CD38 expression as an important prognostic factor in B-cell chronic lymphocytic leukemia

Distinctive immunoglobulin VH gene usage in Japanese patients with chronic lymphocytic leukemia

The incidence of chronic lymphocytic leukemia (CLL) is low in Asian countries including Japan, while CLL is the most common type of leukemia in the west. To elucidate which factors contribute to the low frequency of CLL in Japan, we investigated immunoglobulin (Ig) heavy chain gene usage and somatic hypermutation status in 44 Japanese patients with CLL. Only one of these patients used V(H)1-69. The finding is in striking contrast to data from western countries, where the frequency of CLL expressing V(H)1-69 ranges from 12 to 21%.

CD38 expression levels in chronic lymphocytic leukemia B cells are associated with activation marker expression and differential responses to interferon stimulation

CD38, a surface protein whose expression increases upon normal B-cell activation, is a marker of disease aggression in B-cell chronic lymphocytic leukemia (B-CLL). Higher percentages of CD38-expressing CLL B cells may be found in lymphoid compartments compared to peripheral blood. Therefore, it is possible that although CLL B cells are resting, CD38 may be a marker of recent cell activation prior to entry into the periphery. To address this hypothesis, we examined the association of CD38 expression with other activation antigens identified in gene expression profiling experiments and include CD18, CD49d, CD20, and subunit 5 of the anaphase-promoting complex/cyclosome. We found that all these markers were more highly expressed in leukemic B cells from CD38-positive CLL patients. Lastly, because interferon is known to modulate CD38 expression, we used IFN-alpha to test the ability of CLL B cells to increase CD38 expression in vitro. Interestingly, IFN stimulation only modulated CD38 expression in CLL B cells that already expressed CD38. Taken together, these data suggest that CD38 is a marker of a more recently activated CLL B cell. This in turn may explain the biological and clinical differences between CD38-positive type B-CLL and CD38-negative type B-CLL.

Prognostic usage of V(H) gene mutation status and its surrogate markers and the role of antigen selection in chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease with many patients surviving for decades with minimal or no treatment, whereas others succumb rapidly to their disease despite therapy. In recent years, new molecular prognostic factors have emerged in CLL that have significantly improved the subgrouping of the disease. One of the most important molecular predictors, the immunoglobulin V(H) gene mutation status, divides CLL into two prognostic groups, depending on the presence or absence of somatic hypermutation, where unmutated V(H) genes are associated with considerably worse prognosis than mutated V(H) genes. An exception to this appears to be CLL patients utilizing the V(H)3-21 gene as they have poor outcome irrespective of mutation status. Surrogate markers for the VH gene mutation status have been suggested, such as CD38 and ZAP-70 expression. However, the CD38 level was later shown to display poor correlation to the mutation status, although it may still serve as an independent prognostic factor. More promising is the expression levels of ZAP-70, which appears to be both a strong surrogate marker for V(H) gene mutation status, although discrepancies have been reported, as well as an independent prognostic marker. Immunoglobulin gene analysis has also indicated the possibility of antigen selection in CLL considering the significant bias in V(H) gene usage. Intriguingly, the V(H)3-21+ group and several other CLL subsets using certain V(H) genes was recently reported to display strikingly restricted immunoglobulin gene features, in both their heavy and light chain gene rearrangements, thus further high-lighting the possible role of antigen involvement in CLL development.

Clinical and laboratory parameters that define clinically relevant B-CLL subgroups

B cell-type chronic lymphocytic leukemia (B-CLL) is a heterogeneous disease. This is reflected by the very wide-ranging clinical courses that B-CLL patients experience and by the marked variation in laboratory findings between patients. In this chapter, we will review the various clinical and laboratory parameters that divide B-CLL patients into "subgroups," and correlate the parameters that define them. When feasible, we will also link clinical features to the cellular and genetic characteristics recently defined for these leukemic cells. The discussion is limited to parameters that define phenotypes or subgroups that may relate to disease activity and clinical outcome.

Serum insulin-like growth factor is not elevated in patients with early B-cell chronic lymphocytic leukemia but is still a prognostic factor for disease progression

OBJECTIVES

Insulin-like growth factor 1 (IGF-1) is an important growth and anti-apoptotic factor for the cancer cells in several malignancies and in multiple myeloma recent studies support the hypothesis of a role for IGF-1 in disease progression; however, clinico-biological relevance of IGF-1 was never studied in B-cell chronic lymphocytic leukemia (CLL).

PATIENTS AND METHODS

Using a quantitative sandwich immunoassay technique (ELISA) (Quantikine, Human IGF-1 and IGFBP-3, R&D Systems), we measured the concentration of IGF-1 and its major binding protein IGF-binding protein 3 (IGFBP-3) in serum drawn at the time of diagnosis from 77 Binet stage A CLL patients.

RESULTS

Either IGF-1 or IGFBP-3 were significantly decreased compared with healthy age- and sex-matched controls (P < 0.0001 for both; Mann-Whitney test). Serum levels of IGF-1 and IGFBP-3 paralleled each other (P = 0.002); in contrast, no significant correlation was found between serum levels of IGF-1 and clinico-hematological variables including age (P = 0.253), sex (P = 0.270), Rai clinical substages (P = 0.140), lactate dehydrogenase (P = 0.956), beta2-microglobulin (P = 0.368), lymphocyte count (P = 0.703) and lymphocyte doubling time (LDT, P = 0.233). When correlation were attempted with circulating levels of angiogenic cytokines such as vascular endothelial growth factor (P = 0.971), basic fibroblastic growth factor (P = 0.695), angiogenin (P = 0.282) or adhesion molecules such as vascular cell adhesion molecule-1 (P = 0.318), intercellular adhesion molecule-1 (P = 0.883) and platelet endothelial cell adhesion molecule-1 (P = 0.772) similar results were found. Serum levels of IGF-1 were further evaluated as a dichotomous variable with respect to progression-free survival (PFS), an endpoint surrogate for overall survival in early B-cell CLL. The best separation of curves was seen with the cutoff point at the 75th percentile of IGF-1 levels (i.e., 93 pg/mL). Median PFS was 63 months in the patient group with low IGF-1, compared with a median PFS of 40 months in the remaining patients (P = 0.03). In the multivariate analysis performed including variables significant at univariate analysis [i.e. Rai substage (P = 0.002); LDT (P = 0.004), IGF-1 (P = 0.01)], only Rai substage retained prognostic significance (P = 0.006). However, after removing from analysis LDT (only six of 77 had an LDT < 12 months), either IGF-1 or Rai substage entered the model at a significant level (P = 0.03 and P = 0.01, respectively).

CONCLUSIONS

IGF-1 did not correlate with markers of tumor burden or clinical status in CLL thus suggesting that levels of this cytokine do not reflect the intrinsic malignancy of disease. Results of the present study highlight, however, its involvement in mechanisms of disease progression in early CLL.

