ALBERT

Description: A monoclonal B-cell Lymphocytosis (MBL) is detected in the peripheral blood of around 3% of otherwise healthy adults, the majority of these have a CLL immunophenotype. We have previously demonstrated that the cells in MBL are indistinguishable from good risk CLL, sharing the same immunophenotypic profile, genetic aberrations and IgVH gene usage. MBL exerts an increasing burden on haematology clinics with over 100 new patients diagnosed per annum in our regional haemato-oncology laboratory. This is largely as a result of the increased tendency to investigate patients with a mild lymphocyosis although

Description: Alemtuzumab is a humanized anti-CD52 antibody licensed for refractory B-cell chronic lymphocytic leukemia (B-CLL), when given intravenously at 30 mg thrice weekly. However, the intravenous route is associated with infusion-related reactions and is inconvenient. We measured blood concentrations in 30 relapsed patients treated with intravenous alemtuzumab and in 20 patients from a previously untreated group who received similar doses subcutaneously. Highest trough samples in the intravenous group were less than 0.5 μg/mL to 18.3 μg/mL (mean 5.4 μg/mL). The cumulative dose required to reach 1.0 μg/mL was 13 mg to 316 mg (mean 90 mg). Higher blood concentrations correlated with the achievement of better clinical responses and minimal residual disease. The highest measured concentrations in the subcutaneous group were similar (0.6 μg/mL to 24.8 μg/mL, mean 5.4 μg/mL). However, the cumulative dose to reach 1.0 μg/mL was higher: 146 mg to 1106 mg (mean 551 mg). No antiglobulin responses were detected in 30 patients given intravenous alemtuzumab whereas 2 of 32 patients given subcutaneous alemtuzumab made substantial anti-idiotype responses. Thus, subcutaneous alemtuzumab achieved concentrations similar to those for intravenous alemtuzumab, although with slightly higher cumulative doses. Subcutaneous alemtuzumab is more convenient and better tolerated but may be associated with some patients forming anti–alemtuzumab antibodies, particularly those patients who were previously untreated.

Description: Eradication of minimal residual disease (MRD) in chronic lymphocytic leukemia (CLL) is emerging as a desirable therapeutic end point predicting for better outcome. The monoclonal antibody alemtuzumab (Mabcampath) is approved for patients with fludarabine refractory CLL. We previously published 91 patients with relapsed CLL (74 men and 17 women, median age 58 years [range, 32 to 75 years]; 44 fludarabine-refractory) who received a median of 9 weeks (range 1 to 16) of alemtuzumab, 30mg 3x a week after dose escalation, between 1996 and 2003. 84 patients had i.v. alemtuzumab and 7 received it subcutaneously. Responses to alemtuzumab according to NCI-WG criteria were complete remission (CR) in 32 patients (36%), partial remission (PR) in 17 (19%) and no response (NR) in 42 (46%). Detectable CLL to a level of less than one CLL cell in 10,000 leucocytes, assessed by four-color MRD flow cytometry, was eradicated from the blood and marrow in 18 patients (20%). 8 of these 18 patients were fludarabine refractory. We report here the results of long term follow up of this cohort of patients after a median follow up of 77 months (range 5 to 123 months). Median survival was significantly longer in patients achieving MRD negative responses compared with those with detectable CLL at the end of therapy. The median survival for all 18 MRD negative responders has not been reached but was 87 months for the 8 fludarabine-refractory patients achieving MRD negativity. Overall survival for the 18 patients with MRD-negative remissions was 66% at 72 months (see Figure). MRD positive CR patients had a median survival of 56 months, MRD positive PR patients a median survival of 42 months and non-responders a median survival of 14 months. The median treatment-free interval prior to alemtuzumab for the 18 MRD negative patients was 8 months (range 4 to 35). Excluding planned stem cell transplantation performed in CR, the median time to next treatment for the 18 MRD negative patients was 114 months and 72% (13/18) have required no further therapy. Therefore alemtuzumab can induce MRD negative remissions in CLL resulting in a clear survival advantage with 66% of MRD negative patients alive 6 years after alemtuzumab. The markedly increased treatment-free survival and excellent survival for MRD negative patients strongly suggests that achieving an MRD negative remission is an appropriate therapeutic end-point in relapsed CLL. Figure Figure

