Frequency Of Chronic Lymphocytic Leukemia Research Articles

Epidemiological Characterization and Determination of TP53 and IGHV Mutational Status of a Large Series of Previously-Untreated Chronic Lymphocytic Leukemia (CLL) Patients in Spain: The Epicll Study

Epidemiological Characterization and Determination of TP53 and IGHV Mutational Status of a Large Series of Previously-Untreated Chronic Lymphocytic Leukemia (CLL) Patients in Spain: The Epicll Study

Role of the Isoform p-53 Protein in Failed Cases of Chronic Lymphocytic Leukemia

Introduction It was discovered in the last few years that the production of some percentage of mutant p-53 proteins, with the increased stability in type B lymphocytes, leads to the carcinogenesis process. This discovery led to the identification and quantification of the p-53 protein by different methods such as immuno-histochemistry (IHC), polymerase chain reaction (PCR), single-stranded peptide microarray, (SSPMa), next-generation sequencing (NGS), and the sandwich enzyme-linked immunosorbent assay (sandwich ELISA). Method Using the ELISA technique, the frequency of p-53 protein expression in 20 representative patients diagnosed with CLL-B was analyzed, in order to investigate the relationship of the p-53 protein at the different stages of the disease and the impact on patient survival. ELISA Kit Component: Coated 96-well, Strip Plate 1, Standard (Lyophilized) 2 vials Assay, Diluent (5x) 1 vial x 15 ml, Biotinylated Detection Antibody 2 vials, HRP-Streptavidin Conjugate (800x) 1 vial x 200 µl, Wash Buffer (20x) 1 vial x 25 ml, TMB Substrate 1 vial x 12 ml, Stop Solution H2SO4 1 vial x 8 ml, Plate Sealers 4. Molecular biology technology used in the method The monoclonal p-53 antibody, PAb 240, used in the ELISA method recognizes both mutant and wild-type p-53 under denaturing conditions. Species reactivity is for human or rhesus monkey in conformity with the prospect. The monoclonal antibody PAb 240 recognizes an epitope that is structurally hidden in the wild-type conformation of p-53 and becomes exposed by denaturing the p-53 protein or the mutant conformations of p-53, where point mutations in the P-53 gene alter the terminal structure of the p-53 protein. This ELISA kit is recommended for use in serum, plasma or tissue homogenates. Using other types of sample is not supported. The sample collection protocols below were adapted from the references. 1. Full physical examination of patients diagnosed with CLL All patients were admitted to hospital with symptoms and clinical features of CLL, such as cough, night sweating, and retrosternal pain. Clinical examination and ultrasounds revealed adenopathy and/or splenomegaly, with spleen enlargement of 3 cm above the normal diameter. 2.Immunophenotyping using monoclonal antibodies (Flow Cytometry) CLL-B diagnosis was confirmed by immunophenotyping: monoclonal antibodies in CD5⁺, CD19⁺, CD20⁺, CD23⁺, CD28⁺ receptors, and with B lymphocytes expressing IgM or IgG heavy chains with kappa or lambda light chains. 3.Laboratory Exams: For each of the cases, a 5 Diff Hematology Analyzer was used to perform a haemogram, and blood smear cytology exams on peripheral blood and medullary bone marrow were carried out by May-Grunwald Giemsa staining. The leukemia cells found in the peripheral blood smear had characteristic microscopic morphology, with the small nuclei having mature lymphocytes with full or partially aggregated chromatin and lacking nucleoli. Results Of the 20 patients studied, 14 men have aged 55-85 years and 6 women aged 39-85 years. Patients were treated at the time of these investigations with cytostatic and immunotherapy specific for CLL. Male results: Protein concentration p-53 / µg / dl: 20, 15, 18, 40, 10, 12, 14, 60, 30, 10, 13, 13, 5, 10, 15, 12. Women's results; Protein concentration p-53 / µg / dl: 140, 30, 13, 10, [Graphic 1]. Statistical interpretations: The probability index (NORMDIST) p, was calculated in the value of p = 0.034. The reference interval was established between the values 10-40µg / dl, (m = 24.5 µg / dl. The pathological values in the 3 cases of highly elevated p-53, reflecting the concentration of p-53 protein mutant, were calculated in 2 men in the amount of 60 µg / dl, respectively in 50 µg / dl, and in the female case, it was calculated in the amount of 140 µg / dl, the frequency of chronic lymphocytic leukemia with mutant p-53 protein being higher in men than in women, in ratio 2/1, in accordance with the data from the specialized literature. Conclusions In the context of a heterogeneous malignant disease, such as CLL-B, a simple and inexpensive ELISA method, such as employed in this study, proves useful for identifying patients to be considered as candidates for personalized therapeutic strategies, based on the mutation of the TP- 53 gene and the presence of p-53 isoform protein. Figure Disclosures No relevant conflicts of interest to declare.

