CLL biology and prognosis

Proteomics-Based Regression Model for Assessing the Development of Chronic Lymphocytic Leukemia

The clinical course of chronic lymphocytic leukemia (CLL) is very ambiguous, showing either an indolent nature of the disease or having latent dangerous progression, which, if diagnosed, will require an urgent therapy. The prognosis of the course of the disease and the estimation of the time of therapy initiation are crucial for the selection of a successful treatment strategy. A reliable estimating index is needed to assign newly diagnosed CLL patients to the prognostic groups. In this work, we evaluated the comparative expressions of proteins in CLL blood cells using a label-free quantification by mass spectrometry and calculated the integrated proteomic indexes for a group of patients who received therapy after the blood sampling over different periods of time. Using a two-factor linear regression analysis based on these data, we propose a new pipeline for evaluating model development for estimation of the moment of therapy initiation for newly diagnosed CLL patients.

Examination of clonal evolution in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is one of the most frequent lymphoproliferative diseases. CLL is characterized by unusual heterogeneity, which probably reflects its biological and genetic lack of homogeneity. Clonal chromosome aberrations belong to the most important prognostic and predictive factors in CLL. This research was aimed at observing clonal evolution in CLL at the chromosomal level, and assessing its clinical significance in relation to selected prognostic factors. The study involved 72 untreated patients with CLL. The preliminary investigations using cytogenetic banding analysis (CBA) and FISH were performed at the time of diagnosis, and again after about 24 months to observe clonal changes (clonal evolution). In addition, other parameters were evaluated, i.e., the expression of ZAP-70 kinase, CD38 antigen, and the mutation statuses of IGVH and NOTCH1 genes. Classic prognostic factors, i.e., categorized ZAP70 and CD38 expressions as well as mutations in IGVH and NOTCH1 genes did not influence the course of clonal evolution in the examined group of patients. Clonal evolution was detected in 45.8% of patients by means of CBA, and in 19.4% patients with FISH. Analysis of chromosomal aberrations in the examined group of patients showed that the incidence of 17p deletions and translocations in karyotypes has a negative impact on overall survival. CE was found to be a risk factor for the occurrence of disease progression (OR = 2.22). Our observations indicate that combined CBA and FISH are the most optimal techniques for monitoring clonal evolution in the course of CLL.

Definition of disease-progression risk stratification in untreated chronic lymphocytic leukemia using combined clinical, molecular and virological variables

Prognoses of persons with chronic lymphocytic leukemia (CLL) including time-to-therapy (TTT) and survival is heterogeneous. Risk factors and predictive scoring systems are mostly developed in persons of predominately European descent with CLL. Whether these systems accurately predict TTT and survival of Han Chinese with CLL is unknown. We interrogated clinical and laboratory data from 334 newly diagnosed, untreated Chinese CLL without treatment indication upon diagnosis to identify variables associated with TTT and develop a prognostic score. Binet stage, blood lymphocyte level, TP53 abnormality, unmutated IGHV, prior HBV, and EBV infections were independently associated with TTT in multivariate analyses. We constructed a prognostic score dividing subjects into cohorts with low, intermediate, and high risk from diagnosis to TTT. Median TTTs were 139 months (range, 85-189 months), 25 months (12-38 months), and 4 months (1-7 months; P-value for trend <0.001). We identified variables associated with TTT in Chinese with CLL with no treatment indication and developed a predictive model for survival. Some variables associated with TTT are similar to those of persons of predominately European descent, whereas others, such as HBV and/or EBV infections, operate in Chinese and Europeans but are not currently included in prognostic and predictive staging systems in persons of European descent. They should be investigated.

The International Prognostic Index for Patients with Chronic Lymphocytic Leukemia Has the Higher Value in Predicting Overall Outcome Compared with the Barcelona-Brno Biomarkers Only Prognostic Model and the MD Anderson Cancer Center Prognostic Index

In recent years, new prognostic indexes (PIs) for chronic lymphocytic leukemia (CLL), which include clinical, biological, and genetic variables, have been validated, highlighting the MD Anderson Cancer Center prognostic index (MDACC PI), the CLL-international prognostic index (CLL-IPI), and the Barcelona-Brno biomarkers only prognostic model. The aim of this study is to compare the utility of these PIs in a cohort of Spanish patients. A retrospective analysis of 696 unselected CLL patients newly diagnosed and previously untreated from different Spanish institutions was performed. The MDACC PI, the CLL-IPI, and the biomarkers only PI were applied to these patients, and a comparison of the three PIs was performed. With a median follow-up time of 46 months, 394 patients were alive and 187 had received treatment. The median overall survival (OS) was 173 months and the median time to first therapy (TTFT) was 32 months. Significant differences were obtained in OS and TTFT for all subgroups when applying these PIs, with the CLL-IPI being the one with the higher c-index (0.676 for OS and 0.757 for TTFT). The three PIs were able to discriminate patients in different prognostic subgroups. In our cohort, the CLL-IPI showed higher power in predicting TTFT and OS.

