Witzig, Thomas E.

Abstract Background: Inhibitors of HMG-CoA reductase (“statins”) are effective in reducing the risk of cardiovascular disease. Preclinical data from rodents suggested that they may increase the incidence of some cancers, including lymphoma. However, monitoring of randomized trials in humans have generally found decreased cancer risks, and these findings have been supported by a growing number of observational studies, including three recent reports of a protective association in NHL. The suggested anti-carcinogenic mechanisms for statins include their impact on inflammatory (including a shift from a Th1 to Th2 profile) and angiogenesis pathways, as well as the induction of apoptosis by modulation of signaling pathways, all of which are of biologic relevance in NHL. Methods: We evaluated the history of statin use and risk of NHL in a clinic-based study of 243 newly diagnosed NHL cases and 499 frequency matched controls enrolled at the Mayo Clinic from 2002-2005. Risk factor data were collected using self-administered questionnaires, and included history of use of cholesterol lowering drugs two or more years before diagnosis (for cases) or enrollment (for controls); specific drug names were not available. Unconditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, gender, and residence. NHL subtypes were centrally reviewed, and subtype-specific risks were estimated using polychotomous logistic regression. Results. The mean age at diagnosis was 59.5 years for cases and 55% were men; among controls, the mean age at enrollment was 61.8 years and 54% were men. Twenty-one percent of the cases reported ever using statins compared to 30% of the controls, supporting a lower risk of NHL for ever users (OR=0.69; 95% CI 0.47–1.00). The lowest risk was seen for the longest users; i.e., compared to never users, person who had 10 or more years of use had the greatest reduction in risk (OR=0.52; 95% CI 0.24–1.10). A history of high cholesterol was also inversely associated with risk of NHL (OR=0.72; 95% CI 0.55–0.93). However, the association for the type of treatment for cholesterol lowering varied. Those who were medically treated had inverse association with risk of NHL (OR=0.63; 95% CI 0.46–0.86), while the no treatment and dietary change only groups were found to have no association with risk. The reduction in NHL risk with medical treatment was specific to statin use, as the use of other cholesterol lowering drugs was not associated with risk (OR=1.13; 95% CI 0.50–2.57). These results were not confounded by education, family history of NHL, body mass index, cigarette smoking or alcohol use. In subtype analysis, the inverse association was seen for diffuse large B-cell lymphoma (OR=0.27; 95% CI 0.08–0.90), but not for CLL/SLL or follicular NHL. Conclusions. Statin use was associated with a lower risk of developing NHL, particular diffuse large B-Cell lymphoma.

Abstract Background: Primary systemic amyloidosis (AL) is an incurable plasma cell disorder. Lenalidomide, especially in conjunction with dexamethasone, has been shown to be highly active in patients with multiple myeloma. We previously reported a hematologic response rate of 41% and an organ response rate of 23% among 22 AL patients treated with lenalidomide and on-demand dexamethasone (Dispenzieri et al, Blood 2007). Long term outcomes of AL patients treated with lenalidomide have not yet been described. Methods: Thirty-seven patients were treated on an IRB approved treatment trial with single agent lenalidomide, starting doses of 25 mg in 22 and reduced dose of 15 mg in the last 15. If progression within or no evidence of hematologic response after 3 cycles, dexamethasone was added. Patients were classified according to cardiac biomarker stage (cut-offs for serum troponin T <0.035 ng/ml and NT-proBNP <332 pg/ml--Stage I neither above cutoff; Stage III, both above cut-off; and Stage II, any one above cut-off). Survival estimates were done according to the methods of Kaplan and Meier. Results: Median age was 64 years (range 44–88), with 70% male. Sixty-five percent of patients were previously treated, and the median time from diagnosis to study