Witzig, Thomas E.

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.

AbstractApproximately 60% of patients with diffuse large B-cell non-Hodgkin lymphoma (DLBCL) are curable with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemoimmunotherapy. Epratuzumab (E) is an unlabeled anti-CD22 monoclonal antibody with efficacy in relapsed DLBCL. This phase 2 trial tested the safety and efficacy of combining E with R-CHOP (ER-CHOP) in untreated DLBCL. A secondary aim was to assess the efficacy of interim positron emission tomography (PET) to predict outcome in DLBCL. Standard R-CHOP with the addition of E 360 mg/m2 intravenously was administered for 6 cycles. A total of 107 patients were enrolled in the study. Toxicity was similar to standard R-CHOP. Overall response rate in the 81 eligible patients was 96% (74% CR/CRu) by computed tomography scan and 88% by PET. By intention to treat analysis, at a median follow-up of 43 months, the event-free survival (EFS) and overall survival (OS) at 3 years in all 107 patients were 70% and 80%, respectively. Interim PET was not associated with EFS or OS. Comparison with a cohort of 215 patients who were treated with R-CHOP showed an improved EFS in the ER-CHOP patients. ER-CHOP is well tolerated and results appear promising as a combination therapy. This study was registered at www.clinicaltrials.gov as #NCT00301821.

Abstract The mechanism of cytotoxicity of farnesyltransferase inhibitors is incompletely understood and seems to vary depending on the cell type. To identify potential determinants of sensitivity or resistance for study in the accompanying clinical trial (Witzig et al, page 4882), we examined the mechanism of cytotoxicity of tipifarnib in human lymphoid cell lines. Based on initial experiments showing that Jurkat variants lacking Fas-associated death domain or procaspase-8 undergo tipifarnib-induced apoptosis, whereas cells lacking caspase-9 or overexpressing Bcl-2 do not, we examined changes in Bcl-2 family members. Tipifarnib caused dose-dependent up-regulation of Bim in lymphoid cell lines (Jurkat, Molt3, H9, DoHH2, and RL) that undergo tipifarnib-induced apoptosis but not in lines (SKW6.4 and Hs445) that resist tipifarnib-induced apoptosis. Further analysis demonstrated that increased Bim levels reflect inhibition of signaling from c-Raf to MEK1/2 and ERK1/2. Additional experiments showed that down-regulation of the Ras guanine nucleotide exchange factor RasGRP1 diminished tipifarnib sensitivity, suggesting that H-Ras or N-Ras is a critical farnesylation target upstream of c-Raf in lymphoid cells. These results not only trace a pathway through c-Raf to Bim that contributes to tipifarnib cytotoxicity in human lymphoid cells but also identify potential determinants of sensitivity to this agent.

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.

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.

AbstractCurrent research in lymphoma is focused on two areas of lymphoma biology—the signal transduction pathways used to maintain the growth of malignant lymphocytes and the role of the tumor microenvironment in lymphoma growth and survival. This review focuses on three signaling pathways: the phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway, the B-cell receptor/spleen tyrosine kinase (BCR/Syk) pathway, and the protein kinase C-beta (PKC-β) pathway, known to be important to lymphoma cells. The mTOR inhibitors temsirolimus and everolimus have demonstrated antitumor activity in all types of lymphoma, the Syk inhibitor fostamatinib has activity in diffuse large B-cell lymphoma and chronic lymphocytic leukemia, and the PKC-β inhibitor enzastaurin is being used as consolidation therapy after remission in diffuse large B-cell lymphoma. This review discusses the biology behind the development of each new agent and the results of initial clinical trials. The goal is to provide the hematologist/oncologist background information on these new agents and understand their current and potential role in the management of patients.

