scholarly journals NOTCH1 Activation Negatively Impacts on Chronic Lymphocytic Leukemia Outcome and Is Not Correlated to the NOTCH1 and IGHV Mutational Status

2021 ◽  
Vol 11 ◽  
Author(s):  
Stefano Baldoni ◽  
Beatrice Del Papa ◽  
Filomena De Falco ◽  
Erica Dorillo ◽  
Carlo Sorrentino ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Clinical Course ◽  
Lymphocytic Leukemia ◽  
Wild Type ◽  
New Approach ◽  
Mutational Status ◽  
Time To First Treatment ◽  
The Impact ◽  
First Time

NOTCH1 mutations and deregulated signal have been commonly found in chronic lymphocytic leukemia (CLL) patients. Whereas the impact of NOTCH1 mutations on clinical course of CLL has been widely studied, the prognostic role of NOTCH1 activation in CLL remains to be defined. Here, we analyzed the activation of NOTCH1/NOTCH2 (ICN1/ICN2) and the expression of JAGGED1 (JAG1) in 163 CLL patients and evaluated their impact on TTFT (Time To First Treatment) and OS (Overall Survival). NOTCH1 activation (ICN1+) was found in 120/163 (73.6%) patients. Among them, 63 (52.5%) were NOTCH1 mutated (ICN1+/mutated) and 57 (47.5%) were NOTCH1 wild type (ICN1+/WT). ICN1+ patients had a significant reduction of TTFT compared to ICN1-negative (ICN1−). In the absence of NOTCH1 mutations, we found that the ICN1+/WT group had a significantly reduced TTFT compared to ICN1− patients. The analysis of IGHV mutational status showed that the distribution of the mutated/unmutated IGHV pattern was similar in ICN1+/WT and ICN1− patients. Additionally, TTFT was significantly reduced in ICN1+/ICN2+ and ICN1+/JAG1+ patients compared to ICN1−/ICN2− and ICN1−/JAG1− groups. Our data revealed for the first time that NOTCH1 activation is a negative prognosticator in CLL and is not correlated to NOTCH1 and IGHV mutational status. Activation of NOTCH2 and JAGGED1 expression might also influence clinical outcomes in this group, indicating the need for further dedicated studies. The evaluation of different NOTCH network components might represent a new approach to refine CLL risk stratification.

Serum BAFF (B-CELL Activating Factor Of The TNF Family) predicts time to First Treatment in Early B-CELL Chronic Lymphocytic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4158-4158
Author(s):  
Stefano Molica ◽  
Gaetano Vitelli ◽  
Giovanna Cutrona ◽  
Giovanna Digiesi ◽  
Rosanna Mirabelli ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Serum Concentration ◽  
B Cell ◽  
Serum Levels ◽  
Lymphocytic Leukemia ◽  
B Cell Activating Factor ◽  
Mutational Status ◽  
Time To First Treatment ◽  
The Impact ◽  
Cell Chronic Lymphocytic Leukemia

