Jana Kotašková

miR-34a, miR-29c and miR-17-5p are downregulated in CLL patients with TP53 abnormalities.

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The planar cell polarity pathway drives pathogenesis of chronic lymphocytic leukemia by the regulation of B-lymphocyte migration.

The planar cell polarity (PCP) pathway is a conserved pathway that regulates cell migration and polarity in various contexts. Here we show that key PCP pathway components such as Vangl2, Celsr1, Prickle1, FZD3, FZD7, Dvl2, Dvl3, and casein kinase 1 (CK1)-ε are upregulated in B lymphocytes of patients with chronic lymphocytic leukemia (CLL). Elevated levels of PCP proteins accumulate in advanced stages of the disease. Here, we show that PCP pathway is required for the migration and transendothelial invasion of CLL cells and that patients with high expression of PCP genes, FZD3, FZD7, and PRICKLE1, have a less favorable clinical prognosis. Our findings establish that the PCP pathway acts as an important regulator of CLL cell migration and invasion. PCP proteins represent an important class of molecules regulating pathogenic interaction of CLL cells with their microenvironment.

Whole-exome sequencing in relapsing chronic lymphocytic leukemia: clinical impact of recurrent RPS15 mutations

Fludarabine, cyclophosphamide, and rituximab (FCR) is first-line treatment of medically fit chronic lymphocytic leukemia (CLL) patients; however, despite good response rates, many patients eventually relapse. Although recent high-throughput studies have identified novel recurrent genetic lesions in adverse prognostic CLL, the mechanisms leading to relapse after FCR therapy are not completely understood. To gain insight into this issue, we performed whole-exome sequencing of sequential samples from 41 CLL patients who were uniformly treated with FCR but relapsed after a median of 2 years. In addition to mutations with known adverse-prognostic impact (TP53, NOTCH1, ATM, SF3B1, NFKBIE, and BIRC3), a large proportion of cases (19.5%) harbored mutations in RPS15, a gene encoding a component of the 40S ribosomal subunit. Extended screening, totaling 1119 patients, supported a role for RPS15 mutations in aggressive CLL, with one-third of RPS15-mutant cases also carrying TP53 aberrations. In most cases, selection of dominant, relapse-specific subclones was observed over time. However, RPS15 mutations were clonal before treatment and remained stable at relapse. Notably, all RPS15 mutations represented somatic missense variants and resided within a 7 amino-acid, evolutionarily conserved region. We confirmed the recently postulated direct interaction between RPS15 and MDM2/MDMX and transient expression of mutant RPS15 revealed defective regulation of endogenous p53 compared with wild-type RPS15. In summary, we provide novel insights into the heterogeneous genetic landscape of CLL relapsing after FCR treatment and highlight a novel mechanism underlying clinical aggressiveness involving a mutated ribosomal protein, potentially representing an early genetic lesion in CLL pathobiology.

High Expression of Lymphocyte-Activation Gene 3 (LAG3) in Chronic Lymphocytic Leukemia Cells Is Associated with Unmutated Immunoglobulin Variable Heavy Chain Region (IGHV) Gene and Reduced Treatment-Free Survival

Chronic lymphocytic leukemia (CLL) is characterized by a monoclonal expansion of mature B-lymphocytes. Mutational status of the immunoglobulin variable heavy chain region (IGHV) gene stratifies CLL patients into two prognostic groups. We performed microarray analysis of CLL cells using the Agilent platform to detect the most important gene expression differences regarding IGHV status in CLL cells. We analyzed a cohort of 118 CLL patients with different IGHV mutational status and completely characterized all described prognostic markers using expression microarrays and quantitative real-time RT-PCR (reverse transcription PCR). We detected lymphocyte-activation gene 3 (LAG3) as a novel prognostic marker: LAG3 high expression in CLL cells correlates with unmutated IGHV (P < 0.0001) and reduced treatment-free survival (P = 0.0087). Furthermore, quantitative real-time RT-PCR analysis identified a gene-set (LAG3, LPL, ZAP70) whose overexpression is assigned to unmutated IGHV with 90% specificity (P < 0.0001). Moreover, high expression of tested gene-set and unmutated IGHV equally correlated with reduced treatment-free survival (P = 7.7 * 10(-11) vs. P = 1.8 * 10(-11)). Our results suggest that IGHV status can be precisely assessed using the expression analysis of LAG3, LPL, and ZAP70 genes. Expression data of tested markers provides a similar statistical concordance with treatment-free survival as that of the IGHV status itself. Our findings contribute to the elucidation of CLL pathogenesis and provide novel prognostic markers for possible application in routine diagnostics.

Additional trisomies amongst patients with chronic lymphocytic leukemia carrying trisomy 12: the accompanying chromosome makes a difference

Recurrent cytogenetic abnormalities in chronic lym- phocytic leukemia (CLL), namely deletions of chromo- somes 11q, 13q, 17p and trisomy 12 (+12), define sub- groups of patients with different clinical behavior and response to treatment. 1 We and others previously report- ed a minor proportion of CLL cases with co-existing tri- somies of chromosomes 12 and 19 who share specific clinico-biological characteristics. 2-4 However, since the cohort was small, no definitive conclusions could be drawn. Here, we analyzed a large, multi-institutional series. We confirm and significantly extend previous observations through the identification of subgroups of +12 CLL cases harboring particular concurrent trisomies demonstrating distinctive clinico-biological profiles. We analyzed an unselected cohort of 4486 CLL patients with available classic cytogenetic (n=4285) or high-density 250K single nucleotide polymorphism (SNP)-array (n=201) data. We identified 712 cases (16% of the cohort) carrying +12. 5 Median time from diagnosis to cytogenet- ic/SNP analysis was 1.5 months (range 0-194); the major- ity of cases included in survival analysis were untreated prior to testing (94%). The study was approved by the local Ethics Review Committees. Details of the study cohort and the methodologies used are provided in the Online Supplementary Appendix.