Functional and prognostic role of ZAP-70 in chronic lymphocytic leukaemia

It has become clear that the heterogeneity of chronic lymphocytic leukaemia (CLL) is not a continuous spectrum, but is bipolar. Originally distinguished by the mutational status of the immunoglobulin variable region genes, the two poles are perhaps better identified by the expression of ZAP-70, a signalling molecule normally utilised by T cells rather than B cells, but anomalously expressed in the more aggressive subtype of CLL. Assaying ZAP-70 expression has become progressively simplified so that a directly stained flow cytometric test is currently being evaluated, and a version of this should shortly be available to routine laboratories. In addition, the understanding of the nature of CLL has been advanced rapidly and this should lead to new, better targeted therapies, which in contrast to the current armoury, will work better for the more malignant variants of CLL than for the more benign. In particular, ZAP-70 is especially attractive because its aberrant expression in tumour cells from the more aggressive forms of CLL requires the chaperoning action of activated heat-shock protein 90, which may be specifically inhibited.

ζ-Chain associated protein 70 and CD38 combined predict the time to first treatment in patients with chronic lymphocytic leukemia

BACKGROUND

Zeta-chain associated protein (ZAP)-70 has been proposed as a surrogate marker for immunoglobulin heavy-chain variable region (IgVH) mutation in chronic lymphocytic leukemia (CLL), but it is still not clear whether it is an independent prognostic factor.

METHODS

The authors evaluated ZAP-70 expression by flow cytometry in 201 untreated patients and correlated ZAP-70 levels with CD38 expression, genetic abnormalities detected by fluorescence in situ hybridization (FISH), and the time from diagnosis to first treatment.

RESULTS

Fifty-seven patients (28%) were positive for ZAP-70 (> or = 20%). Positive ZAP-70 status was associated with advanced disease stage, atypical morphology, CD38-positive status, trisomy 12, del(6q), or no detectable abnormalities; negative ZAP-70 status was correlated with del(13q) as a sole abnormality. The treatment-free interval (TFI) was 17.7 months for ZAP-70-positive patients and 44.6 months for ZAP-70-negative patients (P < 0.001). Multivariate analysis in 117 patients identified advanced stage, CD38 > or = 7%, and the absence of del(13q) as a sole abnormality as independent factors for short TFI. Excluding FISH, ZAP-70 status acquired independent prognostic value along with CD38 status. The authors proposed a risk model that combines ZAP-70 and CD38 to identify patients who are likely to progress. When both markers were positive, the TFI was 12 months; when both were negative, the median TFI was 54 months; a median TFI of 26 months was observed in patients who had discordant results (P < 0.00001).

CONCLUSIONS

The current findings suggested that both ZAP-70 and CD38 should be tested prospectively in all patients with early-stage CLL.

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.

Immunoglobulin mutational status detected through single-round amplification of partial V(H) region represents a good prognostic marker for clinical outcome in chronic lymphocytic leukemia

The immunoglobulin (Ig) mutational status in B-cell chronic lymphocytic leukemia (CLL) distinguishes two subsets of patients with different prognosis. Ig status detection is commonly performed with a panel of V(H) family-specific primers. Although this method detects clonal VDJ rearrangement in virtually all cases, it is technically cumbersome and therefore not widely used clinically. Here, we describe a simple and rapid method to establish the mutational status of IgV(H) in CLL. The method is based on a consensus V(H) FR2 primer, used in both polymerase chain reaction (PCR) and sequencing reactions. Overall, monoclonal B-cell populations were detected in 163 of 189 CLL patients (86%). The prognostic value of IgV(H) mutational status was then evaluated by analyzing survival in 146 CLL cases using different V(H) homology cutoffs. CLL prognostic groups were best separated by the classical 98% cutoff: median survival was 127 and 206 months in unmutated and mutated CLL cases, respectively (P = 0.0023). V(H) FR2 consensus and V(H) family PCR were compared in 41 cases, correctly assigning all cases by both methods. Therefore, we suggest a sequential strategy to detect immunoglobulin mutational status in CLL patients by first using the approach described in this study followed by alternative V(H) family-specific PCRs for negative cases.

Revisiting the role of hematopoietic stem cell transplantation in chronic lymphocytic leukemia

Since the advent of hematopoietic stem cell transplantation more than 40 years ago, numerous methods of transplantation have been developed, modified and improved upon. Although hematopoietic stem cell transplantation has been used in a variety of malignant diseases since then, its use in the treatment of chronic lymphocytic leukemia has recently started to gain interest. Patients with chronic lymphocytic leukemia are generally elderly, and because of its relatively benign course, they were not considered suitable candidates for hematopoietic stem cell transplantation. Nonetheless, there have been marked improvements in transplantation techniques, including better conditioning regimens that have decreased treatment-related morbidity and mortality. In this article, the authors review the most recent data on hematopoietic stem cell transplantation in chronic lymphocytic leukemia as well as the change in risk stratification based on newer prognostic factors and its impact on treatment decisions in chronic lymphocytic leukemia.

A gender-based score system predicts the clinical outcome of patients with early B-cell chronic lymphocytic leukemia

To facilitate the development of a prognostic model for early B-cell chronic lymphocytic leukemia (CLL), the Gruppo Italiano Malattie EMatologiche Maligne dell'Adulto (GIMEMA) proposes its multi-institutional effort as a working model. In total, 1138 newly diagnosed Binet stage A patients managed over the last 10 years outside the setting of clinical trials according to a "wait and see" policy form the basis of the present study aimed at investigating prognostic variables affecting disease progression, a surrogate endpoint for overall survival. A 3-stage risk system, simply obtained by summing the variables that proved significant in the multivariate analysis (i.e. short lymphocyte doubling time, advanced Rai substage, high peripheral blood lymphocytosis), is proposed. Clear-cut differences in the 10 year progression-free survival (PFS) were observed among patients scoring 0 (low risk), 1 (intermediate risk), 2-3 (high risk): 67.8, 41.0 and 24.8%, respectively (P<0.0001). The results of the Medical Research Council (MRC) suggesting a better clinical outcome for females prompted us to verify such a gender-related difference within our prognostic categories. Because changes in PFS only reflected gender for patients scoring 0 (P=0.04), the following prognostic subgroups are proposed: (1) females scoring 0; (2) males scoring 0; (3) patients scoring 1-3 whatever gender (10 year PFS: 76.2, 61.4 and 37.8%; P<0.00001). Our long-term database provides an adequate patient sample to generate a generalized risk stratification model based on clinical data. The indolent clinical outcome of women with early CLL is also supported by the higher frequency of the immunoglobulin heavy-chain variable (IgVH) mutational status and lower proportion of 17p and 11q deletions found in such a patient subset in the MRC CLL4 trial.

