B-cell repertoire and clonal analysis in unaffected first degree relatives in familial chronic lymphocytic leukaemia kindred

Monoclonal B cell lymphocytosis (MBL) was detected in four unaffected first-degree relatives (FDR) in a familial chronic lymphocytic leukaemia (CLL) kindred. The proband remains untreated and two male siblings have died. The four unaffected siblings have been followed for a five-year period. All four FDR developed a kappa(+)CD5(+) MBL detected by flow cytometry. Poymerase chain reaction (PCR) for IGHV rearrangement showed evidence of oligoclonality in three of these individuals. Single cell PCR of flow cytometric sorted kappa(+) cells combined with Ig kappa light chain gene sequencing revealed further evidence of monoclonality in two of these individuals. Three of these individuals all showed evidence of hyper-somatic mutations. The B-cell repertoire in unaffected FDR in familial CLL offers a new area to investigate the interface between the immune system and lymphoid neoplasm.     

Flavopiridol circumvents Bcl-2 family mediated inhibition of apoptosis and drug resistance in B-cell chronic lymphocytic leukaemia

Flavopiridol, a synthetic flavone, is currently under clinical investigation for the treatment of B-cell chronic lymphocytic leukaemia (B-CLL). In this study, we examined the in vitro effects of flavopiridol and fludarabine on B-CLL cells from 64 patients (36 treated and 28 untreated) in terms of apoptosis induction and Bcl-2 family expression. Both flavopiridol and fludarabine induced apoptosis in all the samples tested with mean LD(50) values (+/- SD) of 59.7 nmol/l (+/- 36.5) and 6.2 micromol/l (+/- 7.5) respectively. Mean flavopiridol LD(50) values were not significantly different between the treated and untreated patient groups (P = 0.35), whereas the fludarabine LD(50) values were significantly higher in the previously treated patient group (P = 0.01). Bcl-2 and Mcl-1 expression were downregulated in both flavopiridol and fludarabine-induced apoptotic cells, but the increase in Bax expression that accompanied fludarabine-induced apoptosis was not evident in flavopiridol-treated cells. In addition, Bcl-2:Bax ratios were not predictive of flavopiridol cytotoxicity (P = 0.82), whereas they were highly predictive of in vitro responsiveness to fludarabine (P = 0.001). Overall, these findings suggest that flavopiridol exerts its cytotoxic effect through a novel cell-death pathway that is not subject to the Bcl-2 family mediated resistance mechanisms that reduce the efficacy of many conventional chemotherapeutic drugs.     

Antisense-mediated suppression of Bcl-2 highlights its pivotal role in failed apoptosis in B-cell chronic lymphocytic leukaemia

Although advances have been made in the development of more effective treatment modalities, B-cell chronic lymphocytic leukaemia (B-CLL) remains incurable due to the development of drug resistance. Defective programmed cell death mechanisms rather than dysregulation of cell cycle appears to predominate in B-CLL and it is likely that a failure to initiate apoptosis contributes to chemoresistance. Most B-CLL cells contain high levels of the anti-apoptotic protein Bcl-2 and high Bcl-2/Bax ratios have been associated with in vitro resistance to cytotoxic agents. In this study we evaluated the cellular responses to a Bcl-2 antisense oligonucleotide in terms of Bcl-2 mRNA and protein expression and the induction of apoptosis. The antisense molecule induced a specific reduction in Bcl-2 mRNA and protein expression over the 48 h culture period and was associated with increased apoptosis. The study indicates that Bcl-2 protein is central to the mediation of resistance to apoptosis in B-CLL. Therefore Bcl-2 antisense oligonucleotides might be useful in the treatment of B-CLL.     

Valproate synergizes with purine nucleoside analogues to induce apoptosis of B-chronic lymphocytic leukaemia cells

Resistance to chemotherapy and drug toxicity are two major concerns of chronic lymphocytic leukaemia (B-CLL) treatment by purine nucleoside analogues (PNA, i.e. fludarabine and cladribine). We hypothesized that targeting epigenetic changes might address these issues and evaluated the effect of the histone deacetylase inhibitor valproate (VPA) at a clinically relevant concentration. VPA acted in a highly synergistic/additive manner with fludarabine and cladribine to induce apoptosis of B-CLL cells. Importantly, VPA also restored sensitivity to fludarabine in B cells from poor prognosis CLL patients who became resistant to chemotherapy. Mechanism of apoptosis induced by VPA alone or combined with fludarabine or to cladribine was caspase-dependent and involved the extrinsic pathway. VPA, but neither fludarabine nor cladribine, enhanced the production of reactive oxygen species (ROS) and inhibition of ROS with N -acetylcysteine decreases apoptosis of CLL cells. VPA stimulates hyperphosphorylation of p42/p44 ERK, cytochrome c release and overexpression of Bax and Fas. Together, our data indicate that VPA may ameliorate the outcome of PNA-based therapeutic protocols and provide a potential alternative treatment in both the relapsed and front-line resistant patients and in patients with high risk features.     

