ZAP-70 expression, as detected by immunohistochemistry on bone marrow biopsies from early-phase CLL patients, is a strong adverse prognostic factor

Zeta-associated protein-70 (ZAP-70), mostly assessed by flow-cytometry (FC), recently emerged as reliable prognostic factor in chronic lymphocytic leukaemia (CLL) at presentation. We evaluated ZAP-70 expression in 156 CLL patients by immunohistochemistry (IHC) on formalin-fixed bone marrow (BM) biopsies at diagnosis. At presentation, 117 patients (75%) were with Binet stage A, 27 (17%) stage B and 12 (8%) stage C. Median follow-up was 61 months (range 6-242). ZAP-70 was expressed in neoplastic lymphocytes of 69 patients (44%). Concordance between ZAP-70 by IHC and ZAP-70 by FC, immunoglobulin heavy chain variable genes (IGHV) mutational status and CD38 expression was found in 41/46 (89%), 41/49 (80%) and in 60/88 (68%) tested cases, respectively. ZAP-70 expression significantly correlated with advanced Binet stage (B-C), diffuse BM infiltration, increased lactate dehydrogenase (LDH) and beta2-microglobulin serum levels and lymphocyte doubling time <12 months. ZAP-70 positivity was significantly related to poorer time to progression (median 16 months vs 158 of ZAP-70-negative cases) (P<0.0001) and overall survival (median 106 months vs not reached) (P=0.0002); this correlation was confirmed at multivariate analysis. ZAP-70 expression correlated with poorer outcome also when evaluated only in the 117 stage A patients. In conclusion, immunohistological detection of ZAP-70 on formalin-fixed BM biopsies at diagnosis appears a useful methodological approach to identify patients with poor prognosis in CLL.

The detection and significance of minimal residual disease in acute and chronic leukemia

Minimal residual disease (MRD) can be detected in many patients with leukemia who have achieved complete remission as defined by conventional pathology examination. The detection of MRD, be it by flow cytometry or by polymerase chain reaction assays, has now been found to be associated with subsequent relapses in most leukemia subtypes, either following chemotherapy or following hematopoietic stem cell transplantation. These assays are now increasingly used in clinical trial design to optimize therapy and provide a novel way to assess treatment efficacy.

B cell receptors in TCL1 transgenic mice resemble those of aggressive, treatment-resistant human chronic lymphocytic leukemia

B cell chronic lymphocytic leukemia (B-CLL) is a clonal overgrowth of CD5(+) B lymphocytes. In this disease, the B cell antigen receptor (BCR) is intimately linked to disease severity, because patients with BCRs, comprised of unmutated V(H) genes, follow a much more aggressive course. This and related observations suggest that B-CLL derives from a B cell subset comprised of restricted BCR structural diversity and that antigen-selection and drive are major factors promoting the disease. Nevertheless, the initiating event(s) that lead to the development of B-CLL are still unclear, in part because of the lack of an animal model that spontaneously evolves the molecular abnormalities that occur in the human disease. Because overexpression of the TCL1 gene in murine B cells leads to a CD5(+) B cell lymphoproliferative disorder with many of the features of human B-CLL, we studied leukemias emerging in these mice to examine the extent to which their BCRs resemble those in B-CLL. Our data indicate that the immunoglobulin heavy and light chain rearrangements in TCL1 mice display minimal levels of somatic mutations and exhibit several molecular features found in the human disease. Like human B-CLL, TCL1 leukemic rearrangements from different mice can be very similar structurally and closely resemble autoantibodies and antibodies reactive with microbial antigens. Antigen-binding analyses confirm that selected TCL1 clones react with glycerophospholipid, lipoprotein, and polysaccharides that can be autoantigens and be expressed by microbes. This (auto)antigen-driven mouse model reliably captures the BCR characteristics of aggressive, treatment-resistant human B-CLL.

Quality of life in chronic lymphocytic leukemia: a neglected issue

Improvement in quality of life (QoL), together with overall survival and disease-free survival, is a relevant endpoint for patients affected by chronic lymphocytic leukemia (CLL), a disease still considered as not curable. In addition, the study of the QoL can significantly contribute to investigate particular aspects related to different treatments which generally are not taken into account in clinical trials. A comprehensive approach to CLL should include also in the day-by-day practice the development of an appropriate and friendly interaction between the physician and patients aimed at improving the process of adaptation encompassing either the 'watch and wait' phase or the treatment period. The present review points out the role of QoL in the global patient management and care of CLL patients also in view of changes in the philosophy of treatment we have witnessed nowadays.

Fludarabine induces apoptosis in chronic lymphocytic leukemia--the role of P53, Bcl-2, Bax, Mcl-1, and Bag-1 proteins