Abstract We analyzed the correlation between well-established biological parameters of prognostic relevance in B-cell chronic lymphocytic leukemia [CLL] (i.e, mutational status of the immunoglobulin heavy chain variable region [IgVH], ZAP-70− and CD38− expression) and serum levels of BAFF (B-cell activating factor of the TNF family) by evaluating the impact of these variables on the time to first treatment [TFT] in a series of 125 previously untreated Binet stage A B-cell CLL patients. By using a commercial ELISA (R & D Systems, USA) we found that higher levels of BAFF characterized more frequently females (P=0.01), patients with Rai stage 0 (P=0.03), mutated IgVH disease (P=0.008) and low ZAP-70 expression (P=0.04). In contrast, age (P=0.35), peripheral blood lymphocytosis (PBL)(P=0.09), hemoglobin (Hb) level (P=0.64), platelet (PLT) count (P=0.12), serum β2-m (P=0.49), LDH (P=0.85) and percentage of CD38-positive B-CLL cells (P=0.63) did not reflect circulating levels of BAFF. We used an optimal cut-point search to determine how to best split soluble BAFF data. Maximally selected log-rank statistics plots identified a BAFF serum concentration of 311 ng/mL as the best cut-off (P<0.0001). Accordingly, patients who had BAFF levels higher than 311 ng/mL experienced a longer TFT (median 108 months) in comparison to patients whose BAFF levels were lower than 311 ng/mL (median 30 months; P<0.0001). Along with serum concentration of BAFF, the univariate Cox proportional hazard model identified Rai substage I–II (P=0.003), lower PLT count (P=0.04), higher PBL count (P=0.01), increased LDH (P=0.01), ZAP-70 expression > 20% (P=0.02) and absence of mutation of IgVH (P<0.0001) as predictor of shorter TFT. In multivariate analysis only soluble BAFF (Hazard ratio [HR], 6.13; CI 95%, 2.31–16.25) and mutational status of IgVH, (HR= 2.99; CI 95% 1.33–6.76, P=0.008) maintained their discriminating power. The effects of BAFF on TFT were masked by mutational status of IgVH in patients with unmutated IgVH. However, serum levels of BAFF and mutational status of IgVH had a joint effect on TFT in patients with mutated IgVH which translates into a segregation of patients with mutated IgVH in two groups with different TFT according to BAFF levels (HR= 8.9; P<0.0001). Our results indicate that in early B-cell CLL biological profile including among other parameters soluble BAFF may provide a useful insight into the complex interrelationship of prognostic variables. Furthermore, BAFF along with mutational status of IgVH can be adequately used to predict clinical behaviour of patients with low biological risk.

scholarly journals Biological Prognostic Markers in Chronic Lymphocytic Leukemia

2009 ◽  
Vol 52 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Vladimíra Vroblová ◽  
Lukáš Smolej ◽  
Filip Vrbacký ◽  
Karolína Jankovičová ◽  
Monika Hrudková ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Clinical Course ◽  
Variable Region ◽  
Lymphocytic Leukemia ◽  
Initial Assessment ◽  
Western World ◽  
Cd38 Expression ◽  
Cytogenetic Aberrations ◽  
Mutational Status

Chronic lymphocytic leukemia (CLL) is the most frequent leukemic disease of adults in the Western world. It is remarkable by an extraordinary heterogeneity of clinical course with overall survival ranging from several months to more than 15 years. Classical staging sytems by Rai and Binet, while readily available and useful for initial assessment of prognosis, are not able to determine individual patient’s ongoing clinical course of CLL at the time of diagnosis, especially in early stages. Therefore, newer biological prognostic parameters are currently being clinically evaluated. Mutational status of variable region of immunoglobulin heavy chain genes (IgVH), cytogenetic aberrations, and both intracellular ZAP- 70 and surface CD38 expression are recognized as parameters with established prognostic value. Molecules regulating the process of angiogenesis are also considered as promising markers. The purpose of this review is to summarize in detail the specific role of these prognostic factors in chronic lymphocytic leukemia.

High Expression of Haematopoietic Cell Specyfic Lyn Substrate-1 (HS1) Predicts Survival of B-Cell Chronic Lymphocytic Leukemia Patients

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2853-2853
Author(s):  
Aleksandra Butrym ◽  
Miroslaw Majewski ◽  
Justyna Dzietczenia ◽  
Tomasz Wrobel ◽  
Kazimierz Kuliczkowski ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Patient Survival ◽  
Clinical Course ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Mutational Status ◽  
Cell Chronic Lymphocytic Leukemia