ROR1-based immunomagnetic protocol allows efficient separation of CLL and healthy B cells.

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia among adults in the Western world. This lymphoproliferative disorder is defined by the presence of at least 5 9 106 clonal lymphocytes/ml peripheral blood (Hallek,2015). The biggest clinical challenge is the fact that CLL eradication by any available therapy, apart from allogeneic stem cell transplantation, fails to cure the disease, inducing only temporary disease remission, i.e., when the disease does not manifest clinically but CLL cells still persist in the body. During this phase a population of CLL cells often slowly re-expands to trigger CLL relapse. The relapse is often based on the poorly understood but clinically important process of therapy-driven selection of more aggressive CLL subclones (Malcikova et al, 2015).

Inactivation of p53 and amplification of MYCN gene in a terminal lymphoblastic relapse in a chronic lymphocytic leukemia patient

B-cell chronic lymphocytic leukemia (CLL) is an incurable disease with a highly variable clinical course. A proportion of patients eventually progress to a higher stage of malignancy. A recent association has been observed between the presence of aberrant somatic hypermutations in leukemic cells (hypermutations occurring outside of the immunoglobulin locus) and the transformation to a diffuse large B-cell lymphoma or prolymphocytic leukemia. In this study, we report on the rarely observed blastic transformation in a CLL patient who had previously been shown to harbor aberrant somatic hypermutations in the TP53 tumor-suppressor gene (Mol Immunol 2008;45:1525-29). The enzyme responsible, the activation-induced cytidine deaminase, was still active within the transformation, as evidenced by the ongoing class-switch recombination of cytoplasmic immunoglobulins. The transformation was accompanied by a complete p53 inactivation, as well as complex karyotype changes including prominent amplification of MYCN oncogene. Our case-study supports the view that the aberrant somatic hypermutation is associated with transformation of CLL to a more aggressive malignancy.

Decreased WNT3 expression in chronic lymphocytic leukaemia is a hallmark of disease progression and identifies patients with worse prognosis in the subgroup with mutated IGHV

The canonical Wnt pathway, dependent on β‐catenin‐controlled transcription, is the most explored Wnt pathway, known to drive the malignant transformation of multiple cell types. Several reports have suggested that this pathway also participates in chronic lymphocytic leukaemia (CLL) pathogenesis. To get a better insight into the role of the Wnt/β‐catenin pathway in CLL we analysed in detail the expression of the most overexpressed Wnt ligand, encoded by the WNT3 gene, in a well‐defined cohort of 137 CLL patients. Our analysis demonstrated that (i) untreated patients with more aggressive disease (with a notable exception of patients with 11q deletion) express less WNT3, (ii) WNT3 declines with disease progression in a significant proportion of patients and (iii) low WNT3 was identified as a strong independent marker indicating shorter treatment‐free survival in CLL patients with IGHV mutation. Interestingly, CLL‐related lymphoid cell lines, but not stromal cells, failed to respond to the ligand‐induced activation of the Wnt/β‐catenin pathway. This opens the possibility that CLL cells use Wnt‐3 to communicate with the cells in the microenvironment. We thus propose that the Wnt/β‐catenin pathway plays a more complex role in CLL pathogenesis than previously anticipated.

Multiple productive IGH rearrangements denote oligoclonality even in immunophenotypically monoclonal CLL

Multiple productive IGH rearrangements denote oligoclonality even in immunophenotypically monoclonal CLL

Tailored approaches grounded on immunogenetic features for refined prognostication in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) patients with differential somatic hypermutation status of the immunoglobulin heavy variable genes, namely mutated or unmutated, display fundamental clinico-biological differences. Considering this, we assessed prognosis separately within mutated (M-CLL) and unmutated (U-CLL) CLL in 3015 patients, hypothesizing that the relative significance of relevant indicators may differ between these two categories. Within Binet A M-CLL patients, besides TP53 abnormalities, trisomy 12 and stereotyped subset #2 membership were equivalently associated with the shortest time-to-first-treatment and a treatment probability at five and ten years after diagnosis of 40% and 55%, respectively; the remaining cases exhibited 5-year and 10-year treatment probability of 12% and 25%, respectively. Within Binet A U-CLL patients, besides TP53 abnormalities, del(11q) and/or SF3B1 mutations were associated with the shortest time-to-first-treatment (5- and 10-year treatment probability: 78% and 98%, respectively); in the remaining cases, males had a significantly worse prognosis than females. In conclusion, the relative weight of indicators that can accurately risk stratify early-stage CLL patients differs depending on the somatic hypermutation status of the immunoglobulin heavy variable genes of each patient. This finding highlights the fact that compartmentalized approaches based on immunogenetic features are necessary to refine and tailor prognostication in CLL.