The expression of P53, Bcl-2, Bax, Bag-1, and Mcl-1 proteins in CD5/CD20-positive B-chronic lymphocytic leukemia (B-CLL) cells from 30 typical CLL patients was evaluated before and after 48 h of incubation with 10(-6) M fludarabine using multiparametric flow cytometric analysis. Protein expression was correlated with annexin V expression, Rai modified clinical staging, lymphocyte doubling time, and previous treatment. Our main goal was to determine the predictive value of these proteins in CLL cells in terms of disease evolution. Bcl-2 expression decreased from a median fluorescence index (MFI) of 331.71 +/- 42.2 to 245.81 +/- 52.2 (P < 0.001) after fludarabine treatment, but there was no difference between viable cells (331.57 +/- 44.6 MFI) and apoptotic cells (331.71 +/- 42.2 MFI) before incubation (P = 0.859). Bax expression was higher in viable cells (156.24 +/- 32.2 MFI) than in apoptotic cells (133.56 +/- 35.7 MFI) before incubation, probably reflecting defective apoptosis in CLL (P = 0.001). Mcl-1 expression was increased in fludarabine-resistant cells and seemed to be a remarkable protein for the inhibition of the apoptotic process in CLL (from 233.59 +/- 29.8 to 252.04 +/- 35.5; P = 0.033). After fludarabine treatment, Bag-1 expression was increased in fludarabine-resistant cells (from 425.55 +/- 39.3 to 447.49 +/- 34.5 MFI, P = 0.012), and interestingly, this higher expression occurred in patients who had a short lymphocyte doubling time (P = 0.022). Therefore, we could assume that Bag-1 expression in such situation might identify CLL patients who will need treatment earlier.

Loss of CD19 expression in B-cell neoplasms

AIMS

To investigate whether an antibody against an intracellular epitope can detect CD19 in routine biopsy specimens and thus to document in detail its expression in human lymphomas.

METHOD AND RESULTS

A polyclonal antibody to the C terminus of CD19 was used to immunostain paraffin-embedded samples of normal and neoplastic lymphoid tissues. CD19 was widely expressed in normal B cells and in extramedullary plasma cells. It was found in most B-cell neoplasms, but expression in follicular lymphoma was weak (33/69) or negative (four cases). Similarly, CD19 expression in diffuse large B-cell lymphomas was weak (28/56) or negative (eight cases). In T-cell-rich B-cell lymphomas, CD19 was also weak (4/10) or negative (three cases). CD19 was often absent in post-transplant B lymphoproliferative disease, classical Hodgkin's disease and plasma cell neoplasms. An unexpected finding was the frequent absence of CD19 in the neoplastic cells in lymphocyte predominant Hodgkin's disease.

CONCLUSIONS

CD19 can now be detected in routine biopsy specimens. In contrast to the classical pan-B marker CD20, CD19 is not always strongly expressed in B-cell neoplasms. Furthermore, the lymphocytic and histiocytic (L&H) cells of lymphocyte predominant Hodgkin's disease (which express most B-cell-associated markers) commonly lack CD19.

Infrequent Wnt inhibitory factor-1 (Wif-1) methylation in chronic lymphocytic leukemia

The Wnt pathway has been shown recently, to be activated in patients with chronic lymphocytic leukemia (CLL). This is the first study to examine the role of Wnt inhibitory factor-1 (Wif-1) methylation in the pathogenesis of haematolymphoid malignancies. Wif-1, a putative tumor suppressor, is a soluble negative regulator of the Wnt pathway activated in CLL. We studied the role of methylation of Wif-1 in 43 Chinese patients with CLL. At diagnosis, Wif-1 methylation was detected in 5/43 (11.6%) CLL marrow samples. Wif-1 methylation occurred more frequently in patients with advanced age (p = 0.059) but there was no correlation between Wif-1 methylation and sex, lymphocyte count and Rai stage at diagnosis. In conclusion, Wif-1 is infrequently methylated in CLL. Other factors leading to activation of the Wnt pathway warrant further study.

CpG Island Methylation and Expression of the Secreted Frizzled-Related Protein Gene Family in Chronic Lymphocytic Leukemia

B-cell chronic lymphocytic leukemia (CLL) is characterized by a clonal accumulation of mature neoplastic B cells indicating disruption of apoptosis. Restriction Landmark Genome Scanning was done to identify novel target genes silenced by CpG island methylation in CLL. Secreted frizzled-related protein 4 (SFRP4), a negative regulator of the Wnt signaling pathway, was found to be frequently methylated in CLL samples. Wnt signaling has been shown to control normal apoptotic behavior and is required for normal B-cell development whereas aberrant activation of this pathway has been observed in CLL. We show aberrant DNA methylation and silencing of SFRP4, as well as of additional SFRP family members, in primary CLL samples. Induction of their expression in a dose-dependent manner following treatment with a demethylating agent, 5-aza-2'-deoxycytidine, was shown. Of the five SFRP family members studied in detail, SFRP1 was hypermethylated and down-regulated in all CLL patient samples studied, suggesting that this epigenetic event is a critical step during leukemogenesis. Our results suggest that silencing of SFRPs by CpG island methylation is one possible mechanism contributing to aberrant activation of Wnt signaling pathway in CLL.

Basic fibroblast growth factor suppresses p53 activation in the neoplastic cells of a proportion of patients with chronic lymphocytic leukaemia

p53 is the most frequently inactivated gene in human cancers, reflecting its pivotal role in maintaining genomic integrity. The present study was conducted to explore the possibility that tumour cells with no intrinsic defects of the p53 pathway might nevertheless acquire p53 dysfunction through extrinsic suppression of the pathway by microenvironmental factors. Neoplastic cells from patients with chronic lymphocytic leukaemia (CLL) were cultured in the presence or absence of basic fibroblast growth factor (bFGF) and exposed to ionizing radiation (IR) to induce p53 accumulation. bFGF is greatly increased in the plasma of CLL patients and can suppress p53 activation in some experimental models. IR induced a marked increase in p53 levels in 28 samples from 24 patients. bFGF inhibited IR-induced p53 accumulation to some extent in most of these samples and by more than 50% in seven samples from seven patients. Suppression of p53 activation by bFGF was frequently but not always accompanied by upregulation of the p53-inhibitory protein MDM2 and/or phosphorylation of MDM2 at serine 166, and was associated with impaired transcriptional activation of the p53 target gene p21. These observations provide the first demonstration in human cancer cells that the p53 pathway can be suppressed by factors in the tumour-cell microenvironment.