entry was 8.9 months (range 0.4–237). The biomarker staging breakdown was: I, 16%; II, 43%; and III, 41%. As of 7/11/08, 5 patients remain on active therapy. The overall hematologic response rate was 43% (1 CR and 15 PR), with only one patient responding to single agent lenalidomide, and the overall organ response rate was 20%. If one excludes the 13 patients who did not complete 3 months of therapy and have the opportunity of having dexamethasone added to their program, the respective hematologic and organ response rates were 62% and 32%. With a median follow-up of 33.6 months (range 14.4–42), twenty-two patients (59%) have died, but only 2 had deaths possibly related to treatment. Median duration of response, progression free survival and overall survival were 31 months, 14.8 months (95%CI: 5.7–28.1), and 18.8 months (95%CI: 11.7-not reached), respectively. Overall survival from diagnosis was 48 months (95%CI: 21.6–153.6). As shown in Table below, outcomes were dependent on underlying risk stratification and ability to stay on therapy. High risk patients were more likely to drop out early and less likely to respond. High risk patients had shorter OS All Patients Outcome Stage I Stage II Stage III p N 6 16 15 Survival from enrollment, mo NR 18.8 (11.7–33.6) 5.7 (3.2–18.3) 0.01 Survival from Diagnosis, mo NR 48.4 (20.4–62) 21.1 (11.2–31.7) 0.005 Progression Free Survival, mo 34.7 (33.7–NR) 18.3 (6.2–28.1) 4.4 (3–8.6) NS Drop out by cycle 4, % 17 31 60 NS Median # of cycles administered 31 6 3 0.04 Time to response, mo 6.2 (3.6–9.3) 6.4 (5.2–NR) 4.7 (3.8–NR) NS Hematologic response rate, % 83 38 27 0.05 Organ response rate, % 40 20 13 NS Duration of Response, mo NR 27.2 (13.6–NR) NR NS Subgroup analysis of patients receiving >3 cycles of therapy (i.e getting Len and Dex) N 5 12 7 Time on therapy, mo 35.2 8 10.5 Hematologic Response Rate, % 100 50 56 Organ response rate, % 50 27 25 Conclusions: Based on these data, single agent lenalidomide is not recommended for patients with AL; however, lenalidomide in combination with dexamethasone can be associated with good progression free and overall survival rates, even among patients with relapsed or refractory disease.

Abstract Background: The plasma cell labeling index (LI), a slide-based measure of the percentage of bone marrow plasma cells in the S-phase of cell cycle, is a powerful prognostic tool in multiple myeloma (MM). A high LI is a marker of poor outcome, and is a useful adjunct to cytogenetics and fluorescent in-situ hybridization to risk-stratify MM patients. It has been shown to provide additional prognostic information in International Staging System (ISS) stages 1 and 2 patients treated with conventional chemotherapy ± autologous stem cell transplantation. However, the impact of a high LI is not known in patients receiving novel agents that have been integrated into the current treatment paradigm of newly diagnosed MM. The objective of this study was to determine the value of LI in patients treated with thalidomide-dexamethasone (Thal/Dex) or lenalidomide-dexamethasone (Len/Dex). Patients and Methods : Data from 125 newly diagnosed MM patients enrolled in clinical trials with either thalidomide (200mg/d) plus dexamethasone (Thal-Dex; n=50), or lenalidomide (25 mg/d on days 1–21 of a 4-week cycle) plus dexamethasone (Len-Dex; n=75) as initial therapy, were utilized. Patients within both the studies were categorized into 2 LI groups based on baseline LI: high (≥1%) vs. low (<1%) LI. Overall survival (OS) and progression-free survival (PFS) were estimated using Kaplan Meier method, and compared between the two LI groups within the Thal Dex and Len-Dex studies using log rank tests. Results : The median follow-up for patients on Thal-Dex and Len-Dex was 7.5 and 3 years, respectively. 