Phase II study of subcutaneous alemtuzumab without dose escalation in patients with advanced-stage, relapsed chronic lymphocytic leukaemia

This phase II study ( n  = 20) aimed to evaluate type, severity and duration of side-effects and efficacy following subcutaneous (SC) alemtuzumab, without dose-escalation, in advanced-stage relapsed chronic lymphocytic leukaemia (CLL) patients. Alemtuzumab 30 and 3 mg was administered SC simultaneously day 1, followed by 30 mg three times per week. Injection-site-reactions were recorded every 6–24 h until resolved using National Cancer Institute criteria and a new skin toxicity subscale. The first doses of 30 mg and 3 mg produced injection-site-reactions (all but one were grade 1/2) in 13/20 and 9/20 patients, respectively. The second dose (on day 3) resulted in skin-reactions in 10/20 patients and the third, fourth, fifth and sixth injections produced reactions in 6/20, 1/20, 2/20 and 0/20 patients, respectively. Mild flu-like symptoms occurred during week 1 in 10/20 patients. All side-effects had subsided by the sixth dose. 15/20 patients (75%) responded (12 partial responses, three complete responses) with a median time-to-treatment-failure of 20 months. Symptomatic cytomegalovirus-reactivation occurred in 6/20 patients. Two deaths occurred: one bacterial pneumonia and one adenovirus-infection. The present study showed how to assess cutaneous-toxicity in detail and that 30 mg alemtuzumab SC administered upfront was well tolerated. Optimized alemtuzumab therapy in properly selected patients may result in high efficacy even in advanced CLL. Our results need to be confirmed in extended studies.     

An Italian retrospective study on the routine clinical use of low-dose alemtuzumab in relapsed/refractory chronic lymphocytic leukaemia patients

Low‐dose alemtuzumab has shown a favourable toxicity profile coupled with good results in terms of efficacy in relapsed/refractory chronic lymphocytic leukaemia (CLL). We conducted a multicentre retrospective study on the routine clinical use of low‐dose alemtuzumab in this patient setting. One hundred and eight relapsed/refractory CLL patients from 11 Italian centres were included in the analysis. All patients had an Eastern Cooperative Oncology Group performance status ≤2 and the majority (84%) had adenopathies <5cm. Low‐dose alemtuzumab was defined as a total weekly dose ≤45 mg and a cumulative dose ≤600 mg given for up to 18 weeks. The overall response rate was 56% (22% complete remissions). After a median follow‐up of 42·2 months, the median overall survival and progression‐free survival were 39·0 and 19·4 months, respectively. In univariate analysis, response was inversely associated with lymph node (P = 0·01) and spleen (P = 0·02) size, fludarabine‐refractoriness (P = 0·01) and del(11q) (P = 0·009). Advanced age and del(17p) were not associated with a worse outcome. Cumulative dose of alemtuzumab was not associated to response. Toxicities were usually mild and manageable; severe infections occurred in seven patients (7%) during therapy. This retrospective analysis confirms that low‐dose alemtuzumab is a valid and currently used therapeutic option for the treatment of relapsed/refractory CLL.     

Anticipation in familial chronic lymphocytic leukaemia

Anticipation, a phenomenon in which an inherited disease is diagnosed at an earlier age in each successive generation of a family, has been demonstrated in certain heritable neurological disorders and in multiple myeloma, non-Hodgkin's lymphoma and other haematological neoplasms. The present study was conducted to determine whether anticipation occurs in familial chronic lymphocytic leukaemia (CLL). Fourteen published reports of multigenerational familial CLL were analysed for anticipation, together with 10 previously unreported families with familial CLL, and the difference in disease-free survival between generations was determined. The difference between age at onset for each affected parent-child pair was tested against the null hypothesis that there was no difference in age at onset. The age at onset of the studied cases was also compared with that of the Surveillance Epidemiology and End Results (SEER) Program of the U.S. National Cancer Institute. The median ages at onset in the child and parent generations of all families (51.0 and 72.0 years respectively) were significantly different (P < 0.000001), and the null hypothesis was rejected (P < 0.000001). A significant difference was observed between the ages of onset of the child generation and the SEER population (P < 0.00001), but not between the parent generation and the SEER population. Anticipation characterizes familial CLL.     

Standard-dose anti-CD20 antibody rituximab has efficacy in chronic lymphocytic leukaemia: results from a Nordic multicentre study

OBJECTIVES: This prospective multicentre study was conducted to assess the efficacy of the monoclonal anti-CD20 antibody rituximab in patients with chronic lymphocytic leukaemia (CLL). Secondary objectives were defined as the tolerability and feasibility of rituximab in patients with CLL. METHODS: Twenty-four heavily pretreated patients with CLL were treated with a standard dose of 375 mg m-2 of rituximab given once weekly for four doses. RESULTS: The overall response rate was 35% and all the responses were partial as defined by the revised NCI criteria. In 17 (85%) of 20 patients with initially measurable peripheral lymph nodes the size of lymph nodes decreased by at least 50%, while an improvement of the bone marrow infiltration was observed only in two (11%) of 18 evaluable patients. The median duration of the overall response was 12.5 wk. Rituximab was relatively well tolerated. Although side-effects were common (75%) they were usually mild or moderate. There was only one grade 3 adverse event and no grade 4 events. CONCLUSIONS: Standard-dose rituximab has activity in heavily pretreated patients with CLL, although the response is mainly limited to the lymph nodes and of short duration. Since rituximab has in vitro synergism with chemotherapeutic agents and is well tolerated by CLL patients, it is reasonable to investigate rituximab in combination with other treatments.     