[Bcl-2 and Bax protein interaction in B-lymphocytes of peripheral blood in patients with chronic lymphocytic leukemia]

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a neoplastic disease characterized by the accumulation of morphologically mature monoclonal CD5+ B cells in the early phase (G0/G1) of the cell cycle. The accumulation of neoplastically transformed B-lymphocytes (CLL cells) is primarily the consequence of apoptosis blocking in these cells. Bcl-2 proteins are well-known modulators of this process. Some of these proteins are anti-apoptotic while the others are pro-apoptotic. All contain at least one of the four conserved regions called the Bcl-2 homologous domains (BH1-BH4). Evidence indicates that Bcl-2 and Bax form homo- and heterodimers. The anti-apoptotic effect of Bcl-2 protein is based on its ability to bind Bax protein in the heterodimer form, and thus to block the forming of Bax/Bax proapoptotic homodimers. The ratio of Bcl-2/Bax represents the cell autonomous rheostat which determinates the type of the cell reaction to an apoptotic stimulus.

METHODS

The aim of this study was to determine the level of interaction between these two proteins in CLL cells using the co-immunoprecipition method. The study included the analysis of 20 peripheral blood specimens from 20 patients with CLL, and 20 peripheral blood specimens from healthy persons, who were in the control group. Specimens were precipitated with the monoclonal antibody for Bcl-2 protein, and immunoblotted with the palyclonal antibady for Bax protein (IP: Bcl-2/WB:Bax). At the same time, specimens were precipitated with the polyclonal antibody for Bax protein, and immunoblotted with the monoclonal antibody for Bcl-2 protein (IP: Bax/WB:Bcl-2). The intensity of Bcl-2 and Bax protein's binding compared to the control samples of the peripheral blood from healthy persons, was increased in CLL cells.

RESULTS

IP: Bax/WB: Bcl-2 showed a high level of "free" Bcl-2 protein which was not bound in the heterodimer form to Bax protein. Simultaneously IP: Bcl-2/WB: Bax showed that a higher quantity of Bax protein was bound in the heterodimer form to Bcl-2 protein as opposed to the quantity of pro-apoptotic Bax protein potentialy bound in the homodimer form.

CONCLUSION

Further studies involving larger groups of patients are necessary to explore the potential significance of the Bcl-2/Bax protein ratio as a prognositc parameter in the CLL treatment.

Novel sulfasalazine analogues with enhanced NF-kB inhibitory and apoptosis promoting activity

The NF-kB transcription factor plays a key role in the regulation of apoptosis by modulating expression of a wide range of cell death control molecules. NF-kB also plays an important role in human diseases by promoting inappropriate cell survival. Small molecule inhibitors of NF-kB are therefore likely to provide novel therapeutic opportunities. Sulfasalazine (SFZ) is a synthetic anti-inflammatory comprising an aminosalicylate, 5-amino salicylic acid (5-ASA), linked to an antibiotic, sulfapyridine (SPY). SFZ, but not 5-ASA or SPY, inhibits activation of NF-kB. We synthesised a small number of SFZ analogues and determined their ability to inhibit NF-kB activity and promote apoptosis in chronic lymphocytic leukaemia and hepatic stellate cells, where NF-kB plays an important role in cell survival. Remarkably, 3 of the 6 analogues synthesised were significantly more effective (up to 8-fold) inhibitors of NF-kB dependent transcription and this increased activity was associated with enhanced apoptosis. Therefore, it is possible to readily improve the NF-kB inhibiting activity of SFZ and analogues of SFZ may be attractive therapeutic agents for malignancies and chronic liver disease where NF-kB is thought to play a significant role.

Sustained visual recovery after treatment with intrathecal methotrexate in a case of optic neuropathy caused by chronic lymphocytic leukemia

A 68-year-old woman with chronic lymphocytic leukemia (CLL) had acute optic neuropathy associated with cerebrospinal fluid evidence of meningeal spread of CLL. There was no evidence of a hematologic relapse. After undergoing four weekly doses of intrathecal methotrexate, vision improved dramatically and spinal fluid became normal. Four years later, she has near normal vision in the affected eye and remains in hematologic remission. This is the first reported case of successful treatment of optic neuropathy in CLL with intrathecal methotrexate alone.

Survival role of protein kinase C (PKC) in chronic lymphocytic leukemia and determination of isoform expression pattern and genes altered by PKC inhibition

Recent studies have suggested that protein kinase C (PKC) activation plays an important role in survival of chronic lymphocytic leukemia (CLL). In order to characterize the role of PKC in CLL, we investigated the expression pattern of PKC isoforms in CLL cells (7 cases) and evaluated the effect of PKC inhibition on the survival of CLL cells (20 cases). Expression of the classical PKC isoforms beta and gamma, the novel isoform delta and the atypical isoform zeta was seen in all analyzed patient samples by Western blot analysis. Expression of the PKC isoforms alpha, epsilon, and iota was variable. Following incubation with the PKC inhibitor, safingol, CLL cells underwent marked apoptosis in all cases. In order to characterize the molecular events associated with the apoptotic effect of PKC inhibition, gene expression patterns in CLL cells were evaluated by cDNA-microarray analysis. Following safingol treatment, several genes showed marked downregulation and PKC-related proteins demonstrated decreased hybridization signals. Among these proteins, CREB and Daxx were further studied by using Western blotting, nuclear binding assay and confocal immunofluorescent microscopy. These studies showed significant inhibition of these proteins, consistent with the results of microarray gene analysis. Overall, these findings suggest that PKC activation is important for CLL cell survival and that inhibitors of PKC may have a role in the treatment of patients with CLL.