The prognostic value of CD38 expression in chronic lymphocytic leukaemia patients studied prospectively at diagnosis: a single institute experience

The purpose of this study was to assess in chronic lymphocytic leukaemia (CLL) patients the prevalence and clinical impact of CD38 expression, evaluated prospectively at disease presentation, and to verify whether this parameter changes over time. In 242 consecutive and untreated CLL patients, the percentage of CD38+ cases, according to the 7%, 20% and 30% cut-off points, was 21%, 17% and 14%, respectively. Using the 7% threshold, CD38 positivity correlated with male sex, intermediate and high-risk (Rai I-IV) disease, lower Hb and platelet levels, and higher lymphocyte count. Furthermore, patients with a CD38 expression>or=7% showed a significantly lower 3-year probability of treatment-free survival (TFS) than CD38- patients (P<0.0001). At multivariate analysis, CD38 expression remained significantly associated to TFS, together with stage, lymphocyte count and morphology. Also, in the 146 patients with stage 0 CLL a CD38 expression>or=7% identified a subgroup of patients with a significantly lower 3-year probability of TFS (P=0.0005). Furthermore, this parameter did not change in 30 of 31 (97%) re-evaluated patients. In conclusion, this study indicates that, when tested at diagnosis and on fresh material, a CD38 expression>or=7% is an important parameter for the identification of early CLL patients with more aggressive disease and that its expression remains stable over time.

B-chronic lymphocytic leukemia cells exert an in vitro cytotoxicity mediated by tumor necrosis factor α

Tumor necrosis factor alpha (TNFalpha) is constitutively produced by B-chronic lymphocytic leukemia (B-CLL) cells and may act as an autocrine factor for their growth and survival. However, very few data are available on the possible cytotoxic effect of TNFalpha produced by B-CLL cells. This study investigated whether B-CLL cells exert in vitro cytotoxicity by TNFalpha and if so, whether this cytotoxicity can be modulated by cytokines. In 8 of 12 patients (66.6%), B-CLL cells in vitro constitutively produced TNFalpha and exerted a TNFalpha-mediated cytotoxicity, evaluated in an 18-h 51Cr release assay, against the TNFalpha-sensitive Jurkat, U937 and K562 cell lines but not against the TNFalpha-resistant Raji cell line. Involvement of TNFalpha in B-CLL cell cytotoxicity is demonstrated by the fact that anti-TNFalpha antibodies strongly inhibited it and supernatants of cytotoxic cultures contained TNFalpha and mediated a completely TNFalpha-dependent cytotoxicity. When the cytotoxic B-CLL cells were stimulated with interleukin (IL)-2 plus IL-12, there was increased TNFalpha mRNA expression, TNFalpha production and TNFalpha-mediated cytotoxicity. All eight patients with cytotoxic leukemic cells had progressive disease and six of these also expressed high levels of ZAP-70 protein. In the other four patients (33.3%), B-CLL cells did not produce TNFalpha in vitro and were not cytotoxic, either spontaneously or after IL-2 plus IL-12 stimulation. Of these four patients, three had stable disease and one had progressive disease. The patient with progressive disease and one of the three with stable disease expressed low levels of ZAP-70 protein. We conclude that a group of B-CLL patients with progressive disease have leukemic B cells able to exert in vitro a TNFalpha-mediated cytotoxicity, which is modulated by cytokines.

Combined analysis of ZAP-70 and CD38 expression as a predictor of disease progression in B-cell chronic lymphocytic leukemia

Prognostic predictions in B-cell chronic lymphocytic leukemia (B-CLL) at early clinical stage are based on biological disease parameters, such as ZAP-70 and CD38 protein levels, genomic aberrations as well as immunoglobulin variable heavy chain gene (IgV(H)) mutation status. In the current study, ZAP-70 and CD38 expressions were examined by flow cytometry in 252 patients with B-CLL. Cytoplasmic ZAP-70 expression in more than 20% (ZAP-70(+)) and surface CD38 expression on more than 30% (CD38(+)) of B-CLL cells were associated with an unfavorable clinical course. The levels of ZAP-70 and CD38 did not change over time in the majority of patients where sequential samples were available for analysis. Combined analysis of ZAP-70 and CD38 yielded discordant results in 73 patients (29.0%), whereas 120 patients (47.6%) were concordantly negative and 59 patients (23.4%) were concordantly positive for ZAP-70 and CD38 expression. Median treatment-free survival times in patients whose leukemic cells were ZAP-70(+)CD38(+) was 30 months as compared to 130 months in patients with a ZAP-70(-)CD38(-) status. In patients with discordant ZAP-70/CD38 results, the median treatment-free survival time was 43 months. Thus, ZAP-70 and CD38 expression analyses provided complementary prognostic information identifying three patient subgroups with good, intermediate and poor prognosis. Over-representation of high-risk genomic aberrations such as 17p deletion or 11q deletion and distribution of the IgV(H) mutation status in B-CLL discordant for ZAP-70/CD38 pointed toward a distinct biologic background of the observed disease subgroups. This finding was also supported by microarray-based gene expression profiling in a subset of 35 patients. The expression of 37 genes differed significantly between the three groups defined by their expression of ZAP-70 and CD38, including genes that are involved in regulation of cell survival and chemotherapy resistance.

Splenic marginal zone lymphoma: proposal of new diagnostic and prognostic markers identified after tissue and cDNA microarray analysis

Splenic marginal zone lymphoma (SMZL) is a newly recognized lymphoma type whose precise molecular pathogenesis is still essentially unknown. This hampers differential diagnosis with other small B-cell malignancies. With the aim of characterizing this tumor more comprehensively, and of identifying new diagnostic and prognostic markers, we performed cDNA microarray expression profiling and tissue microarray (TMA) immunohistochemical studies in a relatively large series of 44 SMZLs. The results were related to immunoglobulin heavy chain variable region (IgV(H)) mutational status and clinical outcome. SMZLs display a largely homogenous signature, implying the existence of a single molecular entity. Of the genes deregulated in SMZLs, special mention may be made of the genes involved in B-cell receptor (BCR) signaling, tumor necrosis factor (TNF) signaling and nuclear factor-kappaB (NF-kappaB) activation, such as SYK, BTK, BIRC3, TRAF3, and LTB. Other genes observed were SELL and LPXN, which were highly expressed in spleen, and lymphoma oncogenes, such as ARHH and TCL1. In contrast, the genes CAV1, CAV2, and GNG11 located in 7q31, a commonly deleted area, were down-regulated in the entire series. A comparison with the genes comprising the signature of other small B-cell lymphomas identified 3 genes whose expression distinguishes SMZL, namely ILF1, SENATAXIN, and CD40. Shorter survival was associated with CD38 expression, naive IgV(H) genes, and the expression of a set of NF-kappaB pathway genes, including TRAF5, REL, and PKCA.