The Number of Overlapping AID Hotspots in Germline IGHV Genes Is Inversely Correlated with Mutation Frequency in Chronic Lymphocytic Leukemia.

The targeting of mutations by Activation-Induced Deaminase (AID) is a key step in generating antibody diversity at the Immunoglobulin (Ig) loci but is also implicated in B-cell malignancies such as chronic lymphocytic leukemia (CLL). AID has previously been shown to preferentially deaminate WRC (W = A/T, R = A/G) hotspots. WGCW sites, which contain an overlapping WRC hotspot on both DNA strands, mutate at much higher frequency than single hotspots. Human Ig heavy chain (IGHV) genes differ in terms of WGCW numbers, ranging from 4 for IGHV3-48*03 to as many as 12 in IGHV1-69*01. An absence of V-region mutations in CLL patients (“IGHV unmutated”, or U-CLL) is associated with a poorer prognosis compared to “IGHV mutated” (M-CLL) patients. The reasons for this difference are still unclear, but it has been noted that particular IGHV genes associate with U-CLL vs M-CLL. For example, patients with IGHV1-69 clones tend to be U-CLL with a poor prognosis, whereas patients with IGHV3-30 tend to be M-CLL and have a better prognosis. Another distinctive feature of CLL is that ~30% of (mostly poor prognosis) patients can be classified into “stereotyped” subsets, each defined by HCDR3 similarity, suggesting selection, possibly for a self-antigen. We analyzed >1000 IGHV genes from CLL patients and found a highly significant statistical relationship between the number of WGCW hotspots in the germline V-region and the observed mutation frequency in patients. However, paradoxically, this correlation was inverse, with V-regions with more WGCW hotspots being less likely to be mutated, i.e., more likely to be U-CLL. The number of WGCW hotspots in particular, are more strongly correlated with mutation frequency than either non-overlapping (WRC) hotspots or more general models of mutability derived from somatic hypermutation data. Furthermore, this correlation is not observed in sequences from the B cell repertoires of normal individuals and those with autoimmune diseases.

Identification of novel sequence variations in microRNAs in chronic lymphocytic leukemia

MicroRNA (miRNA) expression is deregulated in many tumors including chronic lymphocytic leukemia (CLL). Although the particular mechanism(s) responsible for their aberrant expression is not well characterized, the presence of mutations and single-nucleotide polymorphisms (SNPs) in miRNA genes, possibly affecting their secondary structure and expression, has been described. In CLL; however, the impact and frequency of such variations have yet to be elucidated. Using a custom resequencing microarray, we screened sequence variations in 109 cancer-related pre-miRNAs in 98 CLL patients. Additionally, the primary regions of miR-29b-2/29c and miR-16-1 were analyzed by Sanger sequencing in another cohort of 213 and 193 CLL patients, respectively. Altogether, we describe six novel miR-sequence variations and the presence of SNPs (n = 27), most of which changed the miR-secondary structure. Moreover, some of the identified SNPs have a significantly different frequency in CLL when compared with a control population. Additionally, we identified a novel variation in miR-16-1 that had not been described previously in CLL patients. We show that this variation affects the expression of mature miR-16-1. We also show that the expression of another miRNA with pathogenetic relevance for CLL, namely miR-29b-2, is influenced by the presence of a polymorphic insertion, which is more frequent in CLL than in a control population. Altogether, these data suggest that sequence variations may occur during CLL development and/or progression.

