Course Of Chronic Lymphocytic Leukemia Research Articles

Toward personalized therapy for chronic lymphocytic leukemia

The differences in clinical course of chronic lymphocytic leukemia could have an impact on variations in a patient’s response to therapy. Our published results revealed that thermal transition (95 ± 5°C) in differential scanning calorimetry profiles appear to be characteristic for the advanced stage of CLL. Moreover, a decrease/loss of this transition in nuclei from leukemic cells exposed to drugs ex vivo could indicate their diverse efficacy. It seems that the lack of changes in thermal profile could predict patient’s drug resistance. In this study, we demonstrate the results obtained after drug treatment of leukemic cells by calorimetry, apoptosis-related parameters involved in expression of genes using cDNA microarray and western blot. These data were compared with the patients’ clinical parameters before and after RCC therapy (rituximab + cladribine + cyclophosphamide). The complementary analysis of studied cases with opposite clinical response (CR or NR) revealed a strong relationship between clinical data, differences in thermal scans and apoptosis-related gene expression. We quantified expression of eight of apoptosis-related 89 genes, i.e., NOXA, PUMA, APAF1, ESRRBL1, CASP3, BCL2, BCL2A1 and MCL1. Particular differences in NOXA and BCL2 expression were revealed. NOXA expression in cells of patients who achieved a complete response to RCC therapy was 0.44 times higher in comparison to control ones. Interestingly, in the case of patients who did not respond to immunotherapy, NOXA expression was highly downregulated (RQ = 4.39) as compared with untreated cells. These results were confirmed by distinct cell viability, protein expression as well as by differences in calorimetry profiles.

Autoimmune cytopenias in chronic lymphocytic leukemia.

The clinical course of chronic lymphocytic leukemia (CLL) may be complicated at any time by autoimmune phenomena.The most common ones are hematologic disorders, such as autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP). Pure red cell aplasia (PRCA) and autoimmune agranulocytosis (AG) are, indeed, more rarely seen. However, they are probably underestimated due to the possible misleading presence of cytopenias secondary to leukemic bone marrow involvement or to chemotherapy cytotoxicity. The source of autoantibodies is still uncertain, despite the most convincing data are in favor of the involvement of resting normal B-cells. In general, excluding the specific treatment of underlying CLL, the managementof these complications is not different from that of idiopathic autoimmune cytopenias or of those associated to other causes. Among different therapeutic approaches, monoclonal antibody rituximab, given alone or in combination, has shown to be very effective.

Da li je danas moguća individualizacija terapije kod bolesnika sa hroničnom limfocitnom leukemijom?

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults. This disease can be defined as a clonal disease of unknown etiology characterized by progressive accumulation of functionally incompetent B lymphocytes in the blood, lymph nodes, spleen and bone marrow. In clinical practice, substantial variability can be noticed in the course of CLL. Some patients are asymptomatic at the time of the diagnosis and do not need to be treated for a long time. On the other hand, there are subgroups with rapid disease progression and early resistance to therapy. Identifying the optimal timing and the type of first - line treatment is a major issue in CLL. This paper discusses treatment approaches according to individual risk profiles. While it is important to have prognostic markers, it is also critical to account for the difference between prognostic and predictive markers. A prognostic factor is a situation, condition or characteristic of a patient that can be used to estimate the outcome of the disease irrespective of the treatment given. Treatment response variable is an important difference when it comes to a predictive factor. A predictive factor is a condition or finding that predicts the differential efficacy of a particular therapy based on marker status (i.e. patients with presence or absence of a specific marker will respond differently to a specific treatment). Most factors associated with giving prognosis in CLL have not been proven yet to be a predictive impact. The current therapeutic approach reflects clinical trial reality although many CLL patients present with comorbidities and advanced age. Therefore we need to mark the significance of patients' tailored therapy aimed at avoiding treatment complications.

Polymorphisms of TNF and IL‐10 genes and clinical outcome of patients with chronic lymphocytic leukemia

Genetic variations in tumor necrosis factor (TNF) and interleukin-10 (IL-10) were reported to influence susceptibility to and outcome of patients with non-Hodgkin lymphoma. Therefore, we investigated whether single nucleotide polymorphisms in TNF and IL-10 may play a role in the clinical course of patients with chronic lymphocytic leukemia (CLL). TNF-308G>A, IL-10-3575T>A, and IL-10-1082A>G seem to be functionally relevant, were genotyped in 292 previously untreated patients with CLL. The control group consisted of 192 randomly selected blood donors. The patients carrying TNF-308GG and IL-10-1082AA genotypes presented a higher 3-year treatment-free survival (56.6 vs. 40.6%, P = 0.05) as well as a 10-year overall survival (OS) rates (92.3 vs. 57.6%, P = 0.005) than those with other TNF-308 and IL-10-1082 genotype combinations. Multivariate analysis demonstrated the Rai stage (P = 0.0002), IGHV mutation status (P = 0.01), TNF-308G>A (P = 0.03), and TNF/IL-10 polymorphism-based risk groups (P = 0.05) to be independent factors predicting OS. When the mutated IGHV patients were analyzed, the homozygotes TNF-308GG and IL-10-1082AA presented a higher 10-year OS rate than those carrying other TNF-308 and IL-10-1082 genotypes (100 vs. 67.7%, P = 0.01). In the unmutated IGHV patients, only the TNF-308G>A polymorphism influenced OS. The genetic variations in TNF and IL-10 genes work as independent predictors of survival and may play a role in the clinical course of CLL. It suggests inherited ability of the host to shift the balance between the Th1 and Th2 response, which in turn might contribute to the pathogenesis and prognosis of B-cell malignancies.

