Citations

Abstract Absolute lymphocyte count (ALC) post-autologous stem cell transplantation is an independent predictor for survival in Hodgkin’s Disease (HD). Lymphopenia at diagnosis is associated with worse prognosis in patients with newly diagnosed HD. The role of ALC recovery during standard chemotherapy for HD is unknown. We analyzed all patients managed for HD at the Mayo Clinic from 1986 to 2003. Of the 141 consecutive patients, two patients were excluded due to missing ALC data. Of the 139 patients, 63 patients were females and 76 males. The median age of patients at diagnosis was 31 years (range 6–75 years). 118 (85%) patients presented with nodular sclerosis HD, 10 (7%) with mixed cellularity, 2 (1%) with lymphocyte predominance, 1(1%) with lymphocyte depletion, 4 (3%) with lymphocyte predominant (nodular variant), and 4 (3%) unclassified. Frontline chemotherapy included ABVD (N = 79), MOPP-ABV (N = 47), COPP-ABV (N = 8), BEACOPP (N = 3), and Stanford V (N =2). The median number of cycles was 6 (range: 2–10). The median follow-up for the cohort was 62 months (range: 4–221 months). The ALC recovery was analyzed during the first 4 cycles as 90% of the patients received at least 4 cycles of therapy. Patients with an ALC ≥ 1.3 x 109/l at any time point within the first four cycles of chemotherapy (N = 93) demonstrated improved overall survival (OS) and progression-free survival (PFS) compared to patients with an ALC < 1.3 x 109/L at all time points within the first four cycles of chemotherapy (N =46) (10 years OS and PFS: 91% vs 51%, p < 0.0001; 85% vs 52%, p < 0.0001, respectively). Both groups were balanced for the Hasenclever Index: albumin < 4g/dl (p = 0.1), hemoglobin < 10.5 g/dl (p = 0.46), male gender (p =0.21), age ≥ 45 years (p = 0.06), stage IV disease (p = 0.68), leukocytosis ≥ 15 x 109/L (p = 0.58), and lymphopenia < 600 cell/ml (p = 0.211). Multivariate analysis demonstrated ALC recovery to be independent predictor of OS and PFS when compared to the Hasenclever index. These data suggest a critical role of lymphocyte (immune) recovery during standard chemotherapy in HD.

Abstract Background: High dose therapy with autologous stem cell rescue has been shown to prolong survival in patients with multiple myeloma in randomized controlled trials. However, most of the prospective studies have included younger patients, usually 65 or less. It is important to have a better understanding of the outcome of transplantation in the older patients given the median age of onset of myeloma of 65 years. We retrospectively reviewed our institutions experience with high dose therapy for patients over 70 years. Methods: We identified 35 patients with multiple myeloma, from the transplant database, who were at or over the age of 70 at the time of their high dose therapy. We matched these patients to 70 patients (two matches for each patient), based on stage at transplant (primary refractory, plateau phase, relapse off therapy, or relapse on therapy), Durie Salmon stage, high or low labeling index, conventional cytogenetics (abnormal vs normal), presence or absence of circulating plasma cells at time of transplant, and whether cyclophosphamide was used as part of mobilization in that order of priority. Results: The median age of the two groups were 55.3 (Range 37.3–64.8) and 71.7 (Range 70–75.8) years at the time of transplant. The median time to transplant from diagnosis was similar (6.4 for the older patients compared to 6.9 months for the other, P = NS). Ten of the 35 older patients received reduced dose melphalan (140 mg/2)) compared to 3 patients in the control group; P < 0.01. The median follow up from transplant was 10.1 months for the older patients compared to 18 months for the control group. The overall response rate was similar for the two groups (97.1% for the older patients compared to 95.5 for the control group). Eleven (31%) of the older patients and 17 (24%) of the control patients achieved a CR (P = NS). The post transplant progression free survival estimate at 1 year post transplant was 65.3% for the older patients compared to 66% for the control group (P = 0.3)The two year estimated overall survival from transplant was similar in the two groups; 58% for the older patients compared to 67% for the control group. The overall survival from diagnosis was similar for the two groups (P = 0.6). The median number of days hospitalized was 9 days for the older population compared to 5 days for the control group (P = 0.37). Four patients died within the first one hundred days, one (3%) among the older patient group and 3 (4.3%) in the control group. Conclusions: High dose therapy and autologous stem cell transplantation is feasible in selected patients with multiple myeloma over 70 years. It is likely that these older patients were selected based on their overall performance status, a factor that is difficult to analyze in this retrospective review. Nearly 70% of the elderly patients received full dose melphalan for conditioning (200 mg/m2). The toxicity of transplant as well as the outcome appears to be very similar to the younger patients. Patients with multiple myeloma should not be excluded from high dose therapy solely on the basis of their chronological age.