Advances in chronic lymphocytic leukemia pharmacotherapy

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease that affects B lymphocytes in most cases. Leukemic lymphocytes have prolonged longevity, defined by resistance to apoptosis. These cells can accumulate in peripheral blood, bone marrow, and solid lymphoid organs. CLL may be indolent or aggressive and has a range of prognostic factors such as expression of CD38 and ZAP-70, immunophenotypic and cytogenetic changes, imbalanced apoptosis proteins, and others. Although CLL has a low mortality rate, this disease is generally not considered curable until today. CLL treatment involves alkylating agents and glucocorticoids, purine analogs, monoclonal antibody therapies, and bone marrow transplantation. In recent decades, new drugs have appeared focusing on new targets and specific molecules, such as the BCR receptor, Bruton's tyrosine kinase, phosphatidylinositol 3-kinase, spleen tyrosine kinase, apoptosis proteins and microRNAs. The most appropriate treatment for CLL is one that involves in its protocol a combination of drugs according to the prognostic factors presented by each patient. In this sense, treatment individualization is essential. This article examines standard treatments for CLL and explores new treatments and potential new targets, as well as schematic protocols to understand where we are, how the treatment has evolved, and the advantages and disadvantages of new targets for CLL therapy.

Chronic Lymphocytic Leukemia Patient Clustering Based on Somatic Hypermutation (SHM) Analysis

Somatic Hypermutation (SHM) load in the immunoglobulin heavy variable (IGHV) gene of the clonotypic B cell receptor immunoglobulin (BcR IG) is one of the most important prognostic markers in CLL, segregating patients into two distinct categories, with contrariwise disease course. Over the last years, immunogenetic studies have identified that ∼30% of CLL patients carry (quasi)identical BcR IG and thus can be assigned to different subsets with distinct clinicobiological profiles. This characterization was achieved by applying rules mainly concerning the diversity of the VH complementarity determining region 3 (CDR3). Following, studies have also identified subset-specific somatic hypermutation further highlighting antigen selection in disease ontogeny and evolution. In this study, an innovative attempt to explore possible associations amongst SHMs in different CLL patients is implemented and also the potential correlations with VH CDR3 stereotypy is examined, leading to a new classification algorithm implicating both SHM and CDR3 patterns. All results are classified to a ground level analysis, focusing on the most frequent SHMs, their paired associated amino acid changes and the formation of subgroups sharing the same VH CDR3 pattern, the latter being used as a similarity metric. In addition, all results are compared to established VH CDR3 patterns of the well-known CLL subsets in order to confirm the validity of our findings.

Cytokine Contents in Chronic Lymphocytic Leukemia: Association with ZAP70 Expression

OBJECTIVE

Chronic lymphocytic leukemia (CLL) is a disease that shows varying clinical progression, and expression of the protein tyrosine kinase ZAP70 has been described as a very valuable prognostic factor. Patients with ZAP70 positivity are characterized by worse clinical course and significantly shorter progression-free and overall survival. In this study, intracytoplasmic interferon gamma (IFN-γ) and interleukin-4 (IL-4) content of T, B, and CLL cells in CLL patients and their correlations with Rai staging and ZAP70 positivity were investigated.

MATERIALS AND METHODS

CLL patients newly diagnosed or in follow-up at the İstanbul University İstanbul Medical Faculty Hematology Department were included in this study. These patients were classified according to Rai staging and ZAP70 expression. IL-4, IFN-γ, and ZAP70 expressions in peripheral blood T, B, and CLL cells were measured by four-color flow cytometry.

RESULTS

There was a statistically significant correlation between advanced disease and ZAP70 positivity. IL-4-secreting T cells were significantly increased; however, IFN-γ secretion was significantly decreased in CLL patients compared to healthy individuals, whereas IL-4-secreting B cells were significantly diminished in contrast to T cells.

CONCLUSION

These findings suggest damage in the cellular immunity and that IL-4 might lead to many complications and may be important in disease progression.

Association of Bax Expression and Bcl2/Bax Ratio with Clinical and Molecular Prognostic Markers in Chronic Lymphocytic Leukemia

Background

In chronic lymphocytic leukemia (CLL), in vivo apoptotic resistance of malignant B lymphocytes results, in part, from the intrinsic defects of their apoptotic machinery. These include genetic alterations and aberrant expression of many apoptosis regulators, among which the Bcl2 family members play a central role.

