Ansell, Stephen M.

To gain insight into the genomic basis of diffuse large B-cell lymphoma (DLBCL), we performed massively parallel whole-exome sequencing of 55 primary tumor samples from patients with DLBCL and matched normal tissue. We identified recurrent mutations in genes that are well known to be functionally relevant in DLBCL, including MYD88 , CARD11 , EZH2 , and CREBBP . We also identified somatic mutations in genes for which a functional role in DLBCL has not been previously suspected. These genes include MEF2B , MLL2 , BTG1 , GNA13 , ACTB , P2RY8 , PCLO , and TNFRSF14 . Further, we show that BCL2 mutations commonly occur in patients with BCL2 / IgH rearrangements as a result of somatic hypermutation normally occurring at the IgH locus. The BCL2 point mutations are primarily synonymous, and likely caused by activation-induced cytidine deaminase–mediated somatic hypermutation, as shown by comprehensive analysis of enrichment of mutations in WRCY target motifs. Those nonsynonymous mutations that are observed tend to be found outside of the functionally important BH domains of the protein, suggesting that strong negative selection against BCL2 loss-of-function mutations is at play. Last, by using an algorithm designed to identify likely functionally relevant but infrequent mutations, we identify KRAS , BRAF , and NOTCH1 as likely drivers of DLBCL pathogenesis in some patients. Our data provide an unbiased view of the landscape of mutations in DLBCL, and this in turn may point toward new therapeutic strategies for the disease.

AbstractAlthough proinflammatory and chemotactic cytokines can profoundly affect the tumor microenvironment, and many of them have been shown to have therapeutic efficacy in preclinical models, the role of these molecules in Waldenström macroglobulinemia (WM) remains poorly understood. In this study, simultaneous analysis of WM patient sera and bone marrow biopsies identified a set of dysregulated cytokines including CCL5, G-CSF, and soluble IL-2 receptor, that were significantly elevated in WM patients whereas IL-8 and EGF levels were significantly lower in these patients compared with healthy controls. Interestingly, CCL5 levels positively correlated with features of disease aggressiveness such as elevated IgM levels and bone marrow involvement. Functional analysis of tumor microenvironment revealed a functional correlation between CCL5 levels and IL-6 levels, a proinflammatory cytokine with an important role in normal and malignant B-cell biology. Furthermore, CCL5 stimulated IL-6 secretion in WM stromal cells resulting in increased IgM secretion by WM malignant cells via the JAK/STAT signaling pathway. Thus, together these results define a novel signaling network in the WM tumor microenvironment controlling IgM secretion and suggest CCL5 as a potential target for the treatment of this disease.

AbstractA phase 2 study of the oral farnesyltransferase inhibitor tipifarnib was conducted in 93 adult patients with relapsed or refractory lymphoma. Patients received tipifarnib 300 mg twice daily on days 1-21 of each 28-day cycle. The median number of prior therapies was 5 (range, 1-17). For the aggressive B-cell, indolent B-cell, and T-cell and Hodgkin lymphoma (HL/T) groups, the response rates were 17% (7/42), 7% (1/15), and 31% (11/36), respectively. Of the 19 responders, 7 were diffuse large B-cell non-Hodgkin lymphoma (NHL), 7 T-cell NHL, 1 follicular grade 2, and 4 HL. The median response duration for the 19 responders was 7.2 months (mean, 15.8 months; range, 1.8-62), and 5 patients in the HL/T group are still receiving treatment at 29-64+ months. The grade 3/4 toxicities observed were fatigue and reversible myelosuppression. Correlative studies suggest that Bim and Bcl-2 should be examined as potential predictors of response in future studies. These results indicate that tipifarnib has activity in lymphoma, particularly in heavily pretreated HL/T types, with little activity in follicular NHL. In view of its excellent toxicity profile and novel mechanism of action, further studies in combination with other agents appear warranted. This trial is registered at www.clinicaltrials.gov as #NCT00082888.