Abstract Intravascular lymphoma is a rare subtype of extranodal DLBCL characterized by the proliferation of malignant B-cells within the lumina of blood vessels. Organ involvement is variable and diffuse. Making the diagnosis can be challenging with symptoms persisting for months prior to definitive diagnosis. Treatment to date with standard anthracycline containing chemotherapy regimens has been disappointing with variable response rates, high relapse rates, and median survival times typically measured in months. We report diagnostic, treatment, and follow-up information regarding a group of patients with intravascular lymphoma evaluated at the Mayo Clinic with special attention to those receiving rituximab and/or high dose chemotherapy with or without peripheral blood autologous stem cell rescue. Methods: The medical records of patients with intravascular lymphoma seen at the Mayo Clinic between January 1970 and May 2005 were reviewed. Patients were included if they had evidence of intravascular lymphoma at the time of diagnosis of lymphoma. Pathologic specimens were reviewed for confirmation of diagnosis. Results: Twenty patients with a diagnosis of intravascular lymphoma were identified. Their median age was 66.5 years. Thirteen (65%) had B symptoms at the time of diagnosis and 13 had a performance status ≥ 3. Nine (45%) had an IPI ≥ 4. The median time to diagnosis from the onset of symptoms was 5.5 months. All had stage IV disease with biopsy proven involvement of at least one organ. The sites of disease involvement were CNS (10), marrow (7), lung (5), adrenal (3), kidney (2), lymph node, seminal vesicle, and skin (1). Two patients had involvement of three organs, six had involvement of two organs, and twelve had involvement of one organ. Nineteen patients received chemotherapy: ProMACE/CytaBOM (3), CHOP (6), RCHOP (6), DHAP (1), high dose methotrexate (1), methylprednisolone, nitrogen mustard, rituximab (1), and hyperCVAD (1). Three patients underwent peripheral blood autologous stem cell rescue after conditioning with BEAM. With a median follow-up of 60 months for all patients, the median overall survival was 8 months. No difference in outcome was seen with regard to site of organ involvement, number of organs involved, presence of B symptoms, or IPI. With a median follow-up for those receiving rituximab of 26 months, the median survival has not yet been reached while the median survival for those receiving non-rituximab containing regimens was 6.5 months. Similarly, with a median follow-up for those receiving high dose chemotherapy (hyperCVAD or BEAM) of 9.3 months, the median survival has not yet been reached while the median survival for those not receiving high dose therapy was 7 months. Conclusion: Intravascular lymphoma is a unique and aggressive subtype of DLBCL. The clinical presentation and sites of organ involvement are variable and the time from onset of symptoms to diagnosis can be prolonged. Standard chemotherapeutic treatment leads to poor outcomes. However, survival may be improved upon with newer strategies such as the use of rituximab and/or high dose chemotherapy with or without peripheral blood autologous stem cell rescue.

