Clinical utility of molecular and flow cytometric markers in chronic lymphocytic leukaemia

Background: Chronic lymphocytic leukaemia (CLL) is a clinically heterogeneous disease. While immunoglobulin variable region heavy chain (IgVH) mutational status remains the ‘gold standard’ in molecular prognostication, a range of additional markers is increasingly being used in clinical trials. As awareness of trial data increases, requests to determine these prognostic markers for new CLL patients are becoming more prevalent in Australia. Aim: To explore the clinical utility of currently available prognostic markers for CLL in an Australian cohort. Methods: IgVH mutational status and gene usage was determined and compared with other reported immunophenotypic markers, cytogenetics and clinical outcome as defined by treatment‐free survival (TFS), lymphocyte doubling time and clinical stage in a cohort of 65 CLL patients. Results: An unmutated IgVH gene, high expression of CD38, ZAP‐70, CD25, CD49d, CD54 or low expression of CD49c was associated with shorter TFS indicating an adverse clinical prognosis in our cohort. High expression of each of CD38, ZAP‐70, CD49d and CD54 was significantly associated with an unmutated IgVH gene; however, associations were not absolute. IgVH and CD25 expression retained their significance in multivariate analysis. Concordant CD25^high/IgVH unmutated CLL patients had the shortest median TFS interval (40 months) in our cohort. Conclusions: Molecular and immunophenotypic markers remain useful as adjuncts to clinical prognostication; however, as single parameters they are unable to dictate the timing of therapeutic intervention. The combined use of CD25 and IgVH mutational status may be clinically relevant to CLL prognostication while also providing insight into the biological pathways involved in disease progression.     

Copper levels in patients with hematological malignancies

BackgroundCopper levels are elevated in cancer patients compared to normal subjects. However, few studies have investigated the relationship between copper and hematological malignancies.Methods84 patients with hematological diseases were studied, along with 50 healthy individuals. Copper was measured by flame atomic absorption spectrometry. The patients were classified to 2 homogeneous groups, acute and chronic hematological neoplasms, respectively. For the patients with acute hematological malignancies, relapse and remission were investigated in relation to serum copper levels. For chronic hematological neoplasms, serum copper was connected either with stable or progressive disease. Zeta-chain-associated protein kinase 70 (ZAP70) and CD38 expression, along with the unmutated VH immunoglobulin genes (IgVH) status were also determined for the 22 chronic lymphocytic leukemia (CLL) patients.Results54 patients with relapse or progressive disease had elevated copper levels (mean value 1.8 mg/l), whereas 30 patients either in remission or in stable disease had normal copper levels (mean value 1.01 mg/l) (normal range 0.8–1.3 mg/l).ConclusionHence, our study indicates that serum elevated copper levels are associated with hematological malignancies either in relapse or in disease progression, whereas normal copper levels are linked with hematological neoplasms in remission or in stable disease. Furthermore, we report for the first time an association between high serum copper levels and several adverse prognostic markers in CLL, such as increased expression of ZAP70 and CD38, along with elevated percentage of unmutated IgVH.     

Comparison of flow cytometric methods for the measurement of ZAP‐70 expression in a routine diagnostic laboratory

Chronic lymphocytic leukaemia (CLL) follows a variable clinical course with patient survival ranging from only a few years despite treatment, to several decades in patients who may never require clinical intervention. Determination of the mutational status of a patient's immunoglobulin heavy chain variable region (Ig V_H) gene has been used to provide prognostic information, but this assay is not available in most laboratories. The discovery of the expression of the protein tyrosine kinase zeta‐associated protein (ZAP)‐70 in V_H‐unmutated CLL cases led to its proposal as a surrogate marker for V_H status. This study investigated the measurement of ZAP‐70 expression in CLL using different flow cytometric protocols. Two different antibodies and two different staining methods were compared. The Caltag ZAP‐70 antibody and Fix & Perm kit were the easiest to use and were the most sensitive and specific combination, with 91% concordance between ZAP‐70 expression and V_H status. Three patients (9%) were discordant (two V_H mutated/ZAP‐70 positive, and one V_H unmutated/ZAP‐70 negative). No correlation existed between CD38 and either ZAP‐70 expression or V_H status. Measurement of ZAP‐70 expression using the Caltag antibody/kit combination provides a standardized flow cytometric method that could be introduced into a routine CLL immunophenotyping panel in a clinical diagnostic laboratory.     

