IgVH Mutation Research Articles

CD38 as a prognostic factor in B cell chronic lymphocytic leukaemia (B‐CLL): Comparison of three approaches to analyze its expression

Increased CD38 expression by leukemic cells has been suggested as an adverse prognostic factor in B-CLL. Several approaches have been proposed to quantify its level of expression by flow cytometry. We compared the use of (i) the percentage of CD38 positive cells, (ii) CD38 antibodies bound per cell (ABC), and (iii) a semi-quantitative method based on the shape of the CD38 histogram, within a cohort of 78 B-CLL patients. A decreased overall survival was seen with >30% CD38 positivity among B-CLL cells, with CD38 ABC >100, and with bimodal or unimodal, strongly positive CD38 histograms. However, patients with unimodal weakly positive CD38 histograms also showed a significantly reduced survival as did patients with intermediate proportions (i.e. 5-30%) of CD38+ cells. Furthermore, within the group with <5% CD38 positivity among their B-CLL cells, 84% of patients showed prognostically favourable mutated IGVH gene segments and 100% had low ZAP70 gene expression. For 5-30% CD38 positivity, these proportions were 50 and 83%, while for >30% CD38 positivity, these proportion were only 28 and 56%, respectively. We found a simple method of quantitation of CD38 expression (i.e., >5% CD38 positivity among B-CLL cells) to be sufficient to identify patients with an unfavourable prognosis. The level of CD38 expression as defined with this method correlated well with the IGVH mutation status and ZAP70 gene expression.

New Prognostic Markers in CLL

The individual prognosis of patients with chronic lymphocytic leukemia (CLL) is extremely variable. Although clinical stages remain the basis for assessing prognosis in CLL, a number of biological markers, particularly serum markers, cytogenetic abnormalities, IgVH mutations, CD38 and ZAP-70 expression in leukemic cells offer important, independent prognostic information. Before being incorporated into daily practice, however, these markers require standardization and validation in large, prospective trials. Meanwhile, treatment of patients with CLL not included in clinical studies should be decided on the basis of classical NCI/CLL Working Group criteria. An important area of research in CLL prognostication is the identification of markers useful for predicting response to therapy and its duration. Among them, del(17p), reflecting P53 abnormalities, is particularly important. Also relevant is del(11q), which points to ATM defects. There is also some correlation between IgVH mutational status, ZAP-70 and CD38 expression and response to therapy and its duration, although these relationships need further investigation. Finally, there is increasing evidence that response to therapy, particularly in those cases in which minimal residual disease is eradicated, is associated with longer survival.

Concomitant chronic lymphocytic leukemia and acute myeloid leukemia: Evidence of simultaneous expansion of two independent clones

The simultaneous appearance of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) has been rarely reported, with AML occurring more frequently as a secondary event in patients receiving cytotoxic drugs for a primary lymphoproliferative disorder. We describe a case of simultaneous CLL and AML documented by morphological and cytometric analysis in a previously untreated patient. In particular, on the basis of morphological and immunological features, the patient was diagnosed as being affected by CD34 + /CD13 + /CD33 + /HLA-DR + /CD7 + FAB-M2 AML, along with a B-CLL characterized by neoplastic cells expressing a VH3-53/D3-22/JH4 Ig, bearing, on average, 3.9% IgVH mutations without evidence of antigen-driven selection. To establish whether the two neoplastic cell populations shared some common molecular signature, we performed IgH gene rearrangement studies on CD34 + /CD19− and CD34−/CD19 + immunomagnetically sorted cell populations: only genomic DNA from the CD19 + /CD34− cell fraction revealed the presence of the IgH gene rearrangement. These results provide evidence that the rare concomitant association of CLL and AML likely arises from simultaneous expansion of two independent clones.

A scoring system based on the expression of six surface molecules allows the identification of three prognostic risk groups in B‐cell chronic lymphocytic leukemia

We have previously identified 12 surface antigens whose differential expression represented the signature of B-cell chronic lymphocytic leukemia (B-CLL) subsets with different prognosis. In the present study, expression data for these antigens, as determined in 137 B-CLL cases, all with survivals, were utilized to devise a comprehensive immunophenotypic scoring system of prognostic relevance for B-CLL patients. In particular, univariate z score was employed to identify the markers with greater prognostic impact, while maximally selected log-rank statistics were chosen to define the optimal cut-off points capable to split patients into two groups with different survivals. A weighted immunophenotypic scoring system was developed by integrating results from these analyses. Six antigens were selected: three positive prognosticators (CD62L, CD54, CD49c) and three negative prognosticators (CD49d, CD38, CD79b), with cut-off values ranging from 30% to 50% of positive cells. By weighing the expression of each marker according to its statistical power, a complete scoring system, with point values comprised between 0 (complete absence of phenotypic conditions associated with good prognosis) and 9 (all the phenotypic conditions associated with good prognosis fulfilled), allowed to split the whole set of B-CLL patients, into three distinctive prognostic groups (P = 4.78 x 10(-11)) with high- (score 0-3), intermediate- (score 4-6), and low- (score 7-9) risk of death. The three risk groups showed different distribution of cases as for Rai's stages, IgVH mutations, and ZAP-70 expression. The proposed immunophenotypic scoring system may be an additional useful tool in routine diagnostic/prognostic procedures for B-CLL.