Abstract Abstract 2853 B-cell chronic lymphocytic leukemia (B-CLL) is the most common leukemia in adults in western countries. It is characterized by B lymphocyte accumulation in peripheral blood, bone marrow, lymph nodes and other lymphatic organs. Leukemic cells derive most commonly from B lymphocytes, rarely from T or NK cells. B-CLL is known from its heterogeneous clinical course from indolent to very aggressive. In spite of many known prognostic factors (such as immunoglobulin heavy chain gene mutational status – IgVH, expression of ZAP70 and CD38), is still difficult to classify a single patient to particular risk group and to predict CLL clinical course. That is why new prognostic factors are still needed. HS1 (hematopoietic cell specific Lyn substrate-1) is an intracellular protein, which expression occurs mainly in hematopoietic cells. HS1 plays an important role in regulating T cell immune synapse and affects many functions of NK cells, including the lysis of target cells, adhesion, chemotaxis and clustering of actin in the lytic synapse. The role of HS1 in B cells is poorly understood. This protein was identified in B cells as the primary receptor substrate for phosphorylation by BCR after antigenic stimulation. Other studies have confirmed the role of HS1 in the process of clonal expansion and deletion induced by antigen-receptor interaction in B cells and T. HS1 is rapidly phosphorylated in B cells in the vicinity of tyrosine residues and is a substrate for tyrosine kinases: the Src family and Syk, including Lyn, FGR, Fyn and Lck. It has been shown that HS1 interacts with the cell cytoskeleton in both: normal and leukemic B cells. HS1 protein is an important regulator of motility, migration and adhesion of leukemic cells and is involved in cytoskeleton rearrangement. HS1 can have impact on homing and migration of CLL cells. It can indirectly promote disease progression and influence patient survival. The aim of this study was to evaluate HS1 expression in CLL patients in connection with other known prognostic factors and patient survival. Material and methods: 92 untreated CLL patients (45 women and 47 men), aged between 42 and 88 years (median age 67 years), were included into the study. Diagnosis was made basing on typical clinical, hematological and immunophenotypical picture. The control group was consist of 28 healthy matched people (11 men and 17 women), aged between 36 and 79 years (median age 59 years). HS1 protein expression was determined by western blot. Comparative semi-quantitative indication of the degree of saturation of the bands analyzed by densitometry using the gel documentation system Gel-Doc (Bio-Rad) and a computer program to analyze the 1-D Quantity One (Bio-Rad). Assuming conventional units [AU - arbitrary units], depending on the saturation band, patients were divided into four groups with the expression of HS1 protein expressed in value from 0 to 3. Lack of expression was expressed as 0 [AU], and expression of the strongest, with the highest saturation band measured as 3 [AU]. Mutational status of IgVH, as well as CD38 and ZAP70 expression were also analyzed. Results: HS1 expression was significantly higher in CLL patients comparing to controls. Positive correlation was shown between HS1 and: age (p=0.0454), Rai stage (p=0.0412), leukocytosis (p=0.0129) and β2-microglobulin (p=0.0342). There was negative correlation between HS1 and hemoglobin level (p=0.0464) and platelet count (p=0.0310). Patients with lymphocyte doubling time shorter or equal to 6 months had higher expression of HS1. Expression of HS1 significantly influenced survival of CLL patients. Patients with higher HS1 expression had shorter survival than those with lower HS1 expression (p=0.0329). Conclusions: 1. Higher HS1 expression is observed in more advanced CLL stages. 2. Expression of HS1 in CLL cells is matched with shorter patient survival The relationship between expression of HS1 and survival of patients with B-CLL. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Aberrant Expression of TLR2, TLR7, TLR9, Splicing Variants of TLR4 and MYD88 in Chronic Lymphocytic Leukemia Patients

2021 ◽  
Vol 10 (4) ◽  
pp. 867
Author(s):  
Katarzyna Skorka ◽  
Paulina Wlasiuk ◽  
Agnieszka Karczmarczyk ◽  
Krzysztof Giannopoulos
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Cytotoxic T Cells ◽  
Lymphocytic Leukemia ◽  
Aberrant Expression ◽  
Downstream Signaling ◽  
Splicing Variants ◽  
High Level ◽  
Time To First Treatment ◽  
First Time