36% (18/50) of patients in the Thal-Dex study and 35% (26/75) in the Len-Dex study had high LI. The baseline patient-characteristics, including age, stage (ISS), lactate dehydrogenase, calcium, hemoglobin and creatinine were comparable between the 2 studies. The median OS for patients receiving Thal-Dex was 4.7 years (95% CI 3.1–8.1); 2.3 years (95% CI 1.3–4.6) for patients with LI ≥1 compared to 6.9 years (95% CI: 3.9–NA) for those with LI <1 (P=0.02). The median OS for patients on Len-Dex was not reached for either the high or low LI group (P=0.80). The median PFS for all Thal-Dex patients was 1.7 years (95% CI: 1.4–3.1); 1.3 years (95% CI: 0.2–2.0) for patients with high LI vs.2.3 years (95% CI: 1.3–3.3) for patients with low LI; P = 0.01. The median PFS for Len-Dex patients was 2.6 years (95% CI: 1.8–3.1) years, and no significant difference was observed between the 2 LI groups, with PFS of 2.3 years (95% CI: 1.4–3.1) for patients with high LI, and 3.1 years for patients in the low LI group. Due to a shorter median follow-up of Len-Dex patients, a separate analysis censoring all patients in both the studies at 3 years was performed with similar results. Conclusion : LI remains a significant determinant of PFS and OS in newly diagnosed MM patients treated with Thal-Dex, with high baseline LI predicting poorer outcome. In contrast, during first 3 years of follow-up, the unfavorable prognostic effect of LI is not apparent with Len-Dex therapy, and longer follow-up is needed to determine if Len-Dex therapy overcomes the poor prognostic effect of high LI. Figure Figure

Abstract Background: Our previous work has shown that malignant B cells induce the development of intratumoral Treg cells that inhibit the host anti-tumor response. In contrast to an increase in Treg cells, we found that the number of effector T helper cells (TH1, TH2 and TH17) was low in B-cell NHL tumors, suggesting an imbalance between Treg and TH cells in the tumor microenvironment. Understanding the mechanism(s) of this imbalance is important to the development of treatments to enhance host immunity and in previous work we have shown that signaling through CD70, CD80 and CD86 plays a role. Since soluble factors, particularly TGF-β, have an important role in directing T-cell differentiation, we evaluated in this study the role of TGF-β in the lymphoma microenvironment. Goal: To determine the effect of TGF-β on the generation of intratumoral TH1, TH17 and Treg cells in human B-cell NHL. Results: Human B-cell NHL specimens were obtained from consenting patients and were used for all experiments. Using an ELISA assay, we found that malignant B cells variably secrete TGF-β - median 100 pg/ml per million cells (range: undetectable −229 pg/ml, n=7). Using flow cytometry, we showed that addition of exogenous TGF-β enhanced the expression of Foxp3+ in activated CD4+ or CD4+CD45RA+ or CD4+CD45RO+ nodal T cells, suggesting that TGF-β promotes the generation of Treg cells in tumor microenvironment. In contrast, TGF-β suppressed expression of IFN-g in activated CD4+ T cells and inhibited the up-regulation of IL-12 and IL-23-induced IFN-γ expression in CD4+ cells, indicating that TGF-β suppresses the generation of TH1 cells. TGF-β alone slightly inhibited IL-17 expression in CD4+ T cells; however, TGF-β, in the presence of IL-6 and IL-23, upregulated IL-17 expression in CD4+ T cells, suggesting proinflammatory cytokines are able to reverse the suppression induced by TGF-β. These results indicate that TGF-β plays an important role in the regulation of intratumoral TH17 cell generation. In additional experiments, TGF-β was found to exert a suppressive effect on the proliferation of both CD4+ and CD8+ intratumoral T cells. However, treatment with TGF-β enhanced IL-2 production by intratumoral CD4+ T cells detected by intracellular staining of flow cytometry. Interruption of IL-2 signaling by anti-IL-2 Ab abolished the upregulation of TGF-β-mediated Foxp3 expression and enhanced the production of IL-17 in CD4+ T cells. Furthermore, treatment with anti-IL-2 Ab reversed the inhibition of NHL B cell-mediated TH17 cell generation. Conclusion: These results suggest that TGF-β controls the generation of TH1, TH17 and Treg cells contributing to the imbalance of effector TH cells and inhibitory Treg cells in the tumor microenvironment of B-cell NHL through IL-2. Since malignant B-cells produce TGF-β, these results further support the important role of malignant B cells in the regulation of intratumoral T cell generation and the host immune response.