B‐Cell Chronic Lymphocytic Leukemia, a Clonal Disease of B Lymphocytes with Receptors that Vary in Specificity for (Auto)antigens

B-Cell chronic lymphocytic leukemia (B-CLL) is an incurable disease that is relatively common among aging Caucasians. Patients with this leukemia can be divided into prognostic categories using clinical staging parameters, as well as molecular features [presence or absence of IgVH mutations in rearranged VHDJH segments that code for the leukemic B cell's receptor for antigen (BCR)]. In addition, the deduced amino acid structure of the BCRs from patients that fall into different prognostic categories is shared, to varying degrees, within these groups. In this paper, the molecular features of the genes that code for the BCRs of B-CLL patients are reviewed, and these are compared to antibodies of known specificity. These comparisons suggest that the BCRs of many cases resemble autoantibodies, and in some cases, antibodies to microbial antigens. Antigen-binding analyses confirm these impressions, and also indicate that polyreactivity appears to distinguish cases with worse clinical outcomes differ from those with better outcomes. The persistence of autoreactivity and polyreactivity is somewhat surprising, because IgV DNA sequence analyses suggest that many of the B cells that become leukemic have undergone one form or another of receptor editing. Thus, B-CLL appears to be a disease of B-cell clones that have undergone various types of receptor reconfiguration and yet retain inappropriate antigen-binding properties.

Mutational Status of IgVH Genes in B-Cell Chronic Lymphocytic Leukemia (B-CLL) and Prognosis: Percent Mutations or Evaluation of Antigen-Driven Selection?

Quantitative evaluation of IgVH genes mutations is widely considered a reliable prognosticator in B-CLL. Conversely, conflicting results have been reported regarding the prognostic impact of IgVH gene mutations when evidence of Ag-driven selection is investigated. To address this issue, the mutational status of IgVH genes was analysed in peripheral blood samples of 147 B-CLL patients, all with survivals, by a strategy of RT-PCR and cloning; B-CLL specific IgVH transcripts were analysed for both % mutation and Ag-driven selection by applying a multinomial statistical model evaluating the excess/scarcity of replacement/silent mutations in FR/CDR sequences of IgVH genes. Maximally selected log-rank statistics, applied for IgVH gene % mutations, estimated the most appropriate cutoffs capable to separate B-CLL patients into two subgroups with different survival; this approach identified an absolute peak at 0.2% IgVH mutations and two relative peaks at about 2% and 4% IgVH mutations. We therefore tested the impact of Ag-driven selection on B-CLL patient survival in the context of the cutoffs of 0.2, 2 and 4% IgVH mutations. For each cutoff, B-CLL cases were identified as mutated (M) or unmutated (UM) if the % IgVH mutations were above or below the chosen cutoff, respectively; M B-CLLs with evidence of Ag selection were named significantly mutated (sM), while cases lacking such an evidence were reported as not-sM (nsM). 1) 0.2% IgVH cutoff - The 133 B-CLLs with >0.2% mutations had longer survivals as compared to 14 cases with <0.2% mutations (p=2.6x10-5); regarding the prognostic impact of Ag selection within the 133 M B-CLLs, 78 sM B-CLL patients had longer survivals than the 55 nsM B-CLLs (p=2.7x10-2). This latter group maintained a better prognosis as compared to UM B-CLLs (p=8.8x10-3); 2) 2% IgVH cutoff - Using the standard cutoff, 99 M B-CLL cases, displaying >2% mutations, had longer survivals as compared to 48 UM cases with <2% mutations (p=1.4x10-4); again, within the M B-CLL group, 65 sM B-CLL patients had longer survivals than 34 nsM B-CLLs (p=1.4x10-2); nsM and UM B-CLL patients had similar survivals (p = 0.1); 3) 4% IgVH cutoff - According to this cutoff, 75 B-CLLs were M B-CLLs, while 72 cases were UM B-CLLs. Only percent of IgVH mutations split B-CLLs into two subgroups with different survivals (p=4.9x10-4); sM and nsM B-CLLs with >4% mutations had similar survivals; 4) sM vs. nsM (all cases) - In the absence of any cutoff, the 78 patients with sM B-CLLs had longer survival as compared to the 69 affected by nsM B-CLLs (p=9.6x10-4). By taking together this data, it appears that the use of % IgVH mutations remains the gold-standard for the definition of prognosis in B-CLL; however, at least when the canonical 2% cutoff is applied, a certain caution should be used by predicting patient survival in the absence of information regarding the affinity maturation of B-CLL clones. The expression by B-CLL cells of IgVH segments with evidence of affinity maturation seems to lose its positive prognostic impact when a cutoff is set at 4% IgVH mutations. In addition to its obvious clinical impact, these observations provide a putative explanation of the apparent discrepancies found in the scientific literature about this matter.

Characterization of p53 Abnormalities in CLL Patients in Relation to IGVH Mutation Status and Previous Treatment.

Background: Although the defects in the p53 gene predispose CLL patients for inferior outcome, little is known about the reasons leading to inactivation of this tumor-suppressor. The p53 abnormalities were reported to be associated with unmutated IgVH subtype and may thus arise as a consequence of its more aggressive behaviour, but some reports point also to potentially damaging chemotherapy including alkylating agents.Aims: The aims of the study were to determine the spectrum of p53 mutations in CLL patients treated or monitored at our center and to correlate the data to mutation status of IgVH and to the previous treatment.Methods: We analyzed the status of the p53 gene in 144 patients diagnosed with CLL of all stages using functional analysis in yeasts (FASAY) supplemented by Western-blotting detection of p53 protein expression and I-FISH detection of p53 deletions. We used PCR and direct sequencing to analyze the IgVH rearrangements and mutation status. Results: Our comprehensive approach for monitoring of p53 abnormalities provided us the overall frequency of inactivation within the expected range (14%; usually reported between 10–15%). We noticed a very good overlap between the mutation of one and deletion of the second allele (93%) and between the mutation and corresponding p53 protein over-expression (92%). All the identified mutations in the p53 gene were unambigously determined by direct sequencing from yeast colonies harboring mutated phenotype. We did not find any p53 mutation (n=15) more than once and thus we do not see in our population neither the hot-spots published for CLL in p53 mutation database IARC (codons 248 and 273) nor the hot-spots reported in literature (codons 209 and 143). Inactivation of p53 ocurred markedly more frequently in subtype with unmutated IgVH compared to mutated one (16.7% vs. 5.3%). Moreover, two of the three IgVH mutated cases harbored just p53 deletion without accompanying mutation, slightly over background level. We noticed a very low frequency of the immunoglobulin gene VH3-21 (4.3% in our study vs. 11.2% reported by Tobin et al., Blood 2002; 99: 2262–2264), which was recently reported to be mostly mutated and to be associated with p53 inactivation. Four of the six our cases manifested unmutated IgVH, with two of them showing deletions of p53 or ATM (p53-regulatory kinase), respectively. The overall treatment, which included alkylating agents in 43/48 cases, was markedly more frequent within the subgroup with germ-line IgVH (in 49% of patients) compared to group harboring mutated IgVH (in 7% of patients - none of them with p53 inactivation). In the former subgroup the p53 inactivation in the untreated and treated patients was very similar (17% vs. 20%).Conclusions: The spectrum of p53 mutations in our population is different from those reported in other studies. The inactivation of the p53 was in our study associated with unmutated IgVH locus and does not seem to be primarily the consequence of previous chemotherapy including alkylating agents. Supported by grants NR8445-3/2005, NR8443-3/2005 and NR8448-3/2005 provided by IGA of Ministry of Health of the Czech Republic.