MFI ratio estimation of ZAP-70 in B-CLL by flow cytometry can be improved by considering the isotype-matched antibody signal

Introduction: The IgV_H mutational status of B‐cell chronic lymphocytic leukemia (B‐CLL) is of prognostic value. Expression of ZAP‐70 in B‐CLL is a surrogate marker for IgV_H unmutated (UM). As determination of IgV_H mutational status involves a methodology currently unavailable for most clinical laboratories, it is important to have available a reliable technique for ZAP‐70 estimation in B‐CLL. Flow cytometry (FC) is a convenient technique for this purpose. However, there is still no adequate way for data analysis, which would prevent the assignment of false positive or negative expression. Methods: We have modified the currently most accepted technique, which uses the ratio of the mean fluorescent index (MFI) of B‐CLL to T cells. The MFI for parallel antibody isotype staining is subtracted from the ZAP‐70 MFI of both B‐CLL and T cells. We validated this technique comparing the results obtained for ZAP‐70 expression by FC with those obtained with quantitative PCR for the same patients. Results: We applied the technique in a series of 53 patients. With this modification, a better correlation between ZAP‐70 expression and IgV_H UM was obtained. Conclusions: Thus, the MFI ratio B‐CLL/T cell corrected by isotype is a reliable analysis technique to estimate ZAP‐70 expression in B‐CLL.     

ZAP‐70 expression is associated with increased risk of autoimmune cytopenias in CLL patients

Autoimmune cytopenias (AIC) are frequent in chronic lymphocytic leukemia (CLL) patients, but risk factors and prognostic relevance of these events are controversial. Data about the influence on AIC of biological prognostic markers, as ZAP‐70, are scanty. We retrospectively evaluated AIC in 290 CLL patients tested for ZAP‐70 expression by immunohistochemistry on bone marrow biopsy at presentation. They were 185 men, median age 63 years, 77.9% Binet stage A, 17.6% B and 4.5% C. AIC occurred in 46 patients (16%): 31 autoimmune hemolytic anemias, 10 autoimmune thrombocytopenias, four Evans syndromes, and one pure red cell aplasia. Of the 46 cases of AIC, 37 (80%) occurred in ZAP‐70 positive patients and nine (20%) in ZAP‐70 negatives. ZAP‐70 expression [Hazard Ratio (HR) = 7.42; 95% confidence interval (CI): 2.49–22.05] and age >65 years (HR = 5.41; 95% CI: 1.67–17.49) resulted independent risk factors for AIC. Among the 136 patients evaluated both for ZAP‐70 expression and IGHV status, the occurrence of AIC was higher in ZAP‐70 positive/IGHV unmutated cases (35%) than in patients ZAP‐70 negative/IGHV mutated (6%) or discordant for the two parameters (4%; P < 0.0001). In ZAP‐70 positive patients, occurrence of AIC negatively influenced survival (HR = 1.75; 95% CI: 1.06–2.86). The high risk of developing AIC in ZAP‐70 positive CLL, particularly when IGHV unmutated, should be considered in the clinical management. Am. J. Hematol. 2010. © 2010 Wiley‐Liss, Inc.     

MDM2 SNP309 promoter polymorphism,an independent prognostic factor in chronic lymphocytic leukemia

Background: The single nucleotide polymorphism SNP309 with a change from T to G in the promoter region of the MDM2 gene is shown to increase the MDM2 protein levels and attenuate the p53 levels and associates with disease progression in several tumors. Objective: In this study, the role of the polymorphism was investigated with regard to the clinical outcome in B‐cell chronic lymphocytic leukemia (B‐CLL). Patients: A total of 210 patients with B‐CLL were followed for up to 19 yr. Results: The overall survival (OS) of patients with at least one G‐allele was significantly shorter when compared with those with two T‐alleles (P = 0.024) with a more pronounced difference in patients below the median age. Age at onset of B‐CLL was similar irrespective of MDM2 status. The presence of a G‐allele in combination with TP53 mutations or unmutated IgVH gene status resulted in an additive risk of death. Conclusion: In this report, with a high proportion of B‐CLL patients with an advanced Binet stage and with an unmutated IgVH gene, MDM2 SNP309 was found to be independently associated with OS. The survival difference was more pronounced in younger patients.     