6q deletion detected by fluorescence in situ hybridization using bacterial artificial chromosome in chronic lymphocytic leukemia

Deletions of the long arm of chromosome 6 are known to occur at relatively low frequency (3-6%) in chronic lymphocytic leukemia (CLL), and they are more frequently observed in 6q21. Few data have been reported regarding other bands on 6q involved by cytogenetic alterations in CLL. The cytogenetic study was performed in nuclei and metaphases obtained after stimulation with a combination of CpG-oligonucleotide DSP30 and interleukin-2. Four bacterial artificial chromosome (BAC) clones mapping regions in bands 6q16, 6q23, 6q25, 6q27 were used as probes for fluorescence in situ hybridization in 107 CLL cases in order to analyze the occurrence and localization of 6q aberrations. We identified 11 cases (10.2%) with 6q deletion of 107 patients studied with CLL. The trends of survival curves and the treatment-free intervals (TFI) of patients with deletion suggest a better outcome than the other cytogenetic risk groups. We observed two subgroups with 6q deletion as the sole anomaly: two cases with 6q16 deletion, and three cases with 6q25.2-27 deletion. There were differences of age, stage, and TFI between both subgroups. By using BAC probes, we observed that 6q deletion has a higher frequency in CLL and is linked with a good prognosis. In addition, it was observed that the deletion in 6q16 appears to be the most frequent and, if present as the only abnormality, it could be associated with a most widespread disease.

BRAF mutations in chronic lymphocytic leukemia

BRAF mutations have been shown to occur at a high frequency in melanoma and thyroid cancer, but also at lower frequencies in hematological malignancies. To assess the potential role of BRAF, we have sequenced exons 11 and 15 of BRAF in 138 cases with chronic lymphocytic leukemia (CLL) and 32 cases of B-cell prolymphocytic leukemia (B-PLL). We found an incidence of BRAF mutations of 2.8% in CLL (4/138), while no cases with B-PLL showed BRAF mutations. The analysis of a cohort of patients with fludarabine-refractory disease (n = 87) showed no increase in the mutation incidence, suggesting that this mutation is not selected for during the disease progression. A limited analysis of the effect of BRAF inhibition in primary CLL cells showed no cell death induction in CLL samples with and without BRAF mutations. Our analysis suggests that BRAF mutations occur at a low frequency in CLL. The pharmacological inhibition of MEK/ERK signaling using the mutant BRAF inhibitor PLX4720 showed no effect on viability in vitro in CLL cases.

Translocations Involving the IGH@locus Occur In 3.7% of Chronic Lymphocytic Leukemia and Are Associated with Unmutated IGHV Status and a Shorter Time to Treatment: A Study on 2,135 Cases