Flow Cytometric Detection of ZAP-70 in Chronic Lymphocytic Leukemia: Addition of a Novel Second Monoclonal Antibody Improves Correlation with IgVH Mutation Status.

Background: Expression of ZAP-70 is associated with unmutated immunoglobulin heavy chain variable region genes and poor prognosis in B-cell CLL. Reliable clinical flow cytometric assays have been difficult to establish, as many anti-ZAP-70 antibodies show a suboptimal signal-to-noise ratio, and an imperfect correlation with IgVH mutation status.Methods: We studied fresh peripheral blood or bone marrow specimens from forty-three patients with CLL/SLL. Samples were stained for intracytoplasmic ZAP-70 using a standard monoclonal antibody, 1E7.2/PE (Caltag, Burlingame, CA), and the novel monoclonal antibody J13–1164/PE (kindly provided by BD Biosciences, San Diego, CA). Threshholds were set using isotype-matched negative control antibodies. Mutational status of the IgVH genes was assessed by RT-PCR, followed by standard Sanger DNA sequencing. Divergence from germline IgVH segments (IMGT database) was calculated using VBASE, with 2% or less changes over codons 1–94 of IgVH regarded as unmutated.Results: Staining with J13–1164 revealed a clear apparent cutpoint in levels of positivity, with 26/43 (60%) of the CLL cases showing >49% of cells above the isotype threshhold. Most of the remaining cases (15/43, 35%) showed <26% of cells positive. The 1E7.2/PE reagent yielded a similar number of positive cases, with 28/43 (65%) showing >20% positive cells (the cutpoint suggested by Rassenti et al., N Engl J Med 2004, 351:893). However, staining with 1E7.2 was more difficult to interpret, as many cases had levels of positivity that were close to the cutpoint, with 15/43 (35%) showing 10–30% of cells positive. Both antibodies showed similar degrees of correlation with IgVH mutation status, with 72–75% of unmutated cases showing the expected positivity for ZAP-70, and 57–64% of mutated cases negative for ZAP-70 (see Table 1). The two antibodies yielded concordant results in about half of cases (21/43), and the concordant cases showed a strong correlation with IgVH mutation status: 15/16 cases positive with both antibodies had unmutated genes, and 4/5 cases negative with both antibodies had mutated genes (see Table 2). The cases with discordant staining between the two antibodies were a mixture of cases with mutated or unmutated IgVH genes.Conclusions: The J13–1164 anti-ZAP-70 antibody provides more easily interpretable results in routine clinical use than the 1E7.2 clone, with brighter staining in many cases and a more distinct difference between positive and negative cases in our series. Compared to the 1E7.2 clone, the J13–1164 clone shows a similar degree of correlation with the IgVH mutation status. A combination of both antibodies provides the strongest correlation with IgVH mutation status, with 19/21 concordant cases showing the expected staining pattern.ZAP-70 staining vs IgVH mutation statusUnmutatedMutated1164 positive2151164 negative891E7.2 positive2261E7.2 negative78IgVH mutation status in concordant vs. discordant cases1E7.2 positive1E7.2 negative1164 positive15/16 unmutated6/10 unmutated1164 negative7/12 unmutated4/5 mutated

GRN163L Inhibits Telomerase Activity in B-CLL Cells.

B-CLL cells, like many solid and hematologic malignancies, are characterized by short telomeres, suggesting that they would be acutely susceptible to telomerase inhibition. We and others have documented that CLL patients in poorer prognosis subsets, i.e., those without IgVH mutations, had shorter mean telomere lengths and higher telomerase levels than patients with IgVH mutations (Damle et al, 2004; Keating et al, 2003; Bechter et al 1998, Hultdin et al, 2003). Treatment with the telomerase inhibitor GRN163L, a lipid-conjugated 13-mer thio-phosphoramidate oligonucleotide (Geron Corporation), inhibits the growth of human hepatoma (Djojosubroto et al, 2005), ovarian carcinoma (Ertem et al, 2004, 2005), and multiple myeloma (CAG, MM.1S) cell lines in vitro and in vivo (AACR 2004 and 2005 Annual Meetings). Although no validated human B-CLL xenograft models exist, preliminary data indicate effective inhibition of telomerase in freshly thawed B-CLL cells upon exposure to GRN163L. We will present data demonstrating robust uptake of GRN163L into primary B-CLL patient cells, along with the subcellular distribution of the oligonucleotide into cytoplasmic and nuclear compartments. Comparison of the effect of GRN163L and a mismatch oligonucleotide control on telomerase inhibition will be described. Geron initiated a Phase I/II trial with GRN163L in chronic lymphocytic leukemia in July 2005.

Plasma Is a Reliable Source of mRNA for Testing IgVH Mutation Status in Patients with Chronic Lymphocytic Leukemia.