IGHV-unmutated and IGHV-mutated chronic lymphocytic leukemia cells produce activation-induced deaminase protein with a full range of biologic functions

AbstractClonal evolution occurs during the course of chronic lymphocytic leukemia (CLL) and activation-induced deaminase (AID) could influence this process. However, this possibility has been questioned in CLL because the number of circulating AID mRNA+ cells is exceedingly low; synthesis of AID protein by blood CLL cells has not been demonstrated; the full range of AID functions is lacking in unmutated CLL (U-CLL), and no prospective analysis linking AID expression and disease severity has been reported. The results of the present study show that circulating CLL cells and those within secondary lymphoid tissues can make AID mRNA and protein. This production is related to cell division because more AID mRNA was detected in recently divided cells and AID protein was limited to the dividing fraction and was up-regulated on induction of cell division. AID protein was functional because AID+ dividing cells exhibited more double-stranded DNA breaks, IGH class switching, and new IGHV-D-J mutations. Each of these actions was documented in U-CLL and mutated CLL (M-CLL). Furthermore, AID protein was associated with worse patient outcome and adverse cytogenetics. We conclude that the production of fully functional AID protein by U-CLL and M-CLL cells could be involved in clonal evolution of the disease.

CD38 Variation in Chronic Lymphocytic Leukemia

Abstract 4576 Background:Chronic lymphocytic leukemia (CLL) has a highly variable clinical course. Some patients require treatment early while others can be monitored without therapy. CD38 expression has been shown in multiple cohorts to have prognostic significance. An elevated percentage of CD38 positive CLL lymphocytes at the time of diagnosis is correlated with a more rapid need for therapy and a shorter overall survival. The extent to which CD38 varies during the course of CLL, including after therapy, has only been evaluated in a limited fashion. Methods:From a cohort of over 500 CLL patients at the Duke University and Durham VA Medical Centers, we selected 136 patients in whom we had measured CD38 expression by flow cytometry on two or more occasions. We determined the first, maximum, minimum, and range (maximum – minimum) CD38 values. We compared these values to other molecular prognostic markers using Wilcoxon tests and assessed the prognostic significance of these values using Cox proportional hazard models and Kaplan-Meier analyses. Results:Of the 136 patients, 70% were male and 88% Caucasian, with a median age of 60. The majority had low clinical stage at diagnosis—either Rai stage 0 (68%) or 1 (19%). Molecular prognostic markers were also generally favorable. Eighty-two (67%) patients had mutated IGHV status, 69 (51%) were ZAP70 negative, and 76 (63%) had either 13q deletion or normal cytogenetics, determined by fluorescent in situ hybridization. CD38 expression was measured a median of 5.5 times (2 – 19). The median time between the first and last CD38 measurements was 1206 days (81 – 4109). The median values were 6% (0.6 – 99) for maximum CD38, 1.5% (0 to 84.5) for minimum CD38, and 4.9% (0.2 to 95.3) for CD38 range. Maximum, minimum, and CD38 range were significantly lower in patients with mutated compared to unmutated IGHV status (p < 0.005 for all parameters, Wilcoxon rank sum test). Elevated maximum and CD38 range were significantly associated with a more rapid time to therapy (TTT) and shorter overall survival (OS) in a univariate Cox proportional hazards model (p < 0.03 for all, Wald test). In a multivariate Cox proportional hazards model including first CD38 and maximum CD38 values, only maximum CD38 remained statistically significant. We found that patients with high CD38 variation (CD38 range greater than the median) had significantly shorter TTT and OS than patients with low CD38 variation (p = 0.002 for both, log rank test). Using receiver operator characteristic analyses, we determined that the best cut-off for dichotomizing the first CD38 according to TTT and OS in the entire Duke/Durham VA CLL cohort was 11%. Using this cut-off, 15 patients (11%) converted from CD38 negative to CD38 positive. Using the standard 30% cut-off, 14 patients (10%) converted from CD38 negative to CD38 positive. Patients with a first CD38 measurement less than 11% and subsequent measurements above 11% had a favorable OS, similar to patients with low CD38 for all measurements (p = 0.002, log rank test). However, patients with a first CD38 measurement less than 30% who had subsequent measurements above 30% had an inferior OS, similar to patients with high CD38 for all measurements (p = 0.006, log rank test). Lastly, among 24 patients with CD38 measurements before and after first therapy, the percentage of CD38 positive cells increased in 19 patients (79%), with a median value of 3.2% before to 6.9% after therapy (p = 0.005, Wilcoxon signed rank test). Conclusions:CD38 values vary as patients transition across the disease trajectory. This variation appears to have prognostic significance, with high variation associated with faster time to first therapy and shorter overall survival. Additionally, in our cohort, a patient's maximum CD38 value had more prognostic significance than a single initial measurement. Thus, longitudinally measuring CD38 throughout the clinical course of CLL could aid in the management of CLL patients, refining the initial prognostic assessment, and improving patient counseling and decision making. Disclosures:No relevant conflicts of interest to declare.