Description: Analysis of immunoglobulin heavy chain (IgH) rearrangements in B-CLL differentiates subgroups of patients with significantly different clinical outcomes. Cases can be categorised according to mutational status of the variable (V) segment with unmutated VH regions linked to a worse prognosis. A restricted pattern of use of specific VH, DH and JH gene segments has also been reported in B-CLL. It has been hypothesised that B-CLL originates as a clonal expansion of B-cells that have been selected and activated by contact with self or foreign antigens, leading to those small clones to proliferate, mutate their IGH genes, acquire genetic lesions and eventually become malignant. B-CLL cells normally express low levels of Ig on the surface, normally IgM, although a proportion of patients express IgG or IgA, following the class-switch recombination (CSR) process. We have analysed the pattern of SHM and gene segment usage in this particular subgroup for 44 patients with IgG B-CLL. Successful PCR amplification of recombined Smu-Sgamma switch region DNA was achieved in 40 patients, confirming the presence of IgG class-switching. Mutational analysis of IgH V genes revealed 80% of patients contained more than 2% somatic hypermutation (SHM), with 63% of samples having a greater than 5% SHM rate. For VH gene segment usage, a significant predominance of the VH4 family was seen in 22 cases (50%), followed by VH3 in 17 cases (39%), while VH1 family was found in only 3 of 44 samples, this differs from classical IgM B-CLL where VH3 family usage predominates. Overall, VH4-34 was the most frequently used gene segment (34%), followed by VH3-07 (14%) and VH4-39 (9%). DH6-13 was the most frequently used DH segment (21%), followed by DH6-19 (13%). JH gene segment usage did not differ from normal B-cells, with JH4 being the most frequently used, followed by JH6 and JH5. There was a significant association between VH4-39, DH6-13 and JH5 in three samples all containing unmutated sequence. Together this data reveals a distinct pattern of IGH VDJ rearrangements in IgG B-CLL compared to classical IgM B-CLL. Firstly, the rate of SHM in IgG B-CLL (80%) is significantly higher than the 50% observed in IgM B-CLL. Secondly, VH segment usage pattern differs between the two subgroups with a significant under-representation of VH1 as well as an over-representation of VH4 family members in the IgG subgroup. Finally, there is a striking association between VH4-39 and DH6-13/JH5 in the very few unmutated rearrangements. This could be indicative of a different clonal history of these particular B cells in B-CLL. Together with recent published data, this latter finding suggests that this is a further sub-category exclusive to IgG B-CLL, where selection of a specific antigen receptor may have lead to B-CLL development in such cases. We conclude that class-switched IgG B-CLL contains different molecular features in the IgH genes compared with classical IgM B-CLL, and other B-cell malignancies. The clinical implications of these differences, especially the relationship between the mutational status of the VH genes and outcome in IgG B-CLL, will be further investigated.