AbstractElevated serum levels of the soluble form of IL-2 receptor α (sIL-2Rα) have been correlated with a poor prognosis in a variety of different types of cancers. However, its biologic relevance remains unclear and controversial. In patients with follicular B-cell non-Hodgkin lymphoma (FL), we observed that serum sIL-2Rα levels were elevated compared with controls and that elevated sIL-2Rα levels before treatment were associated with a poor outcome. To explore the mechanism by which sIL-2Rα may contribute to a poor prognosis in FL, we determined the effects of sIL-2Rα on IL-2 signaling and found that the sIL-2Rα–IL-2 complex promoted T-cell differentiation toward to inhibitory Treg cells rather than TH1 or TH17 cells. Shed by activated T cells that express membrane-bound IL-2Rα, sIL-2Rα further enhanced IL-2–mediated phosphorylation of Stat5 thereby significantly up-regulating Foxp3 expression in CD4+ T cells. We found that CD4+ T cells treated with either IL-2 or sIL-2Rα–IL-2 complex, but not with sIL-2Rα alone, inhibited the function of CD8+ T cells. Taken together, these results indicate that sIL-2Rα actually plays an active biologic role in FL by binding IL-2 and promoting IL-2 signaling rather than depleting IL-2 and blocking its function.

Abstract Waldenström macroglobulinemia (WM) is a rare, lymphoplasmacytic lymphoma characterized by hypersecretion of immunoglobulin M (IgM) protein and tumor infiltration into the bone marrow and lymphatic tissue. Our understanding of the mechanisms driving the development and progression of WM is currently by the shortage of representative cell models available for study. We describe here the establishment of a new WM cell line, MWCL-1. Comprehensive genetic analyses have unequivocally confirmed a clonal relationship between this novel cell line and the founding tumor. MWCL-1 cells exhibit an immunophenotype consistent with a diverse, tumor clone composed of both small B lymphocytes and larger lymphoplasmacytic cells and plasma cells: CD3−, CD19+, CD20+, CD27+, CD38+, CD49D+, CD138+, cIgM+, and κ+. Cytogenetic studies identified a monoallelic deletion of 17p13 (TP53) in both the cell line and the primary tumor. Direct DNA resequencing of the remaining copy of TP53 revealed a missense mutation at exon 5 (V143A, GTG>GCG). In accordance with primary WM tumors, MWCL-1 cells retain the ability to secrete high amounts of IgM protein in the absence of an external stimulus. The genetic, immunophenotypic, and biologic data presented here confirm the validity of the MWCL-1 cell line as a representative model of WM.

A 15-gene expression signature predicts whether a patient with diffuse large B cell lymphoma will respond to dacetuzumab, a therapeutic antibody.

Purpose The serum free light chain (FLC) assay quantitates free kappa (κ) and free lambda (λ) immunoglobulin light chains. This assay has prognostic value in plasma cell proliferative disorders. There are limited data on serum FLC in B-cell malignancies. Patients and Methods The association of pretreatment FLC with event-free survival (EFS) and overall survival (OS) in diffuse large B-cell lymphoma (DLBCL) was evaluated in 76 patients from the North Central Cancer Treatment Group trial N0489 (NCT00301821) and 219 patients from the University of Iowa/Mayo Clinic Specialized Program of Research Excellence Molecular Epidemiology Resource (MER). Published reference ranges were used to define an elevated FLC or an abnormal κ:λ FLC ratio. Results Elevated FLC or abnormal κ:λ FLC ratio was present in 32% and 14% of patients, respectively. Patients with elevated FLC had an inferior OS and EFS in both cohorts compared with patients with normal FLC (N0489: EFS hazard ratio [HR], 3.06; OS HR, 3.16; both P < .02; MER: EFS HR, 2.42; OS HR, 3.40; both P < .001; combined EFS HR, 2.57; OS HR, 3.74; both P < .001). All associations remained significant for EFS and OS after adjusting for the International Prognostic Index (IPI). Abnormal κ:λ FLC ratio was modestly associated with outcome in the combined group (EFS HR, 1.61; OS HR, 1.67; both P = .07), but not in patients without corresponding elevated κ or λ. Elevated FLC was the strongest predictor of outcome in multivariable models with the IPI components. Conclusion Increased serum FLC is an independent, adverse prognostic factor for EFS and OS in DLBCL and warrants further evaluation as a biomarker in DLBCL.