Evidence for Autostimulatory Mechanisms in Chronic Lymphocytic Leukemia.

AbstractAbstract 2880 Background:The development and / or course of chronic lymphocytic leukemia (CLL) may be driven by the recognition of antigens through the B cell receptor (BCR). While it has been recognized that the diversity of epitope recognition may be astonishingly confined in CLL, knowledge on antigens recognized by CLL BCRs is still limited. Here, we identified and characterized an epitope recognized by a defined CLL BCR which may broaden our view on potential mechanisms of antigenic drive in CLL. Methods:The B- cell receptor of a random CLL-patient was cloned and expressed as Fab fragment in E.coli. Random phage display reptile litanies we skeletal on the immobilized Fab and landed peptides were tested for specific binding. Specific clones we sequenced and sequences were analyzed for homology to known proteins. Recognition of candidate proteins was verified in brooding assays or recombinant proteins. Results:Screening random phage display peptide libraries, we identified a CLL BCR epitope mimic that displayed a high degree of homology to a conserved peptide string in the variable region of immunoglobulin heavy and light chains. CLL BCR binding to this epitope as well as binding to full length heavy and light immunoglobulin chains was verified by binding assays and a protein array screening. Interestingly, the CLL BCR also interacted with itself, as the identified epitope was also present in its own primary amino acid sequence. Conclusions:These findings suggest the possibility of self-recognition of BCRs within the CLL cell membrane or BCR interactions between neighboring CLL cells. This may potentially result in autostimulation of the leukemic cell independent of “exogenous” antigens and may account for self-sufficient signaling of some CLL-BCRs in driving disease progression. As the peptide mimicking this immunoglobulin epitope is known to be recognized by BCRs of other CLL cases in addition to the index case investigated here, such autostimulatory mechanisms may be relevant to a large number of CLL patients. Disclosures:No relevant conflicts of interest to declare.

Clinical Utility of PET/CT Scanning in Patients with Chronic Lymphocytic Leukemia

AbstractAbstract ▪3903▪This icon denotes a clinically relevant abstractThe clinical utility of 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography-computed tomography (PET-CT) scans in the management of patients with chronic lymphocytic leukemia (CLL) has not been clearly defined. CLL cells typically have low FDG avidity and the addition of the PET component has not been shown to improve the utility of CT scans in the management of patients with CLL. However, patients with CLL are at increased risk of developing FDG avid complications including more aggressive lymphomas, other second malignancies, and infections for which FDG PET-CT scans are a useful imaging modality. We hypothesized that FDG PET-CT scans are sensitive tests for evaluation of these complications in patients with CLL. Patients and Methods:This observational study was performed with IRB approval. We studied all 4030 CLL patients seen at least once in the Division of Hematology at Mayo Clinic Rochester between January 1, 2006 and December 31, 2011 using data prospectively collected into the Mayo Clinic CLL database. We reviewed the clinical and radiological records of the 272 (7%) patients who underwent 526 FDG PET-CT scans of the trunk during this time period to determine the indication for PET-CT scan, results of imaging, and the effects of the use of PET/CT scan on management. Results:Four hundred and seventy two (90%) of the 526 PET-CT scans were reported as abnormal. Of these, 78 (17%) scans were useful in directing a tissue biopsy of high FDG avidity lesions. Of the 37 (8%) positive PET-CT scans that facilitated the diagnosis of new complications of CLL, 21 (4%) scans led to a diagnosis of diffuse large B cell lymphoma and 9 (2%) scans led to a diagnosis of a solid malignancy. The FDG component of 22 PET-CT scans done because of clinical suspicion of complications of CLL were negative, and thus useful in management of these patients. PET-CT scans showed progressive CLL in 138 (29%) studies but in these patients, the PET component of the scan did not provide additional information about the status of the patients' CLL compared to the CT component alone. Conclusions:FDG PET-CT scans are not of proven value in staging CLL or determining response to treatment. However, our data suggest that they could be of considerable value in evaluation for complications, especially more aggressive lymphomas, other cancers, and infections that complicate the course of CLL. Disclosures:Off Label Use: Phase I study using PGG beta glucan in CLL. Zent:Biothera: Research Funding; Genzyme: Research Funding; Genentech: Research Funding; Novartis: Research Funding; GlaxoSmithKline: Research Funding.