Aim

The aim of this study was to investigate the association of pro-apoptotic Bax gene expression and Bcl2/Bax ratio with the clinical features of CLL patients as well as with molecular prognostic markers, namely the mutational status of rearranged immunoglobulin heavy variable (IGHV) genes and lipoprotein lipase (LPL) gene expression.

Methods

We analyzed the expression of Bax mRNA and Bcl2/Bax mRNA ratio in the peripheral blood mononuclear cells of 58 unselected CLL patients and 10 healthy controls by the quantitative reverse-transcriptase polymerase chain reaction.

Results

We detected significant Bax gene overexpression in CLL samples compared to non-leukemic samples (p=0.003), as well as an elevated Bcl2/Bax ratio (p=<0.001). Regarding the association with prognostic markers, the Bcl2/Bax ratio showed a negative correlation to lymphocyte doubling time (r=-0.307; p=0.0451), while high-level Bax expression was associated with LPL-positive status (p=0.035). Both the expression of Bax and Bcl2/Bax ratio were higher in patients with unmutated vs. mutated IGHV rearrangements, but this difference did not reach statistical significance.

Conclusions

Our results suggest that dysregulated expression of Bcl2 and Bax, which leads to a high Bcl2/Bax ratio in leukemic cells, contributes to the pathogenesis and clinical course of CLL.

Protein kinase C in cellular transformation: a valid target for therapy?

The protein kinase C (PKC) family of serine/threonine protein kinases share structural homology, while exhibiting substantial functional diversity. PKC isoforms are ubiquitously expressed in tissues which makes it difficult to define roles for individual isoforms, with complexity compounded by the finding that PKC isoforms can co-operate with or antagonize other PKC family members. A number of studies suggest the involvement of PKC family members in regulating leukaemic cell survival and proliferation. Chronic lymphocytic leukaemia (CLL), the most common leukaemia in the Western world, exhibits dysregulated expression of PKC isoforms, with recent reports indicating that PKCβ and δ play a critical role in B-cell development, due to their ability to link the B-cell receptor (BCR) with downstream signalling pathways. Given the prognostic significance of the BCR in CLL, inhibition of these BCR/PKC-mediated signalling pathways is of therapeutic relevance. The present review discusses the emerging role of PKC isoforms in the pathophysiology of CLL and assesses approaches that have been undertaken to modulate PKC activity.

Generation of a poor prognostic chronic lymphocytic leukemia-like disease model: PKCα subversion induces up-regulation of PKCβII expression in B lymphocytes

Overwhelming evidence identifies the microenvironment as a critical factor in the development and progression of chronic lymphocytic leukemia, underlining the importance of developing suitable translational models to study the pathogenesis of the disease. We previously established that stable expression of kinase dead protein kinase C alpha in hematopoietic progenitor cells resulted in the development of a chronic lymphocytic leukemia-like disease in mice. Here we demonstrate that this chronic lymphocytic leukemia model resembles the more aggressive subset of chronic lymphocytic leukemia, expressing predominantly unmutated immunoglobulin heavy chain genes, with upregulated tyrosine kinase ZAP-70 expression and elevated ERK-MAPK-mTor signaling, resulting in enhanced proliferation and increased tumor load in lymphoid organs. Reduced function of PKCα leads to an up-regulation of PKCβII expression, which is also associated with a poor prognostic subset of human chronic lymphocytic leukemia samples. Treatment of chronic lymphocytic leukemia-like cells with the selective PKCβ inhibitor enzastaurin caused cell cycle arrest and apoptosis both in vitro and in vivo, and a reduction in the leukemic burden in vivo. These results demonstrate the importance of PKCβII in chronic lymphocytic leukemia-like disease progression and suggest a role for PKCα subversion in creating permissive conditions for leukemogenesis.

Immunogenetic studies of chronic lymphocytic leukemia: revelations and speculations about ontogeny and clinical evolution

Over the last decade, immunogenetic analysis of B-cell receptor immunoglobulins (BcR IG) has proved instrumental in dissecting chronic lymphocytic leukemia (CLL) pathogenesis. Initially, it was the finding that the level of somatic hypermutations in rearranged IG heavy-chain genes could define two CLL subtypes associated with a different clinical course that drew attention. As the years ensued, this not only continued to hold strong, but also revealed an unprecedented BcR restriction (aptly coined as "stereotypy"), thus cementing the idea that antigenic elements select the leukemic clones. With all this in mind, in the present review, we focus on the CLL BcR IG, a molecule that clearly lies at the heart of disease pathogenesis, and attempt to distil from past and emerging biologic knowledge the most relevant aspects in the context of the immunogenetics of CLL, while at the same time provoking questions that remain unanswered. We juxtapose CLL with mutated BcR IGs against CLL with unmutated BcR IGs due to their striking clinicobiologic differences; however, when considering ontogeny, common derivation of the two mutational subtypes cannot be excluded. The issue of stereotypy is intertwined throughout and we also raise the subject of isotype-switched CLL, which, despite its rarity, contributes intriguing ontogenetic hints.