Abstract The proposed immune-mediated mechanisms of action of Rituximab (ADCC or “vaccinal” effect) suggest that the efficacy of rituximab therapy depends on the immunocompetency of the host. Therapies, such as IL-12, that stimulate the immune system may increase the efficacy of rituximab. Recently, we reported that absolute lymphocyte count (ALC), as a surrogate maker of immune recovery, is a survival prognostic factor in autologous stem cell transplantation for non-Hodgkin’s lymphoma (NHL). We hypothesize host immune competence (i.e, normal ALC counts) would predict a superior survival in NHL patients treated with rituximab-based regimens. The primary end-point of the study was to assess whether the ALC count prior to rituximab therapy predicted progression-free survival (PFS) and the second end-point was to identify which lymphocyte subset was responsible for affecting PFS. We studied 41 NHL patients that participated in our Phase I interleukin-12 plus rituximab study. These patients were selected because the Phase I study required baseline ALC count and flow cytometry analysis providing lymphocyte subset data prior to treatment. There were 20 females and 21 males in the study. The median age of the cohort was 53 years (range: 34–84). PFS was assessed from the initial date of treatment. The median follow-up was 42 months (1–84 months). Patients with an ALC ≥ 0.9 × 109/l experienced a superior PFS versus an ALC < 0.9 × 109/l prior to rituximab therapy (31 months vs 4 months, p < 0.0001). The relapse rate in the ALC ≥ 0.9 × 109/l group was 55% (11/20) versus 95 % (20/21) in the ALC < 0.9 × 109/l (p < 0.0016). Patients with a CD4 count ≥ 500 cells/μl also experienced a superior PFS versus a CD4 count < 500 cells/μl (21 months vs 9 months, p < 0.0062). The relapse rate in the CD4 count ≥ 500 cells/μl group was 56% (9/16) versus 88 % (22/25) in the CD4 count < 500 cells/μl (p < 0.0216). No association with PFS was identified for CD3, CD8, CD19, CD16/56, the use of IL-12, or lymphoma type by WHO classification. CD4 count was found to be an independent prognostic factor for PFS. In the subgroup of patients with follicular lymphoma, patients with an ALC ≥ 0.9 × 109/l experienced a superior PFS versus an ALC < 0.9 × 109/l prior to rituximab therapy (35 months vs 9 months, p < 0.0076). The relapse rate in the ALC ≥ 0.9 × 109/l group was 45% (5/11) versus 90 % (9/10) in the ALC < 0.9 × 109/l (p < 0.0243). Patients with a CD4 count ≥ 500 cells/μl also experienced superior PFS versus a CD4 count < 500 cells/μl (not reached vs 9 months, p < 0.0098). The relapse rate in the CD4 count ≥ 500 cells/μl group was 29% (2/7) versus 86 % (12/14) in the group with a CD4 count < 500 cells/μl (p < 0.0216). CD4 count was found to be an independent prognostic factor for PFS when compared to the Follicular Lymphoma International Prognostic Index at the time of treatment. Our data suggest the significance of an immunocompetent host in predicting the efficacy of rituximab therapy. These data support our previous report that patients with higher number of activated CD4+ cells at the lymphoma site have a better prognosis (Ansell et al, JCO2001; 19: 720–6). These findings warrant further studies to understand the role of ALC (i.e, CD4 count) in the mechanism of action of rituximab. Supported in part by CA69912

Abstract We previously have reported that autograft absolute lymphocyte count (A-ALC) is a possible prognostic factor for survival after autologous peripheral blood stem cell transplant (ASCT) for myeloma (MM). Factors affecting A-ALC in MM are unknown. We hypothesize that method of stem cell mobilization, hematopoietic growth factor (HGF) vs. HGF+Cytoxan chemotherapy (C+HGF), directly affects A-ALC collection. 