The Nature of the Antigen Determines Leukemia Development and Behavior in the Eμ-TCL1 Transgenic Mouse Model of CLL

AbstractAbstract 181Studies conducted over the past decade have revealed a strong association between the mutational status of the immunoglobulin heavy-chain variable region (IGHV) genes and clinical course in patients with chronic lymphocytic leukemia (CLL). In patients with aggressive CLL, the leukemic cells typically express B cell receptors (BCRs) encoded by unmutated IGHV genes, whereas these genes are most often mutated in leukemic cells from patients with indolent disease. The mutational status of the IGHV genes reflects features of the antigen, such as antigen structure, form, presentation and affinity, indicating that the difference in the clinical course between IGHV-unmutated and IGHV-mutated CLL could be due to recognition of different types of antigens. In line with this possibility, recent studies have shown that IGHV-unmutated CLL (U-CLL) cells frequently express polyreactive BCRs that bind with low affinity to both microbial antigens and autoantigens translocated or exposed on apoptotic cells, whereas such reactivity is infrequent in IGHV-mutated CLL (M-CLL).To further explore the possibility that the clinical course in CLL is determined by the availability of particular types of antigenic stimuli, we investigated the impact of different antigen/BCR interactions on leukemia development and behavior in the Eμ-TCL1 transgenic mouse model of CLL. We initially established three cohorts of Eμ-TCL1 transgenic mice that expressed transgenic BCRs with different antigen specificity. Two of these cohorts expressed low-affinity unmutated transgenic BCRs reactive with the antigens phosphatidylcholine (PtC) and Sm (IgPtC and IgSm, respectively), whereas the third cohort expressed a high-affinity mutated transgenic BCR (IgHEL) specific for the antigen hen egg lysozyme (HEL). Of note, Sm is a ribonucleoprotein complex that is translocated to the surface of apoptotic cells and has been shown to be recognized by certain human U-CLL BCRs, whereas PtC is a cell membrane component that is exposed on senescent red blood cells and gut bacteria. Because no data are currently available regarding the reactivity of the M-CLL BCRs, we subdivided the cohort of Eμ-TCL1/IgHEL double transgenic mice into four additional cohorts. These included a cohort without antigen (Eμ-TCL1/IgHEL), a cohort in which HEL was provided as a foreign antigen (Eμ-TCL1/IgHEL double transgenic mice repetitively immunized with particles coated with HEL and CpG oligonucleotides), a cohort in which HEL was provided as a soluble autoantigen (Eμ-TCL1/IgHEL/sHEL triple transgenic mice) and a cohort in which HEL was provided as a membrane-bound autoantigen exposed on apoptotic cells (Eμ-TCL1/IgHEL/mHEL-KK triple transgenic mice). Each cohort consisted of 12–14 animals, of which at least 8 have been followed for >1 year.Animals from all cohorts developed CD5-positive B cell leukemias, but only in Eμ-TCL1/IgSm and Eμ-TCL1/IgPtC mice the leukemic cells expressed a transgenic BCR. In Eμ-TCL1/IgHEL mice the leukemias were always derived from the small percentage of B cells that express an endogenous BCR, whereas B cells that express the transgenic IgHEL BCR were never transformed. Interestingly, leukemia development and progression was more rapid in Eμ-TCL1/IgPtC than Eμ-TCL1/IgSm transgenic mice (7/14 at 6 months of age and 2/10 at 8 months of age, respectively). Since PtC is expressed as both a foreign- (gut flora) and self- (senescent red blood cells) antigen, we investigated whether suppression of gut flora will affect the growth of adoptively transferred Eμ-TCL1/IgPtC leukemias. Pretreatment of syngeneic recipient mice with a three-week course of broad-spectrum antibiotics significantly delayed leukemia growth, suggesting that PtC is more potent in driving the expansion of the leukemic clone when expressed as a foreign than self antigen.To summarize, these data demonstrate that U-CLL can be induced by both microbial antigens and autoantigens exposed on apoptotic cells, including autoantigens that are recognized by human CLL cells, such as Sm. In contrast, M-CLL can not be induced by chronic or repetitive antigen stimulation, regardless whether the antigen is provided as a foreign antigen, as a soluble autoantigen, or as a membrane-bound autoantigen exposed on apoptotic cells. Collectively, these data suggest that the mechanisms that drive U-CLL and M-CLL are different and indicate that only U-CLL is an antigen-driven disease. Disclosures:No relevant conflicts of interest to declare.

Small Lymphocytic Lymphoma and Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world, characterized by peripheral blood B-cell lymphocytosis as well as lymphadenopathy, organomegaly, cytopenias, and systemic symptoms. Chronic lymphocytic leukemia cells have a distinctive immunophenotype, and the disease has a characteristic pattern of histological infiltration in the lymph node and bone marrow. The clinical course of CLL is heterogeneous, with some patients presenting with very indolent disease and other patients having a more aggressive malignancy. It is known that genetic abnormalities underlie this difference in clinical presentation. Some patients may present solely with lymphadenopathy, organomegaly, and presence of infiltrating monoclonal B cells with the same immunophenotype as CLL cells, but lacking peripheral blood lymphocytosis. This disease is called small lymphocytic lymphoma (SLL) and has been considered for almost 2 decades to be the tissue equivalent of CLL. Both CLL and SLL are currently considered different manifestations of the same entity by the fourth edition of the World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. It is suspected that differential expression of chemokine receptors (e.g., reduced expression of R1 and CCR3 in SLL cells), integrins (e.g., CLL cells have lower expression of integrin αLβ2), and genetic abnormalities (a higher incidence of trisomy 12 and lower incidence of del(13q) is found in SLL) may explain some of the clinical differences between these 2 disorders. However, there is still a lack of knowledge on the precise biological basis underlying the different clinical presentations of CLL and SLL. It is expected that future studies will shed light on the pathophysiology of both disorders.

