Expression and Activity of the NF-κB Subunits in Chronic Lymphocytic Leukaemia: A Role for RelB and Non-Canonical Signalling.

BACKGROUND: Canonical NF-κB signalling by p65 (RelA) confers chemo-resistance and poor survival in chronic lymphocytic leukaemia (CLL). The role of non-canonical NF-κB signalling (leading to RelB and p52 subunit activation) in CLL is less understood, but given its importance in other B-cell tumour types, we theorised that RelB and p52 may also contribute to the pathology of CLL. METHODS: DNA binding activity of all five NF-kB subunits, p65, p50, RelB, p52, and c-Rel, was quantified using ELISA and correlated to ex vivo chemoresistance, CD40L-stimulated signalling (to mimic the lymph node microenvironment), and clinical data. RESULTS: Importantly, we show for the first time that high basal levels of RelB DNA binding correlate with nuclear RelB protein expression and are associated with del(11q), ATM dysfunction, unmutated IGHV genes, and shorter survival. High levels of nuclear p65 are prevalent in del(17p) cases (including treatment-naïve patients) and also correlate with the outcome. CD40L-stimulation resulted in rapid RelB activation, phosphorylation and processing of p100, and subsequent CLL cell proliferation. CONCLUSIONS: These data highlight a role for RelB in driving CLL cell tumour growth in a subset of patients and therefore strategies designed to inhibit non-canonical NF-κB signalling represent a novel approach that will have therapeutic benefit in CLL.

DNA-dependent protein kinase is a therapeutic target and an indicator of poor prognosis in B-cell chronic lymphocytic leukemia.

PURPOSE: del(17p), del(11q), and associated p53 dysfunction predict for short survival and chemoresistance in B-cell chronic lymphocytic leukemia (CLL). DNA-dependent protein kinase (DNA-PK) is activated by DNA damage and mediates DNA double-strand break repair. We hypothesized that inhibiting DNA-PK would sensitize CLL cells to drug-induced DNA damage and that this approach could increase the therapeutic index of agents used to treat CLL. EXPERIMENTAL DESIGN: Fifty-four CLL cases were characterized for poor prognosis markers [del(17p), del(11q), CD38, and ZAP-70]. In selected cases, DNA-PK catalytic subunit (DNA-PKcs) expression and activity and p53 function were also measured. Ex vivo viability assays established sensitivity to fludarabine and chlorambucil and also tested the ability of a novel DNA-PK inhibitor (NU7441) to sensitize CLL cells to these drugs. The effects of NU7441 on fludarabine-induced DNA damage repair were also assessed (Comet assays and detection of gammaH2AX). RESULTS: DNA-PKcs levels correlated with DNA-PK activity and varied 50-fold between cases but were consistently higher in del(17p) (P = 0.01) and del(11q) cases. NU7441 sensitized CLL cells to chlorambucil and fludarabine, including cases with del(17p), del(11q), p53 dysfunction, or high levels of DNA-PKcs. NU7441 increased fludarabine-induced double-strand breaks and abrogated drug-induced autophosphorylation of DNA-PKcs at Ser2056. High DNA-PK levels predicted for reduced treatment-free interval. CONCLUSIONS: These data validate the concept of targeting DNA-PKcs in poor risk CLL, and demonstrate a mechanistic rationale for use of a DNA-PK inhibitor. The novel observation that DNA-PKcs is overexpressed in del(17p) and del(11q) cases indicates that DNA-PK may contribute to disease progression in CLL.

High dose chlorambucil in the treatment of lymphoid malignancies.

High dose chlorambucil has been shown to be an effective single-agent treatment in chronic lymphocytic leukemia (CLL), and to be useful as part of combination chemotherapy in low-grade non-Hodgkin's (NHL) and Hodgkin's disease (HD). In general, it is well tolerated and can be used in an outpatient setting. The optimum dose of chlorambucil has not been defined and there are numerous different dosing schedules available. Pharmacokinetic studies suggest decreased bioavailability with successive cycles, probably due to accelerated metabolism. There is good evidence that regimens which use higher doses of chlorambucil have a better outcome than standard dose therapy. Most of the trials which have compared chlorambucil with fludarabine have not used a higher dose regimen of chlorambucil and cannot truly be described as comparative. There is an increase in the incidence of grade 3 and 4 neutropenia and also of sepsis with fludarabine treatment, compared to chlorambucil. Fludarabine produces a higher initial response rate in CLL but no statistical difference has been shown in long term survival between fludarabine and high dose chlorambucil. In the treatment of lymphoma, single agent chlorambucil does not confer a durable remission. There have been good results with combination chemotherapy regimens such as CID and PECC. The oral route of administration of these combinations makes them particularly useful as part of palliative chemotherapy. A further point to consider is that chlorambucil is very much cheaper than fludarabine and other newer agents. Chlorambucil should not automatically be overlooked in favor of more recently developed drugs such as fludarabine. There is good evidence that the drug is an effective treatment at a suitable dose, and there is a need for randomized trials to compare it fully with other current treatments.

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.

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.

Survival in young patients (less than 40 years) with follicular lymphoma: a population based study by the Scotland and Newcastle Lymphoma Group.