191 consecutive MM patients between 1994 and 2004 were analyzed retrospectively. Patients generally were mobilized with C+HGF prior to 2003. Thereafter, C+HGF was reserved largely for those with ≥4% circulating peripheral blood plasma cells (PC), a negative prognostic indicator. No patients were transplanted in disease relapse or refractory disease. Patients also were matched for age, sex, β2-microglobulin, conventional cytogenetics, LDH, c-reactive protein, number of prior therapies, plasma cell labeling index (PCLI), pre-mobilization ALC, and % bone marrow (BM) PC. The groups HGF (n=80) and C+HGF (n=111) differed with respect to the conditioning regimen (p < 0.0001), and presence of (≥4%) circulating peripheral blood PC (p<0.005). The primary end-point of the study was to assess the correlation between HGF vs C+HGF, and A-ALC. The secondary endpoint was to determine if HGF vs C+HGF affected survival post-ASCT. Patients mobilized with HGF had a higher A-ALC compared to those mobilized with C+HGF [0.764 x 109 lymphocytes/kg (range: 0.146–1.803) vs. 0.212 (range: 0.016–1.26), p<0.0001]. No association was identified between A-ALC and conditioning regimens (p = 0.19) and PC (p = 0.31). Median overall survival (OS) and progression-free survival (PFS) were longer in those mobilized with HGF vs. C+HGF (not reached vs. 48 months, p<0.0150; not reached vs. 21 months, p<0.007, respectively). Multivariate analysis demonstrated that age ≥50 vs age ≤50 (p<0.05) and A-ALC ≥0.5 vs <0.5x109 lymphocytes/kg (p<0.0397) were independent predictors of OS. Factors influencing PFS in the multivariate analysis included circulating PC ≥4% vs <4% (p<0.0157), PCLI ≥ 1% vs PCLI ≤ 1% (p<0.0107), and A-ALC ≥0.5 vs <0.5x109 lymphocytes/kg (p<0.0042). On multivariate analysis, the method of stem cell mobilization and the conditioning regimen did not have a statistically significant effect on either OS or PFS. We hypothesize that the differences in PFS and OS seen between the HGF vs C+HGF mobilization groups are mediated through the A-ALC. These data suggest that mobilization regimens should not only collect CD34+ stem cells, but also be optimized to collect an A-ALC target which may impact on PFS and OS post-ASCT.

Abstract Two death receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5), expressed in a wide variety of cancer cell types including lymphoma, enable TRAIL (TNF related apoptosis inducing ligand), a member of the TNF ligand superfamily, to induce apoptosis. HGS-ETR1 (TRM-1, mapatumumab) is a fully human monoclonal antibody agonistic to TRAIL-R1 with preclinical evidence of anti-tumor activity in vitro and in vivo. We conducted a phase 2 multicenter study of HGS-ETR1 in 40 subjects with relapsed or refractory NHL. Patients were included on the study if they had relapsed/refractory NHL of any histologic subtype, irrespective of the number of previous treatment regimens. HGS-ETR1 was administered at 2 dose levels: 3 mg/kg (8 subjects) or 10 mg/kg (32 subjects) every 21 days in the absence of disease progression or prohibitive toxicity for up to 6 cycles. The primary endpoint was tumor response evaluated with the International Working Group Criteria after every third treatment. Responses were confirmed between 4 and 8 weeks after initial documentation of response. Secondary endpoints included safety and tolerability. The median age of subjects was 62 years (range 32–81) (24M:16F) with an ECOG performance status 0–2. Subjects had received up to 12 previous therapeutic regimens (69% received 3 or more prior regimens). Original histologic classification is presently available for 34 subjects (14 follicular, 7 diffuse large B-cell, 6 mantle cell, 1 small lymphocytic, 2 peripheral T-cell, 1 anaplastic large cell, 3 lymphomas not classified). Preliminary response data are available for all 40 subjects. 3 subjects (8%), all with follicular lymphoma, had clinical responses (1CR, 2PR). Additionally, 12/40 subjects (30%) had stable disease, and the remainder had progressive disease at the time of first evaluation. 8 subjects (7 follicular) remain on study without disease progression for >5 to >13 months. One subject with a PR (special permission) has continued to receive HGS-ETR1 (10 cycles to date). Subjects tolerated therapy well with no subjects discontinuing therapy due to toxicity related to drug. There have been 10 reported SAEs, 2 of which were considered possibly/probably related to HGS-ETR1 administration (shingles, fever). In conclusion, HGS-ETR1 can be safely administered to heavily treated NHL patients. Clinical responses were seen in 3/14 follicular lymphoma subjects to date. Final data for all subjects will be reported at the meeting. These data suggest that HGS-ETR1 has activity in heavily pretreated lymphoma patients and further studies in combination with agents active in lymphoma are justified.