Immune Dysfunction in Chronic Lymphocytic Leukemia: The Role for Immunotherapy

A key feature of the clinical course of chronic lymphocytic leukemia (CLL) is that it induces a state of immunosuppression, causing increased susceptibility to infections and failure of anti-tumor immune responses. Cytotoxic chemotherapy still forms the mainstay of most current treatment regimens, but is not curative, and its lack of specificity means that it also targets normal immune cells, exacerbating this immunosuppression. This can result in effective treatments being limited by infectious complications, particularly in the elderly who comprise the majority of patients with this disease. Immunotherapy potentially offers a way out of this dilemma, due to its improved specificity and ability to enhance immune responses to both the tumor and infectious agents. There has been a dramatic increase in the range of available immunotherapeutic options over the past decade, and many are now in the process of making the transition to the clinic. This review will discuss both the immune defect in CLL, and emerging immunotherapies, including CD40 ligand gene therapy, lenalidomide, CLL vaccines, CXCR4 antagonists, and adoptive cellular immunotherapies such as chimeric antigen receptor modified T-cells.

Integrative genomic analysis implicates gain of PIK3CA at 3q26 and MYC at 8q24 in chronic lymphocytic leukemia.

The disease course of chronic lymphocytic leukemia (CLL) varies significantly within cytogenetic groups. We hypothesized that high-resolution genomic analysis of CLL would identify additional recurrent abnormalities associated with short time-to-first therapy (TTFT). We undertook high-resolution genomic analysis of 161 prospectively enrolled CLLs using Affymetrix 6.0 SNP arrays, and integrated analysis of this data set with gene expression profiles. Copy number analysis (CNA) of nonprogressive CLL reveals a stable genotype, with a median of only 1 somatic CNA per sample. Progressive CLL with 13q deletion was associated with additional somatic CNAs, and a greater number of CNAs was predictive of TTFT. We identified other recurrent CNAs associated with short TTFT: 8q24 amplification focused on the cancer susceptibility locus near MYC in 3.7%; 3q26 amplifications focused on PIK3CA in 5.6%; and 8p deletions in 5% of patients. Sequencing of MYC further identified somatic mutations in two CLLs. We determined which catalytic subunits of phosphoinositide 3-kinase (PI3K) were in active complex with the p85 regulatory subunit and showed enrichment for the α subunit in three CLLs carrying PIK3CA amplification. Our findings implicate amplifications of 3q26 focused on PIK3CA and 8q24 focused on MYC in CLL.

Impact of immunoglobulin heavy chain variable region mutational status on the outcome of patients with chronic lymphocytic leukemia harboring isolated 13q deletion.

6608 Background: Several prognostic factors can predict the course of chronic lymphocytic leukemia (CLL). Among them, the IGVH mutational status and the presence of cytogenetic abnormalities are the strongest predictors of outcome. Mutated IGVH and deletion 13q independently confer a survival advantage. CLL patients with mutated IGVH in combination with deletion 13q have a better prognosis when compared to their unmutated IGVH counterparts. However, there is limited data on the outcome of patients harboring favorable deletion 13q and the unfavorable unmutated IGVH. This study aimed at identifying patients with these two indicators in order to obtain important prognostic information. Methods: We used the Moffitt Cancer Center Total Cancer Care (TCC) database to find patients with a diagnosis of CLL between January 1993 and December 2009. Individual charts were reviewed for demographic data and CLL cytogenetics, including IGVH mutation status and presence of deletion 13q. We analyzed the impact of having deletion 13q in combination with an unmutated IGVH on the overall survival (OS) for this subset of CLL patients using Kaplan Meier curves with SPSS statistical software. Results: 546 patients were identified during the aforementioned time period with a diagnosis of CLL. Median age was 62.5 years. 144 (26.4%) of these patients had IGVH and cytogenetic analysis available. 53 patients had 13q deletion as their sole genetic abnormality. Patients with unmutated IGVH and positive for deletion 13q were 19/53 (35.8%). Patients with mutated IGVH and positive for deletion 13q were 34/53 (64.2%). Patients with mutated IGVH and positive for deletion 13q had an OS of 17 years. While patients with unmutated IGVH and positive deletion 13q had a lower median OS of 12 years (91.2% vs 78.9%, p=0.05). Hazard ratio for patients with IGVH mutated and positive deletion 13q was 0.4, p=0.05. Conclusions: Mutated IGVH appears to be associated with improved OS in patients with isolated 13q deletion when compared to patients with unmutated IGVH and isolated 13q deletion. Further research is needed to assess these mutations in relation to other cytogenetic abnormalities in CLL.