We have examined in a population-based observational study the survival of young patients (less than 40 years) with follicular lymphoma (FL) treated conventionally and followed for up to 17 years (minimum 10, median 13 years). Data were derived from the Scotland and Newcastle Lymphoma Group (SNLG) database from 1986. Histology of all available cases was reviewed to ensure that patients met the modern criteria for diagnosis of FL. Of 55 patients identified from the database, 46 were confirmed to have follicular lymphoma. There were 25 males and 21 females, median age 34 years (range 16-39). Thirty-four patients presented with advanced stage disease (Stages III and IV). The majority of patients received initial treatment with chemotherapy, though 7 had surgery (biopsy or splenectomy) alone and 7 radiotherapy alone. All 12 patients with early stage disease showed a complete response (CR) with initial therapy; 6 relapsed and 2 have died (1 of transformation to high grade non-Hodgkin's lymphoma). Overall survival of patients presenting with stage IIIA disease was 68% at 10 years, and 69% for patients in stages IIIB and IV. The SNLG prognostic index for low grade non-Hodgkin's lymphoma was predictive for overall survival. The 71% overall survival in this patient cohort at 10 years provides a baseline for comparison with the results of a more aggressive approach to treatment.

Fasting homocysteine levels in adults with type 1 diabetes and retinopathy.

BACKGROUND AND METHODS: Whether hyperhomocysteinemia is associated with diabetic retinopathy is still being debated. We measured homocysteine and thrombomodulin, a marker of endothelial cell damage, in patients with type 1 diabetes mellitus and retinopathy (n=25) and in a well-matched group of diabetic patients without retinopathy (n=23). All patients had normal serum creatinine and no macroalbuminuria. RESULTS: Fasting homocysteine levels were higher in the group with retinopathy than in the group without retinopathy (8.75+/-1.9 vs. 7.69+/-1.6 micromol/l, P<0.05). Microalbuminuria was more prevalent in the group with diabetic retinopathy and it correlated with homocysteine levels in this group (p<0.05). Microalbuminuria was the most powerful independent determinant of homocysteine levels in multiple regression analysis in the group with retinopathy (p<0.01). Thrombomodulin levels were not different in the two groups (36.6+/-9.7 vs. 34.9+/-11.1, p>0.1) and there was no correlation between homocysteine and thrombomodulin levels in either group. CONCLUSIONS: The slight rise in homocysteine levels in patients with diabetic retinopathy was possibly caused by the early nephropathy as indicted by microalbuminuria. This small rise in homocysteine levels was not associated with endothelial dysfunction, as measured by serum thrombomodulin levels.

High-dose chlorambucil for the treatment of chronic lymphocytic leukaemia and low-grade non-Hodgkin's lymphoma.

Chlorambucil has been used for many years for the treatment of low-grade B-cell lymphoproliferative disorders, including chronic lymphocytic leukaemia and low-grade non-Hodgkin's lymphoma. There is evidence in the literature that increasing the dose of chlorambucil produces better results than 'standard' doses in terms of response rates and overall survival. There is also evidence that this approach may be at least as effective as the use of fludarabine, as well as being very much less expensive. We describe a high-dose chlorambucil (HDC) regimen, which involves a sustained but intermittent dose of chlorambucil, i.e. 30 mg/d for 4 d per week for 4 weeks, followed by a further four courses at fortnightly intervals for 8 weeks (a total of eight 4-d courses) given as a single drug over an initial 12-week period. The outcome of treatment in previously treated and untreated patients was excellent, with a median time to treatment failure of 33 months for the patient cohort overall and for previously treated and chemotherapy-naive patients of 13 and 104 months respectively. In patients previously treated with fludarabine, 78% had a response. Autoimmune haemolytic anaemia was reversed in one patient. Toxicity, both haematological and other, was minimal. We propose that escalated-dose chlorambucil regimens should be compared with fludarabine in randomized controlled trials, rather than 'standard' lower dose protocols.

Quantification improves the prognostic value of CD38 expression in B-cell chronic lymphocytic leukaemia.

Recent studies have shown that CD38 expressed as a percentage of the antigen positivity can predict prognosis and disease progression in patients with B-cell chronic lymphocytic leukaemia (B-CLL). The present study showed that quantification of CD38 expressed as antibody-binding capacity (ABC) improves the prognostic value of the percentage of CD38 positivity in B-CLL. In a cohort of 81 patients with B-CLL, a level of CD38 expression of > or = 30% and an ABC value of 250 proved statistically valid cut-off points to predict disease progression (% CD38: P=0.0027; ABC: P < 0.0001). There was a positive and significant correlation between the percentage of CD38 expression and ABC (r=0.7; P < 0.0001). There was a better discrimination of survival using ABC rather than percentage CD38 positivity (P < 0.0001 compared with P=0.0027). Only ABC predicted for survival in patients under 60 years of age (P=0.0076) or with stage A disease (P=0.0195). Both percentage CD38 and ABC discriminated between time to first treatment for all patients but only ABC predicted time to treatment for stage A patients (P=0.0004). In conclusion, CD38 positivity is an important prognostic factor in B-CLL. However, quantification of CD38 is superior to the percentage positivity and should be used clinically in conjunction with other variables of predictive value to identify B-CLL patients that are likely to progress.