Abstract MALT lymphoma is a genetically unique disorder and five mutually exclusive chromosomal translocations have been identified thus far in this disease: t(11;18), t(14;18), t(1;14), t(1;2) and t(3;14). Despite this genetic heterogeneity, all but one of the translocations affect the NF-κB signaling pathway, which is critical if not essential for antigen receptor mediated B- and T-cell activation and likely enhances MALT lymphoma growth. However, the known translocations are present in only 25% of cases suggesting that additional uncharacterized translocations exist. We used long-distance inverse polymerase chain reaction (LDI-PCR) technique to clone a novel IGH translocation partner in a 60-year-old female with a history of Sjogren’s syndrome and primary MALT lymphoma involving the parotid gland. The breakpoint on chromosome 14 occurred within the IGHSA2 switch region while the breakpoint on chromosome X fell within Xp11.4. The breakpoint on chromosome Xp11.2 fell between two genes, GPR82 and GPR34, both of which code for orphan G-protein coupled receptors (GPCRs). The breakpoint also fell within and disrupted a larger gene called CASK (a membrane-associated guanylate kinase-MAGUK). To determine the prevalence of this translocation in MALT lymphoma we performed interphase FISH studies on 64 MALT lymphomas using a breakapart probe for GPR82. Only the index case had an abnormal split signal pattern. We next designed primers to perform real-time quantitative RT-PCR for the genes located on Xp11 and found that GPR34 RNA was highly expressed, a 49-fold increase, in the patient carrying the t(X;14)(p11.4;q32) translocation compared to a normal splenic B cell control. Expression of GPR82 and CASK RNA was similar between normal B cells and the patient carrying the t(X;14)(p11.4;q32) translocation. These data suggest that the GPR34 gene is dysregulated upon its translocation to the IGHSA2 switch region. We then measured GPR34 RNA expression in a panel of MALT lymphomas (n=12) and found that GPR34 was expressed at levels higher than that seen in normal B cells with an average increase of 11 fold, 9/11 of which had an expression lever greater than 3-fold over normal splenic B cells. In a gastric MALT lymphoma specimen arising in a 67-year-old male, we saw a 64 fold increase in GPR34 expression. Interphase FISH studies performed on this specimen showed an extra intact GPR34 signal but no translocation involving IGH or GPR34, suggesting that other mechanisms, including gene dosage effect, can upregulate GPR34. GPR34 RNA was also detected in other normal B cell populations and histologic subtypes of NHL but not to the extent seen in MALT lymphoma; values represent the expression of GPR34 normalized to β-actin and a normal B cell control (value of 1.0): t(X;14)(p11.4;q32) specimen, 49.0; MALT lymphoma, 11.0 (n=12); peripheral blood B cells, 0.48 (n=2); normal bone marrow B cells, 0.97 (n=3); follicular lymphoma, 2.47 (n=3); marginal zone B cell lymphoma, 2.47 (n=3); diffuse large cell lymphoma, 0.36, (n=3); mantle cell lymphoma, 2.67 (n=3); and multiple myeloma 0.52 (n=6). The receptor encoded by GPR34 is most similar to the PY2 receptor subfamily of GPCR and GPR34 mRNA transcripts are particularly abundant in mast cells while lower levels were detected in other immune cells including B cells. However, little is known about its natural ligand, biologic function, or the signaling cascades activated by its engagement. Because the NF-κB signaling pathway has been shown to be a common downstream target of MALT lymphoma translocations we first examined the impact of GPR34 expression on phosphorylation of Iκ-Bα. Transient expression of a YFP-GPR34 expression plasmid in HeLa cells results in increased phosphorylation of Iκ-Bα compared to the YFP control. Additionally, we observed increased phosphorylation of ERK1/2 in GPR34-expressing cells, however no change in phosphorylation of GSK3β was detected. In summary, these data identify a novel IGHS translocation partner in MALT lymphoma and suggest that dysregulation of GPR34 is commonly found in MALT lymphoma. Overexpression of GPR34 results in activation of the NF-κB and MAP kinase pathways and may be a novel mechanism by which MALT lymphoma occurs.

Abstract Introduction: Mantle-cell lymphoma (MCL) is a type of B-cell non-Hodgkin lymphoma (NHL) that typically responds to initial chemo-immunotherapy, but with a relatively short duration of response (DR) and progression-free survival (PFS) when treated with conventional chemotherapy agents. Although the overall survival (OS) of MCL has improved, most patients are not cured and new agents are needed. A sub-analysis of a recent phase II trial (NHL-002) investigating the efficacy and safety of lenalidomide in patients with relapsed or refractory MCL, demonstrated a promising overall response rate (ORR) of 53% with a median DR of 11.9 months. A confirmatory international phase II trial (NHL-003) of single-agent lenalidomide was initiated for patients with relapsed/refractory aggressive NHL that had received at least one prior treatment and had measurable disease. In this report, we analyze the current results from the MCL patients enrolled in this trial. Methods: Patients with relapsed or refractory MCL and measurable disease ≥2 cm after at least 1 prior treatment regimen were eligible. Patients received 25 mg of lenalidomide orally once daily on days 1–21 of every 28-day cycle. Patients continued therapy until disease progression or toxicity. The 1999 IWLRC methodology was used to assess response and progression. Results: This report focuses on the 39 MCL patients that were enrolled and evaluable for response assessment. Median age was 66 (33–82) years and 29 (74%) patients were male. Median time from diagnosis to lenalidomide treatment was 3.4 (0.4–9) years. Patients had received a median of 3 (1–8) prior treatments, and 23% (9/39) of patients had received prior bortezomib treatment. The ORR with lenalidomide was 41% (16/39), including 13% (5/39) complete response (CR)/unconfirmed CR, and 28% (11/39) partial responses. Ten (26%) patients had stable disease. The most common grade 3 or 4 adverse events were neutropenia (51%) and thrombocytopenia (25%), anemia (13%), fatigue (10%) and febrile neutropenia (10%). Conclusion: These results confirm that lenalidomide oral monotherapy is effective in the treatment of patients with relapsed or refractory MCL, with manageable side effects.