Mutational Status and Gene Repertoire of IGHV-IGHD-IGHJ Rearrangements in Serbian Patients With Chronic Lymphocytic Leukemia

The mutational status and configuration of immunoglobulin heavy variable (IGHV) gene rearrangements was analyzed in 85 Serbian patients with chronic lymphocytic leukemia (CLL). We found that 55.3% of cases belonged to mutated and 44.7% to unmutated CLL, progressive disease predominating in the unmutated subset. IGHV gene use resembled that obtained for Mediterranean countries, except for underrepresentation of the IGHV4 subgroup in our cohort. Chronic lymphocytic leukemia (CLL) results from the clonal expansion of mature B lymphocytes and is characterized by extreme clinical heterogeneity. One of the most reliable prognostic markers in chronic lymphocytic leukemia (CLL) is the mutational status of immunoglobulin heavy variable (IGHV) genes, which defines 2 subsets, mutated CLL (M-CLL) and unmutated CLL (U-CLL), with different clinical courses. Biased IGHV gene use between M-CLL and U-CLL clones, as well as population differences in the IGHV gene repertoire have been reported. In this study, mutational status and configuration of IGHV-IGHD-IGHJ rearrangements in 85 Serbian patients were analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing methodology. We found that 55.3% of cases belonged to M-CLL and 44.7% belonged to U-CLL, with progressive disease predominating in the unmutated subset. Most frequently expressed was the IGHV3 subgroup (55.7%), followed by IGHV1 (27.3%), IGHV4 (12.5%), IGHV5 (2.3%), IGHV2 (1.1%), and IGHV6 (1.1%). The distribution of IGHD subgroups was as follows: IGHD3, 39.1%; IGHD2, 21.8%; IGHD6, 12.6%; IGHD1, 10.3%; IGHD4, 8%; IGHD5, 6.9%; and IGHD7, 1.1%. The most frequent IGHJ gene was IGHJ4 (48.9%), followed by IGHJ6 (28.4%), IGHJ3 (11.4%), and IGHJ5 (11.4%). In 15.3% of cases, heavy complementarity-determining region 3 (VH CDR3) amino acid sequences could be assigned to previously defined stereotyped clusters. Our study showed a strong correlation between IGHV gene mutational status and clinical course of CLL. IGHV gene use was comparable to that obtained for Mediterranean countries, with the exception of the IGHV4 subgroup, which was underrepresented in our cohort.

Prognostic significance of del 17p, ZAP-70 and CD38 as independent indicators for B-CLL: correlation to response to treatment and disease outcome

Prognostic markers as CD38 and ZAP-70 and specific chromosomal abnormalities as del 17p have now been developed to refine the risk of progressive disease in chronic lymphocytic leukemia (CLL). This study analyzed 40 recently diagnosed, untreated B-CLL patients for CD38 and ZAP-70 expression by flow cytometry and for del 17p by conventional cytogenetics (CCG) and by fluorescence in situ hybridization (FISH) technique to evaluate their effect on the clinical course of CLL and as risk factors for disease progression in addition to their impact on response to treatment and disease outcome. Twenty healthy age- and sex-matched subjects were included as a control. The results revealed that CD38 and ZAP-70 expression were detected in 42.5% and 47.5% of cases, respectively. They were associated with an unfavorable clinical course. Higher levels were significantly associated with increased risk of unfavorable response to treatment (P=0.003), with poor clinical outcome (P=0.0001). Del 17p was detected in 35% of cases by FISH technique and in 7.5% by CCG. The deletion was significantly associated with progressive clinical course; poor response to treatment (P=0.007) but not with disease outcome (P=0.103).Combined analysis of ZAP-70 and CD38 yielded concordantly negative results in 50% of patients and concordantly positive results in 40% of patients, while 10% were discordant. CD38+/ZAP-70+ patients were significantly associated with progressive disease (P<0.05) and with del 17p than CD38−/ZAP-70- patients (P=0.008).Time to disease progression (TDP) was 6months among CD38+/ZAP-70+ patients as compared to 16months in CD38−/ZAP-70− patients. In patients with discordant results, the TDP was 9months. Over-representation of the three parameters (CD38, ZAP-70 and del 17p) was detected in 22.5% of cases, and pointed towards even shorter TDP (4.5months), more aggressive disease; more resistance to chemotherapy and poor outcome thus providing a precise tool for identifying high-risk patients.In conclusion, the combined expression of CD38 and ZAP-70 together with del 17p in CLL is a precise diagnostic tool for identifying high-risk patients and convey rapid progression; they are accurate predictors of clinical outcome thus could be used to indicate when more novel chemotherapeutic approaches are needed and provided help in guiding individual patient treatment.

Epigenetic Silencing of the Circadian Clock Gene CRY1 is Associated with an Indolent Clinical Course in Chronic Lymphocytic Leukemia

Disruption of circadian rhythm is believed to play a critical role in cancer development. Cryptochrome 1 (CRY1) is a core component of the mammalian circadian clock and we have previously shown its deregulated expression in a subgroup of patients with chronic lymphocytic leukemia (CLL). Using real-time RT-PCR in a cohort of 76 CLL patients and 35 normal blood donors we now demonstrate that differential CRY1 mRNA expression in high-risk (HR) CD38+/immunoglobulin variable heavy chain gene (IgVH) unmutated patients as compared to low-risk (LR) CD38−/IgVH mutated patients can be attributed to down-modulation of CRY1 in LR CLL cases. Analysis of the DNA methylation profile of the CRY1 promoter in a subgroup of 57 patients revealed that CRY1 expression in LR CLL cells is silenced by aberrant promoter CpG island hypermethylation. The methylation pattern of the CRY1 promoter proved to have high prognostic impact in CLL where aberrant promoter methylation predicted a favourable outcome. CRY1 mRNA transcript levels did not change over time in the majority of patients where sequential samples were available for analysis. We also compared the CRY1 expression in CLL with other lymphoid malignancies and observed epigenetic silencing of CRY1 in a patient with B cell acute lymphoblastic leukemia (B-ALL).