Functional toll-like receptors (TLRs) could modulate anti-tumor effects by activating inflammatory cytokines and the cytotoxic T-cells response. However, excessive TLR expression could promote tumor progression, since TLR-induced inflammation might stimulate cancer cells expansion into the microenvironment. Myd88 is involved in activation NF-κB through TLRs downstream signaling, hence in the current study we provided, for the first time, a complex characterization of expression of TLR2, TLR4, TLR7, TLR9, and MYD88 as well as their splicing forms in two distinct compartments of the microenvironment of chronic lymphocytic leukemia (CLL): peripheral blood and bone marrow. We found correlations between MYD88 and TLRs expressions in both compartments, indicating their relevant cooperation in CLL. The MYD88 expression was higher in CLL patients compared to healthy volunteers (HVs) (0.1780 vs. 0.128, p < 0.0001). The TLRs expression was aberrant in CLL compared to HVs. Analysis of survival curves revealed a shorter time to first treatment in the group of patients with low level of TLR4(3) expression compared to high level of TLR4(3) expression in bone marrow (13 months vs. 48 months, p = 0.0207). We suggest that TLRs expression is differentially regulated in CLL but is similarly shared between two distinct compartments of the microenvironment.

scholarly journals Prognostic Impact of NOTCH1 Hotspot Mutation in TP53-Mutated Patients with Chronic Lymphocytic Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3283-3283
Author(s):  
Barbara Kantorova ◽  
Jitka Malcikova ◽  
Veronika Navrkalova ◽  
Jana Smardova ◽  
Kamila Brazdilova ◽  
...  
Keyword(s):  
Overall Survival ◽  
Chronic Lymphocytic Leukemia ◽  
Tp53 Mutation ◽  
Direct Sequencing ◽  
Lymphocytic Leukemia ◽  
The Other ◽  
Wild Type ◽  
Tp53 Mutations ◽  
Time To First Treatment ◽  
Hotspot Mutation

Abstract Introduction A presence of activating mutations in NOTCH1 gene has been recently associated with reduced survival and chemo-immunotherapy resistance in chronic lymphocytic leukemia (CLL). However, a prognostic significance of the NOTCH1 mutations with respect to TP53mutation status has not been fully explained yet. Methods An examined cohort included 409 patients with CLL enriched for high risk cases; in 121 patients consecutive samples were investigated. To determine the TP53 mutation status, a functional analysis of separated alleles in yeast (FASAY, exons 4-10) combined with direct sequencing was performed; the ambiguous cases were retested using an ultra-deep next generation sequencing (MiSeq platform; Illumina). The presence of NOTCH1 hotspot mutation (c.7544_7545delCT) was analyzed using direct sequencing complemented by allele-specific PCR in the selected samples. In several patients harboring concurrent NOTCH1 and TP53 mutations, single separated cancer cells were examined using multiplex PCR followed by direct sequencing. A correlation between mutation presence and patient overall survival, time to first treatment and other molecular and cytogenetic prognostic markers was assessed using Log-rank (Mantel-cox) test and Fisher's exact test, respectively. Results The NOTCH1 and TP53 mutations were detected in 16% (65/409) and 27% (110/409) of the examined patients, respectively; a coexistence of these mutations in the same blood samples was observed in 11% (19/175) of the mutated patients. The detected increased mutation frequency attributes to more unfavorable profile of the analyzed cohort; in the TP53-mutated patients missense substitutions predominated (75% of TP53 mutations). As expected, a significantly reduced overall survival in comparison to the wild-type cases (147 months) was observed in the NOTCH1-mutated (115 months; P = 0.0018), TP53-mutated (79 months; P < 0.0001) and NOTCH1-TP53-mutated patients (101 months; P = 0.0282). Since both NOTCH1 and TP53 mutations were strongly associated with an unmutated IGHV gene status (P < 0.0001 and P = 0.0007), we reanalyzed the IGHV-unmutated patients only and interestingly, the impact of simultaneous NOTCH1 and TP53 mutation presence on patient survival was missed in this case (P = 0.1478). On the other hand, in the NOTCH1 and/or TP53-mutated patients significantly reduced time to first treatment was identified as compared to the wild-type cases (41 months vs. 25 months in NOTCH1-mutated, P = 0.0075; 17 months in TP53-mutated, P < 0.0001; and 18 months in NOTCH1-TP53-mutated patients, P = 0.0003). The similar results were observed also in the subgroup of the IGHV-unmutated patients, with the exception of patients carrying sole NOTCH1 mutation (P = 0.2969). Moreover, in the NOTCH1-TP53-mutated patients an increased frequency of del(17p)(13.1) was found in comparison to the TP53-mutated patients only (72% vs. 56%); this cytogenetic defect was not detected in the patients with sole NOTCH1 mutation. Our results might indicate, that NOTCH1 mutation could preferentially co-selected with particular, less prognostic negative type of TP53 defects. Notably, in our cohort the NOTCH1 mutation predominated in the patients harboring truncating TP53 mutations localized in a C-terminal part of the TP53 gene behind the DNA-binding domain (P = 0.0128). Moreover, in one of the NOTCH1-TP53-mutated patients the analysis of separated cancer cells revealed a simultaneous presence of NOTCH1 mutation and TP53 in-frame deletion in the same CLL cell. In contrast, in the other examined NOTCH1-TP53-mutated patient the concurrent NOTCH1 mutation and TP53 missense substitution (with presumed negative impact on patient prognosis) were found in different CLL cells. Conclusions The parallel presence of NOTCH1 hotspot mutation might be detected in a significant proportion of TP53-mutated patients and it seems to be associated with less prognostic unfavorable TP53 mutations. Nevertheless, these preliminary data should be further confirmed in a large cohort of patients. This study was supported by projects VaVPI MSMT CR CZ.1.05/1.1.00/02.0068 of CEITEC, IGA MZ CR NT13493-4/2012, NT13519-4/2012 and CZ.1.07/2.3.00/30.0009. Disclosures Brychtova: Roche: Travel grants Other. Doubek:Roche: Travel grants Other.