In vivo measurements document the dynamic cellular kinetics of chronic lymphocytic leukemia B cells

Due to its relatively slow clinical progression, B cell chronic lymphocytic leukemia (B-CLL) is classically described as a disease of accumulation rather than proliferation. However, evidence for various forms of clonal evolution suggests that B-CLL clones may be more dynamic than previously assumed. We used a nonradioactive, stable isotopic labeling method to measure B-CLL cell kinetics in vivo. Nineteen patients drank an aliquot of deuterated water (2H2O) daily for 84 days, and 2H incorporation into the deoxyribose moiety of DNA of newly divided B-CLL cells was measured by gas chromatography/mass spectrometry, during and after the labeling period. Birth rates were calculated from the kinetic profiles. Death rates were defined as the difference between calculated birth and growth rates. These analyses demonstrated that the leukemic cells of each patient had definable and often substantial birth rates, varying from 0.1% to greater than 1.0% of the entire clone per day. Those patients with birth rates greater than 0.35% per day were much more likely to exhibit active or to develop progressive disease than those with lower birth rates Thus, B-CLL is not a static disease that results simply from accumulation of long-lived lymphocytes. Rather, it is a dynamic process composed also of cells that proliferate and die, often at appreciable levels. The extent to which this turnover occurs has not been previously appreciated. A correlation between birth rates and disease activity and progression appears to exist, which may help identify patients at risk for worsening disease in advance of clinical deterioration.

Reversal of bone marrow angiogenesis in chronic lymphocytic leukemia following fludarabine therapy

We evaluated bone marrow (BM) angiogenesis in 12 responding patients with Binet stage B chronic lymphocytic leukemia who received either chlorambucil or fludarabine. Microvessel density (MVD) was compared between pre-treatment marrow samples and those obtained after at least 4 cycles of chemotherapy. BM angiogenesis decreases in all patients but one, although subset analysis revealed the decrease of BM angiogenesis was significant only in patients who received fludarabine. Even if based on a small number of patients, these results point out the potential in vivo anti-angiogenic activity of fludarabine.

Richterʼs Syndrome

Richter's syndrome, that is, transformation of chronic lymphocytic leukemia to a large cell or immunoblastic lymphoma, occurs in up to 10% of patients with chronic lymphocytic leukemia. The onset of Richter's syndrome is characterized by worsening systemic symptoms, rapid tumor growth, and/or extranodal involvement. Median survival with conventional chemotherapy is less than 6 months. Therapy with more recent therapeutic regimens, such as hyperCVXD (fractionated cyclophosphamide, vincristine, liposomal daunorubicin, and dexamethasone), augmented hyperCVXD, and yttrium-90 ibritumomab tiuxetan, has not produced major improvements in response rates or overall survival. Improvement in the outcome of patients with Richter's syndrome may be aided by a more comprehensive understanding of the pathogenesis of Richter's syndrome; therapy could then be targeted against specific abnormalities. Current data indicate that the transformation of chronic lymphocytic leukemia to a large-cell or immunoblastic lymphoma is associated with abnormalities in cell cycle regulation (e.g., loss of the cell cycle inhibitors p16(INK4a) and p27(KIP1) ) and DNA repair (e.g., mutations and/or deletions of the p53, ATM, and p14(ARF) genes and epigenetic silencing of the MLH1 gene). However, the critical event leading to transformation is unclear. Given the poor prognosis of patients with Richter's syndrome, every effort should be made to enroll these patients into clinical trials evaluating novel agents with the appropriate correlative studies.

Lower levels of surface B-cell-receptor expression in chronic lymphocytic leukemia are associated with glycosylation and folding defects of the μ and CD79a chains

Low levels of B-cell-receptor (BCR) expression are the hallmark of tumoral B lymphocytes in B-cell chronic lymphocytic leukemia (B-CLL). These cells also respond inadequately to stimulation through the BCR. This receptor consists of a surface immunoglobulin associated with a CD79a/CD79b heterodimer. We previously showed that the intracellular synthesis of BCR components, from transcription onward, is normal. Here, we investigated the glycosylation status and cellular localization of μ, CD79a, and CD79b chains in 10 CLL patients differing in surface immunoglobulin M (IgM) expression. We reported a severe impairment of the glycosylation and folding of μ and CD79a. These defects were associated with the retention of both chains in the endoplasmic reticulum and lower levels of surface IgM expression. In contrast, no clear impairment of glycosylation and folding was observed for CD79b. No sequence defects were identified for BCR components and for the chaperone proteins involved in BCR folding processes. These data show, for the first time, that lower levels of BCR surface expression observed in CLL are accounted for by an impaired glycosylation and folding of the μ and CD79a chains.