T/B ratio does not reflect levels of ZAP70 expression in clonal CLL B-cells due to ZAP70 overexpression in patient T-cells

Flow cytometry is the reference technique for assessing ZAP70 expression, a marker of poor prognosis in CLL. One of the most common methods is to assess ZAP70 levels in CLL cells by calculating the ratio between ZAP70 mean fluorescence intensities (MFIs) in residual T-cells and CLL B-cells (ZAP70 T/B ratio). In this study, we developed a new method for ZAP70 labeling. Cells were labeled with a combination of anti ZAP70 phycoerythrin-conjugated SBZAP monoclonal antibody (mAb) and mAbs against CD45, CD19, and CD5. The latter three were used to specifically gate on different lymphocyte subsets. Staining was performed in absence (test) or in presence of excess unconjugated SBZAP mAb (isoclonic control). A so-called ZAP70 isoclonic ratio between SBZAP MFIs in the test and isoclonic control was calculated. A series of 32 patients with CLL and 10 normal controls were studied. Prediction of IGHV mutation status by ZAP70 isoclonic and T/B ratios was similar. By using the ZAP70 isoclonic ratio, we showed that ZAP70 expression was increased in T-cells from CLL patients. Nearly all cases with increased ZAP70 expression in CLL cells were associated with high ZAP70 expression in cognate T-cells. Therefore, the ZAP70 isoclonic ratio was more likely to closely reflect the biology of ZAP70 dysregulation rather than the T/B ratio. These results also explained why ZAP70 T/B ratios were artefactually close to normal in cells from CLL patients with high levels of ZAP70.

A possible role for oxidation stress in lymphoid leukaemias and therapeutic failure

The aim of this study was to evaluate the role of oxidative stress in the pathobiology of lymphoid leukaemias and its involvement in leukaemic relapse. For this purpose the generation of peroxides by mononuclear cells, the erythrocyte activity of superoxide-dismutase (SOD) and glutathione peroxidase (GL-PX), and the plasma levels of reduced glutathione (GSH) and vitamin E (VIT E) were determined in 52 patients with two different types of lymphoid leukaemias, chronic lymphocytic leukaemia (CLL) and acute lymphoblastic leukaemia (ALL), 36 prior to chemotherapy and 16 treated patients. A decrease in SOD and GL-PX activities was observed in ALL patients prior to therapy, while a decrease in GSH and VIT E plasma levels was observed in untreated CLL, as compared to age-matched controls. An increase in peroxides formation occurred in both types of leukaemia, as compared to age-matched controls. There are significant differences for GSH, VIT E and peroxides generation between the different types of leukaemias. In relapsed ALL patients a decrease in peroxides generation was observed which may be due to the increase of the non-enzymatic defences GSH and VIT E. These data suggest the involvement of oxidative stress in acute and chronic lymphoid leukaemias and leukaemic relapse.

Relevance of stereotyped B-cell receptors in the context of the molecular, cytogenetic and clinical features of chronic lymphocytic leukemia

Highly homologous B-cell receptors, characterized by non-random combinations of immunoglobulin heavy-chain variable (IGHV) genes and heavy-chain complementarity determining region-3 (HCDR3), are expressed in a recurrent fraction of patients affected by chronic lymphocytic leukemia (CLL). We investigated the IGHV status of 1131 productive IG rearrangements from a panel of 1126 CLL patients from a multicenter Italian study group, and correlated the presence and class of HCDR3 stereotyped subsets with the major cytogenetic alterations evaluated by FISH, molecular prognostic factors, and the time to first treatment (TTFT) of patients with early stage disease (Binet A). Stereotyped HCDR3 sequences were found in 357 cases (31.7%), 231 of which (64.7%) were unmutated. In addition to the previously described subsets, 31 new putative stereotypes subsets were identified. Significant associations between different stereotyped HCDR3 sequences and molecular prognostic factors, such as CD38 and ZAP-70 expression, IGHV mutational status and genomic abnormalities were found. In particular, deletion of 17p13 was significantly represented in stereotype subset #1. Notably, subset #1 was significantly correlated with a substantially reduced TTFT compared to other CLL groups showing unmutated IGHV, ZAP-70 or CD38 positivity and unfavorable cytogenetic lesions including del(17)(p13). Moreover, subset #2 was strongly associated with deletion of 13q14, subsets #8 and #10 with trisomy 12, whereas subset #4 was characterized by the prevalent absence of the common cytogenetic abnormalities. Our data from a large and representative panel of CLL patients indicate that particular stereotyped HCDR3 sequences are associated with specific cytogenetic lesions and a distinct clinical outcome.