Abstract Background: A significant percentage of DLBCL patients present with a composite histology, often seen as a node containing both follicular lymphoma and DLBCL or DLBCL in the node and discordant indolent lymphoma in the bone marrow. Literature from the pre-rituximab era suggests DLBCL patients with transformed lymphoma or composite histology have worse outcome than de novo DLBCL. Here we report on early events in a cohort of R-CHOP treated patients. Goal: To determine whether patients with composite lymphoma have an inferior event free survival (EFS) and overall survival (OS) compared to de novo diffuse large B-cell lymphoma when treated with R-CHOP. Methods: Newly diagnosed patients treated with an R-CHOP containing regimen were prospectively enrolled in our Lymphoma SPORE registry from 9/2002 through 6/2007. Pathology was centrally reviewed. All patients were followed for retreatment, disease progression, and death. Results: 401 DLBCL patients were enrolled; 14% (57/401) had a composite histology. 33 patients had DLBCL and another histology, predominantly follicular lymphoma (n=29), in the same node. 20 patients had a non-DLBCL histology in a distinct location from the DLBCL; this was primarily indolent lymphoma in the bone marrow (n=15). 4 patients had both. 19% (75/401) of patients died during follow-up and 30% (121/401) had an event (death due to any cause, progression, or retreatment). Median follow-up for living patients was 34 months (range, 5–73). Composite DLBCL patients had higher event-free (3 year EFS = 79%) and overall (3 year OS = 93%) survival then de novo DLBCL (3 year OS = 66%, 3 year EFS 79%), p=0.05 and p=0.005 respectively. These differences remained statistically significant after adjusting for the International Prognostic Index (IPI): EFS HR = 0.53, 95% CI: 0.29–0.97, p=0.02; OS HR=0.28, 95% CI: 0.10–0.76, p=0.002. OS and EFS for composite DLBCL more closely resembled R-CHOP treated grade III follicular lymphoma (A,B) from the same cohort (3 year EFS = 81%, 3 year OS = 93%). Improved outcome for composite DLBCL was consistent whether the additional histology was in the same node or distinct from the DLBCL. Conclusions: R-CHOP treated DLBCL patients with indolent discordant bone marrow involvement or other composite histology have improved early OS and EFS compared to de novo DLBCL. Further follow-up is needed to assess the long-term prognosis of composite DLBCL in the rituximab era. Histology N Age > 60 Stage III/IV LDH > ULN PS > 1 >2 EN Sites 3 YR EFS 3 YR OS * Denotes statistically significant difference at p=0.05 de novo DLBCL 344 58% 56% 56% 17% 22% 66% 78% Composite DLBCL 57 65% 77%* 34%* 18% 32% 79%* 93%* Figure Figure

Abstract Background: The combination of lenalidomide and dexamethasone (Rev/Dex) has been shown to be a highly effective therapy for multiple myeloma (MM). Over half of the patients with newly diagnosed MM achieve a complete response with prolonged therapy. More recently, a phase III trial demonstrated improved survival with use of lenalidomide and low dose dexamethasone with one year survival in excess of 90%. We report the initial results from a phase II trial combining lenalidomide and low dose dexamethasone with cyclophosphamide (CRd) as initial therapy of newly diagnosed MM. Methods: The trial was initiated in July 2006 and completed the target accrual of 33 patients by July 2007. The treatment protocol consisted of lenalidomide given orally at a dose of 25 mg daily on days 1–21 of a 28-day cycle. Dexamethasone (dex) was given orally at a dose of 40 mg on days 1, 8, 15, and 22 of each cycle. Cyclophosphamide at a dose of 300 mg/m2 was given on days 1, 8, and 15 of each cycle. Patients also received an aspirin once daily as thromboprophylaxis. Response was defined as a decrease in serum monoclonal (M) protein by 50% or higher and a decrease in urine M protein by at least 90% or to a level less than 200 mg/24 hours, confirmed at least 4 weeks apart. Results: The median age was 63 years (range, 44–79). Eight patients (24%) had ISS stage III disease. At this time, 19 of the 33 patients are evaluable for confirmed responses (i.e., off-study or completed at least 4 cycles of therapy). Of these, 2 achieved VGPR and 13 had a partial response giving an overall response rate of 79%. The response rate was affected by 5 of 19 patients who went off study within three cycles due to toxicities [interstitial nephritis (1 pt), multiple grade 3 toxicities including infection (1 pt) atrial fibrillation