The mutational status of the immunoglobulin heavy-chain variable-region (IgVH) gene in the leukemic cells of patients with chronic lymphocytic leukemia (CLL) is an important prognostic marker. Lack of IgVH mutation is associated with rapid disease progression and shorter survival. The assay used to determine IgVH mutation status requires specific amplification of the mRNA of the expressed clonal IgVH gene in CLL. However, in some patients with CLL or lymphocytic lymphoma, the bulk of the disease resides in the lymph nodes or bone marrow, with few circulating leukemic cells. In addition, contamination of leukemic clonal cells by reactive polyclonal plasma cells can cause difficulty in obtaining homogenous IgVH mRNA for sequencing, and may therefore lead to failed sequencing or sequencing of the wrong IgVH mRNA. We have reported that plasma is enriched with leukemia-specific DNA, RNA, and protein because of the high turnover of leukemic cells relative to non-neoplastic cells. We thus reasoned that plasma might be a more reliable source of IgVH mRNA than cells from peripheral blood or bone marrow, where mixed populations of leukemic cells and non-neoplastic lymphocytes or plasma cells could hinder sequencing. We tested the plasma from 8 patients in whom routine (cell-based) testing for IgVH mutation status failed to yield results due to a paucity of leukemic cells (<10% of total cells). The plasma of all the 8 samples showed unique, easily defined amplification products of the IgVH mRNA. Sequencing of these products showed the presence of mutated IgVH in 5 patients and unmutated IgVH in 3. Testing paired plasma and cell samples from 19 patients with CLL showed identical mutation rates and family types of the expressed IgVH gene. In contrast, plasma from 20 normal individuals showed no IgVH amplification products that could be sequenced. This data suggest that plasma can be used as an alternative to cells for testing IgVH mutation status. More importantly, plasma is more reliable when few leukemic cells are in circulation and the bulk of the tumor is in the bone marrow or lymph nodes.

Dexamethasone Induces Apoptosis “Ex Vivo” in Chronic Lymphocytic Leukemia Cells with Either Unmutated IgVH Genes or High ZAP-70 Expression.

Patients with chronic lymphocytic leukemia (CLL) and unmutated IgVH genes or high ZAP-70 expression have poorer prognosis than those with mutated IgVH genes or low ZAP-70 levels. This is in part related to the resistance of unmutated and ZAP-70 positive cases to treatment agents that induce apoptosis in a p53-dependent manner. It has been suggested that corticosteroids are active in CLL through p53-independent pathways. The aim of this study was to analyze the “ex vivo” response to dexamethasone in CLL cells according to the IgVH mutational status and ZAP-70 expression. Frozen lymphocytes from 60 patients with CLL were analyzed for ZAP-70 expression and IgVH mutational status (n=44). Cells were cultured and treated using fludarabine (5μgr/ml), mitoxantrone (0.5μgr/ml), FCM (fludarabine 1μgr/ml, maphosphamide 1μgr/ml and mitoxantrone 0.5 μgr/ml), and dexamethasone (5.2 μg/mL). Cell viability and apoptosis were determined by annexinV/PI staining and FACscan analysis at three different time points and conditions (0h and 24h without treatment, and 24h with treatment). The expression of glucocorticoid receptor (GR) isoforms alpha, beta and gamma was analyzed by Quantitative RT-PCR in 20 cases. Dexamethasone-induced apoptosis was significantly higher in patients with unmutated IgVH and/or high ZAP-70 expression (≥20%) than in those with mutated IgVH and/or low ZAP-70 expression (median cell viability 65% vs. 81%, respectively; p<0.001). In contrast, mitoxantrone induced higher cell toxicity in patients with IgVH mutations or low ZAP-70 expression (p=0.009). No differences in cell viability were found according to ZAP-70 expression or IgVH mutational status after “ex vivo” treatment with fludarabine or FCM (p=0.649 and p=0.055, respectively). Expression of different GR isoforms was similar in corticosteroid-responders and non-responders. In conclusion, in this study CLL cells with unmutated IgVH genes or high ZAP-70 expression showed a higher cell mortality after “ex vivo” exposure to dexamethasone than those with mutated IgVH genes or low ZAP-70 expression, with no relationship with the expression of the different GR isoforms. These data give conceptual support to trials aimed at determining the role of dexamethasone in the treatment of patients with CLL and poor prognostic features or resistant to fludarabine. [Display omitted]

A National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) Phase II Study of Oral Fludarabine in Untreated B-Cell Chronic Lymphocytic Leukemia.