Description: INTRODUCTION: CLL is a disorder with a wide variation in outcome. Patients with adverse cellular features are often refractory to treatment and have a short overall survival. Individuals with CLL-type MBL are unlikely to require treatment and in most cases will eventually die of an unrelated cause. Many factors that predict a poor outcome have been identified, including stage, IGHV mutation status, ZAP-70 expression, and deletions of chromosomes 17p (TP53) and/or 11q23 (ATM). Deletions and mutations in TP53 are generally not presenting features and appear to require clonal evolution. One hypothesis is that the degree of intraclonal variation in genes targeted by the somatic hypermutation machinery, e.g. IGHV and BCL6, may predict the potential for clonal evolution. We have previously tested 66 antigens for their capacity to differentiate proliferating CLL cells, resting CLL cells and normal B-cells and identified 30 potentially relevant markers, including common markers such as CD38 and less frequently used markers such as the Leukocyte-associated immunoglobulin-like receptor 1 (LAIR1). AIM: To compare the expression of relevant cell surface markers with the degree of intraclonal variation in the IGHV and BCL6 genes and to determine if these markers can be used to differentiate CLL-type MBL and CLL with or without adverse biological features. METHODS: The cell surface phenotype was assessed by 6-colour cytometry in 133 patients: 22 CLL with deletion 17p or 11q23, 69 CLL with no adverse prognostic chromosomal abnormalities, and 42 MBL. Surface phenotype was also compared with IGHV mutation status in a cohort of 29 CLL patients (16 ≤2% IGHV mutation, 13 〉2% IGHV mutation). These antigens were also assessed using 4-colour flow cytometry in 20 cases (4 MBL, 16 CLL) and compared with IGHV & BCL6 mutation status and degree of intraclonal variation (defined as the proportion of mutations that were detected in a single clone only), and with ZAP-70 (AF488-1E7.2) expression. RESULTS: CLL cases with ≤2% IGHV mutation showed increased expression of CD38 (6.8 fold, p 0.02), CD49d (4.9-fold, P = 0.04), IgD (2.0-fold, P = 0.05), ZAP-70 (1.5-fold, P=0.04) and decreased expression of LAIR-1 (6.2-fold, P = 0.003) in comparison to CLL cases with 〉2% IGHV mutation. CLL cases with deletions of 17p and 11q23 showed decreased expression of CCR6 (1.7-fold, P = 0.0001), IgD (1.3-fold, P = 0.03) and LAIR-1 (7.1-fold, P2% overall IGHV mutation in both IGHV (median 0.075% vs. 0.049% unique mutations, P〉0.05) and BCL6 (median 0.10% vs. 0.095% unique mutations, P〉0.05). However, there was an inverse relationship between BCL6 and IGHV intraclonal variation and cases with the highest levels of BCL6 intraclonal variation showed significantly decreased expression of CD39 (1.9-fold, P = 0.04) and LAIR1 (4.7-fold, P = 0.019). CONCLUSIONS: There were no markers or marker combinations that could discriminate MBL from CLL. The key differences were decreased expression of markers that are expressed during cell cycle, i.e. CD23, and adhesion markers such as CD62L and CD49d. These markers show sequential changes with disease stage, supporting the hypothesis that cellular interactions are central to the accumulation and expansion of CLL cells. However, the marker most consistently associated with adverse biological features is LAIR1, which is weak or negative in CLL with ≤2% IGHV mutation, high levels of intraclonal variation and TP53 or ATM deletions. LAIR-1 is an inhibitory receptor involved in regulating classs-witching. LAIR1 is strongly expressed in normal circulating peripheral B-cells. As with other prognostic markers, expression is a continuous variable and therefore a suitable cutoff will need to be identified. However, fluorochrome-conjugated antibodies are readily available and expression on CLL cells is stable for several days in EDTA samples which should minimise inter-laboratory analytical variation. LAIR1 expression in CLL is more closely associated with IGHV mutation status than CD38 or ZAP-70 expression. LAIR1 is a promising prognostic marker that appears to be central to the development of aggressive CLL as there is a strong association between downregulation of LAIR1, intraclonal heterogeneity in BCL6 and development of TP53 and ATM deletions.

Description: Monoclonal chronic lymphocytic leukemia (CLL)–phenotype cells are detectable in 3.5% of otherwise healthy persons using flow cytometric analysis of CD5/CD20/CD79b expression on CD19-gated B cells. To determine whether detection of such CLL-phenotype cells is indicative of an inherited predisposition, we examined 59 healthy, first-degree relatives of patients from 21 families with CLL. CLL-phenotype cells were detected in 8 of 59 (13.5%) relatives, representing a highly significant increase in risk (P = .00002). CLL-phenotype cell levels were stable with time and had the characteristics of indolent CLL. Indolent and aggressive clinical forms were found in family members, suggesting that initiation and proliferation involves distinct factors. The detection of CLL-phenotype cells provides a surrogate marker of carrier status, potentially facilitating gene identification through mapping in families and direct analysis of isolated CLL-phenotype cells.

Description: Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia resulting from a somatic mutation in a hemopoietic stem cell. In most cases of hemolytic PNH, the majority of the marrow cells are derived from the PNH clone. Recent evidence has indicated, however, that the majority of the most primitive peripheral blood stem cells (PBSCs) in PNH appear to be of normal phenotype. This has led to tentative suggestions that normal PBSCs could be collected and used for autologous transplantation. We have investigated this possibility in four PNH patients by treating them with granulocyte colony-stimulating factor (G-CSF) in an attempt to mobilize normal progenitors. The expression of glycosylphosphatidylinositol (GPI)-linked proteins was analyzed by flow cytometry on mature neutrophils, late stem cells (CD34+/CD38+), and primitive stem cells (CD34+/CD38−). The phenotyping and stem cell quantitation was performed in steady-state blood and post–G-CSF administration. The most primitive PBSCs (CD34+/CD38−) were almost all normal before G-CSF treatment, even when the patients' neutrophils were mainly PNH. However, after G-CSF, the cells that were mobilized into the peripheral blood were of a similar phenotype to the mature neutrophils, ie, mainly PNH. It is possible that PNH-stem cells are preferentially destroyed by complement in the peripheral blood leaving only normal cells in the circulation. After G-CSF, the PNH cells in the marrow are released into the blood. Our findings suggest that it would be difficult to collect sufficient numbers of normal stem cells for autologous transplantation.