Abstract MicroRNAs (miRNAs) are small noncoding RNAs that are approximately 20–22 nucleotides with critical functions in cell growth, survival, and differentiation. These conserved sequences can regulate expression of multiple genes and are often tissue specific and dysregulated in malignancies. Thus, miRNA profiling has been used to create signatures for many solid tumors. These profiles have been used to classify tumors and to help predict survival and outcome. In the present study, we utilized the DiscovArray miRNA profiling service (Asuragen Services, Austin, TX) which utilizes a custom-manufactured Affymetrix GeneChip® from Ambion that covers miRNAs derived from the Sanger miRBase (http://microrna.sanger.ac.uk/sequences/index.shtml) and over 11,000 predicted miRNAs derived from published reports. The signal processing implemented was a multi-step process involving probe-specific signal detection calls, background estimation and correction, constant variance stabilization and global normalization. For each probe, an estimated background value was subtracted derived from the median signal of a set of G-C-matched anti-genomic controls. Arrays within a specific experiment were normalized together according to variance stabilization method. Detection calls were based on a Wilcoxon rank-sum test of the miRNA probe signal compared to the distribution of signals from GC-content matched anti-genomic probes. For statistical hypothesis testing, a two-sample t-test, with assumption of equal variance, was applied. One-way ANOVA was used for multiple group comparison. Probes were considered to be differentially expressed based on two criteria: a p-value of < 0.001 and glog2 difference > 1. miRNA expression was analyzed in all malignant B lineage cells (CD19+ CD138+) (n=8), malignant B cells alone (CD19+) (n=6) and plasma cells alone (CD138+) (n=3) from Waldenström macroglobulinemia (WM) patients. The expression was compared to malignant CD19+ B cells from chronic lymphocytic leukemia (CLL) patients (n=5), malignant plasma cells (CD138+) from multiple myeloma (MM) patients (n=5) and to B lineage cells (CD19+ CD138+) (n=4), CD19+ B-lymphocytes (n=3) and CD138+ plasma cells (n=6) from healthy donors. Data analysis based on a total of approximately 11,000 miRNAs analyzed shows that CD19+ CD138+ cells (double sorting) from WM patients did not cluster as a unique group. Some samples had a pattern similar to CLL, some similar to MM and others similar to CD19+ CD138+ cells from healthy controls. This lack of clear signature was observed by others in gene expression profiling and CGH arrays. We therefore hypothesized this lack of clustering was due to the lymphoplasmacytic nature of WM cells and therefore we analyzed B cells (CD19+) and plasma cells (CD138+) separately. miRNA expression in B cells (CD19+) identifies a signature in normal B cells that is absent in both WM B cells (CD19+) and CLL cells. There is also a set of miRNAs that are absent in normal B cells that are expressed in WM B cells and CLL. In addition, WM B cells had a unique miRNA signature that is unique compared to CLL and normal B cells. An additional set of miRNAs were expressed and clustered only in CLL patients. Similar to B cells, plasma cell (CD138+) analysis in WM, MM and healthy donors shows a clustering pattern that identifies normal plasma cells from MM plasma cells. WM plasma cells had a miRNA signature that is unique only to WM patients, however, a subset of miRNAs shared an expression pattern with MM plasma cells. While miRNAs can target multiple genes, some of the genes that are targets of the miRNAs identified in this analysis include XBP-1, Blimp-1, IRF-4, Bcl-6 and TACI. These target genes are known to be important in B cell and plasma cell development. In summary, we have analyzed miRNA expression in malignant B cells (CD19+) and malignant plasma cells (CD138+) from WM patients and compared their expression pattern to their normal counterpart as well as malignant counterpart in CLL B cells and MM plasma cells. Our analysis shows that WM B cells have a miRNA signature unique to WM only and one that is shared by CLL cells. Similarly, WM plasma cells have a unique miRNA signature but also has some miRNAs that are shared by malignant plasma cells in MM. These miRNAs target genes involved in B cell differentiation. Analysis of the functional roles of these miRNAs will and their regulation will further our understanding of the regulation of B cells development in normal and malignant conditions.