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.     

Multidrug resistance mechanisms in chronic lymphocytic leukaemia

We evaluated the presence of P-glycoprotein (P-gp)-170, multidrug resistance protein (MRP), lung resistance protein (LRP)-56 and Bcl-2 in CD19-positive cells from 100 cases of chronic lymphocytic leukaemia (CLL). P-gp-170 was found in 73% of the CLL cases with no significant difference regarding stage or previous treatment. LRP-56 protein was homogeneously distributed with no differences for stage or treatment. MRP protein was detected at a low level of expression in 49.4% of CLL patients with no differences for stage or treatment. Bcl-2 protein was expressed at a high level in all CLL patients and higher levels were found in the advanced stage. This leads us to conclude that P-gp, MRP, LRP-56 and Bcl-2 are frequently expressed in CLL. P-gp, MRP and LRP are not correlated to stage or previous treatment. Bcl-2 is higher in advanced-stage patients. The clinical and biological significance of these zMDR mechanisms in CLL remains to be fully explained.     

Bcl10 in chronic lymphocytic leukaemia and T-cell prolymphocytic leukaemia

Bcl10 is a cancer gene recently identified in B-cell lymphomas of mucosa-associated lymphoid tissues. It has been suggested as a target for mutation in multiple types of tumour including follicular lymphoma, T-cell acute lymphoblastic leukaemia and Sezary syndrome. To evaluate further the role of Bcl10 in human adult haematological cancers, we screened for mutations samples from 24 patients with B-cell chronic lymphocytic leukaemia (CLL) and 18 samples from patients with T-cell prolymphocytic leukaemia (T-PLL). No pathogenic mutations were detected in any of the samples analysed, strongly suggesting that Bcl10 is not involved in the development of CLL or T-PLL and that its involvement may be restricted to other haematological malignancies.     

Chemical exposures and risk of chronic lymphocytic leukaemia

Literature on the role of chemicals in the development of chronic lymphocytic leukaemia (CLL) and monoclonal B-cell lymphocytosis in humans is sparse. This research is complicated by the rarity of these outcomes and the different disease classifications used over time. Several studies have noted excesses of CLL among farmers and a few have pointed to specific chemicals. Reports suggesting elevated CLL rates in the rubber and petroleum industries point to a possible role for solvents and other chemicals. The few studies that focus on specific chemicals suggest that CLL should be more carefully evaluated in relation to possible exposure to chemicals and solvents, particularly for benzene and butadiene. Pooled analyses of CLL studies within consortia offer an opportunity to investigate the possible aetiological role of chemical exposures with improved statistical power.     

Molecular pathogenesis of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is characterised by the clonal expansion of mature, CD5 positive, B lymphocytes in the blood, marrow, lymph nodes and spleen. For the majority of patients, CLL follows an indolent clinical course, while a proportion of patients experience rapid disease progression. Despite the strong correlation between certain genetic defects and prognosis, there remains no single unifying pathogenic lesion in CLL. With recent advances in therapy it is increasingly important to stratify CLL patients according to risk. This has been highlighted by two recent studies, the first showing that immunoglobulin heavy chain mutational status predicts a durable response to frontline chemoimmunotherapy and the second showing that complex karyotype is a stronger predictor of poor response to ibrutinib and venetoclax therapy than TP53 deletion. In this review we discuss the molecular features of CLL and how technological advances can identify patient subsets and stratify them according to risk.     

The biological and clinical relationship between CD5+23+ monoclonal B-cell lymphocytosis and chronic lymphocytic leukaemia

A CD5(+)23(+) monoclonal B-cell population is detectable in approximately 3% of the general adult population. The phenotype of the monoclonal CD5(+)23(+) B cells is identical to chronic lymphocytic leukaemia (CLL) with respect to a large number of proteins in addition to the standard diagnostic markers used to identify CLL. Studies in CLL families and direct assessment of genetic features indicate a close biological association between indolent CLL and the CLL-phenotype cells detected in individuals with a normal blood count. Patients with a CLL-phenotype monoclonal B-cell lymphocytosis (MBL) often have increasing CLL cell counts with time and some progress to a stage requiring treatment. Analysis of intraclonal variation in the immunoglobulin heavy chain gene suggests a process of clonal diversification rather than clonal selection in the early stages of disease progression. CLL-phenotype MBL is detectable in approximately 10% of cases referred for investigation of a lymphocytosis and future studies should be directed towards the detection of factors which identify MBL patients at risk of disease progression.