Monoclonal B‐cell lymphocytosis is closely related to chronic lymphocytic leukaemia and may be better classified as early‐stage CLL

The World Health Organization classification uses a cut‐off point of 5·0 × 10⁹/l cells with a chronic lymphocytic leukaemia (CLL)‐phenotype in peripheral blood to discriminate between monoclonal B‐lymphocytosis (MBL) and B‐CLL. This study analysed 298 MBL patients by multi‐parameter flow cytometry, chromosome banding analysis (CBA)/fluorescence in situ hybridization (FISH), and IGHV mutation status and compared them with 356 CLL patients. In MBL, CBA more frequently revealed a normal karyotype and FISH identified less frequently del(6q), del(13q) (as sole alterations), and del(17)(p13). Within the MBL cohort, a shorter time to treatment (TTT) was found for ZAP‐70‐positivity, 14q32/IGH‐translocations (CBA), del(11)(q22·3) (FISH) and unmutated IGHV status. Higher CD38 and ZAP‐70 expression, del(11)(q22·3) (FISH), trisomy 12 (FISH), and 14q32/IGH‐translocations (CBA) were correlated with a shorter TTT in the combined cohort (MBL + CLL); a sole del(13)(q14) (FISH) correlated with longer TTT. Regarding overall survival, unmutated IGHV status and ‘other’ alterations (CBA) had an adverse impact. There was no correlation between the concentration of CLL‐cells and TTT or overall survival. Multivariate analysis confirmed a negative impact on TTT for del(11)(q22·3)/ATM, trisomy 12 (both by FISH), and 14q32/IGH‐translocations by CBA. These data emphasize a close relationship between MBL and CLL regarding clinically relevant parameters and provide no evidence to strictly separate these entities by a distinct threshold of clonal B‐cells.     

Expression level of lipoprotein lipase in Chinese patients with chronic lymphocytic leukemia and its correlation with other prognostic factors

Chronic lymphocytic leukemia (CLL) is the most common adult form of leukemia in the Western world, however, infrequent in the Eastern. It shows a remarkable heterogeneity, with some patients having an almost normal lifespan, others surviving only several years after diagnosis despite intensive therapy. To investigate lipoprotein lipase (LPL) expression level in Chinese patients with CLL and its correlation with other prognostic factors, including immunoglobulin heavy-chain variable region (IgVH) mutation status, Binet stages, ZAP-70 protein and CD38 expression level, semiquantitative RT-PCR was used to detect LPL expression in peripheral blood samples of 58 Chinese patients with CLL. LPL expression level was significantly correlated with IgVH mutational status (r = 0.348, P = 0.010), Binet stages (r = 0.276, P = 0.036), ZAP-70 protein (r = 0.431, P = 0.001) and CD38 (r = 0.546, P < 0.001). Patients with unmutated IgVH genes had higher expression of LPL than patients with IgVH mutations. The higher expression level of LPL was also associated with higher level of ZAP-70 and CD38, and more aggressive Binet stage. We also analyzed LPL expression in different cytogenetic subgroups. Higher LPL level was found in patients with unfavorable cytogenetic aberrations (deletion in 17p13 or 11q22) in contrast to lower level in good risk cytogenetics (deletion in 13q as the sole abnormality) (r = 0.404, P = 0.002). It was showed that LPL expression correlates with IgVH mutational status and other clinical or laboratory prognostic factors, and might be applied for the assessment of prognosis in patients with CLL.     