A phase I study of imatinib mesylate in combination with chlorambucil in previously treated chronic lymphocytic leukemia patients

PURPOSE

The tyrosine kinase inhibitor, imatinib, has the potential to indirectly inhibit DNA repair. This mechanism of action has been shown to mediate sensitization to chlorambucil in chronic lymphocytic leukemia (CLL). To evaluate this effect in vivo, we performed a phase I study of chlorambucil combined with imatinib in relapsed CLL patients.

METHODS

The three dose levels studied included imatinib at 300, 400, or 600 mg/day. Imatinib was given on days 1-10, and chlorambucil (8 mg/m(2) daily) was given on days 3-7 of a 28-day cycle (up to 6 cycles).

RESULTS

Eleven patients participated in this study. Low-grade gastrointestinal toxicities were observed in a dose-dependent manner. Forty-five percent of patients responded (two unconfirmed CRs and three PRs). Two responding patients were fludarabine refractory. The in vitro IC(50) of chlorambucil alone or in the presence of 5 μM imatinib in CLL lymphocytes correlated with the decrease in lymphocyte counts on day 15. Imatinib plasma concentrations achieved in patients were in the range of those effective in in vitro sensitization studies.

CONCLUSION

The combination of chlorambucil and imatinib in patients with previously treated CLL was well tolerated and showed evidence of clinical efficacy. Based on our results, we recommend the 400 mg daily dose of imatinib on days 1-10 with 8 mg/m(3) chlorambucil on days 3-7 every 28 days as the phase II dose. This represents the first clinical trial examining the potential synergy between a tyrosine kinase inhibitor and a conventional alkylating agent for the treatment of CLL.

Telomere dysfunction and fusion during the progression of chronic lymphocytic leukemia: evidence for a telomere crisis

We performed single-molecule telomere length and telomere fusion analysis in patients at different stages of chronic lymphocytic leukemia (CLL). Our work identified the shortest telomeres ever recorded in primary human tissue, reinforcing the concept that there is significant cell division in CLL. Furthermore, we provide direct evidence that critical telomere shortening, dysfunction, and fusion contribute to disease progression. The frequency of short telomeres and fusion events increased with advanced disease, but importantly these were also found in a subset of early-stage patient samples, indicating that these events can precede disease progression. Sequence analysis of fusion events isolated from persons with the shortest telomeres revealed limited numbers of repeats at the breakpoint, subtelomeric deletion, and microhomology. Array-comparative genome hybridization analysis of persons displaying evidence of telomere dysfunction revealed large-scale genomic rearrangements that were concentrated in the telomeric regions; this was not observed in samples with longer telomeres. The telomere dynamics observed in CLL B cells were indistinguishable from that observed in cells undergoing crisis in culture after abrogation of the p53 pathway. Taken together, our data support the concept that telomere erosion and subsequent telomere fusion are critical in the progression of CLL and that this paradigm may extend to other malignancies.

Multiplex ligation-dependent probe amplification versus multiprobe fluorescence in situ hybridization to detect genomic aberrations in chronic lymphocytic leukemia: a tertiary center experience

Cytogenetic abnormalities play a major role in the prognosis of patients with chronic lymphocytic leukemia (CLL). Several methods have emerged to try to best identify these abnormalities. We used fluorescence in situ hybridization (FISH) to determine the frequency of cytogenetic changes in our CLL patient population. We also evaluated the effectiveness of multiplex ligation-dependent probe amplification (MLPA) in detecting these abnormalities. Sixty-two B-CLL patients and 20 healthy controls were enrolled, and FISH and MLPA analyses were performed on peripheral blood samples. Using FISH, genomic aberrations were found in 73% of patients and presented as follows: single 13q14.3 deletion (60%), trisomy 12 (7%), ATM deletion (6%), 17p13.1 deletion (2%). MLPA analyses done on 61/62 patients showed sensitivity and specificity values of 90% and 100% respectively. MLPA revealed several additional copy number changes, the most common being 19p13 (LDLR and CDKN2D). Moreover, the cost for MLPA analysis, including technical time and reagents, is 86% less than FISH. In conclusion, cytogenetic abnormalities are a common finding in CLL patients, and MLPA is a reliable approach that is more cost effective and faster than FISH. Despite MLPA limitations of sensitivity, it can be used as a first-line screen and complementary test to FISH analysis.