[Current and perspective treatment of chronic lymphocytic leukemia]

Chronic lymphocytic leukemia represents the most frequent hematological malignancy in the western population. Important role in its pathogenesis has the inhibition of apoptosis, disturbances in differentiation of B-lymphocytes, slightly increased proliferation and induction of angiogenesis. Current treatment options (chemotherapy and immunotherapy) can improve the quality of life and prolong disease-free survival, but the overall survival is not significantly influenced. The only curative treatment alternative is the allogeneic hematopoietic stem cell transplantation. However, this treatment is accompanied by the risk of peritransplantation mortality and its use is limited for younger patients. Number of new compounds is clinically tested. New drugs can influence intracellular events such as induction of apoptosis or inhibition of the transduction cascade. Review summarises treatment alternatives and presents an algorithm for their clinical application.

Ionizing radiation and chronic lymphocytic leukemia

The U.S. government recently implemented rules for awarding compensation to individuals with cancer who were exposed to ionizing radiation while working in the nuclear weapons complex. Under these rules, chronic lymphocytic leukemia (CLL) is considered to be a nonradiogenic form of cancer. In other words, workers who develop CLL automatically have their compensation claim rejected because the compensation rules hold that the risk of radiation-induced CLL is zero. In this article we review molecular, clinical, and epidemiologic evidence regarding the radiogenicity of CLL. We note that current understanding of radiation-induced tumorigenesis and the etiology of lymphatic neoplasia provides a strong mechanistic basis for expecting that ionizing radiation exposure increases CLL risk. The clinical characteristics of CLL, including prolonged latency and morbidity periods and a low case fatality rate, make it relatively difficult to evaluate associations between ionizing radiation and CLL risk via epidemiologic methods. The epidemiologic evidence of association between external exposure to ionizing radiation and CLL is weak. However, epidemiologic findings are consistent with a hypothesis of elevated CLL mortality risk after a latency and morbidity period that spans several decades. Our findings in this review suggest that there is not a persuasive basis for the conclusion that CLL is a nonradiogenic form of cancer.

Quantitative analysis of nucleoside transporter and metabolism gene expression in chronic lymphocytic leukemia (CLL): identification of fludarabine-sensitive and -insensitive populations

Resistance to fludarabine is observed in the clinic, and molecular predictive assays for benefit from chemotherapy are required. Our objective was to determine if expression of nucleoside transport and metabolism genes was associated with response to fludarabine therapy in patients with chronic lymphocytic leukemia (CLL). CLL cells from 56 patients were collected prior to treatment with fludarabine. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on sample RNA to determine the relative levels of mRNA of 3 nucleoside transporters that mediate fludarabine uptake (human equilibrative nucleoside transporter 1 [hENT1], human equilibrative nucleoside transporter 2 [hENT2], and human concentrative nucleoside transporter 3 [hCNT3]), deoxycytidine kinase (dCK), and 3 5'-nucleotidases (ecto-5'nucleotidase [CD73], deoxynucleotidase-1 [dNT-1], and cytoplasmic high-Km 5-nucleotidase [CN-II]). Two-dimensional hierarchical cluster analysis of gene expression identified 2 distinct populations of CLL. Cluster 2 patients experienced a 3.4-fold higher risk of disease progression than cluster 1 patients (P = .0058, log-rank analysis). Furthermore, independent analysis of the individual genes of interest revealed statistically significant differences for risk of disease progression (adjusted hazard ratios [HRs]) with underexpression of dNT-1 (HR = 0.45; P = .042), CD73 (HR = 0.40; P = .022), and dCK (HR = 0.0.48; P = .035), and overexpression of hCNT3 (HR = 4.7; P = .0007) genes. Subjects with elevated hCNT3 expression experienced a lower complete response rate to fludarabine therapy (11% vs 69%; P = .002). No hCNT3-mediated plasma membrane nucleoside transport was detected in CLL samples expressing hCNT3 message, and hCNT3 protein was localized to the cytoplasm with immunohistochemical and confocal microscopy.

Perspectives in chronic lymphocytic leukemia biology and management

Considerable progress has been achieved in the comprehension of the pathogenesis, prognosis, assessment, and treatment of chronic lymphocytic leukemia. However, this progress also has introduced new enigmas in the fields of biology, prognosis, and treatment. This article discusses some unanswered questions in these different topics.

Recent advances in the molecular biology and immunobiology of chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (B-CLL) has long been viewed as a relatively homogeneous disease caused by the accumulation of monoclonal immature, immunoincompetent B cells with faulty apoptotic capacities. However, recent evidence, reviewed here, demonstrates that at least two different B-CLL subgroups exist with different clinical courses and outcomes. The malignant cells from both B-CLL subgroups are antigen-experienced cells that have a normal apoptotic apparatus and turnover continually. The leukemic cells of the two B-CLL subgroups have engaged antigen before transformation, although primarily the cells of patients in the poor outcome subgroup can respond to antigens following transformation. The difference in the ability to respond to antigen as a full-fledged B-CLL probably accounts for the different biological features and clinical outcomes of the patients in these subgroups.