ZAP-70 upregulation in transformed B cells after early pre-BI cell transplant into NOD/SCID mice

Understanding of the signal transduction pathways that lead to B cell development is of extreme interest to learn how alterations in these pathways might initiate malignant transformation. Long-term cultured early pre-BI cells can differentiate into IgM+ B cells after transplant into NOD/SCID mice, offering the possibility to explore checkpoints in B cell development. Using DNA microarray and Western blot analysis of IgM+ B cells vs parental early pre-BI cells, we demonstrated that zeta-associated protein 70 (ZAP-70) is upregulated in our B cell differentiation model. Unlike parental ZAP-70- early pre-BI cells, ZAP-70+ IgM+ B cells exhibited a transformed phenotype, as indicated by BCL-6 expression, a high Ki-67 proliferation index, resistance to IL-7 deprivation-induced apoptosis, and an increased repopulation rate in NOD/SCID mice. These data show the characterization and generation of a novel murine leukemia model with many similarities to human ZAP-70+ B cell chronic lymphocytic leukemia.

CD38 and CD100 lead a network of surface receptors relaying positive signals for B-CLL growth and survival

This work addresses the question whether CD38, a negative prognostic marker in B-cell chronic lymphocytic leukemia (B-CLL), plays a role in neoplastic B-cell growth and survival. We show that CD38+ B-CLL cells bind to murine fibroblasts transfected with the CD31 ligand. The interaction triggers an extensive remodeling of the B-CLL membrane, with relocalization of BCR/CD19 to the CD38/CD31 contact areas, and it also increases cell survival and proliferation. A second event is the up-modulation of the survival receptor CD100, restricted to proliferating cells, and a concomitant decrease of CD72 (low-affinity CD100 ligand and negative regulator of immune responses). The most efficient signals are delivered through sequential interactions between CD38/CD31 and CD100/plexin-B1 (high-affinity CD100 ligand), as inferred by coculture experiments using specific transfectants and blocking monoclonal antibodies (mAbs). The finding that nurselike cells from B-CLL patients express CD31 and plexin-B1, which deliver growth and survival signals to CD38+/CD100+ B-CLL cells, further confirms the model proposed. These findings show that a set of normal receptors and ligands ruling physiologic signaling pathways in B lymphocytes becomes detrimental when expressed in the context of B-CLL cells, ultimately leading to the generation of a tumor reservoir.

ZAP-70 is expressed by a subset of normal human B-lymphocytes displaying an activated phenotype

The Syk family tyrosine kinase ZAP-70 is essential for normal T-cell development and signaling. Recently, leukemic cells from some patients with B-cell chronic lymphocytic leukemia (B-CLL) were shown to express ZAP-70. Owing to the prognostic value of B-CLL ZAP-70 expression, this phenotype may reflect intrinsic biological differences between the two subsets of disease. However, it remains unclear whether CLL-B cells aberrantly acquire ZAP-70 expression during the transformation process or whether ZAP-70 may be expressed under certain conditions in normal human B-lymphocytes. To discriminate between these two possibilities, we assessed ZAP-70 expression in normal human B-lymphocytes. Our data demonstrate that ZAP-70 is expressed in a subpopulation of tonsillar and splenic normal B-lymphocytes that express an activated phenotype. Furthermore, ZAP-70 expression can be induced in vitro upon stimulation of blood and tonsillar B cells. Finally, we show that phosphorylation of ZAP-70 occurs in tonsillar B cells with stimulation through the B-cell receptor. These results provide new insight into normal human B-cell biology as well as provide clues about the transformed cell in B-CLL.

Variability in the degree of expression of phosphorylated IkappaBalpha in chronic lymphocytic leukemia cases with nodal involvement

PURPOSE

Based on previous preliminary observations, we hypothesize that the molecular and clinical variability of chronic lymphocytic leukemia (CLL) reflects differences in the degree of nuclear factor (NF)-kappaB activation, as determined by the expression of phosphorylated IkappaBalpha (p-IkappaBalpha).

EXPERIMENTAL DESIGN

The expression profile (mRNA and protein expression) was analyzed with the Centro Nacional de Investigaciones Oncologicas Oncochip, a cDNA microarray containing 6386 cancer-related genes, and a tissue microarray (TMA). The results were correlated with the IgV(H) mutational status, ZAP-70 expression, cytogenetic alterations, and clinical outcome.

RESULTS

We found correlations between the presence of p-IkappaBalpha, a surrogate marker of NF-kappaB activation, and changes in the expression profile (mRNA and protein expression) and clinical outcome in a series of CLL cases with lymph node involvement. Activation of NF-kappaB, as determined by the expression of p-IkappaBalpha, was associated with the expression of a set of genes comprising key genes involved in the control of B-cell receptor signaling, signal transduction, and apoptosis, including SYK, LYN, BCL2, CCR7, BTK, PIK3CD, and others. Cases with increased expression of p-IkappaBalpha showed longer overall survival than cases with lower expression. A Cox regression model was derived to estimate some parameters of prognostic interest: IgV(H) mutational status, ZAP-70, and p-IkappaBalpha expression. The multivariate analysis disclosed p-IkappaBalpha and ZAP-70 expression as independent prognostic factors of survival.

CONCLUSIONS

A variable degree of activation of NF-kappaB, as determined by the expression of p-IkappaBalpha, is an identifiable event in CLL, and is correlated with changes in the expression profile and overall survival.

Analysis of VH gene sequences using two web-based immunogenetics resources gives different results, but the affinity maturation status of chronic lymphocytic leukaemia clones as assessed from either of the resulting data sets has no prognostic significance

Some cellular and molecular features of chronic lymphocytic leukaemia (CLL) cells that are associated with prognosis may reflect the context within which their progenitors encountered antigen. It follows that the nature of antigen drive in CLL could influence the clinical course and we were prompted to assess the impact, if any, of affinity maturation (an antigen-driven process) on prognosis. Statistical models for assessing affinity maturation status are typically applied to V(H) gene sequence data analysed using a web-based resource like IMGT or VBASE. Since these resources differ with respect to some key relevant features, we evaluated a cohort of CLL cases by applying statistical models to V(H) data derived from both IMGT and VBASE. Important differences between the resulting data sets became apparent. These resulted from database variance and because IMGT and VBASE define complementarity-determining and framework regions (CDRs, FRs) in different ways. Thus, the numbers of mutations identified and their distribution between CDRs/FRs varied between the data sets for the majority of clones. Consequently, two different but overlapping sets of cases with evidence of affinity maturation were defined. Notwithstanding their differences, no significant associations of affinity maturation status with CD38 expression, p53 functional status or survival were identifiable in either data set.

Role of B-cell antigen receptor-associated molecules and lipid rafts in CD5-induced apoptosis of B CLL cells

A total of 40 patients with B-CLL were investigated for CD5-triggered apoptosis and categorized as 20 resistant (group I) and 20 sensitive patients (group II). The densities of surface IgM (sIgM) and CD5 were lower in group I than group II, as were the percentages of CD79b+, CD38+, and Zap70-expressing B cells. CD5 signaling was mediated through the BCR in group II B cells, as established by coimmunoprecipitation of CD5 and CD79a and tyrosine phosphorylation of CD79a. Following colocalization of CD5 and sIgM in membrane lipid rafts (LRs), Syk became associated with these molecules, whereas SHP-1 was uncoupled from CD5. Nonresponsiveness to CD5 cross-linking in group I was ascribed to three possible abnormalities, and defined as three subgroups of patients. In subgroups Ia and Ib, CD5 and sIgM colocalized within the LRs. SHP-1 remained attached to the BCR in subgroup Ia, but not in subgroup Ib, where signal transduction was associated with an excess of truncated CD79b. In subgroup Ic, CD5 and sIgM segregated into different LRs, resulting in no signaling of apoptosis.

