Page 243 - 2021_03-Haematologica-web

Letters to the Editor
Other recurrently somatically affected genes were PAX5 (n=2) and TP53 (n=2). One patient harbored the IGH-CEBPA fusion, which was also found in an addition- al patient at relapse (unfortunately, in this patient we could not investigate its presence at initial diagnosis). Of note, a recent transcriptomic study described a rare sub- group of BCP-ALL defined by gene expression signature, which was enriched for the ZEB2 H1038 mutation and the IGH-CEBPE fusion (likely functionally similar to IGH-CEBPA).3 However, unlike in our patients, these two genetic lesions did not co-occur in individual patients with the respective gene expression signature in the cited study. Last but not least, three of 32 patients harbored additional aberrations of ZEB2 itself: a missense mutation affecting the second allele was found in one patient and out-of-frame fusions predicted to result in C-terminal truncation and modification of the ZEB2 protein were found in two patients (Table 1, Online Supplementary Figure S2); in both, the H1038 mutation was located on the rearranged allele.
We further utilized RNA sequencing data to analyze the potential presence of gene expression signatures associated with ZEB2mut. Unsupervised hierarchical clustering analyses revealed clusters that were enriched for either Q1072 or H1038 ZEB2mut (Figure 2). None of these clusters involved all patients with the respective ZEB2mut, and, moreover, the “H1038 ZEB2mut cluster” involved additional patients without ZEB2mut. Thus, ZEB2mut seems to impact the gene expression signature, albeit less specifically and prominently compared to (at least some) subtype-defining genetic lesions (e.g., DUX4r, ETV6-RUNX1).9,15 Whether the potential difference in gene expression signatures associated with H1038 versus Q1072 ZEB2mut truly derives from the ZEB2mut type or whether it is (also) attributable to differences in the spec- tra of accompanying genetic lesions remains unclear.
In summary, in this study we determined the frequency of H1038/Q1072 ZEB2mut in newly diagnosed and relapsed cases of pediatric B-other ALL and the impact of these mutations on outcome. While the discovery part of the study suggested that ZEB2mut is a potential risk fac- tor, and the overall data from the discovery plus valida- tion cohorts also confirmed significant enrichment of ZEB2mut in relapsed cases (26/857 at diagnosis vs. 13/138 at relapse; P=0.0013), the original finding was only partly validated in independent cohorts. We may only speculate whether differences in treatment between the AIEOP-BFM ALL 2000 and 2009 protocols, potential selection biases in validation cohorts (that were non-con- secutive and the validation relapse cohort did not include isolated extramedullary relapses) and/or small numbers of ZEB2mut-positive patients could have contributed to these partially discordant findings. Although our study included more than 800 cases of newly diagnosed B-other ALL, the limited number of ZEB2mut-positive patients did not allow us to analyze the potential associ- ation of all biological and clinical features on relapse risk in deep detail. Nevertheless, we found no significant association between relapse occurrence and ZEB2mut type, ZEB2mut variant allele frequency, ALL subtype, concomitant genetic lesions, sex (although males tended to relapse more frequently than females: 70% vs. 32% relapse incidence, P=0.06), age, white blood cell count or risk. Given the relatively low frequency of ZEB2mut, and potential dependence of its prognostic impact on addi- tional genetic/clinical factors, other studies on well-char- acterized larger cohorts would be needed to further elu- cidate the clinical relevance of the mutations, as well as
biological studies addressing their functional conse- quences.
We found genetic and demographic differences between patients with distinct ZEB2 mutations. There are currently no experimental data supporting an assumption that distinct ZEB2mut types have the same (yet unknown) functional impact and biological conse- quences; moreover, ZB2 function can be further altered in patients with ZEB2 fusions. Thus, although we did not observe differences in relapse rate with respect to muta- tion type in our study, sub-analyses considering mutation types as separate entities should be emphasized in future studies.
Marketa Zaliova,1,2,3 Eliska Potuckova,1,2 Julius Lukes Jr,1,2 Lucie Winkowska,1,2 Julia Starkova,1,2 Iveta Janotova,3
Lucie Sramkova,1,2,3 Jan Stary,2,3 Jan Zuna,1,2,3
Martin Stanulla,4 Martin Zimmermann,4 Beat Bornhauser,5 Jean-Pierre Bourquin,5 Cornelia Eckert,6,7 Gunnar Cario8 and Jan Trka1,2,3
1CLIP: Childhood Leukemia Investigation Prague, Prague, Czech Republic; 2Department of Pediatric Hematology and Oncology, Second Faculty of Medicine, Charles University, Prague, Czech Republic; 3University Hospital Motol, Prague, Czech Republic; 4Department
of Pediatric Hematology and Oncology, Hannover Medical School, Hannover, Germany; 5Division of Pediatric Oncology, University Children's Hospital, Zürich, Switzerland; 6Department of Pediatric Oncology/Hematology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; 7German Cancer Consortium and German Cancer Research Center, Heidelberg, Germany and 8Department of Pediatrics, University Medical Center Schleswig- Holstein, Kiel, Germany
Correspondence:
MARKETA ZALIOVA - marketa.zaliova@lfmotol.cuni.cz JAN TRKA -jan.trka@lfmotol.cuni.cz doi:10.3324/haematol.2020.249094
Disclosures: no conflicts of interest to disclose.
Contributions: MZa and JT designed and led the study, MZa, EP, JL and LW performed molecular genetic analyses, MZa and MZi per- formed statistical analyses, MZ, JuS, IJ, LS, JaS, JZ, MS, MZi, BB, JPB, CE, GC and JT provided material, data and/or technologies. All authors participated in the data analysis and/or interpretation, MZ wrote the draft. All authors revised the draft and contributed to the final manuscript.
Funding: this study was supported by grants from the Czech Health Research Council (NV15-30626A) and Charles University (Primus/MED/28, UNCE 204012) and by the project (Ministry of Health, Czech Republic) for conceptual development of research organi- zation 00064203 (University Hospital Motol, Prague, Czech Republic). The research infrastructure was supported by the Ministry of Education, Youth and Sports (NPU I n. LO1604 and LM2015091).
References
1. Goossens S, Peirs S, Van Loocke W, et al. Oncogenic ZEB2 activation drives sensitivity toward KDM1A inhibition in T-cell acute lym- phoblastic leukemia. Blood. 2017;129(8):981-990.
2. Goossens S, Radaelli E, Blanchet O, et al. ZEB2 drives immature T- cell lymphoblastic leukaemia development via enhanced tumour- initiating potential and IL-7 receptor signalling. Nat Commun. 2015; 6:5794.
3. Li JF, Dai YT, Lilljebjorn H, et al. Transcriptional landscape of B cell precursor acute lymphoblastic leukemia based on an international study of 1,223 cases. Proc Natl Acad Sci U S A. 2018; 115(50):E11711-E11720.
4. Liu YF, Wang BY, Zhang WN, et al. Genomic profiling of adult and pediatric B-cell acute lymphoblastic leukemia. EBioMedicine. 2016; 8:173-183.
5. Schroeder MP, Bastian L, Eckert C, et al. Integrated analysis of
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