A proliferation-inducing ligand (APRIL) serum levels predict time to first treatment in patients affected by B-cell chronic lymphocytic leukemia

Purpose: A proliferation‐inducing ligand (APRIL), a tumor necrosis factor superfamily member involved in B‐lymphocytes differentiation and survival, plays a role in protecting B‐Cell Chronic lymphocytic leukemia (B‐CLL) cells from apoptosis. Having observed that APRIL serum (sAPRIL) levels were higher in B‐CLL patients with CLL at diagnosis as compared to healthy donors (14.61 ± 32.65 vs. 4.19 ± 3.42 ng/mL; P < 0.001), we tested the correlation existing in these patients between sAPRIL, clinical–biological parameters and disease progression. Experimental design: sAPRIL levels were measured by ELISA in 130 patients with B‐CLL at diagnosis and in 25 healthy donors. Results: sAPRIL levels did not correlate with gender, age, clinical stage, blood cell counts, β2‐microglobulin (β2M) levels, ZAP‐70 and CD38 expression. Using median sAPRIL natural logarithm (ln) as cutoff, we distinguished two groups of patients (APRIL_LOW and APRIL_HIGH) who were comparable with regard to clinical–biological parameters and overall survival, but different with regard to time to the first treatment (TTFT; P = 0.035). According to univariate analysis, high lymphocyte count, high β2M, Binet stage B–C, ZAP‐70 expression and ln(sAPRIL) above median were associated with earlier TTFT. Advanced clinical stage, high β2M, ZAP‐70 expression and ln(sAPRIL) above median remained independently predictive of shorter TTFT at multivariate analysis. Moreover, sAPRIL increased its prognostic significance when patients were stratified according to independent favorable clinical–biological characteristics (low β2M, stage A and lack of ZAP‐70 expression). Conclusions: sAPRIL is a novel indicator of shorter TTFT in B‐CLL and a predictor of progression especially in patients otherwise considered at low risk according to validated prognostic factors.     

Comparison between oral and intravenous fludarabine plus cyclophosphamide regime as front-line therapy in patients affected by chronic lymphocytic leukaemia: influence of biological parameters on the clinical outcome

The fludarabine plus cyclophosphamide (FC) regimen was reported to be superior to chlorambucil or fludarabine alone in terms of complete response (CR), overall response (OR) and progression-free survival (PFS) in previously untreated patients with chronic lymphocytic leukaemia (CLL). In the present study, we compared the efficacy and toxicity of FC administered through oral and intravenous route in 65 untreated patients affected by advanced CLL. No statistical differences were noticed between the two routes of administration in terms of OR, PFS, time to re-treatment (TTR) and overall survival (OS) of analysed patients. We also assessed the influence on the clinical outcome of the mutation status of the immunoglobulin variable region heavy chain (IgVH) gene, of the cytogenetic abnormalities and of the expression of ZAP70 and CD38 in patients' primary samples. Among the 58 evaluable patients, 31 (53%) achieved a CR and 18 (31%) a partial response. The median PFS was 35?months, median TTR was 42?months and median OS was not reached after 45?months (range, 1?C161). A significantly lower OR rate was noticed in patients with high-risk cytogenetic abnormalities (del 17p, del 11q). In this study, high-risk cytogenetic abnormalities and unmutated IgVH genes were independent predictors of TTR. These results underline the importance of biological stratifications in front-line treatment of CLL patients. We confirm that FC is an effective regimen with mild toxicities; it could be recommended for patients with low-risk biological parameters who represent, in our experience, about 30% of the total.     

NOTCH1 mutations in CLL associated with trisomy 12

Two recent studies reported whole-genome sequencing of chronic lymphocytic leukemia (CLL) samples and found repeated mutations in the XPO1 and NOTCH1 genes. XPO1 was found mutated in 2.4% of cases, while NOTCH1 was found mutated in 12.2% or 15.1% of CLL samples. Here we report the results of sequencing of XPO1 and NOTCH1 in 186 CLL cases. Our results confirmed frequency of XPO1 mutations. However, we found only 5 NOTCH1 mutations in 127 IGVH unmutated/ZAP70(+) CLL samples (4%), and one mutation was found in IGVH mutated/ZAP70(-) CLL for a total percentage of 1.5%. Because 4 of 6 mutated samples also showed trisomy 12, we sequenced NOTCH1 in an additional 77 cases with trisomy 12 CLLs, including 47 IGVH unmutated/ZAP70(+) cases. Importantly, we found 41.9% NOTCH1 mutation frequency in aggressive trisomy 12 CLL cases. Our data suggest that activation of NOTCH1 plays a critical role in IGVH unmutated/ZAP70(+) trisomy 12 CLL.     