Fludarabine is a key drug in the treatment of CLL, and the oral formulation has an efficacy and safety profile similar to the intravenous formulation in previously treated patients (pts). The NCIC CTG conducted a phase II study evaluating the overall response rate (ORR) to oral fludarabine in previously untreated pts. Leukemia cells were studied for common cytogenetic abnormalities by FISH, expression of ZAP-70, and IgVH mutational status, to assess whether these parameters influence response to therapy. Eligibility criteria included diagnosis of CLL confirmed by lymphocytosis of >5×109/L, leukemia-cell expression of CD5, CD19, and CD23 with light chain restriction, and indication for treatment. Pts were treated with oral fludarabine 40 mg/m2/day × 5 days every 28 days for a max of 6–8 cycles. Response evaluation was based on NCI-WG criteria. Interphase FISH was performed on PBMCs, evaluating for deletion of ATM at 11q22.3, D13S319 at 13q14.3, D12Z1 at 12p11.1-q11.1, and p53 at 17p13.1. ZAP-70 expression and IgVH mutation analysis of CLL cells were assessed before therapy in all patients, and in a subset, after therapy.Results: 126 eligible pts were enrolled between Aug2002–Jan2004 at 26 institutions. Median age was 60.9 years, male 62%, female 38%. Distribution by Rai stage was I 25%, II 43%, III 14%, and IV 18%. The ORR at the completion of therapy was 64%, with 18% CR, 3% unconfirmed CR, 43% PR, 13% SD, and 13% PD. At median follow-up of 23.2 months, median progression-free survival (PFS) was 15.3 months (95% CI 13.6–16.7). Median overall survival has not been reached. 92 pts completed protocol defined therapy; 12 discontinued due to toxicity, 8 due to progressive disease and 13 for other reasons, including 1 pt withdrawn due to AIHA. Hematologic toxicity (NCI-WG) included thrombocytopenia, grade 3/4 (14/126; 11%), and neutropenia, grade 3/4 (54/126; 51%). FISH analysis revealed abnormal cytogenetics in 79% of 122 evaluable cases, with del (13) in 58%, del (11) in 23%, +12 in 14%, and del (17) in 5%, with more than 20% of CLL cells having each abnormality. All 6 pts with del (17) had a significantly poorer PFS relative to pts without a del (17) (Hazard Ratio 7.4, 95% CI 3.06–17.98). IgVH sequencing completed on 102/126 samples at the time of this analysis, and 62% of cases had unmutated IgVH (>98% homology to known IgVH gene), whereas 39% expressed mutated IgVH genes. Forty-three (68%) of 63 cases with unmutated IgVH, but only 5 (14.6%) of 39 cases with mutated IgVH expressed ZAP-70, a concordance rate similar to that observed previously. Of total 125 cases examined, 55 were ZAP-70 positive and 70 were negative; leukemia-cell expression of ZAP-70 was unchanged after therapy in 47/52 (90%) of cases successfully examined. ORR in the pts with ZAP-70-positive/unmutated IgVH CLL cells was 63% versus 77% in the ZAP-70-negative/mutated IgVH group (P=0.22).Conclusions: Oral fludarabine as a single agent in untreated CLL is associated with response rates and toxicity profile comparable to that of intravenous fludarabine given on a similar schedule. Leukemia-cell expression of ZAP-70 generally correlated with the use of unmutated IgVH genes and appeared unaltered following treatment in most cases studied. Patients with ZAP-70-negative/mutated IgVH CLL had a better ORR although this did not reach statistical significance.

Significant Differences in the IGVH and BCL6 Mutation Status in Aggressive B-Cell Lymphomas with and without MYC Breakpoints.

Somatically mutated IGVH regions are a hallmark of germinal center (GC) B-cells. Moreover, aberrant somatic hypermutation (SHM) of oncogenes, like changes in the 5′ non-coding region of the BCL6 gene occurring in 75% of DLBCL, are a mechanism of oncogene activation independently of chromosomal translocations.Large scale mutational screening using DHPLC and direct sequencing was applied to determine the somatic hypermutation status of clonal IGVH as well as several oncogenes like BCL6 and MYC in a series of more than 250 aggressive B-cell lymphomas included in the Deutsche Krebshilfe funded network “Molecular Mechanisms in Malignant Lymphoma”. Mutation patterns were correlated with the results of molecular cytogenetic analyses. MYC breakpoints detected by FISH clearly differentiated two groups of aggressive B-NHL with significantly different VH mutation status. MYC-positive lymphomas by FISH carried VH genes with a mutation frequency significantly lower compared to aggressive lymphomas lacking these features (median 4.8% vs.11.,0%, p<0.0001). Similarly, the mutation frequency of BCL6 was significantly lower in MYC-positive than in MYC-negative lymphomas (median 0.13% vs 0.25% p=0,020). We observed a bias in VH gene usage in both groups with an overrepresentation of VH4 (40% in both groups) and VH3 gene (24% in MYC-positive, 40% in MYC-negative). The group of MYC-positive lymphomas was heterogeneous with regard to the pattern of chromosomal aberrations. (IGH, MYC, BCL2, BCL6, MALT1 and REL loci). Lymphomas with IG-MYC fusion lacking breakpoints in BCL2, BCL6, MALT1 or REL loci as well as non-MYC associated IGH translocations displayed a median IGVH mutation frequency of 4,8% vs. 12,2% in those cases with additional chromosomal translocations (p=0.0060).Molecular classification of aggressive B-cell lymphomas according to MYC breakpoints distinguishes subgroups with significant differences in the VH and BCL6 mutation frequencies.

Surface Antigens Identified by Antibody Microarray That Correlate with IgVH Mutational Status and ZAP70 Expression in CLL.

A new method has been developed to evaluate leukemias based on binding of cells in suspension to a microarray of cluster of differentiation (CD) monoclonal antibodies (mAbs) immobilized on nitrocellulose film on a microscope slide. Cell binding is proportional to antigen expression. This method allows simultaneous evaluation of 88 different CD antigens and is feasible with homogeneous populations of mononuclear cells obtained from blood of patients with leukemia. This methodology is potentially useful in diagnosis and classification of different leukemias and lymphomas and it may further aid in identifying and distinguishing subgroups of patients within a particular diagnosis. We utilized this methodology to assess its effectiveness in distinguishing prognostic subgroups in patients with chronic lymphocytic leukemia (CLL), those with mutated versus unmutated IgVH genes and those with <20% ZAP70+ versus >20% ZAP70+ cells. Unmutated IgVH genes were defined as >98% homologous to germline. To do this we identified 101 unselected samples from CLL patients for which IgVH mutational status and/or ZAP70 expression were known. Both IgVH status and ZAP70 expression were known for 70, in 6 only IgVH status, and in 25 only ZAP70 was known. IgVH mutational status and ZAP70 expression were concordant in 62/70 cases. Patient characteristics (median and range) were as follows: age=59yrs(37–82); abs lym=23k/μL(3.6–123); β2M=2.3mg/L(1.2–9.5); # prior treatments= 0(0–6). 20 had Rai low-risk; 67 had Rai-intermediate-risk, and 14 had Rai high-risk disease; 78 were previously untreated. Reduced space linear discrimination analysis and empirical Bayes moderated t-test was used to evaluate relationships between microarray binding and patients with “good prognosis” (IgVH mutated or ZAP70-) and “poor prognosis” (IgVH unmutated or ZAP70+). Empirical Bayes analysis was used to identify CD antigens with significant differential expression between the “good prognosis” and “poor prognosis” groups. Although there was not a significant difference in overall expression between the two groups, there were antibodies that had significantly different levels of binding. For the IgVH unmutated group, increased binding was noted with CD95, CD38, CD2, CD13, CD11a, CD86, CD25, CD9, CD22 (p<.05; FDR-adjusted). For the ZAP70+ group, increased binding was noted for CD38, CD2, CD95, CD49d, CD79b, kappa, and CD11a (pFDR<.05). In the IgVH/ZAP70 concordant cases, the following had increased binding with the “poor prognosis” group (IgVH unmutated/ZAP70+): CD38, CD95, CD2, CD13, CD24, CD9, and CD11a (pFDR<.05). There is clear evidence of differential binding on the mAb microarray between prognostic groups, although it is not yet possible to accurately predict ZAP70 or IgVH mutation status based on microarray results. Work continues to correlate these findings with flow cytometry and with other meaningful prognostic factors such as β2M; Rai stage, etc. In addition, follow-up continues to assess correlations between microarray results and significant clinical endpoints including survival. This is a simple immunomicroarray method that may be useful and important to enhance the classification and prognostic assessment of patients with lymphoid malignancies, including CLL, based on correlations between an extensive immunophenotype and clinical endpoints.