Successful long-term monotherapy with rituximab in a patient with chronic lymphocytic leukemia of the B-cell-lineage: a case report

Introduction

Treatment of chronic lymphocytic leukemia of the B-cell-lineage is strongly based upon clinical staging because of the heterogeneous clinical course of this disease.

Case presentation

We describe a 62-year-old patient with newly diagnosed chronic lymphocytic leukemia of the B-cell-lineage who did not respond to several chemotherapy regimens including chlorambucil, fludarabine and cyclophosphamide, developing a marked neutropenia and thrombocytopenia with life-threatening infections. Further chemotherapy appeared not feasible because of bone marrow toxicity. The patient was treated with 600 mg/m² rituximab weekly followed by eight courses of biweekly therapy and then by long-term maintenance therapy, achieving almost complete remission of the symptoms and disease control.

Conclusion

After resistance to standard chemotherapy with chlorambucil and fludarabine, a patient with chronic lymphocytic leukemia of the B-cell-lineage was successfully treated with rituximab.

Calorimetric study as a potential test for choosing treatment of B-cell chronic lymphocytic leukemia

Differential scanning calorimetry (DSC) and complementary techniques were utilized to evaluate the sensitivity of B-cell chronic lymphocytic leukemia (B-CLL) cell samples in vitro exposed to cladribine or fludarabine in combination with mafosfamide. Mafosfamide, the active in vitro form of cyclophosphamide with both purine analogs produced the cytotoxic effect on mononuclear cell probes, however, to a different degree. Our results indicated that higher sensitivity of examined leukemic cell samples to the used drug combinations was usually accompanied by a marked decrease or even a complete loss of thermal transition at 95+/-3 degrees C in DSC scans of nuclear preparations as well as by more significant reduction of cell viability, higher extent of DNA damage estimated by the comet assay and by dropping/disappearance of anti-apoptotic protein Mcl-1 in comparison with untreated cells. We have also observed that the reduction of transition at 95+/-3 degrees C in thermal scans of nuclear preparations isolated from blood of B-CLL randomized patients who showed response to cladribine or fludarabine combined with cyclophosphamide, i.e., CC and FC, respectively, corresponded with the decrease or disappearance of anti-apoptotic proteins Bcl-2 and/or Mcl 1. In conclusion, these in vitro and in vivo studies revealed that quick DSC technique, usually supplemented by other methods, is a potent tool to distinguish efficacy of B-CLL treatment and could be helpful in choosing the most effective manner of treatment for this type of leukemia.

Relative value of ZAP-70, CD38, and immunoglobulin mutation status in predicting aggressive disease in chronic lymphocytic leukemia

Leukemia-cell expression of ZAP-70, CD38, or unmutated immunoglobulin heavy chain variable region genes (U-IGHV) each is associated with aggressive disease in patients with chronic lymphocytic leukemia (CLL). To assess the relative strength of each marker, we defined thresholds for designating a case as positive for CD38 or ZAP-70 in a test cohort of 307 patients and used these data-defined criteria to stratify patients in an independent cohort of 705 patients. Multivariable analysis revealed that ZAP-70 was the strongest risk factor. Knowledge of the IGHV mutation status or CD38 did not improve our ability to predict the time to first treatment except for ZAP-70-negative cases, which could be segregated into 2 groups of intermediate-risk or low-risk disease based on whether they expressed unmutated or mutated IGHV. ZAP-70 maintained its high relative prognostic value for the subset of patients with early-stage, asymptomatic disease, including patients evaluated within 1 year of diagnosis. Although it is premature to recommend therapy based on these risk factors, patients with ZAP-70-positive CLL cells should be monitored closely for disease progression as they have a median time from diagnosis to requiring initial therapy by standard criteria of approximately 3 years.

Immunoglobulin diversity gene usage predicts unfavorable outcome in a subset of chronic lymphocytic leukemia patients

Survival of patients with B cell chronic lymphocytic leukemia (B-CLL) can be predicted by analysis of mutations in the immunoglobulin heavy chain variable gene (IGHV). Patients without mutations (unmutated [UM]) are at greater risk for disease progression and death than patients with mutations (M). Despite this broad prognostic difference, there remains wide intragroup variation in the clinical outcome of UM patients, especially those with low/intermediate Rai risk disease. We evaluated UM B-CLL patients with low/intermediate Rai risk to determine the relationship between IGHV, IGH diversity (IGHD), and IGH joining (IGHJ) gene usage and time to treatment (TTT). Irrespective of IGHV usage, UM patients whose B-CLL cells expressed the IGHD3-3 gene had a significantly shorter TTT than other UM B-CLL patients, and specifically, use of the IGHD3-3 gene in reading frame 2 (RF2) predicted shorter TTT. As expected, Rai risk was the best single prognostic factor for TTT; however, IGHD usage was also a significant variable for TTT. Therefore, both IGHD gene and IGHD RF usage have prognostic relevance in UM B-CLL patients with low/intermediate Rai risk disease. In addition, these data support the concept that antigen-driven selection of specific Ig receptors plays a role in the clinical course of B-CLL.