Abstract Diffuse large B cell lymphoma (DLBCL) is an aggressive form of non-Hodgkin lymphoma and the treatment of these patients has improved with rituximab-based chemo-immunotherapy. However, approximately 40% of patients die of their disease and new agents with novel mechanisms of action are needed for this disease. The mammalian target of rapamycin (mTOR) has emerged as an important therapeutic target in cancer cells and rapamycin and its derivatives, which specifically inhibit mTOR, are now being actively evaluated. Recent clinical trials of mTOR inhibitors have demonstrated that a fraction of patients (35%) with relapsed DLBCL respond to single-agent temsirolimus (Smith S et al J Clin Oncol 26; May 20 Supplement abstract 8514) or everolimus (Reeder et al 2007 ASH Annual Meeting Abstracts 110 (11) abstract 121) in relapsed DLBCL, however most patients are resistant to this therapy. The mechanism of this resistance remains a subject of major therapeutic significance. Herein, we report that cells from DLBCL lines (DHL-6, Ly7 and Ly3) and primary tissues from DLBCL patients (n=10) display persistent activation of the mTOR pathway as determined by phosphorylation of mTOR targets S6 ribosomal protein (S6rp) and 4E-binding protein 1 (4E-BP1). Treatment of human DLBCL cells with various doses of rapamycin predictably demonstrated a decrease in proliferation but less than 10% reduction in overall cell survival. However, rapamycin suppressed the phosphorylation of S6rp and 4E-BP1, indicating an inhibition of raptor-mTOR (mTORC1) signaling. Paradoxically, rapamycin also concurrently increased, through a negative feedback mechanism, the phosphorylation of Akt that may contribute to drug resistance. Interestingly we found that rapamycin treatment also increased the phosphorylation of eIF4E, a survival protein downstream of mTOR, which may also be responsible for resistance of rapamycin along with Akt. To determine whether the observations found in vitro are clinically relevant, we obtained peripheral blood samples from patients with aggressive lymphoma treated with the rapamycin derivative everolimus. The levels of phosphorylated Akt and eIF4E were increased in 3 of 3 patient samples at 48 hrs and after 1 cycle compared to untreated control. Our observations therefore suggest that rapamycin derivatives potently activate Akt and eIF4E activity via activation of the mTORC2 assembly, in addition to its well-characterized ability to suppress the mTORC1 pathway. Treatment of DLBCL cells with histone deacetylase (HDAC) inhibitor LBH589 induced growth inhibition of DLBCL cells at nanomolar concentrations in a dose dependent manner in association with hyperacetylation of histones H3 and H4. LBH alone was able to inhibit the phosphorylation of S6rp and 4E-BP1, while combined treatment with rapamycin inhibited the phosphorylation of S6rp and 4EBP1 to a greater extent than either agent alone. Surprisingly LBH inhibited constitutive as well as rapamycin-induced activation of Akt and eIF4E in a time and dose dependent manner. Our co-immunoprecipitation data suggest that LBH alone was able to alter the level of intact mTORC2 by reducing the amounts of rictor bound to mTOR, which is further decreased when combined with rapamycin. In support of this model, rapamycin combined with LBH exhibited enhanced synergistic inhibitory effects on survival and proliferation of DLBCL cells. The mTOR pathway is also considered to control the translation of specific mRNA species, some of which are involved in cell cycle control and angiogenesis (e.g. cyclin D1, c-Myc and HIF-1a). LBH alone down-regulated expression of c-Myc and HIF-1a, while have no effect on cyclin D1 expression. Combination of LBH with rapamycin further decreased expression of c-Myc and HIF-1a. Overall these results indicate that pharmacological inhibition of the mTOR pathway by rapamycin and LBH interferes with essential survival and proliferating pathways in DLBCL cells. We propose that the rapamycin-induced functional blockade of Akt and eIF4E is inhibited by LBH, and the combination increased the anti tumor activity of rapamycin. In summary, our data provide a mechanistic basis for enhancing mTORtargeted cancer therapy by combining an mTOR inhibitor with a HDAC inhibitor such as LBH. A phase I/II trial of this combination is planned.