Comparison of IgH Gene Rearrangement Configuration between Hairy Cell Leukemia (HCL) and Hairy Cell Leukemia Variant (HCL-v).

Hairy cell leukemia (HCL) is a rare B-cell disorder, with a variant form, which differs from the former in clinical behaviour, morphology and immunophenotype. The resemblance of these malignancies to splenic marginal zone lymphoma (SMZL), has led to the suggestion that they may share a common clonal progenitor that homes within the marginal zone of the splenic germinal centres. The immunophenotype and recent global gene expression results offer some support for this view, with a similar profile seen in HCL, and a subset of memory B-cells that are localized to the marginal zone. However, studies of the mutational status of the Ig genes are controversial. The majority of HCL cases are mutated, whereas up to 30% of SMZL cases are unmutated. Further investigation to understand these differences and to identify the cell of origin in these disorders is needed. In addition, there are no data on gene expression or VH mutation in HCL-variant (HCL-v), an entity with a poorer outcome and for which there is as yet no effective therapy.We have analysed a series of 13 HCL and 23 HCL-v, for the configuration of the Ig heavy chain rearrangements. VDJH rearrangements were PCR-amplified and sequenced using an automated 3130xL sequencer (Applied Biosystems, Warrington, UK). The sequences obtained were compared to the closest germline segments using V-base (CRI, Cambridge, UK) in order to study the level of somatic hypermutation as well as gene segment usage in IgH rearrangements.The majority of the HCL (92%) showed more than 2% deviation from the closest germline VH gene segment, compared to only 17/23 (74%) in the HCL-v cases. In the mutated cases, the percentage of mutation was similar for HCL and HCL-v (mean 5.8% and 5.9%, respectively), and none of the cases appeared to show ongoing hypermutation. Within the HCL-v group, 4 out of the 6 unmutated cases used VH4-34 segment, and the remaining 2 used VH1-03. Both genes are known to be associated with autoimmune diseases, and they are excluded from the normal and malignant memory plasma cell repertoires. Also, JH5 segment was found in 47% of the HCL-v, while it was absent in the HCL repertoire. This finding is particularly interesting, as JH5 segment is normally under-represented in most normal and malignant B-cells, except for a characteristic group of IgG-expressing chronic lymphocytic leukemias. Our data suggest that HCL-v is, unlike HCL, heterogeneous regarding IgVH mutations, but has restricted IgH repertoire that, at least in some cases, might be derived from activated, self-reactive B-lymphocytes that have not experienced the germinal-centre reaction.

Coexistence of Mutated and Unmutated IgVH Forms in Patients with Chronic Lymphocytic Leukemia.

The mutation status of the immunoglobulin heavy chain variable region (IgVH) gene is an independent prognostic indicator in patients with chronic lymphocytic leukemia (CLL). Unmutated IgVH is associated with rapid disease progression and shorter survival. The assay for determining IgVH mutation status depends on specific amplification of the mRNA of the expressed clonal IgVH. The presence of more than 1 clone in patients with CLL has been speculated and can be documented when the 2 clones express different light chains. Determining the IgVH gene family that is expressed in subclones also allows the confirmation of the presence of two clones in some cases. We describe 3 patients with two clones of CLL discovered in the process of determining the IgVH mutation status. PCR amplification of the expressed IgVH mRNA yielded 2 distinct bands. Sequencing each band separately revealed 2 different clones in each patient. Interestingly, each clone had a different mutation profile. In 2 of the 3 patients, the 2 clones were from completely different IgVH gene families (VH1-2 with VH2-5 and VH4-34 with VH5-51); both of these patients showed kappa light chain restriction. In the third patient the expressed IgVH gene family was VH3-21 in both clones, but 1 was mutated (6.8%) and the second was unmutated. Two of the 3 patients had evidence of aggressive disease with hepatosplenomegaly and lymphadenopathy; 1 of these patients expressed the VH3-21 gene family, which is known to be associated with aggressive disease irrespective of its mutation status. The other patient had a 9-year history of indolent disease without therapy. The intensity of the expressed IgVH clones as determined by PCR indicated that the mutated clones were dominant in 2 patients (approximately 80%). In the patient with VH3-21 expression, the unmutated clone accounted for 80% of total expressed IgVH. These data suggest that the presence of more than 1 clone should be considered when testing for IgVH mutation status and, more importantly, that evolution of a more aggressive second clone should be suspected. The presence of 2 clones—1 arising in naïve cells and the second in memory cells—suggests the possibility that the first hit occurred very early in the ontogeny of lymphocytes and that a second hit occurred at a later stage. However, the presence of naïve and memory clones in the same family raises the possibility that the naïve leukemic cells might still go through the germinal center programming process.