Description: BACKGROUND: The WHO and iwCLL diagnostic criteria for CLL rely on morphology and immunophenotype based on the co-expression of CD19/CD5/CD23 on B-cells with weak CD20 and monoclonal sIg expression. These diagnostic criteria are likely to persist in the near future because there is no specific diagnostic molecular abnormality for CLL. The current criteria have some limitations affecting reproducibility, particularly flexibility in marker expression with many centres using a scoring system that permits absence of CD5 or CD23. Potentially informative new markers have been identified but there is no consensus yet on which should be routinely assessed. AIM: To identify reproducible criteria and to achieve a consensus on markers recommended for the diagnosis of CLL METHODS: ERIC/ESCCA members were invited to classify 35 flow-cytometry markers as being required or recommended for the diagnosis of CLL. Consensus was considered to be achieved if 〉75% of participants agreed on the marker classification. A diagnostic panel was identified by the steering committee and characteristics of component markers that could be reproducibly validated within an individual laboratory were identified. The proposed panel was assessed in 13 different centres. RESULTS: Responses were received from 154 members (100 laboratory staff, 14 clinicians and 36 from both laboratory and clinic) with a diagnostic workload 〉20 cases per week in 23/154 (15%), 5-20 in 82/154 (53%) and

Description: Abstract 2002 Introduction: Monoclonal B-cells with a Chronic Lymphocytic Leukemia (CLL) phenotype are detectable in more than 10% of adults in the general population using high sensitivity flow cytometry assays designed to detect minimal residual disease after treatment. However, the prevalence of MBL with a phenotype corresponding to other B-lymphoproliferative disorders (B-LPD) is less than 2% of the general population even using the most sensitive assays. No studies have reported CD10+ MBL whereas several studies have demonstrated that the t(14;18) is frequently detectable in the general population at a level which should be detectable by flow cytometry. The lack of CD10+ MBL may indicate that the t(14;18) alone rarely results in the expansion of a clonal B-cell population in the blood, or that currently available assays are inadequate for detecting circulating follicular lymphoma. We have previously investigated 66 markers to determine the best candidates for diagnosis and monitoring B-LPD, which were then tested in over 1500 cases. We have developed a single-tube assay to screen for residual disease that can detect lymphoma cells when they represent as few as 1 in 10,000 leucocytes. The aim of this study was to asses the frequency with which lymphoma-phenotype monoclonal B-cells are detected in the general population using a high sensitivity assay. Methods: Cells from 679 individuals (342 male, 337 female, median age 64, range 40–99) with a normal blood count and no current or prior history of cancer were incubated with antibodies to Kappa, Lambda, CD19, CD20, CD5, CD10, LAIR1, CXCR5 and 0.5 million cells were acquired using a BD FACSCanto II cytometer. In cases with detectable MBL further phenotyping was performed and B-cells were selected and stored for FISH and molecular clonality studies. Results: MBL was detected 129/679 cases (19.0%): CLL-type MBL in 86/679 cases (12.7%), non-CLL MBL in 60/679 cases (8.8%) with both CLL-type and non-CLL MBL were present in 17/679 cases (2.5%). Within the non-CLL MBL group, in 21/60 cases the monoclonal B cells had no additional features to confirm a neoplastic population and it was not possible to ascertain whether these were neoplastic cells or a reactive population with a highly skewed kappa/lambda ratio. Of the remaining 39 specimens: none showed evidence of germinal centre differentiation; 12 (1.7% of total) showed a phenotype most consistent with marginal zone lymphoma/lymphoplasmacytic lymphoma; and 27 cases expressed strong levels of LAIR1 coupled with strong CD19 and CD20 and an extended phenotype that is relatively rare in clinical B-LPD, restricted to hairy cell leukemia and a small proportion (

Description: BACKGROUND: Minimal residual disease (MRD) in CLL is an independent predictor of progression-free and overall survival after chemo-immunotherapy. Data from the DCLLSG trials indicate that a high, intermediate and low risk of disease progression is seen in patients with 〉1%, 0.01-1%, or 1% vs. 0.01-1% vs 1% MRD predicts equivalent or worse outcome than a clinical PR. PB MRD analysis at 18 months after randomisation (~1 year after treatment) was also strongly predictive of outcome: 98% of patients with 1%, 0.01-1%, or 1% MRD equating to 1% MRD equating to