lymphoblastic Leukaemia (ALL) results from the acquisition of genetic alterations in a stem/progenitor cell population that undergoes complex processes of diversification and selection. We use a variety of genome-wide screening approaches, including the latest cutting-edge technologies, to identify copy number and sequence alterations that i) are likely to contribute to leukaemia emergence, ii) cause resistance and relapse and iii) qualify as biomarkers. The molecular mechanisms by which various oncogenic proteins exert their function as well as the respective effects are being investigated in various in vitro and in vivo models. Current projects include the following: Clonal heterogeneity and evolution of ALL Acute lymphoblastic leukaemia (ALL) is the prevalent cancer in children and adolescents and a heterogeneous disease entity with only half of it being genetically characterized by either a recurrent chromosomal translocation or a hyperdiploid karyotype. Additionally, and contrary to the previously notion, the individual leukaemia comprises various cell populations, which differ with regard to their patterns of secondary alterations whereby the initiating or founder mutation represents sometimes the only common one. Relapses usually evolve from small subclones that are present at initial diagnosis and their selection during chemotherapy suggests that they harbour mutations likely to confer drug resistance (Konrad et al. 2003). Therefore, these alterations or the founder mutation, if in fact still required for disease maintenance, represent ideal targets for novel treatment strategies. We have recently addressed these issues in three major subgroups of childhood ALL carrying ETV6-RUNX1 (ER) (Kuster et al. 2011), P2RY8-CRLF2 (Morak et al. 2012) or a high hyperdiploid (HD) karyotype (Inthal et al. 2012). Our data suggest that the majority of ER-positive and HD ALL relapses evolve from a clone that is ancestral to both the relapse and the initial leukaemia and that particular relapse-associated genetic alterations may confer resistance to glucocorticoids in both ALL subgroups, albeit with different underlying mechanisms. Moreover, the P2RY8-CRLF2 fusion does not seem to be an early or crucial mutation for relapse emergence because initially small clones do not progress and relapses frequently do not harbour the fusion present at initial diagnosis. Current studies, also employing NGS, are aiming to complement and extend these initial findings and to identify the respective founder mutation in the latter ALL subgroup. Molecular and functional consequences of ETV6-RUNX1 expression in leukaemia While the role of the ETV6-RUNX1 fusion gene in leukaemia initiation is well established, its function in leukaemia is still poorly understood. We recently discovered by an shRNA approach that the expression of the chimeric transcription factor is required for survival, proliferation and maintenance of the malignant phenotype, implying that the leukaemia cell is “addicted” to this oncogene (Fuka et al. 2012; Diakos et al. 2007). These cellular functions concur with a heavily deranged transcriptional program that appears mainly derived from ETV6-RUNX1-mediated gene repression (Fuka et al. 2011). Among the perturbed specific functions and signaling pathways, we identified the mitotic checkpoint (Krapf et al. 2010), the p53 pathway (Kaindl et al. 2013) and the critical pro-survival PI3K/Akt pathway. These data therefore suggest that ETV6-RUNX1 itself, or its downstream pathways, would represent perfect drug targets for this particular subtype of leukaemia because the clonal variegation of secondary aberrations need not be taken into account. Further research includes the in-depth analysis of particular pathways and interactions and the mode of downstream target regulation by ETV6-RUNX1. Translational research into development and validation of biomarkers Focusing primarily on the intermediate risk group of childhood ALL, where the vast majority of relapses occur, we are testing the most promising genetic alterations for their qualification as useful biomarkers in current treatment protocols.
Selected Articles IKZF1plus Defines a New Minimal Residual Disease-Dependent Very-Poor Prognostic Profile in Pediatric B-Cell Precursor Acute Lymphoblastic Leukemia. Stanulla M, Dagdan E, Zaliova M, Möricke A, Palmi C, Cazzaniga G, Eckert C, Te Kronnie G, Bourquin JP, Bornhauser B, Koehler R, Bartram CR, Ludwig WD, Bleckmann K, Groeneveld-Krentz S, Schewe D, Junk SV, Hinze L, Klein N, Kratz CP, Biondi A, Borkhardt A, Kulozik A, Muckenthaler MU, Basso G, Valsecchi MG, Izraeli S, Petersen BS, Franke A, Dörge P, Steinemann D, Haas OA, Panzer-Grümayer R, Cavé H, Houlston RS, Cario G, Schrappe M, Zimmermann M; TRANSCALL Consortium; International BFM Study Group. J Clin Oncol. 2018 Apr 20;36(12):1240-1249. Progenitor B-1 B-cell acute lymphoblastic leukemia is associated with collaborative mutations in 3 critical pathways. Gough SM, Goldberg L, Pineda M, Walker RL, Zhu YJ, Bilke S, Chung YJ, Dufraine J, Kundu S, Jacoby E, Fry TJ, Fischer S, Panzer-Grümayer R, Meltzer PS, Aplan PD. Blood Adv. 2017 Sep 8;1(20):1749-1759. The enigmatic role(s) of P2RY8-CRLF2. Panzer-Grümayer R, Köhrer S, Haas OA. Oncotarget. 2017 Oct 26;8(57):96466-96467. Characterization of Rare, Dormant, and Therapy-Resistant Cells in Acute Lymphoblastic Leukemia. Ebinger S, Özdemir EZ, Ziegenhain C, Tiedt S, Castro Alves C, Grunert M, Dworzak M, Lutz C, Turati VA, Enver T, Horny HP, Sotlar K, Parekh S, Spiekermann K, Hiddemann W, Schepers A, Polzer B, Kirsch S, Hoffmann M, Knapp B, Hasenauer J, Pfeifer H, Panzer-Grümayer R, Enard W, Gires O, Jeremias I. Cancer Cell. 2016 Dec 12;30(6):849-862. Genomic and transcriptional landscape of P2RY8-CRLF2-positive childhood acute lymphoblastic leukemia. Vesely C, Frech C, Eckert C, Cario G, Mecklenbräuker A, Zur Stadt U, Nebral K, Kraler F, Fischer S, Attarbaschi A, Schuster M, Bock C, Cavé H, von Stackelberg A, Schrappe M, Horstmann MA, Mann G, Haas OA, Panzer-Grümayer R. Leukemia. 2017 Jul;31(7):1491-1501. Genomics and drug profiling of fatal TCF3-HLF-positive acute lymphoblastic leukemia identifies recurrent mutation patterns and therapeutic Options. Fischer U, Forster M, Rinaldi A, Risch T, Sungalee S, Warnatz HJ, Bornhauser B, Gombert M, Kratsch C, Stütz AM, Sultan M, Tchinda J, Worth CL, Amstislavskiy V, Badarinarayan N, Baruchel A, Bartram T, Basso G, Canpolat C, Cario G, Cavé H, Dakaj D, Delorenzi M, Dobay MP, Eckert C, Ellinghaus E, Eugster S, Frismantas V, Ginzel S, Haas OA, Heidenreich O, Hemmrich-Stanisak G, Hezaveh K, Höll JI, Hornhardt S, Husemann P, Kachroo P, Kratz CP, Te Kronnie G, Marovca B, Niggli F, McHardy AC, Moorman AV, Panzer-Grümayer R, Petersen BS, Raeder B, Ralser M, Rosenstiel P, Schäfer D, Schrappe M, Schreiber S, Schütte M, Stade B, Thiele R, von der Weid N, Vora A, Zaliova M, Zhang L, Zichner T, Zimmermann M, Lehrach H, Borkhardt A, Bourquin JP, Franke A, Korbel JO, Stanulla M, Yaspo ML. Nat. Genet. 2015 Sep;47(9):1020-1029.