Differential control of G0programme in chronic lymphocytic leukaemia: a novel prognostic factor

Chronic lymphocytic leukaemia (CLL) is a unique malignancy where quiescent B cells accumulate in the peripheral blood. Since clinical outcomes in CLL are very heterogeneous, it is of utmost importance to correctly assess the disease prognosis in each individual case. Recently, it has been shown that high ZAP-70 [Zeta-chain (T-cell receptor) associated protein kinase (70 kDa)] expression level strongly correlates with lack of IgV(H) mutations and poor prognosis in B-CLL. As CLL malignant cells are arrested in G(0), we investigated whether Dipeptidyl Peptidase 2 (DPP2), a serine protease that plays a key role in keeping cells in the quiescent state, is involved in cell-cycle control in CLL. We have previously shown that specific inhibition of DPP2 results in apoptosis of normal lymphocytes. In this study, cell apoptosis experiments were conducted in 38 patients with B-CLL. Two distinct subsets of B-CLL were identified, susceptible and resistant to DPP2-inhibition-induced apoptosis. If resistant to apoptosis (42.1%), the CLL cells have higher expression of ZAP-70 and exhibit a worse prognosis, such as shorter treatment-free time period. Thus, resistance vs. susceptibility to DPP2-inhibiton induced apoptosis can be employed as a novel prognostic factor in CLL.

Mutational status of IgVH genes consistent with antigen-driven selection but not percent of mutations has prognostic impact in B-cell chronic lymphocytic leukemia

Mutational status of immunoglobulin heavy-chain variable-region (IgVH) genes, along with CD38 expression, is a prognostic marker in B-cell chronic lymphocytic leukemia (B-CLL). Configuration of IgVH genes displaying > 2% mismatch has been shown to correlate with longer survivals. In a series of 64 B-CLLs, we failed to confirm the prognostic value of the IgVH gene mutational status by using the suggested cutoff. However, the IgVH mutational status maintained its prognostic value only when evidence of antigen-driven selection could be documented. This was accomplished by applying statistical methods aimed at evaluating a significant skewing of replacement mutations from framework to complementary determining regions, as it occurs during germinal center differentiation of B cells. These data caution against wide application of the 2% somatic mutation cutoff as a prognostic determinant without demonstration of antigen-driven selection.

Histopathology of B-cell chronic lymphocytic leukemia

Histologic and immunohistologic findings of B-cell chronic lymphocytic leukemia/small lymphocytic leukemia are revised in the light of the more recent knowledge on the pathobiology of the disease. The guidelines for the optimal handling of the bioptic samples are provided. The relevance of the examination of trephines and surgical specimens is outlined with special reference to the identification of risk factors in individual patients.

Quantification of CD38 expression in B-cell chronic lymphocytic leukemia (B-CLL): a comparison between antibody binding capacity (ABC) and relative median fluorescence (RMF)

We have previously shown that quantification of CD38 expression using microbeads of specific antibody binding capacity (ABC) improves the prognostic value of CD38 expression in B-cell chronic lymphocytic leukemia, particularly for Binet Stage A patients. Quantification of CD38 expression using beads is expensive, time consuming and could be difficult to implement in a routine clinical laboratory. The calculation of relative median fluorescence (RMF) using the median fluorescence intensities of the test and control samples, is even more simply and cheaply obtained by flow cytometry and could be used as an alternative way of quantifying antigen expression. The present study demonstrates that RMF is an effective prognostic indicator in B-CLL that correlates closely with ABC in predicting disease-specific survival and time to progression for all patients. RMF predicted overall survival and time to progression in all patients (P < 0.0001 for both), in Binet Stage A patients (P < 0.0001 for both) and in Stage A patients under 60 years (P = 0.0299 and P = 0.0143, respectively). ABC predicted overall survival and time to progression in all patients (P < 0.0001 for both) in Stage A patients (P = 0.0024 and P < 0.0001, respectively) and in Stage A patients under 60 (P = 0.0379 and P = 0.0032, respectively). RMF is more effective than percentage CD38 positivity > 30% or > 20% in predicting disease-specific survival in Stage A patients of all ages (CD38 < > 30%: P = 0.0853, CD38 < > 20%: P = 0.0894) and in those under 60 years old (CD38 < > 30%: P = 0.5438, CD38 < > 20%: P = 0.2872). Also, RMF is more effective in predicting time to progression of Binet Stage A patients less than 60 years (P = 0.0143), while percentage CD38 positivity of 30%, 20% or 7% did not achieve statistical significance (P = 0.1103, = 0.0547, = 0.3399, respectively). We suggest that CD38 RMF could be used clinically as an alternative to ABC to identify patients with B-CLL that are likely to progress and require early treatment.

Advances in the understanding of biology and prognosis in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has a heterogeneous clinical course and outcome. Recent advances in the diagnosis and molecular characterization of CLL permit improved prediction of disease prognosis, which could result in better management. We review the biology and diagnosis of CLL and the role of analysis of immunoglobulin heavy-chain variable region mutation status, molecular cytogenetics (interphase fluorescence in situ hybridization), and the expression of CD38 and ZAP-70 in the evaluation and management of patients with CLL.

Applications of Flow Cytometry and Immunohistochemistry to Diagnostic Hematopathology

Objective.—Diagnostic hematopathology depends on the applications of flow cytometric immunophenotyping and immunohistochemical immunophenotyping combined with the cytomorphology and histologic features of each case. Select cases may require additional ancillary cytogenetic and molecular studies for diagnosis. The purpose of this review is to focus on the applications of flow cytometric and immunohistochemical immunophenotyping of paraffin-embedded tissue to diagnostic hematopathology. Advantages and disadvantages of these techniques are examined.

Data Sources.—The literature is extensively reviewed (PubMed 1985–2003) with an emphasis on the most recent applications and those that are most useful clinically, both diagnostically and prognostically.

Study Selection.—Studies were selected based on statistically significant results in large studies with reported adequate clinical follow-up.

Data Extraction.—The methodology was reviewed in the selected studies to ensure reliable comparison of reported data.

Data Synthesis.—Flow cytometric immunophenotyping offers the sensitive detection of antigens for which antibodies may not be available for paraffin immunohistochemical immunophenotyping. However, paraffin immunohistochemical immunophenotyping offers preservation of architecture and evaluation of expression of some proteins, which may not be available by flow cytometric immunophenotyping. These techniques should be used as complimentary tools in diagnostic hematopathology.

Conclusions.—There are extensive applications of flow cytometric and immunohistochemical immunophenotyping to diagnostic hematopathology. As cytogenetic and molecular findings evolve in diagnostic hematopathology, there may be additional applications of flow cytometric and immunohistochemical immunophenotyping to this field of pathology.