Association of a novel regulatory polymorphism (−938C>A) in the BCL2 gene promoter with disease progression and survival in chronic lymphocytic leukemia

Blood ◽  
2006 ◽  
Vol 109 (1) ◽  
pp. 290-297 ◽  
Author(s):  
Holger Nückel ◽  
Ulrich H. Frey ◽  
Maja Bau ◽  
Ludger Sellmann ◽  
Jens Stanelle ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Cox Regression ◽  
Gene Promoter ◽  
Lymphocytic Leukemia ◽  
Disease Stage ◽  
Genotype Distribution ◽  
Single Nucleotide ◽  
Regulatory Polymorphism ◽  
Time To First Treatment

Abstract Bcl-2 plays a key role in the regulation of apoptosis. We investigated the role of a novel regulatory single-nucleotide polymorphism (−938C>A) in the inhibitory P2 BCL2 promoter in B-cell chronic lymphocytic leukemia (B-CLL). The −938C allele displayed significantly increased BCL2 promoter activity and binding of nuclear proteins compared with the A allele. Concomitantly, Bcl-2 protein expression in B cells from CLL patients carrying the −938 AA genotype was significantly increased compared with CC genotypes. Genotype distribution between 123 CLL patients (42 AA, 55 AC, 26 CC) and 120 genotyped healthy controls (36 AA, 63 AC, 21 CC) was not significantly different, suggesting that genotypes of this polymorphism do not increase the susceptibility for B-CLL. However, median time from first diagnosis to initiation of chemotherapy and median overall survival were significantly shorter in patients with −938AA genotype (38 and 199 months, respectively) compared with AC/CC genotypes (120 and 321 months, respectively; P = .008 and P = .003, respectively). Multivariable Cox regression identified the BCL2−938AA genotype as an independent prognostic factor for the time to first treatment (hazard ratio [HR] 1.9; P = .034) together with disease stage at diagnosis (HR 2.5; P = .004) and ZAP-70 status (HR 3.0; P = .001). The BCL2−938AA genotype is associated with increased Bcl-2 expression and a novel unfavorable genetic marker in patients with B-CLL.