Abstract Waldenström macroglobulinemia (WM) is a B-cell malignancy characterized by the aberrant production of a monoclonal IgM protein that may lead to hyperviscosity. Although this is a major factor causing significant morbidity in patients, little is known about the mechanisms that regulate monoclonal protein synthesis. Cytokines are protein mediators that are known to be involved in many biological processes, and can profoundly affect tumor cells and the tumor microenvironment. Many cytokines have been shown to have potent therapeutic efficacy in preclinical cancer models; however, the role of cytokine networks in WM is not fully understood and few studies have described the precise functional roles of cytokines in WM. To address this issue we performed a multiplex ELISA analysis to test cytokine levels in sera from patients with WM. We found that Rantes/CCL5 is significantly elevated in WM patients and correlates with disease activity. Elevated expression of RANTES in the serum was confirmed by ELISA and was also detected in the bone marrow of WM patients by ELISA and immunohistochemistry. RANTES expression serves as a marker for recruitment of immune cells and is associated with a wide range of immune-mediated diseases. However, the impact of RANTES in WM is not known. We analyzed the expression of receptors for Rantes by flow cytometry and found that WM B cells and stromal cells express CCR1 and CCR3, but not CCR5. Using a standard chemotaxis assay, we determined that Rantes had no effect on B cell or stromal cell recruitment. Rantes also had no effect on B cell or stromal cell survival, however it did promote stromal cell proliferation (p<0.04). The interaction between Rantes and IL-6 has been described in an autoimmune disease model. Since stromal cells secrete significantly more IL-6 than WM B cells, we treated stromal cells with Rantes for 24 hr and found that Rantes increases IL-6 secretion (p<0.03). To characterize the mechanism of Rantes-mediated IL-6 secretion, we transfected stromal cells with an IL-6 promoter construct and treated with Rantes for 12 hr and found a significant increase in IL-6 promoter activity (p<0.0162) indicating Rantes can regulate IL-6 transcription. Bioinformatics analysis of the IL-6 promoter indicates the presence of multiple candidate binding sites for transcription factors that have been previously shown to play a role in the biology of B cells, including NFkB, AP1, and GLI. Co-transfection of stromal cells with an IL-6 reporter construct and a plasmid expressing GLI1, GLI2 or GLI3 demonstrates that GLI2 and GLI3 proteins can regulate the IL-6 promoter. We then transfected stromal cells with a reporter construct containing 8X-GLI binding sites and demonstrate that Rantes can regulate GLI transcription further supporting a role for the interaction between Rantes and IL-6 through GLI transcription factors. IL-6 rich tumor microenvironment supports malignant cells. Elevated IL-6 levels have no effect on survival of BCWM.1 cells or CD19+ 138+ cells from WM patients, but leads to upregulation of IgM secretion by BCWM.1 cells and CD19+ CD138+ cells from WM patients, and increases their proliferation (p<0.0039). IL-6 activates Erk1/2 and Jak/ Stat in WM and stimulation of the IgM secreting cells BCWM.1 with IL-6 in the presence of PD98059 MAPK inhibitor had no effect on IgM secretion. However, stimulation of BCWM.1 cells with IL-6 in the presence of JakI inhibitor abolished the IL-6 mediated IgM secretion suggesting IL-6 mediated increase in IgM secretion occurs through Jak/ Stat signaling pathway. Analysis of Rantes levels in other B cell malignancies including follicular lymphoma, chronic lymphocytic leukemia, monoclonal gammopathy of undetermined significance and multiple myeloma indicates that Rantes is elevated in other B cell lymphoproliferative disorders and suggest Rantes may play a similar role in other malignancies. In summary, our data identifies a novel Rantes-GLI-IL-6 interplay in the stromal microenvironment that promotes IgM production by malignant B cells. This therefore provides multiple new potential therapeutic avenues, targeting both malignant cells and the microenvironment to control malignant cell growth, and immunoglobulin secretion in WM and Ig-mediated diseases.