Spectrum of Neurologic Complications in Chronic Lymphocytic Leukemia

Neurologic disease is believed to be an unusual complication during the course of chronic lymphocytic leukemia. Nevertheless, it has already been proven in autopsy series that the incidence of occult nervous system infiltration is much higher than was previously expected. The advent of more potent drugs to treat this lymphoproliferative disorder has brought a new hope for a possible cure in the future. However, an appropriate systemic treatment for central nervous system infiltration of this disease is still lacking. Also, due to the potent immunosuppressive properties of the agents used in the up-front treatment, for example, the purine nucleoside analogues, we have witnessed an increase in the incidence of opportunistic infections, with progressive multifocal leukoencephalopathy being one of the most serious. The goal of this review is to summarize the spectrum of neurologic derangements linked to chronic lymphocytic leukemia and to raise clinicians' awareness to recognize the possibility of such associations.

Reduced c-FOS Is Associated with Poor Prognosis and Clinical Course in Chronic Lymphocytic Leukemia

Abstract 2433We have previously shown that silencing of the tumor suppressor gene, DAPK1, by genetic and epigenetic mechanisms is associated with the pathogenesis of CLL. To elucidate genes and pathways involved in DAPK1 transcriptional regulation, genome-wide siRNA screens were performed using a novel transgene reporter system involving a stably-integrated BAC construct expressing luciferase under the control of the DAPK1 locus. c-FOS and other members of the FOS gene family were identified as positive regulators, implicating the AP-1 pathway in DAPK1 transcription. A subsequent comprehensive examination of the FOS, JUN and ATF gene families in CLL and healthy B cells was performed. As the expression of the AP-1 gene family is highly subject to fluctuations in stress and mitogenic stimuli, freshly isolated cells were cultured using autologous serum conditions, allowing for a uniform establishment of baseline gene expression. This work reveals an alteration of the relative composition of AP-1 transcription factors in CLL, demarked by a substantial reduction in c-FOS gene expression. We find that the inducibility of c-FOS in CLL following MAPK activation by TPA (ERK-MAPK) is impaired 7.0-fold relative to healthy B cells and is completely abrogated following anisomycin (p38-MAPK) stimulation. The level of c-FOS induction following TPA activation can be used to clearly segregate CLL patients into two non-overlapping groups, those with low (mean=4.0-fold reduced expression; range=3.0–7.2; n=9) and very low (mean=21.7-fold reduced expression; range=17.6–36.7; n=8) following one hour induction versus healthy B cells. The very low c-FOS induction cases are characterized by poor prognostic indicators (IGHV unmutated (0/9 in low vs. 5/8 in very low); 17p, 6q deletion (0/9 in low vs. 3/8 in very low); and a substantially shorter time to progression (102.7±40.4 months in low vs. 10.8±8.6 in very low). Patients with very low c-FOS induction also demonstrate elevated c-MYC induction following activation. TPA-dependent ERK phosphorylation and activation of other immediate early genes, such as EGR1 and c-JUN, is intact in both CLL groups, absolving MAPK pathway dysfunction as a relevant c-FOS silencing mechanism. Reduced c-FOS expression can be partially explained, in the majority of very low c-FOS inducible cases, by elevated levels of miR-155 and miR-221 targeting the c-FOS transcript. Reduced expression of c-FOS and the resulting reconfiguration of AP-1 transcription factor composition may be involved in the pathogenesis of CLL and the subsequent silencing of DAPK1. Disclosures:No relevant conflicts of interest to declare.

Mutations of NOTCH1 Are An Independent Predictor of Survival in Chronic Lymphocytic Leukemia