[Apoptosis in pathogenesis of B-cell chronic lymphocytic leukemia]

B-cell chronic lymphocytic leukemia (B-CLL), a clonal expansion of B CD5+ cells, is the most frequent type of adult leukemia in western countries. Accumulation of neoplastic B-cells is caused not by their higher proliferation rate, but by their prolonged life-span due to dysregulation of apoptosis. Many proteins act as inducers or inhibitors in controlling apoptosis. A high level of antiapoptotic BCL-2 protein is detected in B cells of B-CLL. Other factors, such as NF-kappaB, PI-3K and PKC, are also involved in the inhibition of malignant cell apoptosis. A high level of p27kip1, an inhibitor of cyclin-dependent kinase that correlates with the degree of in vitro apoptosis, is found in B-CLL cells. The autologous interaction between BAFF, APRIL, and their ligands may also be involved in apoptosis inhibition in B-CLL. Some external factors e.g. cytokines, may suppress apoptosis of malignant cells. IL-4, IL-2, IFN-gamma, and TNF are proven inhibitors, while IL-5 and IL-10 are inducers of apoptosis of these cells. Even though there are reports characterizing some mechanisms of B-CLL cell apoptosis, relatively less is still known about the complex regulation of this process. This requires more precise research, as new anti-leukemic drugs influence the regulation of apoptosis of neoplastic B lymphocytes.

Fludarabine treatment of patients with chronic lymphocytic leukemia induces a p53-dependent gene expression response

Fludarabine, the current standard treatment for B-cell chronic lymphocytic leukemia (CLL), can induce apoptosis in CLL cells in vitro, and a number of molecular mechanisms contribute to its cytotoxicity. Using gene expression profiling, we investigated the molecular consequences of fludarabine treatment of patients with CLL in vivo. In 7 patients with CLL, a consistent gene expression signature of in vivo fludarabine exposure was identified. Many of the fludarabine signature genes were known p53 target genes and genes involved in DNA repair. In vitro treatment of CLL cells with fludarabine induced the same set of genes as observed in vivo, and many of these genes were also induced by in vitro exposure of CLL cells to ionizing radiation. Using isogenic p53 wild-type and null lymphoblastoid cell lines, we confirmed that many of the fludarabine signature genes were also p53 target genes. Because in vivo treatment with fludarabine induces a p53-dependent gene expression response, fludarabine treatment has the potential to select p53-mutant CLL cells, which are more drug resistant and associated with an aggressive clinical course. These considerations suggest that fludarabine treatment should be given in strict accordance to the current National Cancer Institute (NCI) guidelines that have established criteria of disease activity that warrant treatment.

Chylothorax as a result of chronic lymphocytic leukemia: case report and review of the literature

Chylothorax occurs when a disruption in the thoracic duct allows chyle to escape into the pleural space. The most commonly reported cause is malignancy, especially lymphoma. However, chylothorax caused by chronic lymphocytic leukemia is rarely reported in the literature. We describe a patient who developed chylothorax secondary to chronic lymphocytic leukemia. In addition, the pathogenesis, diagnosis, and treatment of chylothorax are reviewed.

Among circulating hematopoietic cells, B-CLL uniquely expresses functional EPAC1, but EPAC1-mediated Rap1 activation does not account for PDE4 inhibitor-induced apoptosis

Type 4 cyclic adenosine monophosphate (cAMP) phosphodiesterase (PDE4) inhibitors and other agents that raise intracellular cAMP levels induce apoptosis in B-cell chronic lymphocytic leukemia (B-CLL) but not in T-CLL or peripheral blood T cells. Two principal effector proteins for cAMP are protein kinase A (PKA) and EPAC (exchange protein directly activated by cAMP), a Rap guanosine 5′-diphosphate (GDP) exchange factor. We here examine whether varying expression of EPAC accounts for the discrepant sensitivity of B-CLL and T cells to PDE4 inhibitor-induced apoptosis. B-CLL and peripheral blood B cells express EPAC1 transcript, whereas T-CLL, peripheral blood T cells, monocytes, and neutrophils do not. Treatment with the PDE4 inhibitor rolipram induces Rap1 activation in B-CLL cells but not in peripheral blood B cells, T-CLL, or any of the normal hematopoietic lineages examined. The EPAC-specific cAMP analog 8CPT-2Me-cAMP (8-(4-chloro-phenylthio)-2′-O-methyladenosine-3′,5′-cAMP) activates Rap1 in B-CLL cells, but, unlike rolipram/forskolin or 8-Bromo-cAMP, it does not induce PKA activation, as judged by phosphorylation of the transcription factor cAMP-response element binding protein (CREB). Unexpectedly, whereas rolipram/forskolin and 8-Bromo-cAMP induce apoptosis in B-CLL cells, 8CPT-2Me-cAMP decreased basal apoptosis in B-CLL cells by an average of 25% (P &lt; .002). Our results demonstrate that B-CLL cells uniquely activate Rap1 in response to PDE4 inhibitors and suggest that physiologic stimuli that activate EPAC may transmit an antiapoptotic signal. (Blood. 2004;103:2661-2667)

2-Chlorodeoxyadenosine alone and in combination with cyclophosphamide and mitoxantrone induce apoptosis in B chronic lymphocytic leukemia cells in vivo

The purpose of the study was to determine some apoptotic events in mononuclear cells obtained from peripheral blood of patients with B-cell chronic lymphocytic leukemia (B-CLL) during and after therapy with 2-chlorodeoxyadenosine (2-CdA; C), and the combination of 2-CdA with cyclophosphamide (CC), or 2-CdA with mitoxantrone and cyclophosphamide (CMC). Western blot technique was performed to estimate expression/proteolytic degradation of generally accepted apoptotic markers, i.e., Bcl-2 protein, lamin B, PARP-1, and caspase-3 in leukemic cells isolated from blood samples of patients before treatment and subjected to drug(s) administration. The decrease of antiapoptotic protein Bcl-2 expression and proteolytic cleavage of nuclear proteins--lamin B and PARP-1 were observed in leukemic cells of patients treated according to the above therapy protocols, however, each to a different level among the studied groups. The obtained results indicated also that procaspase-3 was cleaved and activated in leukemic cells of three drug(s) treated groups. However, the cleavage of procaspase-3 and the generation of fragments with mol. mass of 17/20 kDa occurred especially effectively among patients treated according to CMC regimen. The changes in expression/proteolytic degradation of the above selected apoptotic markers, are accompanied by the appearance of apoptotic morphology in leukemic cells originated from blood of patients treated with the above drug(s) in comparison to untreated ones.