Abstract The tumor microenvironment in B-cell non-Hodgkin’s lymphoma (NHL) plays an important role in supporting the growth and survival of malignant lymphocytes. In contrast, the extent to which this is true in T-cell NHL is less clear. While professional monocytederived antigen-presenting cells (MDC) are required for T-cell activation and survival, a growing body of evidence demonstrates that MDC may promote the survival of malignant T cells. Immunohistochemical staining of skin biopsies from cutaneous T-cell lymphoma (CTCL) patients (n=11) demonstrated a rich infiltrate of CD68+ macrophages and CD1a+ dendritic cells (DC). As these cells are derived from CD14+ monocytes, we examined the role of monocytes in promoting survival in malignant T cells obtained from CTCL patients (n=9). Initially, peripheral blood mononuclear cells (PBMC) were either depleted of CD14+ monocytes (>85% depleted) or mock-depleted prior to being cultured. Viability of malignant CD4+CD7− T cells was determined by Annexin V/7-AAD staining. While 90.9% (S.D. +/− 0.4%) of mock-depleted malignant T cells were viable, only 73.9% (S.D. +/− 1.3%) of monocyte-depleted cells remained viable, suggesting that monocytes may promote the survival of malignant T cells. In a similar fashion, HuT-78 cells (Sézary Syndrome cell line) were cocultured with CD14+ monocytes from normal donors. Compared with HuT-78 cells alone, the presence of CD14+ monocytes resulted in a 2.7 fold increase in thymidine incorporation (n=5; S.D. +/− 0.6). This is largely due to cytokine production, as the same experiment performed with a transwell insert resulted in a 2.1 fold increase in HuT-78 thymidine incorporation (n=5; S.D. +/− 0.4). Similar results were obtained using additional Sézary Syndrome (i.e. SeAx) and Mycosis Fungoides (i.e. MyLa) cell lines. Monocytes obtained from normal donors were subsequently cultured and cell-free conditioned media was obtained 48 hours later. Media supplemented with monocyte-conditioned media (monocyte-CM) prevented the induction of apoptosis in CTCL cell lines as measured by thymidine incorporation, trypan blue exclusion and Annexin V/propidium iodide staining. This affect was monocyte-specific, as neither T-cell nor B-cell conditioned media were observed to promote survival of CTCL cell lines. Furthermore, monocyte-CM had no affect on resting or anti-CD3 activated normal T cells. We next cultured malignant T cells obtained from PBMC (n=6) or skin biopsies (n=3) from CTCL patients in the presence or absence of monocyte-CM and assessed cell viability by Annexin V staining. 32.1% (S.D. +/− 14.7%) and 60.5% (S.D. +/− 21.5%) of malignant T cells isolated from PBMC remained viable in the absence or presence of monocyte-CM, respectively; 13.0% (S.D. +/− 10.8%) of malignant T cells isolated from skin biopsies remained viable, compared with 26.5% (S.D. +/− 8.2%) of cells grown in the presence of monocyte-CM (p=.03). Given the prevalence of MDC within CTCL-involved skin and their potential role in promoting the survival of malignant T cells, one may predict that malignant T cells may recruit monocytes in a chemokinedependent fashion. Therefore, cell-free conditioned media from CTCL cell lines (HuT- 78, SeAx, MyLa) was collected and used to promote monocyte chemotaxis in a standard chemotaxis assay. Only neutralization of CCL5 (RANTES) was capable of abrogating monocyte chemotaxis, demonstrating that the production of CCL5 by malignant T cells promotes monocyte migration. Therefore, we examined serum CCL5 levels by ELISA from both normal donors (n=24) and CTCL patients (n=23) and found an approximately 3-fold elevation in serum CCL5 in CTCL patients (normal donors: mean CCL5 10.0 ng/mL; 95% CI 7.1–13.0; CTCL patients: mean 29.2 ng/mL; 95% CI 20.6–37.8; p<0.0001). Serial serum samples were available for 6 patients, 4 of whom had progressive disease. Serum CCL5 increased from a mean of 17.9 ng/mL before progression (S.D. +/− 7.0) to 44.8 ng/mL (S.D. +/− 20.0) after progression (p=.04). In contrast, serum CCL5 decreased by at least 50% in both patients with responsive disease. Our findings demonstrate that monocytes, recruited by malignant T cells in a CCL5-dependent fashion, promote the survival of lymphoma cells in CTCL, thus raising the possibility that targeting tumor-associated monocytes and MDC may represent a novel therapeutic strategy in CTCL.