Molecular and Clinical Analysis of a Midwest Cohort of B-CLL Patients Utilizing the Immunoglobulin VH 1-69 Gene.

The prognostic power of immunoglobulin (Ig) somatic mutation status in B cell chronic lymphocytic leukemia (B-CLL) is widely appreciated and has served as the rationale to systematically determine this molecular feature in B-CLL patients. Consistent with other reports, our study of Ig mutation status in a large cohort of B-CLL patients (n=599) found the most commonly used Ig heavy chain variable (VH) region gene was VH 1–69. The VH1–69 gene is of particular interest as there are numerous reports demonstrating that VH1–69 expressing B-CLL cells predominantly express the 51p1-like allele in an unmutated (UM) form and it is frequently associated with use of the D gene segment, D3-3; the J gene segment, JH6; and a relatively long third, complementarity-determining region (CDR3). Despite molecular definition of a commonly used form of VH1–69 in B-CLL, the clinical significance of CLL B cell usage of this prototypic form of VH1–69 remains to be determined. The goal of this study, therefore, was to perform a molecular and clinical analysis on our cohort of B-CLL patients expressing the VH1–69 gene. Our cohort consisted of 19 females and 55 males, with 89.5% expressing UM Ig VH. The 51p1-like allele was present in 75.7% of patients and the predominant D region used was D3 (64.7%). Patients in our cohort were classified by Rai risk as follows: 20 low (28.2%), 40 intermediate (56.3%), and 11 high (15.5%). For those patients with Rai stage available, analysis of specific D and J regions resulted in 16 D3-3/JH6 (26.7%); 14 D3-3/non-JH6 (23.3%); 16 non-D3-3/JH6 (26.7%); and 14 non-D3-3/non-JH6 (23.3%). Despite observing an overwhelming majority of leukemic cells with UM Ig VH, and the known relationship between mutation status and disease progression, it is interesting that our cohort included almost 30% with a low Rai risk. Of note, Ig VH mutation status did not segregate with Rai risk group or VH1–69 allele use (although few patients overall were mutated). However, an UM Ig VH status was associated with a CDR3 length >20 (p = 0.001) and with use of the JH6 segment (p = 0.003). When mutation status was analyzed in concert with specific use of the D3-3 allele, no relationship emerged; however, when this D region allele was analyzed for JH6 vs non-JH6 usage, combination of the D3-3 allele with JH6 was significantly associated with an UM Ig VH status (p = 0.004). Moreover, when J and D segment usage was analyzed in concert with Rai stage group, a significant (p = 0.019) relationship emerged between paired use of D3-3 and a JH6 segment and advanced (intermediate/high) Rai stage. Strikingly, only 1 of 18 VH1–69 patients with low Rai risk for whom D and J data were available expressed the specific combination of D3-3 and JH6. Although analysis of a larger cohort is clearly required to more formally and fully evaluate these relationships, to our knowledge, this is the first suggestion that D and J usage in VH1-69 expressing B-CLL patients correlates with advanced stages of disease. Because Ig VH usage is not believed to change over the course of disease, it is tempting to speculate that VH1–69 B-CLL patients that do not express the prototypic VH1–69 receptor may have a more favorable disease course. In summary, these data add further support to the notion that there is selection for specific Ig receptors in B-CLL and that the antigenic specificity of certain receptors may be associated with risk of progression.

Expression of CD49c and CD49d Chains of β1 Integrins Identifies B-CLL Subsets with Different Prognosis and Distinct Immunophenotypic Profiles.

Introduction: Although expression of β1 integrins was analyzed in B-cell chronic lymphocytic leukemia (B-CLL), little is known about the clinical behaviour and the phenotyic profile of B-CLLs with different patterns of β1 integrin expression.Methods: Expression of β1 integrins (α1-α6) was investigated by flow cytometry along with other 30 surface molecules (B-cell markers, cell-adhesion-molecules, activation inducers, complement activity regulators) in 155 B-CLLs, 106 characterized for clinical stage (Rai's stages), 121 for IgVH mutations, 79 for ZAP-70 expression and 109 with survival data.Results: In agreement with previous studies, also in our B-CLL series CD49c, CD49d and, to a lesser extent, CD49e resulted the most expressed β1 integrins, with mean expression values, evaluated as % of positive cells, of 59%, 36% and 26% (range 1-100%), respectively. Since expression of CD49c and CD49d have been recently identified by us as part of the immunophenotypic signatures of B-CLLs with different prognosis (J Cell Physiol 204, 113, 2005), the present study was designed to define: 1) the real prognostic impact and the optimal cutoffs for CD49c and CD49d splitting patients into two groups with different survivals; 2) the immunophenotypic and molecular features of B-CLL subsets expressing different levels of CD49c and CD49d. 1) By applying the maximally selected log-rank statistics, we identified cutoff values of 40% and 30% of positive cells for CD49c and CD49d, respectively; therefore, B-CLL cases were divided in CD49chigh or CD49clow and CD49dhigh or CD49dlow if the expression of the molecules was above or below their respective cutoffs. The CD49chigh B-CLL subset (n=78) displayed longer survival as compared to CD49clow cases (n=31; p=2.0x10-2, log-rank test); conversely, CD49dhigh B-CLLs (n=46) had shorter survivals, as compared to the CD49dlow subset (n=62; p=1.2x10-3). 2) Supervised analyses were performed by comparing the expression of a wide panel of surface antigens in CD49chigh vs. CD49clow and CD49dhigh vs. CD49dlow B-CLLs. In addition, B-CLL subgroups, as identified by CD49c and CD49d expression, were compared for IgVH mutations (2% cutoff), ZAP-70 expression (30% cutoff) and Rai's stages distribution (stages 0-I vs. II-IV). According to these analyses, CD62L, CD22, CD55, CD29, CD11c, CD54 and CD40 were the molecules significantly over-expressed in good prognosis CD49chigh B-CLLs, as compared to CD49clow cases (p<0.05; t-test); consistently, CD49chigh vs. CD49clow B-CLLs had mutated:unmutated (M:UM) ratios of 2.2 vs. 0.6 (p=9.2x10-3; Chi-square Test). Bad prognosis CD49dhigh B-CLLs, as compared to CD49dlow cases, over-expressed CD38, CD29, CD49e, CD79b and displayed a lower expression of CD11c (p<0.05). In the same subsets, M:UM ratios were 0.6 (CD49dhigh) or 3.4 (CD49dlow; p=4.2x10-5; Chi-square Test); finally, the frequency of both ZAP-70+ cases and cases with advanced Rai's stages (II-IV) was significantly higher (p=5.6x10-4 and 2.9x10-2, respectively) in CD49dhigh B-CLLs.Conclusion: CD49c and CD49d identify B-CLL subsets with peculiar clinico-biological features, allegedly originating from different normal B cell counterparts; under a clinical standpoint, CD49c and CD49d may be employed as additional prognosticators for B-CLLs.