[Molecular pathogenesis of chronic lymphocytic leukemia with emphasis on cell cycle regulation and apoptosis]

In spite of the fact that many papers dealing with the chronic lymphocytic leukemia include a sentence in Introduction, that the molecular pathology of the disease "is still largely unknown", the amount of accumulated information is impressive and enables to create the first models of the overall genesis of this "most frequent leukemia in the Western world". Since many studies have confirmed that B-CLL lymphocytes in peripheral blood are anchored in G0/G1-phase of the cell cycle, the recent general opinion is, that CLL is primarily caused by defects in apoptosis--lymphocytes are slowly accumulating, being not able to "die properly". However, it becomes evident, that in the microenvironment appropriate for the cell growth, i.e. in the bone marrow and lymph nodes, B-CLL lymphocytes proliferate and they are subsequently accumulated in peripheral blood. This review summarizes namely the knowledge about status and expression of key genes regulating apoptosis and cell cycle in B-CLL lymphocytes, including p53, ATM, MDM2, Bcl-2/Bax, caspase-3, CDK-inhibitor p27, cyclins D2 and D3. Relationship between some of these genes and the standard therapy is discussed and prospective therapeutic alternatives resulting from the new molecular-genetic findings are presented.

Chronic lymphocytic leukaemia: new biological markers for assessing prognosis

Well-established clinical staging systems continue to form a basis for deciding when to initiate treatment and assigning prognosis in chronic lymphocytic leukaemia. However, these staging systems do not identify those patients with early-stage disease who will progress to require treatment. Recent developments have provided a variety of prognostic markers, which can determine those patients with poor prognosis disease. For example, serum markers (soluble CD23), cell surface (CD38) and cytoplasmic (ZAP70) proteins, cytogenetics and immunoglobulin gene mutational status have all been utilised for this purpose. In order for patients to benefit fully from these discoveries they need to be translated into rapid, standardised and cost-effective clinical laboratory tests. The current range of prognostic markers, and techniques for measuring them are discussed.

B-cell chronic lymphocytic leukaemia: a polymorphic family unified by genomic features

Human cancer is characterised by complex molecular aberrations which result in a wide variety of clinical manifestations. B-cell chronic lymphocytic leukaemia (B-CLL) is particularly diverse, both in terms of molecular changes and clinical course, and consequently our understanding of the pathology of this disease is generally poor. Furthermore, the heterogeneity of this tumour type coupled with the absence of an obvious genetic "hallmark", such as gain of oncogene function or loss of suppressor-gene function, has led many investigators to question whether B-CLL is a single disease entity. In most cases, B-CLL does not show specific reciprocal chromosomal translocations as found in other haemopoietic malignant diseases. The genomic instability of B-CLL results in numerous different types of chromosomal losses and gains, giving rise to unsettled karyotypes among individuals with this disease. Nevertheless, genetic data imply that B-CLL is a single disease characterised by a common gene-expression profile and by the existence of specific subtypes that may have clinical correlates in patients.

Cytokine and adhesion molecule concentrations in blood of patients with B-cell chronic lymphocytic leukaemia with regard to disease progression

PURPOSE

To examine concentrations of IL-8, E-selectin and VCAM-1 in blood plasma, culture supernatant and isolated broken lymphocytes in patients with chronic lymphocytic leukaemia (CLL), at I and III stage of the disease according to Rai's classification and in healthy individuals constituting controls. Two types of lymphocyte cultures were carried out--nonstimulated and stimulated with mitogen.

MATERIAL AND METHODS

A concentration assay of substances mentioned above was made using ready immuno-enzymatic sets of the ELISA type.

RESULTS

In all cases, plasma concentrations of IL-8, E-selectin and VCAM-1 were the highest in III stage of CLL and moderately increased in I stage comparing to control. The concentrations of IL-8 in culture supernatants and in broken lymphocytes and concentration of VCAM-1 in lymphocytes were increased in both stages of CLL. In contrast concentrations of E-selectin were decreased in lymphocytes in both types of culture. Significant decrease of E-selectin and VCAM-1 concentrations were observed in supernatants of nonstimulated cultures.

CONCLUSION

Significant increase of E-selectin, IL-8 and VCAM-1 concentration in blood plasma may support higher activity and suggest the higher ability of leukaemic lymphocytes to migration. Increased IL-8 concentration in isolated, broken, stimulated lymphocytes may be a characteristic feature of the biochemical processes of leukaemic lymphocytes. The lowest values of E-selectin and VCAM-1 concentrations in culture supernatants and broken lymphocytes may suggest their degradation during in culture.