Surrogate molecular markers for IGHV mutational status in chronic lymphocytic leukemia for predicting time to first treatment

2015 ◽  
Vol 39 (8) ◽  
pp. 840-845 ◽  
Author(s):  
Fortunato Morabito ◽  
Giovanna Cutrona ◽  
Laura Mosca ◽  
Marianna D’Anca ◽  
Serena Matis ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Chronic Lymphocytic Leukemia ◽  
Lymphocytic Leukemia ◽  
Mutational Status ◽  
Time To First Treatment

Serum BAFF (B-Cell Activating Factor of the TNF Family) Compared with Immunoglobulin Heavy-Chain Mutation Status, ZAP-70 and CD38 as a Predictor of Time to First Treatment in Early B-Cell Chronic Lymphocytic Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3093-3093
Author(s):  
Stefano Molica ◽  
Gaetano Vitelli ◽  
Giovanna Cutrona ◽  
Giovanna Digiesi ◽  
Rosanna Mirabelli ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Heavy Chain ◽  
Immunoglobulin Heavy Chain ◽  
Serum Levels ◽  
Lymphocytic Leukemia ◽  
B Cell Activating Factor ◽  
Mutational Status ◽  
Time To First Treatment ◽  
Cell Chronic Lymphocytic Leukemia

Abstract We analyzed the correlation between well-established biological parameters of prognostic relevance in B-cell chronic lymphocytic leukemia [CLL] (i.e, mutational status of the immunoglobulin heavy chain variable region [IgVH], ZAP-70- and CD38-expression) and serum levels of BAFF (B-cell activating factor of the TNF family) by evaluating the impact of these variables on the time to first treatment [TFT] in a series of 69 previously untreated Binet stage A B-cell CLL patients. By using a commercial ELISA (R & D Systems, USA) we found that higher levels of BAFF characterized more frequently patients with Rai stage 0 (P=0.008) and mutated IgVH (P=0.03). In contrast, peripheral blood lymphocytosis (P=0.06), serum β2-m (P=0.159), LDH (P=0.333) and percentage of ZAP-70-positive (P=0.242) or CD38-positive B-CLL cells (P=0.142) did not reflect circulating levels of BAFF. The relationship among various bio-pathological parameters, analyzed by the multiple correspondence analysis (MCA), showed two different clinico-biological profiles. The first, characterized by higher BAFF serum levels (i.e., > 336 ng/mL), presence of mutation in the IgVH, low percentage of CD38-positive B-CLL cells (< 30%) and low LDH was associated with a stable pattern of disease generally not requiring therapy. The second, defined by lower BAFF levels, absence of mutation in the IgVH, high percentage of CD38- positive B-CLL cells and high LDH was associated with a more progressive pattern of disease and a shorter TFT. After a median follow-up time of 35 months (range, 2–120 months) 26 (37.6%) out of 69 patients experienced a need for chemotherapy. Kaplan-Meier estimates of patientsTFT, plotted after searching the best cut-off for BAFF (i.e., 336 ng/mL), demonstrated that low BAFF concentration was associated with a shorter TFT (median TFT 36 months) while median was not reached by patients with BAFF levels higher than 336 ng/mL (P<0.0001). Along with lower serum levels of BAFF (Hazard Ratio [HR], 0.19; P<0.0001), the univariate Cox proportional hazard model identified absence of mutation in IgVH (HR, 0.17; P<0.0001), CD38-positivity (HR, 3.32; P=0.01) and lower platelet count (HR, 0.19; P=0.03) as predictor of shorter TFT. Finally, in multivariate analysis only mutational status of IgVH (HR, 0.25; P=0.007) and serum concentration of BAFF (HR, 034; P=0.04) affected significantly TFT. Our results indicate that in early B-cell CLL clinico-biological profile including among other parameters BAFF may provide a useful insight into the complex interrelationship of prognostic variables and semplify their interpretation. The possible presence of BAFF isoform in B-CLL could peraphs account for the unexpected correlation between low soluble BAFF levels and poor clinical outcome in patients with early disease.