Molecular genetics and its clinical relevance

Molecular genetic methods such as fluorescence in situ hybridization and DNA sequencing have greatly improved our understanding of pathogenic events and prognostic markers in chronic lymphocytic leukemia (CLL). There are genomic aberrations detected in over 80% of CLL cases, and genes potentially involved in the pathogenesis were identified with ATM in a subset of cases with 11q deletion and p53 in cases with 17p13 deletion. Genetic subgroups with distinct clinical features have been identified, such as 11q deletion, which is associated with marked lymphadenopathy and rapid disease progression, whereas 17p deletion predicts for treatment failure with alkylating agents, fludarabine, and short survival times. There is mutation status of the VH genes that allows the separation into patients with long (mutated VH) or short (unmutated VH) survival times. V-gene usage, VDJ structure, and gene expression differences in the two subgroups allow insights into differential pathogenic mechanisms and provide further prognostic information (V3-21 usage, ZAP-70 expression). The VH mutation status and genomic abnormalities have been shown to be of independent prognostic value in multivariate analysis, seem to allow outcome predication irrespective of the clinical stage, and may therefore allow a risk assessment for individual patients early in the course of their disease.

Current guidelines in defining therapeutic strategies

The past three decades have brought major changes in the approach toward chronic lymphocytic leukemia (CLL). This disease was considered a simple form of leukemia for which the only goal of treatment was control of the leukocytosis and of the symptoms related to disease expansion. Many biologic discoveries have increased our understanding of the disease process. New prognostic markers have been identified and are being incorporated into clinical practice. Now, CLL is considered a complex and challenging leukemia for which multiple treatment options are emerging, from chemotherapy to monoclonal antibodies, from vaccines to immunomodulatory strategies. The evaluation of treatment results also has been revolutionized: clones carrying genetic aberrations are monitored, and patients who have had a response are assessed for the presence of minimal residual disease.

Clinical staging and prognostic markers in chronic lymphocytic leukemia

In this article we provide a brief review of the two staging systems in chronic lymphocytic leukemia, and we discuss the more recently identified, new prognostic markers that are of interest to clinicians and researchers in this field.

The prognostic value of CD38 expression and its quantification in B cell chronic lymphocytic leukemia (B-CLL)

A large number of prognostic factors are available to help predict the outcome of patients who present with B-cell chronic lymphocytic leukemia (B-CLL). These include clinical stage, leukemic cell morphology, lymphocyte doubling time, the pattern of infiltration in bone marrow trephine biopsies, cytogenetic abnormalities, p53 function and serum factors such as beta-2 microglobulin. Two recently described major prognostic factors are immunoglobulin heavy chain variable region (IgVH) mutation status and cell membrane expression of CD38. These are both highly significant independent prognostic factors, but are not closely correlated. Whereas IgVH mutational status is a time consuming and demanding technique, only available in a limited number of centres, CD38 expression by flow cytometry is relatively simple and rapidly obtained in most diagnostic laboratories. The predictive value of CD38 expression is enhanced by measurement of antigen density in terms of antibody binding capacity (ABC) rather than as the percentage of cells expressing the antigen. ABC correlates closely with relative median fluorescence (RMF), a parameter which is even more simply and cheaply obtained by flow cytometry. One of these methods of determining CD38 expression should be employed routinely. Recent work suggests that membrane ZAP-70 expression determined by flow cytometry will prove to be an accurate proxy for IgVH mutational status and this assay will be within the reach of any laboratory skilled in flow cytometry. The combination of ZAP-70 expression, CD38 antigen density, p53 function and the concentration of serum factors such as soluble CD23, is likely to provide extremely accurate prognostic information in future studies. This will assist in identifying Stage A patients who may benfit from early and/or more intensive treatment, as well as Stage B and C patients who may require alternative treatment strategies at the outset.

Cryptic deletion involving the ATM locus at 11q22.3∼q23.1 in B-cell chronic lymphocytic leukemia and related disorders

B-cell chronic lymphocytic leukemia (B-CLL) follows a heterogeneous clinical course, and several biological parameters have been investigated to try to predict its clinical outcome. New staging systems including cytogenetics and CD38 expression as predictive values have been developed. Deletions of 11q22.3 approximately q23.1 detected at diagnosis in cases of CLL patients have been associated with a relatively aggressive disease. This region, which contains the ataxia telangiectasia mutated (ATM) locus, may be implicated in the pathogenesis of lymphoid malignancies. We developed a set of dual-color specific probes to evaluate the ATM deletion by means of fluorescence in situ hybridization (FISH). We also used flow cytometry to investigate CD38 expression. Forty-one patients with CLL or low-grade B-cell lymphomas were studied at diagnosis or before treatment. FISH showed that only three CLL patients had deletions in the 11q23 locus; all three had progressive disease and were resistant to treatment. These data show that our FISH set of probes efficiently detects ATM deletions in CLL. No correlation was found between ATM deletions and CD38 expression level. These results confirm the prognostic significance of ATM deletions in CLL.

1513A/C polymorphism in the P2X7 receptor gene in chronic lymphocytic leukemia: absence of correlation with clinical outcome

Purinergic P2X7 receptors are ligand-gated cation channels expressed on the cells of the immune and hemopoietic system which have been shown to mediate the ATP-induced apoptotic death of monocytes, macrophages and lymphocytes. A common single nucleotide polymorphism within the P2X7 gene has been described in exon 13 (1513A/C), the gene products encoding fully active and non-functional proteins. We genotyped the P2X7 1513A/C polymorphism using DNA from 111 patients with chronic lymphocytic leukemia (CLL) and 97 healthy controls using polymerase chain reaction (PCR) amplification followed by Hha1 restriction analysis. We found no significant difference in allele frequency between CLL patients and controls. Time periods from diagnosis to initiation of chemotherapy, a surrogate marker for disease progression, were not different in patients displaying the combined 1513A/C and C/C or the 1513A/A genotype (P = 0.97). Similar results were observed in a subgroup analysis of prognostically more favorable CD38-negative and ZAP-70-negative CLL patients. In conclusion, our data do not support a role of the P2X7 genotype as a prognostic marker in B-cell CLL.

Hodgkin and non-Hodgkin lymphoma involving bone marrow

The role of bone marrow examination in diagnosis and staging of patients with Hodgkin lymphoma, B-non-Hodgkin lymphoma, and T-non-Hodgkin lymphoma is reviewed. Optimal routine and specialized bone marrow examination techniques are discussed. The salient morphologic, immunophenotypic, and genetic features of mature and immature B, T neoplasms and classic Hodgkin lymphoma in bone marrow are delineated, along with recommendations to distinguish these overt neoplasms from non-neoplastic processes.