An overview of young CLL patients: a single-centre experience from Turkey

Chronic lymphocytic leukaemia (CLL) is generally considered to be a disease of the older population. The aim of this retrospective study was to determine whether younger subjects with CLL (< or = 55 years of age) were different from older patients in their clinical features and prognoses. A total of 198 CLL patients registered to the centre were analyzed: 47 (24%) were 55 years of age or younger and 37 who were followed up regularly were included in the study. The male/female ratio was significantly higher in young patients (3.7 vs. 1.51; p = 0.02). More young patients were asymptomatic than old patients at initial presentation (38.3% vs. 28.5%; p > 0.05). The clinical features, laboratory findings, the distribution of both age groups into clinical stages, and the overall response rate to treatment were similar. The median time to follow-up was 62 months. During this period, 14 of the young patients died (48.3%); all were males. The median survival was longer in the young (64.5 vs. 47 months, p > 0.05). The 5-year survival rate of young patients was more than the old (57% vs. 31%), but the 10-year survival rates did not differ between the two groups (7% vs. 8%). The rate of CLL-related death was higher in young patients (71% vs. 59%; p > 0.05). Univariate analysis revealed no prognostic factor which could influence the survival probability of young patients. In this study, the prognostic values of some variables could not be assessed accurately as the number of regularly followed young patients was low and some data were missing. However, it is expected that survival will be longer in young CLL patients, so the search for different curative treatment strategies will continue.

Pregnancy and successful labor in the course of chronic lymphocytic leukemia

Pregnancy and leukemia are difficult to manage. Protecting the mother from hemorrhage and infection and the fetus from developmental failure are the main aims. Chronic lymphocytic leukemia (CLL) has been seen very rarely with pregnancy. In this article, the successful labor of a 43-year-old woman with CLL is reported. She was not a candidate for chemotherapy at that time. She was without symptoms when she got pregnant. In the 30th gestational week she was found to have urinary tract infection and preterm labor and she was stabilized. Gestational diabetes and preeclampsia were also determined after that period and managed. The patient was delivered by cesarean section in the 39th gestational week. Cord blood was collected and preserved. No postpartum complication was seen in either the patient or the infant. This is one of the rare cases presenting CLL with pregnancy in the literature.

Apoptosis in lymphocytic leukemias and lymphomas

Most current classifications of lymphoid neoplasms define the tumors based on the cell of origin, phenotype, genetic abnormalities, and clinical features. Here it is proposed that human lymphocytic tumors can be categorized based on the propensity and capacity of the tumor cells to undergo apoptosis. The first category is defined by malignant cells that are resistant to apoptosis due to expression of anti-apoptotic factors such as bcl-2 and cellular inhibitors of apoptosis (IAPs). These tumors would include CLL and follicular lymphomas, as well as some malignancies in which the tumor cells are infected by viruses that co-opt cell survival pathways, such as human T-cell leukemia/lymphoma virus (HTLV)-1. The second category, in which the malignant cells are apoptosis-prone, would include tumors arising in the context of impaired cytotoxic T-cell function. These neoplasms would include some human immunodeficiency virus (HIV)-related lymphomas such as Burkitt's lymphoma, and post-transplantation lymphomas. The third category would include neoplasms of intermediate sensitivity to apoptosis, some of which are associated with infection such as mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach. Although this classification is tentative, it should evolve in parallel with our understanding of pathogenic mechanisms in lymphoid neoplasia, and provides a novel framework with which to consider the appropriateness of specific therapeutic strategies. Distinctions among lymphocytic tumors in terms of the likelihood of response to therapies such as antisense to bcl-2 related proteins, inhibitors of NF-kappa B activity, and new approaches aimed at bolstering the host's immune response, would cross standard classifications based on the T or B-cell origin of the tumor cells.

[Whipple's disease as a complication of chronic lymphocytic leukemia treated with fludarabine]

The case of 53-year-old man who suffered from chronic lymphocytic leukemia since 1993 was presented. In the 6th year of treatment fludarabine was administered. Few days after administration of drug the patient developed watery diarrhoea not responding to treatment. We excluded both infectious etiological factors and infiltration of intestine in course of chronic lymphocytic leukemia. Histopathological examination with monoclonal antibodies and periodic acid-Schiff stain (PAS) revealed Whipple's disease as the reason of enteropathy. During 6 months diarrhoea caused extreme dyselectrolitemia, renal insufficiency and finally death of the patient.

Challenges in treating hematologic malignancies

During the past 40 years substantial progress has been made in the treatment of hematologic malignancies, particularly in some subgroups of patients. Today, cure is attainable for patients with Hodgkin's disease and a considerable proportion of patients with high-grade non-Hodgkin's lymphoma. Prognosis is improving in patients with acute promyelocytic leukemia and, to some extent, those with acute lymphoblastic and myeloid leukemias. However, the majority of patients who suffer from a hematologic malignancy live with incurable disease. In CLL, outside the setting of a clinical trial, it is advisable to postpone treatment until the manifestation of clinical symptoms. It is yet to be determined whether treatment strategies based on new prognostic parameters such as cytogenetics can change the course of disease. In indolent lymphomas, cure is not attainable for the vast majority of patients; the median survival of 9 to 10 years has remained unchanged for several decades. Nevertheless, there has been a dramatic change in therapeutic paradigms in the past few years. For the first time, with the use of new cytostatic drugs and recombinant monoclonal antibodies, it is possible to achieve molecular remissions. Whether this will translate into cure or prolonged survival is still to be determined. In Hodgkin's disease, which is curable when treated with radiotherapy, chemotherapy, or combined therapy, depending on the stage of disease, the focus of future studies must be on prevention of early relapse and on primary resistant disease, both of which present a very poor prognosis. Finally, regardless of underlying malignancy and prognosis, the preservation of quality of life is of major consideration in the setting of hematologic malignancies.