Extensive Intraclonal Diversification in a Subgroup of Chronic Lymphocytic Leukemia Patients with Stereotyped IGHV4-34/IGKV2-30 B cell Receptors: Implications for Ongoing Interactions with Antigen.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2337-2337
Author(s):  
Lesley-Ann Sutton ◽  
Efterpi Kostareli ◽  
Anastasia Hadzidimitriou ◽  
Nikos Darzentas ◽  
Athanasios Tsaftaris ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Heavy Chain ◽  
Conflicts Of Interest ◽  
Lymphocytic Leukemia ◽  
B Cell Receptors ◽  
Valuable Insight ◽  
Cell Receptors ◽  
Mutational Status ◽  
The Impact

Abstract Abstract 2337 Poster Board II-314 Several studies indicate that the development of chronic lymphocytic leukemia (CLL) may be influenced by antigen (Ag) recognition through the clonotypic B cell receptors (BCRs). However, it is still unclear whether Ag involvement is restricted to the malignant transformation phase or whether the putative Ag(s) may continuously trigger the CLL clone. Valuable insight into these issues may be gleaned from the study of intraclonal diversification (ID) within the immunoglobulin (IG) genes through ongoing somatic hypermutation (SHM). Definitive data regarding ID within IG genes in CLL remains limited and conflicting. In the present study we systematically explored the presence of ID within IG genes of CLL, not only at cohort level but also in subgroups defined by BCR stereotypy and IG gene mutational status. We thus conducted a large-scale subcloning study of both IG heavy and light variable genes, in a total of 1496 and 1008 subcloned sequences from 71 and 56 CLL cases, respectively. The analysis was intentionally biased to cases expressing IGHV4-34/IGKV2-30 IGs (subset #4) and IGHV3-21/IGLV3-21 IGs (subset #2) that exhibit distinctive, subset-biased SHM patterns. PCR reactions were run using the high-fidelity Accuprime Pfx polymerase and at least 14 colonies/case were analyzed. All “non-ubiquitous” sequence changes from the germline were evaluated and recorded as follows: (i) unconfirmed mutation (UCM) - a mutation observed in only one subcloned sequence from the same sample (ii) confirmed mutation (CM) - a mutation observed more than once among subcloned sequences from the same sample. Analysis of heavy chain sequences revealed that 40% (28/71) of cases carried intraclonally diversified IGHV-D-J genes with CMs amongst subclones, whilst 32% (23/71) of cases carried only UCMs. The remaining 28% (20/71) of cases carried sets of identical IGHV-D-J subcloned sequences. Although most cases showed no or low levels of ID, an intense and, likely, functionally driven ID was evident in selected cases, especially those belonging to subset #4. The distinct ID in subset #4 was statistically significant when compared to all other groups defined by IGHV gene usage and mutation status, BCR stereotypy or heavy chain isotype. Subsequent analysis of the clonotypic light chains revealed that the impact of ID was generally low, with the outstanding exception again relating to subset #4. In fact, of 22 IGKV-J rearrangements exhibiting CMs, 11 (50%) utilized the IGKV2-30 gene and notably 10/11 (91%) of these were expressed by subset #4 cases. In such cases, the expressed IGKV2-30 gene was affected by an active and precisely targeted ID, analogous to their partner IGHV4-34 gene. These findings suggest that the SHM mechanism may continuously operate in certain subsets of CLL patients, particularly those cases expressing stereotyped IGHV4-34/IGKV2-30 BCRs typical of subset #4. In such cases, the observed ID patterns attest to the very precise targeting of the SHM process and may be considered as evidence for a “stereotyped response” to an active, ongoing interaction with Ag(s). Disclosures: No relevant conflicts of interest to declare.

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