Current approach to diagnosis and management of chronic lymphocytic leukemia

The care of patients with chronic lymphocytic leukemia (CLL) has changed dramatically during the past decade. This review summarizes the work-up of lymphocytosis and the current diagnostic criteria and management of CLL. Although clinical staging (Rai and Binet) remains the foundation for determining prognosis, 50% of patients with early-stage disease at diagnosis will experience an aggressive course of disease with early progression and premature death due to CLL. New laboratory techniques (CD38, fluorescence in situ hybridization [FISH]) can identify some patients with early-stage CLL at high risk of rapid disease progression. The array of treatment options has expanded in recent years and now includes monoclonal antibodies used alone or in combination with purine nucleoside analogues and alkylating agents, which have culminated in dramatically improved response rates. Supportive care guidelines now include vaccination strategies, surveillance for secondary malignancies, and aggressive management of infectious complications. An early hematology consultation is recommended for all patients at diagnosis to identify and counsel high-risk patients with early-stage disease who may benefit from more frequent follow-up or early treatment as part of a clinical trial.

Phenotypical alterations induced by glucocorticoids resistance in RPMI 8226 human myeloma cells

Resistance to glucocorticoids (GCs) frequently appears during treatment of hematological malignancies. This study investigates the phenotypical alterations observed in human myeloma cell sublines resistant to glucocorticoids. Using the RPMI8226 cell line, the cytotoxic efficiencies of four glucocorticoids, and the phenotypes of isolated resistant sublines were analyzed. Methyl-prednisolone and dexamethasone exhibited the higher toxic effects on RPMI8226 cells. All corticoids were able to induce drug-resistance. Resistant sublines showed an increased expression of the alpha-isoform of the glucocorticoid receptors (GRs), and specific modulations in CD23, CD38, CD44 and CD58 expressions. Thus, glucocorticoid resistance in RPMI8226 cells is accompanied by significant phenotypical alterations that could be implicated in survival enhancement to therapy and/or tumor spreading.

Oral fludarabine has significant activity in patients with previously untreated chronic lymphocytic leukemia, and leads to increased STAT1 levels in vivo

Fifteen patients with previously untreated chronic lymphocytic leukemia (CLL) were treated with oral fludarabine. Toxicities were mainly hematologic, and the response rate was 80%. To assess the effect of fludarabine on the transcription factor STAT1, blood samples obtained on study entry were treated in vitro with fludarabine for 24 h, and the majority of samples displayed an expected decrease in STAT1. To determine whether similar changes occurred in vivo, we developed a flow cytometric assay to quantitate STAT1 levels. On completion of fludarabine cycle 1, CLL cells showed increased STAT1 in the majority of patients, in contrast to the in vitro findings. This may reflect a survival advantage for cells that express high levels of STAT1. In conclusion, oral fludarabine is highly active and merits further investigation in previously untreated patients with CLL. Larger studies are indicated to determine optimal timing of STAT1 assessment, and if changes in STAT1 represent an in vivo indicator of response to purine analog therapy.

A set of commercially available fluorescent in-situ hybridization probes efficiently detects cytogenetic abnormalities in patients with chronic lymphocytic leukemia

PURPOSE

To investigate a simplified panel of fluorescent in-situ hybridization (FISH) probes for evaluation of patients with chronic lymphocytic leukemia (CLL) and to correlate results from this technique with known prognostic factors.

METHODS

We retrospectively reviewed the FISH and conventional cytogenetic results, and clinical and laboratory data of 44 patients with CLL.

RESULTS

FISH was more sensitive than conventional cytogenetics in detecting genomic aberrations (75% vs. 16%, P < 0.0001). Trisomy 12 was significantly correlated with the cell surface marker of CD38 expression (P = 0.0017).

CONCLUSION

This FISH panel reliably detects prognostically important genomic abnormalities in CLL and is suitable for widespread use.

ZAP-70 expression is a prognostic factor in chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (B-CLL) is a heterogenous disease with a highly variable clinical course. Recent studies have shown that expression of the protein tyrosine kinase ZAP-70 may serve as a prognostic marker in B-CLL. Employing a semiquantitative RT-PCR assay, we examined purified leukemia B cells of 39 CLL patients for the expression of ZAP-70 mRNA transcripts. Significant ZAP-70 mRNA levels exceeding those found in control samples with 5% T cells were detected in 36% of the CLL cases. Patients in the ZAP-70 positive cohort were characterized by an unfavorable clinical course with a significantly shorter progression-free survival as compared to the ZAP-70-negative patients (64%). These results were confirmed by flow-cytometric analysis of the ZAP-70 protein, and expanded to a larger patient cohort (n=67). A combined statistical analysis of 79 patients showed that the two patient subgroups also differed with regard to overall survival and a panel of known clinical prognostic factors including LDH, thymidine kinase serum levels and expression of the CD38 surface antigen by the leukemic cell clone. The level of ZAP-70 expression did not change over time in the majority of patients where sequential samples were available for analysis.

Biallelic IgH rearrangements in patients with indolent lymphoproliferative disorders: Molecular and practical implications

We report a group of patients (pts) with indolent lymphoproliferative disorder who had both alleles for the immunoglobulin heavy chain genes rearranged (biIgH). This group of 17 pts consisted of 9 small lymphocytic lymphomas (SLL) and 8 chronic lymphocytic leukemia (CLL). The polymerase chain reaction (PCR) amplification of clonal immunoglobulin heavy (IgH) rearrangement using the complementarity determining region III (CDRIII) constantly retrieved two distinct bands in all PCR informative samples of those pts. To rule out biclonality, we evaluated samples by fluorescein activated cell sorting (FACS) analysis and sequenced the PCR products. We were able to obtain both IgH sequences from 12 patients. FACS suggested biclonality in one case, which also correlated with sequencing results as both IgH rearrangements were in-frame. Recently, we reported a patient who sustained transformation into an aggressive disease after biIgH was detected in the setting of monoclonal disease (Cerny et al., 2003b, Haematologica 88(05):ECR15 B.). We decided to compare clinical characteristics and prognosis of 17 pts with biIgH and 37 pts with monoIgH rearrangements. Although we found some minor differences in disease characteristics between both groups, these did not translate into a significantly different overall survival. Our findings suggest that true biclonal cases of CLL are rare.

Advances in the diagnosis and classification of chronic lymphoproliferative disorders

In this review, we have highlighted recent advances in chronic lymphoproliferative disorders that commonly involve the peripheral blood. As we have seen, our concepts of certain diseases are changing. Molecular genetic and immunophenotypic studies are allowing more precise characterization of CLL and defining important biologic markers that predict clinical behavior. Prolymphocytic leukemia is now more narrowly defined and its relationship to nucleolated variants of MCL is now apparent. With new reagents and techniques applied to problems such as identification of Sezary cells and T-cell monoclonality determination, our ability to diagnose, monitor, and provide prognostic information is improving. Insight into the biology of these diseases also may provide new therapeutic targets in the future.