Quantification of ZAP-70 expression in chronic lymphocytic leukemia: T/B-cell ratio of mean fluorescence intensity provides stronger prognostic value than percentage of positive cells

Expression of ZAP-70 measured by flow cytometry belongs to the most powerful prognostic parameters in chronic lymphocytic leukemia (CLL). However, many technical factors such as setting of the positivity threshold may significantly influence results.. Quantification using mean fluorescent intensity (MFI) may eliminate the subjective error which is inevitable in the isotype control method. The aim of the present project was therefore to assess the prognostic significance of ZAP-70 using three different methods. Between 2005 and 2010 we measured ZAP-70 expression in 157 patients with CLL (108 males, 49 females, median age 60 years [range, 31-82]; low/intermediate/high Rai risk in 41/48/11%). Expression of ZAP-70 was determined by flow cytometry using phycoerythrin (PE)-conjugated monoclonal antibody, clone 1E7.2. Evaluation was performed by 1) percentage of positive cells compared to isotype control (cut-off 20%), 2) MFI ratio of T-cells/CLL cells (cut-off 3.0); 3) MFI ratio of ZAP-70/isotype control on CLL cells (cut-off 2.5). MFI method with T-cells/CLL cells ratio was the best in the identification of patients with unfavourable outcome: ZAP-70 positive patients had significantly shorter time to treatment (TTT, median 24 vs. 55 months, p=0.0001) and overall survival (OS, median 97 vs 174 months, p=0.0074). The differences in TTT a OS were not significant with the use of isotype percentage and MFI isotype methods. Combined analysis of ZAP-70 with CD38 expression or IgVH mutation status lead to identification of a subgroup with the longest TTT and OS (ZAP-70 and CD38 negative, p<0.0001 and p=0.012; ZAP-70 negative and mutated IgVH genes, p<0.0001 and p=0.0019). In conclusion, our results suggest that measurement of ZAP-70 expression in CLL by MFI using T-cells/CLL cells ratio might be the optimal method for accurate prediction of clinical course. Combined analysis of ZAP-70 with CD38 or IgVH mutation status further refined individual patient′s prognosis.     

CD38 as a prognostic marker in CLL

Cell-surface expression of CD38 in CLL has been recognised recently as a marker of progressive disease and poor outcome. In contrast to traditional staging systems, CD38 is able to identify progressive cases at an early stage. Measurement of CD38, in conjunction with other novel prognostic factors such as p53 and ZAP-70 helps to identify patients who might benefit from early and more intensive therapy. In addition, CD38 positivity can predict unmutated IgVH gene mutation status in most cases. These features, together with its easy applicability, render CD38 a valuable tool in the routine diagnostics of CLL. Questions remaining to be clarified about CD38 include the incidence and significance of its variations during the course of the disease, the optimal method to define CD38 positivity and the impact of different methodologies on results. Only after these issues are resolved can the definitive place of CD38 be defined in the diagnostics of CLL.     

CD38 as a prognostic marker in CLL

Cell-surface expression of CD38 in CLL has been recognised recently as a marker of progressive disease and poor outcome. In contrast to traditional staging systems, CD38 is able to identify progressive cases at an early stage. Measurement of CD38, in conjunction with other novel prognostic factors such as p53 and ZAP-70 helps to identify patients who might benefit from early and more intensive therapy. In addition, CD38 positivity can predict unmutated IgVH gene mutation status in most cases. These features, together with its easy applicability, render CD38 a valuable tool in the routine diagnostics of CLL. Questions remaining to be clarified about CD38 include the incidence and significance of its variations during the course of the disease, the optimal method to define CD38 positivity and the impact of different methodologies on results. Only after these issues are resolved can the definitive place of CD38 be defined in the diagnostics of CLL.     