Murine models for chronic lymphocytic leukaemia

CLL (chronic lymphocytic leukaemia) is characterized by the clonal outgrowth of B-lymphocytes with the distinctive phenotype: CD19(hi)CD5(+)CD23(+)IgM(lo). These malignant B-cells accumulate in the PB (peripheral blood) and lymphoid organs, and are generally arrested at the G(0)/G(1)-phase of cell cycle and display a resistance to apoptosis. To date, most of the CLL research has been carried out using PB samples obtained from patients with established CLL, which have proved instrumental in characterizing the disease. However, while CLL cells appear to have a defect in apoptosis in vivo, they rapidly undergo apoptosis ex vivo, suggesting that CLL cells are dependent on microenvironmental signals to enhance cell survival. One approach used to define the cellular and molecular events that govern CLL has been the development of murine models that replicate the human disease. As well as providing a deeper understanding of the potential triggers for CLL, these models provide preclinical in vivo systems to test novel therapies. The focus of the present review will be to highlight the recent advances in the development of mouse models for CLL.

Stereotyped patterns of somatic hypermutation in subsets of patients with chronic lymphocytic leukemia: implications for the role of antigen selection in leukemogenesis

Somatic hypermutation (SHM) features in a series of 1967 immunoglobulin heavy chain gene (IGH) rearrangements obtained from patients with chronic lymphocytic leukemia (CLL) were examined and compared with IGH sequences from non-CLL B cells available in public databases. SHM analysis was performed for all 1290 CLL sequences in this cohort with less than 100% identity to germ line. At the cohort level, SHM patterns were typical of a canonical SHM process. However, important differences emerged from the analysis of certain subgroups of CLL sequences defined by: (1) IGHV gene usage, (2) presence of stereotyped heavy chain complementarity-determining region 3 (HCDR3) sequences, and (3) mutational load. Recurrent, “stereotyped” amino acid changes occurred across the entire IGHV region in CLL subsets carrying stereotyped HCDR3 sequences, especially those expressing the IGHV3-21 and IGHV4-34 genes. These mutations are underrepresented among non-CLL sequences and thus can be considered as CLL-biased. Furthermore, it was shown that even a low level of mutations may be functionally relevant, given that stereotyped amino acid changes can be found in subsets of minimally mutated cases. The precise targeting and distinctive features of somatic hypermutation (SHM) in selected subgroups of CLL patients provide further evidence for selection by specific antigenic element(s).

Molecular heterogeneity in chronic lymphocytic leukemia is dependent on BCR signaling: clinical correlation

Chronic lymphocytic leukemia (CLL), the most frequent form of adult leukemia in Western countries, is characterized by a highly variable clinical course. Expression profiling of a series of 160 CLL patients allowed interrogating the genes presumably playing a role in pathogenesis, relating the expression of functionally relevant signatures with the time to treatment. First, we identified genes relevant to the biology and prognosis of CLL to build a CLL disease-specific oligonucleotide microarray. Second, we hybridized a training series on the CLL-specific chip, generating a biology-based predictive model. Finally, this model was validated in a new CLL series. Clinical variability in CLL is related with the expression of two gene clusters, associated with B-cell receptor (BCR) signaling and mitogen-activated protein kinase (MAPK) activation, including nuclear factor-kappaB1 (NF-kappaB1). The expression of these clusters identifies three risk-score groups with treatment-free survival probabilities at 5 years of 83, 50 and 17%. This molecular predictor can be applied to early clinical stages of CLL. This signature is related to immunoglobulin variable region somatic hypermutation and surrogate markers. There is a molecular heterogeneity in CLL, dependent on the expression of genes defining BCR and MAPK/NF-kappaB clusters, which can be used to predict time to treatment in early clinical stages.

Functional variations in the JWA gene are associated with increased odds of leukemias

The association between the -76G>C in the 5'-flanking region and 723T>G in JWA exon three variants were examined for risk of leukemia development in a hospital-based case-control study of 201 leukemia patients and 243 cancer-free controls in a Chinese population. Studies showed that the -76C allele was associated with significantly increased odds of leukemia but the 723G allele was correlated with marked decreased odds of leukemia. Variation in the -76C allele resulted in almost complete loss of oxidative stress stimulated transcription activities of the promoter fragment.