AbstractAbstract 3596 Introduction:Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with a variable clinical course and a large spectrum of treatment options. Based on FISH data, a prognostic classification system has been established with 13q deletions as sole abnormality associated with a favorable prognosis and 17p and 11q deletions correlating with an unfavorable outcome. Recently, the combined evaluation of FISH data, IGHV mutation status and chromosome banding analysis (CBA) revealed that the impact of distinct genetic parameters differs with respect to overall survival (OS) and time to treatment (TTT). Thus far only few data is available on less frequent genetic abnormalities such as 14q deletions and translocations involving the IGH@ locus (tIGH). Therefore, we analyzed CLL with tIGH in detail with respect to frequency, partner genes and impact on prognosis. Methods/Patients:78 CLL cases with tIGH were identified from 2,135 CLL sent to our laboratory for diagnostic work-up. All cases had been evaluated by immunphentotyping, FISH and CBA. Result:The most frequent tIGH was t(14;19)(q32;q13) (BCL3, n=21) followed by t(14;18)(q32;q21) (BCL2, n=19), t(8;14)(q24;q32) (CMYC, n=7) and t(11;14)(q13;q32) (CCND1, n=6). In the remaining 25 cases 5 recurrent translocations (t(2;14)(p13;q32), n=3; t(4;14)(p16;q32), FGFR3, n=2; t(11;14)(p15;q32), n=2; t(14;17)(q32;q25), n=2; and t(7;14)(q21;q32), n=2) were observed while the remaining 14 translocations were identified in single cases only. In 9/78 cases (11.5%) the tIGH was the sole abnormality. Recurrent additional chromosome abnormalities were +12 (n=7), del(13q) (n=9), del(11q) (n=3). A 17p deletion was observed in 1 case. In two cases tIGH was present only in a subclone and was a secondary abnormality occurring in addition to an del(11q) and a +12, respectively. CLL with tIGH were compared to 401 CLL without tIGH comprising all other genetic subgroups (subdivided according to Döhner et al.: del(17p) n=26, del(11q) n=42, +12 n=42, “normal” n=88, del(13q) sole n=177 and del(14q) n=26). An unmutated IGHV status was more frequent in CLL with tIGH as compared to all others (26/46 (54.3%) vs 128/353 (36.3%); p=0.023). For 53 cases with tIGH and all cases of the non-tIGH cohort clinical follow-up data was available. Median OS was 143.8 months (mo) in CLL with tIGH and 72.9 mo in patients with del(17p) while it was not reached in all other subgroups. In Cox regression analysis only del(17p) and mutated IGHV status were significantly associated with OS (p<0.0001, relative risk (RR)=7.0; p=0.014, RR=0.38). Median TTT was as follows: total cohort: 60.9 mo; tIGH: 27.8 mo; del(17p): 58.9 mo; del(11q): 19.7 mo; +12: n.r.; “normal” 63.9 mo; del(13q) sole: 83.0 mo and del(14q): 21.0 mo. In univariate Cox regression analysis the following parameters were significantly associated with shorter TTT: tIGH (p=0.004, RR=1.82), del(11q) (p<0.0001, RR=2.55), and del(14q) (p=0.007, RR=2.1), while del(13q) sole and mutated IGHV status were associated with longer TTT (p<0.0001, RR=0.40; p<0.0001, RR=0.23). In multivariate analysis including tIGH, del(11q), del(14q) and del(13q) sole all parameters retained their impact on TTT. However, if IGHV mutation status was included in the model only the mutated IGHV mutation status retained an impact on TTT (p<0.0001, RR=0.26). Next, patients with tIGH were subdivided according to their partner genes. Median OS was not reached in all subgroups, while median TTT was as follows: t(11;14): 101.2 mo, t(14;18): 47.9 mo, t(14;19): 11.0 mo, t(8;14): 18.5 mo and other partner genes: 27.8 mo. In univariate Cox regression analysis only t(14;19) was significantly associated with shorter TTT (p<0.001, RR=3.1). Including t(14;19) into multivariate analysis revealed a significant impact of both mutated IGHV mutation status and t(14;19) on TTT (p<0.0001, RR=0.286; p=0.004, RR=3.60). Conclusion:Translocations involving the IGH@ locus occur at low frequency in CLL. They are associated with unmutated IGHV status and a shorter TTT. TTT is especially short in cases with t(14;19). The prognostic impact of t(14;19) is independent of IGHV mutation status. In contrast CLL with t(11;14) and t(14;18) are neither associated with shorter OS nor shorter TTT. This data supports the application of CBA in CLL in order to identify all clinically relevant chromosomal aberrations, including those not detected by routine FISH analysis. Disclosures:Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Dicker:MLL Munich Leukemia Laboratory: Employment. Schnittger:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

Developmentally restricted immunoglobulin heavy chain variable region gene expressed at high frequency in chronic lymphocytic leukemia.

During fetal development, murine and human B-lineage cells rearrange and express a highly restricted set of immunoglobulin heavy chain variable region genes (VH genes). We noted that a VH gene of the restricted human fetal repertoire, designated 51p1, potentially could encode the VH region of two human IgM rheumatoid factor proteins. These rheumatoid factors share a cross-reactive idiotype (CRI) defined by reactivity with G6, a murine monoclonal antibody that recognizes an antibody heavy chain determinant present on many human IgM autoantibodies, particularly rheumatoid factors. Recently, we found that the G6 CRI also is expressed frequently by neoplastic CD5 (Leu1) B cells from patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma. However, neoplastic CD5-negative B cells from patients with lymphomas of follicular center cell origin rarely express this CRI. Here, we report that G6-reactive leukemic cells from two unrelated CLL patients express a VH gene that shares greater than 99% homology with a rearranged VH gene previously isolated from the leukemic cell DNA of another CLL patient and that is identical to VH 51p1. Using the polymerase chain reaction, we find that this VH gene is rearranged, and presumably expressed, in the genomic DNA of all examined cases of G6-reactive CLL or small lymphocytic lymphoma. Thus these data indicate that the autoantibody-associated G6 CRI is a serologic marker for a conserved and developmentally restricted VH1 gene that is expressed at high frequency in CD5 B-cell malignancies and early B-cell ontogeny.