Igbeta(CD79b) mRNA expression in chronic lymphocytic leukaemia cells correlates with immunoglobulin heavy chain gene mutational status but does not serve as an independent predictor of clinical severity

The etiology of chronic lymphocytic leukemia (CLL) is poorly understood and its course is highly variable. Somatic hypermutation (SHM) of the immunoglobulin heavy chain (IgV(H)) gene and ZAP70 protein expression have been reported as prognostic indicators. However, these assays are not widely available and their concordance is imperfect. Thus a need exists to identify additional molecular determinants of CLL. The Igbeta (CD79b) subunit of the B cell antigen receptor is essential for B lymphocyte function. Defects in Igbeta expression are implicated in CLL pathogenesis. We have analyzed Igbeta mRNA expression in CLL cells in 40 consecutive patient samples. About 75% of the samples showed the expected decrease of Igbeta surface staining. Igbeta mRNA levels covered a wider range, did not correlate with Igbeta surface staining, but clearly distinguished the normal and CLL lymphocyte populations. Remarkably, Igbeta mRNA levels correlated strongly with SHM; Igbeta mRNA levels in CLL cells were significantly higher in patients with an unmutated IgV(H) gene when compared with those in whom IgV(H) was hypermutated (P = 0.008). In contrast, no correlation was observed between Igbeta mRNA levels and ZAP70 expression. Multiple parameters abstracted from chart reviews were used to estimate severity of CLL in each case. While severity correlated strongly with ZAP70 staining, and to a lesser extent with SHM status, there was no correlation with Igbeta mRNA levels. These data establish a strong linkage between Igbeta mRNA expression and SHM in CLL and highlight the complex relationships between biochemical parameters and clinical status in this disease.     

Baff serum level predicts time to first treatment in early chronic lymphocytic leukemia

We analyzed the correlation between well‐established biological parameters of prognostic relevance in B‐cell chronic lymphocytic leukemia (CLL) [i.e. mutational status of the immunoglobulin heavy chain variable region (IgVH), ZAP‐70 and CD38 expression] and serum levels of B cell–activating factor (BAFF of the TNF family) by evaluating the impact of these variables on the time to first treatment (TFT) in a series of 169 previously untreated CLL patients in Binet stage A. Higher levels of BAFF were more frequently associated with female gender (P = 0.02), younger age (P = 0.01), Rai stage 0 (P = 0.002), higher platelet count (P = 0.005), mutated IgVH disease (P = 0.002), higher occurrence of normal cytogenetic profile or presence of 13q deletion (P = 0.02), low ZAP‐70‐ (P = 0.003), and CD38‐expression (P = 0.02). Maximally selected log‐rank statistic plot identified a serum BAFF concentration of 0.313 ng/mL as the best cut‐off (P < 0.0001). This threshold recognized two subsets of patients with different TFT (P < 0.0001). Because in multivariate analysis soluble BAFF [Hazard ratio (HR), 8.23; confidence Interval (CI) 95%,3.0–22.6, P < 0.0001] and mutational status of IgVH (HR = 2.60; CI 95% 1.10–6.14, P = 0.03) maintained the discriminating power their combined effect on clinical outcome was assessed. When three groups were considered: ( 1 ) low‐risk (n = 93), patients with concordant IgVH_mut and higher soluble BAFF; ( 2 ) intermediate‐risk (n = 50), patients with IgVH_mut and low BAFF levels or IgVH_unmut and soluble higher BAFF;( 3 ) high‐risk (n = 26), patients with concordant IgVH _unmut and low soluble BAFF, the 2‐yr TFTs were, respectively, 95%, 85%, and 41% (P < 0.0001). In conclusion, our results indicate that in early B‐cell CLL, the biological profile including among other parameters soluble BAFF may provide a useful insight into the complex interrelationship of prognostic variables.