Chronic lymphocytic leukemia with 6q− shows distinct hematological features and intermediate prognosis

Cytogenetic and fluorescence in situ hybridization studies were successfully performed in 217 chronic lymphocytic leukemia (CLL). In all, 13 patients with 6q21 deletion were identified and characterized in comparison with 92 patients with 'favourable' karyotype (normal or 13q-), 69 cases with 'intermediate risk' (1-2 anomalies) and 43 cases with 'unfavourable' karyotype (complex, 11q- or 17p-). Six out of 13 cases with 6q- showed an excess of atypical lymphocytes, a finding confirmed at the histologic level; >20% CD38+ cells were seen in 5/6 cases. IGVH mutational status revealed >98% homology to the germline sequence in 4/10 cases. When compared with the 'favourable' group, patients with 6q- showed a higher white blood cell (WBC) count, frequent splenomegaly, atypical morphology, CD38+ and short time from diagnosis to first treatment and short survival. A higher median WBC count was found in the 6q- group vs the intermediate-risk group; survival was shorter in the unfavourable group. To ascertain if the 6q- anomaly was an independent factor predicting for an inferior outcome among those patients with 'favourable' cytogenetics, we performed an analysis of prognostic factors in 105 patients (92 'favourable' plus 13 with 6q-), showing that the 6q- chromosome maintained its prognostic significance at multivariate analysis (P=0.02) along with stage (P=0.01). We conclude that CLL with 6q- is characterized by a high incidence of atypical morphology, classical immunophenotype with CD38 positivity and intermediate incidence of IGVH somatic hypermutation. Clinicobiological features and outcome show that this cytogenetic subset of CLL should be allocated in an intermediate-risk category.

Flow cytometry in lymphoma diagnosis and prognosis: useful?

Flow cytometry has become an important tool in the diagnosis of mature lymphoid neoplasms and the determination of prognosis in selected cases. The advantages of flow cytometry are based largely on its ability to analyse, rapidly and simultaneously, multiple cell properties in a quantitative manner. Flow cytometric immunophenotyping is useful in diagnosing lymphoma under the WHO classification system, where lymphoid neoplasms are separated into distinct clinical entities based upon morphology, immunophenotype, genetic abnormalities and clinical features. Flow cytometry can quantify the expression of proteins associated with a good or poor prognosis, detect multidrug resistance, and measure cell proliferation, making it useful in measuring prognostic indicators in lymphoid neoplasia. The unique attributes of flow cytometry therefore make it a valuable technique in the diagnosis and classification of lymphomas as well as the assessment of prognostic markers in lymphoma patients.

Prognosis at diagnosis: integrating molecular biologic insights into clinical practice for patients with CLL

Heterogeneity in the clinical behavior of patients with chronic lymphocytic leukemia (CLL) makes it difficult for physicians to accurately identify which patients may benefit from an early or more aggressive treatment strategy and to provide patients with relevant prognostic information. Given the potential efficacy of newer therapies and the desire to treat patients at "optimum" times, it is more important than ever to develop sensitive stratification parameters to identify patients with poor prognosis. The evolution of risk stratification models has advanced from clinical staging and use of basic laboratory parameters to include relevant biologic and genetic features. This article will review the dramatic progress in prognostication for CLL and will propose statistical modeling techniques to evaluate the utility of these new measures in predictive models to help determine the optimal combination of markers to improve prognostication for individual patients. This discussion will also elaborate which markers and tools should be used in current clinical practice and evaluated in ongoing clinical trials.

CD38 is a signaling molecule in B-cell chronic lymphocytic leukemia cells

The prognosis for patients with B-cell chronic lymphocytic leukemia (B-CLL) is generally less favorable for those expressing CD38. Our working hypothesis is that CD38 is not merely a marker in B-CLL, but that it plays a receptor role with pathogenetic potential ruling the proliferation of the malignant clone. CD38 levels were generally low in the patients examined and monoclonal antibody (mAb) ligation was inefficient in signaling. Other cellular models indicated that molecular density and surface organization are critical for CD38 functionality. Interleukin 2 (IL-2) induced a marked up-modulation and surface rearrangement of CD38 in all the patients studied. On reaching a specific expression threshold, CD38 becomes an efficient receptor in purified B-CLL cells. Indeed, mAb ligation is followed by Ca2+ fluxes and by a markedly increased proliferation. The unsuitability of CD38 to perform as a receptor is obviated through close interaction with the B-cell-receptor (BCR) complex and CD19. On mAb binding, CD38 translocates to the membrane lipid microdomains, as shown by a colocalization with the GM1 ganglioside and with CD81, a raft-resident protein. Finally, CD38 signaling in IL-2-treated B-CLL cells prolonged survival and induced the appearance of plasmablasts, providing a pathogenetic hypothesis for the occurrence of Richter syndrome.

New directions in the diagnosis and treatment of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia of adults in Western countries. It is a systemic haematological malignancy that originates from B cells (B-CLL) in 95% of patients, while only a minority are derived through malignant transformation of T cells (T-CLL). Although B-CLL is classified as a non-Hodgkin's lymphoma, several issues make this leukaemia a unique entity among malignant lymphoma. Inhibition of the programmed cell death (apoptosis) and upregulation of the anti-apoptotic protein Bcl-2 are key elements of the pathophysiology of B-CLL cells and define clinical prognosis. Furthermore, B-CLL cells are arrested in G0/G1 phase of the cell cycle. Dysfunctional apoptosis and cell cycle are the main reasons for the clinical enigma, that CLL can not yet be cured with conventional chemotherapy. However, the molecular pathways that are responsible for this characteristic feature of the B-CLL cells still need further definition.Recently, considerable progress has been made in defining the molecular basis for the pathogenesis of CLL and in finding new therapeutic options. Recent studies indicate that B-CLL cells may be delineated from two main groups of normal B cells, i.e. pre- and postgerminal B cells, and can be distinguished through lack of or existence of mutations of the V heavy chain gene. This differential mutational status of the Ig V gene has significant impact on patient survival. Modern cytogenetic methods such as fluorescence in situ hybridisation (FISH) have opened a new era in the molecular analysis of CLL cells. Determining the chromosomal aberration of the leukaemic cells has become a standard scientific programme for each clinical trial. The cytogenetic profile may soon help to define a clinical risk profile and guide the various treatment strategies. Further progress has been made in the therapy of CLL. Purine analogues such as fludarabine were able to induce significant improvement in remission rates; however, they did not lead to improved survival. Chimera of murine or rat monoclonal antibodies and human antibodies were designed to treat CLL. Antibodies such as rituximab and alemtuzumab (Campath-1H), directed against CD20 and CD52, respectively, appear as attractive alternatives to conventional chemotherapy because of their lack of significant myelotoxicity. Studies using myeloablative chemotherapy followed by autologous or allogeneic stem cell transplantation were initiated with the hope of finding a cure for CLL. In contrast to autologous stem cell transplantation, allogeneic transplants appear to display a plateau of relapse rates. In conclusion, for many years CLL was considered as a chronic haematological malignancy that required only few diagnostic tools and for whom no hope of cure could be offered. The current review focuses on recent improvements in diagnosis and treatment of CLL that have opened a new era in the management of patients with this systemic malignancy.