Abstract Background. Vitamin K1 (phylloquinone) is a fat soluble vitamin found mainly in green leafy vegetables, with smaller amounts found in other vegetables, vegetable oils, and some fruits. Vitamin K-dependent gamma-carboxylation of specific glumatic acid residues is critical to the functioning of several key proteins in the coagulation cascade. Vitamin K compounds also inhibit IL-6 and other inflammatory cytokines and serve as transcription factors that foster cell-cycle arrest and apoptosis, pathways relevant to lymphomagenesis. We tested the hypothesis that dietary and supplemental intake of Vitamin K was inversely associated with risk of NHL and the common subtypes of diffuse large B cell, follicular, and chronic lymphocytic leukemia/small lymphocytic lymphomas. Methods. We evaluated dietary and supplemental intake of vitamin K and NHL risk in a clinic-based study of 603 newly diagnosed NHL cases and 1007 frequency-matched controls enrolled at the Mayo Clinic from 2002-2008. Usual diet two years before case diagnosis or control enrollment was assessed using a self-administered, 128-item food frequency questionnaire. Dietary intake of vitamin K was estimated using the Food Processor SQL system. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI), adjusted for age, sex, residence, and total energy. NHL subtypes were centrally reviewed, and subtype-specific risks were estimated using polychotomous logistic regression. Results. The mean age at diagnosis was 60.8 years for cases and 57% were male; for controls, the mean age at enrollment was 60.1 years and 53% were male. Median intake of vitamin K from diet among controls was 63.5 ug/day; 16% used a multivitamin supplement that included vitamin K. NHL risk was inversely associated with intake of dietary vitamin K (p-trend=0.001); compared to intake &lt;39.3 ug/d, risk was decreased for intakes of 39.3-63.4 ug/d (OR=0.76; 95% CI 0.57-1.02), 63.5-107.7 ug/d (OR=0.74; 95% CI 0.55-1.00), and &gt;107.7 (OR=0.56; 95% CI 0.40-0.77). There was an U-shaped association for supplemental intake of Vitamin K and NHL risk; compared to no use, supplemental intake of &lt;5.9 ug/d (OR=0.63; 95% CI 0.37-1.08) and 5.9-17.6 ug/d (OR=0.53; 95% CI 0.30-0.93) were inversely associated with NHL risk, while intake of &gt;17.6 ug/d (OR=1.13; 95% CI 0.73-1.74) showed no association. There was no evidence of heterogeneity by NHL subtype (p=0.4). Further adjustment for education, family history of NHL, pack-years of smoking, body mass index, and alcohol consumption did not alter these results, nor did adjustment for a food-frequency questionnaire-based estimate of total antioxidant intake. Conclusion: Higher intake of vitamin K from the diet was inversely associated with risk of NHL overall and for the major subtypes. These first results, which require replication, suggest that the coagulation pathway or other biologic effects of vitamin K may play a role in lymphomagenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2811.

Abstract Background. MBL is defined as a monoclonal expansion of B lymphocytes (&lt; 5 × 109/L) in the blood without associated lymphadenopathy or organomegaly; MBLs with a chronic lymphocytic leukemia (CLL) immunophenotype have been termed as CLL-like MBL. The prevalence of CLL-like MBL in the general population is 3.5-12% but increases with age; however, the frequency is even higher (∼13-18%) among unaffected relatives from CLL families (i.e., families with two or more CLL members). We and others have found that a small proportion of individuals with CLL-like MBL individuals and lymphocytosis will progress to CLL requiring treatment (∼1.1% per year). Because CLL and NHL have been shown to aggregate together within families, suggesting a shared pathogenesis, we evaluated the frequency of MBL in NHL families. Methods. Individuals were obtained from an ongoing study of NHL families (i.e., families with 2 or more NHL members). However, we limited to NHL families with at most 1 individual with CLL due to the known increased frequency of MBL in CLL families. Multi-color flow cytometry was performed on fresh peripheral blood samples. A CBC and differential count was simultaneously obtained using an automated blood cell counter. Five possible flow diagnoses were defined as: CLL-like MBL (CD5+CD20dim), atypical MBL (CD5+CD20bright), non-CLL like MBL (CD5−), and normal immunophenotype (NIPT). Medical records of NHL cases were reviewed to confirm disease. Results. A total of 30 individuals from 16 NHL families had available flow cytometry results. The mean age at flow analysis was 56 years (range 37− 83 years). We identified 5 individuals with MBL from 4 families: 3 of the 6 had CLL-like MBL, 1 had atypical MBL, and 1 had non-CLL like MBL. The remaining 25 individuals had a NIPT. Thus, the MBL rate in NHL families is 17% (5/30). Among the CD5+ MBL (both CLL-like and atypical MBL) individuals, all were female and the mean absolute lymphocyte count was 1.4 × 109/L. Of interest, 1 of the CLL-like MBL individuals is from a family where two members had monoclonal gammopathy of uncertain significance (MGUS). Conclusion: Our data show that MBLs of various phenotypes can be found at a higher prevalence in NHL families than that of the general population. Further, the frequency of MBL in NHL families is comparable to that of CLL families. Although more work is needed, our results suggest that MBL may be clustering within NHL families, and thus support a possible common inherited predisposition of NHL and CLL, with MBL signifying a shared early pathogenetic step. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1853.