Abstract 283The clinical course of chronic lymphocytic leukemia (CLL) ranges from very indolent, with a nearly normal life expectancy, to rapidly progressive leading to death and occasionally undergoing transformation to Richter syndrome (RS). TP53 disruption identifies a fraction of high risk CLL destined to experience a very short survival. High risk CLL, however, cannot be fully recapitulated by TP53 disruption and other lesions of cancer genes may be implicated in this aggressive phenotype. Analysis of the CLL coding genome has recently disclosed that the NOTCH1 proto-oncogene is recurrently mutated at CLL presentation. Here we assessed the prognostic role of NOTCH1 mutations in CLL. Two series of previously untreated CLL were utilized as training (n=309, median follow-up 6 years) and validation (n=230, median follow-up 7 years) cohorts. NOTCH1 mutations were analyzed by DNA Sanger sequencing in blind with respect to clinical data. In the training series, NOTCH1 mutations occurred in 34/309 (11.0%) patients, being mostly represented (26/34, 76.5%) by a recurrent two bp frameshift deletion (c.7544_7545delCT). The remaining NOTCH1 mutations (8/34, 23.5%) were frameshift deletions other than c.7544_7545delCT (n=7) and frameshift insertions (n=1). All mutations were predicted to disrupt the NOTCH1 PEST domain. CLL with NOTCH1 mutations preferentially carried unmutated IGHV genes (76.5%, p<.001). Other characteristics at presentation associated with NOTCH1 mutations were advanced Rai stage (26.5%, p=.006) and trisomy 12 (44.1%, p<.001). By univariate analysis, NOTCH1 mutations associated with an increase in the hazard of death (HR: 3.77; 95% CI: 2.14–6.66) and a significant overall survival OS shortening (p<.001) (Fig. 1A). Multivariate analysis selected NOTCH1 mutations as an independent risk factor of OS (HR: 4.22; 95% CI: 2.15–8.28; p<.001), after adjusting for age (p<.001), Rai stage (p=.005), IGHV mutation status (p=.465), 11q22-q23 deletion (p=.128), trisomy 12 (p=.183) and TP53 disruption (p<.001). The poor prognosis conferred by NOTCH1 mutations was attributable, at least in part, to a shorter time to progression requiring treatment (p<.001), and a higher cumulative probability of RS development (p=.026). Although NOTCH1 mutated patients were devoid of TP53 disruption in 31/34 (91.2%) cases, the OS predicted by NOTCH1 mutations was similar to that of TP53 mutated/deleted CLL (Fig. 1C). Analysis of the validation series confirmed: i) the prevalence of NOTCH1 mutations at CLL presentation (26/230, 11.3%); ii) the spectrum of NOTCH1 mutations at CLL presentation (c.7544_7545delCT: 21/26, 80.7%; other mutations: 5/26, 19.3%) iii) the adverse prognostic impact of NOTCH1 mutations in CLL both by univariate analysis (Fig. 1B) and by multivariate analysis (HR: 2.08; 95% CI: 1.10–3.93; p=.023); iv) the preferential mutually exclusive distribution of NOTCH1 mutations and TP53 disruption (25/26, 96.2%); v) that OS of NOTCH1 mutated CLL is similarly poor as that of TP53 disrupted CLL (Fig. 1D). The current study on 539 CLL documents that NOTCH1 mutations: i) represent one of the most frequent cancer gene mutations known to be involved at CLL presentation; ii) identify a subgroup of patients showing poor OS similar to that of TP53 disrupted cases; iii) exert a prognostic role independent of widely accepted clinical and genetic risk factors; iv) predict OS in series from different institutions, as documented by the training-validation approach chosen for the design of this study. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Polymorphisms of Mir-34b/c, Mir-146a and Mir-196a-2 and Predisposition to Chronic Lymphocytic Leukemia and Monoclonal B-Cell Lymphocytosis

Abstract 4585Since microRNAs control expression of protein-coding oncogenes and tumor suppressor genes, functional microRNAs single nucleotide polymorphisms (SNPs) may modulate the risk of tumorigenesis including susceptibility to chronic lymphocytic leukemia (CLL). In this case-control study we investigated whether pri-miR-34b/c rs4938723 (T-to-C), miR-196a2 rs11614913 (C-to-T) and miR-146a rs2910164 (G-to-C) SNPs influence predisposition to CLL or monoclonal B-cell lymphocytosis (MBL). miR-34 family members are direct transcriptional targets of tumor suppressor p53, and miR-34b/miR-34c have been recently proposed as regulators of TCL1 (T-cell leukaemia/lymphoma 1) expression in CLL. A rs4938723 SNP in the promoter region of pri-miR-34b/c might affect transcription factor GATA binding and pri-miR-34b/c expression. Alterations in miR-196a2 and miR-196a2 may represent common cancer predisposition pathways as miR-196a2 rs11614913 and miR-146a rs2910164 have been recently associated with altered risk of different solid tumors including breast, lung, prostate and liver cancers. Additionally, we verified the impact of these microRNA SNPs on prognostic factors and clinical course of CLL. Genotyping was performed using PCR-based assays in a total of 561 Caucasians including 195 patients with CLL, 166 patients with MBL and 200 healthy control individuals. The assessed minor allele frequencies (MAFs) of the investigated SNPs were as follows: for rs4938723 SNP C allele frequency was 0.37 in CLL, 0.36 in MBL and 0.30 in controls, for rs11614913 SNP T allele frequency reached 0.43 in CLL, 0.42 in MBL and 0.39 in controls, and for rs2910164 SNP C allele frequency was 0.29 in CLL, 0.30 in MBL and 0.26 in controls. Logistic regression analysis did not detect significant associations of CLL or MBL with studied genotypes or alleles (p>0.05). Moreover, none of the tested genetic variants was found to influence CLL patients' progression-free survival (PFS) or overall survival (OS) with median follow-up time from diagnosis of 3.0 (0–13.9) years. In conclusion, our data suggest that investigated SNPs in pri-miR-34b/c, miR-146a and miR-196a-2 genes are not likely to play a major role in the susceptibility to CLL and MBL or in clinical outcome of CLL. Disclosures:No relevant conflicts of interest to declare.