AbstractImmunosuppression is a known risk factor for B-cell non-Hodgkin lymphoma (NHL), yet mechanisms of tumor-associated immunosuppression remain to be fully characterized. We examined the immunophenotype of 40 NHL patients and 27 age-matched healthy volunteers to better understand systemic immune suppression. NHL peripheral blood mononuclear cells had significantly decreased interferon-γ production and proliferation. This suppression was not the result of regulatory T cells, interleukin-6 or interleukin-10, as these factors were not different between NHL and healthy volunteers (controls). We were able to restore T-cell proliferation by removing NHL monocytes, suggesting that these monocytes are suppressive. This suppression was mediated in part through arginine metabolism as exogenous arginine supplementation partially overcame monocytes' suppression of T-cell proliferation in vitro and NHL patients had elevated arginase I in their plasma. NHL monocytes had impaired STAT1 phosphorylation and interferon-α production to CpG stimulation and a dendritic cell differentiation deficiency. Further studies demonstrated that monocytes from NHL patients had decreased HLA-DR and Tumor necrosis factor-α receptor II (CD120b) expression compared with controls (CD14+HLA-DRlow/−CD120blow). Patients with increased ratios of CD14+HLA-DRlow/− monocytes had more aggressive disease and suppressed immune functions. In summary, we report that CD14+HLA-DRlow/− monocytes are a major and multifactorial contributor to systemic immunosuppression in NHL.

Abstract Background: The t(14;18)(q32;q21) translocation is the most commonly observed chromosomal translocation in non–Hodgkin's lymphoma (NHL), resulting in constitutive Bcl-2 expression and apoptosis inhibition. In addition, germline variation in both BCL2L11 (BIM) and CASP9, known regulators of apoptosis, has recently been linked to NHL risk. We conducted a comprehensive evaluation of 36 apoptosis pathway genes with risk of NHL. Methods: We genotyped 226 single-nucleotide polymorphisms (SNP) from 36 candidate genes in a clinic-based study of 441 newly diagnosed NHL cases and 475 frequency-matched controls. We used principal components analysis to assess gene-level associations, and logistic regression to assess SNP-level associations. MACH was used for imputation of SNPs in BCL2L11 and CASP9. Results: In gene-level analyses, BCL2L11 (P = 0.0019), BCLAF1 (P = 0.0097), BAG5 (P = 0.026), and CASP9 (P = 0.0022) were associated with NHL risk after accounting for multiple testing (tail strength, 0.38; 95% confidence interval, 0.05-0.70). Two of the five BCL2L11 tagSNPs (rs6746608 and rs12613243), both genotyped BCLAF1 tagSNPs (rs797558 and rs703193), the single genotyped BAG5 tagSNP (rs7693), and three of the seven genotyped CASP9 tagSNPs (rs6685648, rs2020902, and rs2042370) were significant at P &lt; 0.05. We successfully imputed BCL2L11 and CASP9 SNPs previously linked to NHL, and replicated all four BCL2L11 and two of three CASP9 SNPs. Conclusion: We replicated the association of BCL2L11 and CASP9 with NHL risk at the gene and SNP level, and identified novel associations with BCLAF1 and BAG5. Impact: Closer evaluation of germline variation of genes in the apoptosis pathway with risk of NHL and its subtypes is warranted. Cancer Epidemiol Biomarkers Prev; 19(11); 2847–58. ©2010 AACR.

Abstract Vitamin D insufficiency is common globally and low levels are linked to higher cancer incidence. Although vitamin D insufficiency is related to inferior prognosis in some cancers, no data exist for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). We evaluated the relationship of 25(OH)D serum levels with time-to-treatment (TTT) and overall survival (OS) in newly diagnosed CLL patients participating in a prospective cohort study (discovery cohort) and a separate cohort of previously untreated patients participating in an observational study (confirmation cohort). Of 390 CLL patients in the discovery cohort, 119 (30.5%) were 25(OH)D insufficient. After a median follow-up of 3 years, TTT (hazard ratio[HR] = 1.66; P = .005) and OS (HR = 2.39; P = .01) were shorter for 25(OH)D-insufficient patients. In the validation cohort, 61 of 153 patients (39.9%) were 25(OH)D insufficient. After a median follow-up of 9.9 years, TTT (HR = 1.59; P = .05) and OS (HR 1.63; P = .06) were again shorter for 25(OH)D-insufficient patients. On pooled multivariable analysis of patients in both cohorts adjusting for age, sex, Rai stage, CD38 status, ZAP-70 status, immunoglobulin heavy chain variable (IGHV) gene mutation status, CD49d status, and cytogenetic abnormalities assessed by interphase fluorescent in situ hybridization testing, 25(OH)D insufficiency remained an independent predictor of TTT (HR = 1.47; P = .008), although the association with OS was not significant (HR = 1.47; P = .07). Vitamin D insufficiency is associated with inferior TTT and OS in CLL patients. Whether normalizing vitamin D levels in deficient CLL patients would improve outcome merits clinical testing.