Bortezomib induces different apoptotic rates in B-CLL cells according to IgVH and BCL-6 mutations

BACKGROUND

B-cell chronic lymphocytic leukemia (B-CLL) is a remarkably heterogeneous disorder. Some patients have an indolent disease whereas others undergo a more agressive presentation needing treatment. New therapeutics approaches are necessary for the treatment of B-CLL. Bortezomib (Btz), is a proteasome inhibitor, currently undergoing clinical trials whose function, at least in part, by stabilizing the IkappaBalpha protein and inhibiting NFkappaB activation.

OBJECTIVE

The objective of this work was to study the effects of Btz on isolated human B-CLL cells, in vitro, and to correlate the differential rates of apoptosis induction with biological variables.

MATERIAL AND METHODS

31 B-CLL samples, from patients in stage A of Binet were used for this study, and the apoptotic effect of Btz on these cells was measured.

RESULTS

Our data show that Btz treatment of B-CLL cells induces apoptosis in a time and dose-dependent manner. The apoptosis induction is mediated in part by inhibition of NFkappaB and is dependent on caspases activation. Interesting, in IgVH mutated cells, Btz have statistically significant differences in their in vitro activity on B-CLL cells according to their BCL-6 mutational status.

CONCLUSIONS

Btz is a promising pharmacologic agent for the treatment of B-CLL, but its efficacy seems to be related to IgVH and BCL-6 mutational status, therefore, it could be interesting to further investigate the mechanisms involved in the different behavior of the cells in response to apoptosis induction by this drug.

Correlation of ZAP-70 expression in B cell leukemias to the ex vivo response to a combination of fludarabine/genistein

The role of ZAP-70 expression on the ex vivo response of blood cells from CLL and PLL patients to a combination of fludarabine, a purine analog, and genistein, a tyrosine kinase inhibitor was studied. Patient cells were studied for the expression of ZAP-70 mRNA and its relation to the induction of apoptosis in response to treatment with genistein 15-60 muM and/or fludarabine 3 muM. The combination of genistein and fludarabine resulted in a significantly increased induction of apoptosis relative to the fludarabine alone. The ex vivo patient cells with a high ZAP-70 expression underwent more apoptosis in response to genistein than did patient cells with a low ZAP-70 mRNA expression. In contrast, basal IL-10 mRNA expression correlated negatively with apoptosis induction in response to genistein (P < 0.01). These studies suggest that, in malignant B cells that express elevated levels of the ZAP-70 signaling molecule, genistein may inhibit the ZAP-70 tyrosine kinase activity, resulting in cell death. The ZAP-70 may serve as a target for therapy. In addition, these studies suggest that the IL-10 expression by malignant B cells may not only suppress anti-tumor T cell responses in vivo, but also promote the survival of malignant B cells despite treatment with chemotherapeutic agents.

Comparison of methods for determining zeta-chain associated protein – 70 (ZAP-70) expression in patients with B-cell chronic lymphocytic leukemia (B-CLL)

BACKGROUND

Zeta-chain associated protein of 70kDa (ZAP-70) is the most promising surrogate marker for the immunoglobulin heavy chain variable region (IgV(H)) mutation status in B-cell chronic lymphocytic leukemia (B-CLL). Crespo et al. proposed the detection of ZAP-70 by flow cytometry. Recently several novel monoclonal antibodies appeared on market.

METHODS

We compared different staining methods utilizing monoclonal antibodies (moAb) against ZAP-70: anti-ZAP-70 PE, clone 1E7.2, anti-ZAP-70 PE, clone 17A/P-ZAP70 directly stained with flourochrome as well as anti-ZAP-70 antibody, clone 2F3.2 stained with Zenontrade mark Alexa Fluor(R) 488 Labeling Kit. Additionally different reagents for permeabilization such as IntraPrep, FIX & PERM, Perm/Wash and 70% ethanol/paraformaldehyde were used to find the most clinically relevant and easy assay to determine ZAP-70 expression in B-CLL. Moreover we compared results of ZAP-70 expression assessed by whole blood protocol with those obtained using-peripheral mononuclear cells isolated from whole blood.

RESULTS

Anti-ZAP-70 moAb clone 17A/P-ZAP70 gave elevated results for all B-CLL patients as well as healthy controls. Staining with anti-ZAP-70 moAb clone 1E7.2 and anti-ZAP-70 moAb clone 2F3.2 was effective in distinguishing negative and positive cells for ZAP-70 protein expression. Not statistically significant discrepancies of ZAP-70 expression were noticed between different fixation and permeabilization methods.

CONCLUSION

Basing on results obtained during this study we can recommend use of anti-ZAP-70 PE, clone 1E7.2 moAb utilizing whole blood protocol with commercial kits for permeabilization as an easy method that brings compatible results to the original method proposed by Crespo et al.