Soluble Syndecan-1 (sCD138) Is an Independent Prognostic Factor in Patients with Chronic Lymphocytic Leukemia.

Syndecan-1 (sCD138) is a transmembrane heparan sulfate-bearing proteoglycan expressed in epithelial cells as well as hematopoitic cells that demonstrate plasmacytioid differentiation. CD138 is believed to play a role in cell-cell and cel-matrix interaction. A soluble form of CD138 (sCD138) has been reported to be elevated in multiple myeloma. Higher levels of sCD138 have been reported to correlate with poor outcome in myeloma. While some cells in patients with chronic lymphocytic leukemia (CLL) can demonstrate plasmacytoid differentiation, CD138 is usually not expressed in B-cell CLL. We investigated the levels of circulating sCD138 in the plasma of 104 patients with CLL and correlated these levels with clinical behavior. sCD138 levels were elevated in patients with CLL as compared with normal control subjects (median, 52.8, range: 13.4-252.7 ng/mL) (P<0.01). Patients with levels of sCD138 higher than the median (53 ng/mL) had significantly shorter survival (Figure; P=0.0002). More importantly, this association was independent of both the IgVH mutation status and beta2- microglobulin levels. The same was true whether patients were previously treated (40 patients, P=0.004) or not (64 patients, P=0.01). Patients who had mutated IgVH but high sCD138 levels (>53 ng/mL) had significantly shorter survival than those with mutated IgVH and lower levels of sCD138. Similarly, patients with unmutated IgVH but high levels of sCD138 (>53 ng/mL) had significantly shorter survival than those with lower levels of sCD138 and unmutated IgVH (P=0.007). When CLL patients were dichotomized into 2 groups according to the median level of sCD138, there was significant positive correlation with age, platelet count, male sex, white cell count, and sCD23 level (all P<0.05). In contrast, no significant correlation with these prognostic factors or survival was found when sCD138 was considered as a continuous variable. This suggests that the role of sCD138 is more related to its presence or absence. The data presented here suggest that sCD138 is a powerful independent prognostic factor in CLL, and further studies are needed to explore its biological role and the potential of targeting this pathway as a therapeutic approach. [Display omitted]

Proteomic Analysis of Chronic Lymphocytic Leukemia Cells Identifies Vimentin as a Novel Prognostic Factor for Aggressive Disease.

The IgVH mutation status is an independent predictor of time to treatment and survival in CLL. However, the biological basis of this difference is unknown. Clinical use of the IgVH mutation status as a prognostic marker is limited due to the technical difficulties of assessing this feature. As such, we probed for differences in protein expression by CLL cells with unmutated (UM) vs mutated (M) IgVH using phage peptide display libraries (PDPL).Methods: PDPL consists of phages engineered to express random peptides (7-mer) on the coat protein. From approximately 2x1011 phages displaying all possible permutations of 7-mer peptide, we selected phages binding to UM cells by incubation with 106 UM cells and elution of bound phages. Then, from numerous phages initially binding to UM cells, we subtracted phages binding to M cells by multiple incubations with M cells (106). Thus, the phages that bound only to UM cells were selected. The procedure was repeated multiple times to increase selection specificity. The peptide sequences displayed by selected phages were evaluated. We identified phage targets on UM cells by immunoprecipitation (IP) of CLL protein with specific phage and by sequencing of precipitated protein. The expression of target protein in CLL cells was confirmed by immunobloting and flow cytometry.Results: Sequencing of phages from the 3rd round of selection (UM v. M) revealed several peptides, with the most predominant being FPSAHFL. IP identified the cellular target for FPSAHFL as vimentin, an intermediate filament protein involved in cell motility and activation. The level of vimentin expressed by CLL cells varied between patient samples (n=15). UM CLL cases were found to express higher levels of vimentin (the mean MFI was 1002; SD 381), than cases of M CLL (mean MFI 547; SD 109), p=0.0128. To evaluate the prognostic significance of vimentin, we assessed vimentin expression by flow cytometry in a separate subgroup of 40 CLL patients. Archived cell samples collected between 6/2000 – 6/2001 were used. The median follow up was 81 months (40–233). Vimentin expression (MFI) as a continuous variable was a risk factor for a shortened time to treatment (TTT) with a proportional hazard ratio of 4.152 (95% CI 1.33–15.220, p=0.0317). Using MFI closest to the median (and rounded to 2 decimal places) as a cutoff, we stratified patients in high (n=21) and low (n=19) vimentin expression groups. The median times to treatment (TTT) in patients with high vs low level expression of vimentin were 2.8 and 12.9 years respectively, p=0.0025 (Fig.).Conclusion: Using novel proteomic technology, we found that CLL cells with unmutated IgVH expressed higher levels of vimentin than CLL cells with mutated IgVH. A high-level of vimentin expression defined by flow cytometry appears to be associated with high-risk disease. Validation of these findings could allow for the vimentin level to be used as a surrogate marker for expression of unmutated IgVH in CLL. [Display omitted]