and infection (1 pt)] or alternative treatment [no response and possible renal toxicity (1 pt) and progression at 4 cycles (1 pt)]. Overall, hematological toxicity was the most common with grade 4 toxicity seen in 6 patients (20%). Non-hematological grade 3 or higher toxicities included fatigue (4 pts), thrombosis (3 pts) and renal failure (2 pts). One patient with thrombosis came off study for other toxicities, and the other two continued on study with anticoagulation. Thirteen patients (43%) had dose reductions of both cyclophosphamide and lenalidomide, most commonly due to hematological toxicity. So far, 12 patients have gone off study, 6 went to stem cell transplant, 3 due to adverse events, 1 due to disease progression and 2 patients went to alternate treatment. Conclusions: CRd has excellent activity in newly diagnosed myeloma with an estimated overall response rate of 79%. Response evaluation of the entire 33 patients will be presented at the meeting. We believe that the initial use of a 300 mg/m2 dose of cyclophosphamide resulted in 5 of the first 19 pts experiencing early toxicity and withdrawal. As a result, an expansion of the current trial is evaluating lower doses of cyclophosphamide (300 mg fixed dose). Full analysis of this study will be needed to determine if CRd can improve outcome compared to Rd.

Abstract B cell non-Hodgkin lymphoma (NHL) is a serious and frequently fatal illness. Some of the genetic changes that lead to lymphoma have been discovered, but many of the other contributing mechanistic details underlying transformation events are not yet known. Members of the TNF super-family have been shown to be key mediators in the formation and regulation of both normal and malignant cell growth. APRIL (A Proliferation Inducing-ligand), a TNF family member expressed by monocytes, macrophages, and tumor cells, stimulates B-cell NHL growth and transgenic over-expression of APRIL in mice results in B cell hyperplasia and lymphoma. The ability of APRIL to bind to TNFR related receptors, BCMA (B Cell Maturation Antigen) and TACI (Transmembrane Activator and CAML Interactor), and with lower affinity to heparan sulfate proteoglycans (HSPG) has complicated studies to better understand APRIL mediated signaling. It has been shown that NHL cells variably express TACI and BCMA, with TACI being most predominant, however, the specific mechanisms of how APRIL induces NHL cell growth remain to be fully defined. Therefore, we sought to specifically characterize APRIL-mediated signaling events through TACI to better understand the role of this receptor-ligand interaction in B cell NHL biology. Using a TACI-expressing NHL cell line (Karpas) we found that APRIL consistently increased NHL cell proliferation, but had very little effect on cell survival. Since the PI-3K/Akt pathway has been shown to be important in regulating cell cycle progression, we explored the possibility that APRIL-TACI interactions resulted in activation of this pathway. We found that stimulation of TACI-expressing NHL cells with APRIL results in phosphorylation of Akt but had no effect on NF-kB classical pathway activation. Because APRIL can also bind to cells via proteoglycans, we also tested the ability of APRIL to activate Akt in the presence of heparin and found that APRIL-mediated Akt phosphorylation was still detectable. These results suggest that APRIL-mediated signaling occurs independent of proteoglycan binding. In addition to activating Akt, we also found that stimulation of NHL cells with APRIL resulted in up-regulation of cyclin D1 and p21, but not c-myc and p27. Inhibition of the PI3K/AKT signal transduction pathway with the pharmacological inhibitor wortmannin prevented APRIL-induced proliferation as well as up-regulation of p21 and cyclin D1 levels suggesting that PI-3K kinase is required. To further substantiate the contribution of TACI in APRIL-mediated signaling, we selectively targeted TACI expression using a siRNA approach. When TACI expression was inhibited, APRIL no longer induced NHL-B cell proliferation, Akt phosphorylation or up-regulation of p21 and cyclin D1. Taken together, these studies suggest that APRIL-TACI interactions result in activation of the PI3K/Akt pathway and up-regulation of cyclin D1 and p21, and help define the mechanism by which APRIL enhances B cell NHL growth. The inhibition of APRIL by blocking APRIL/receptor or interruption of downstream signaling may provide potential therapeutic option for patients with B-cell non-Hodgkin’s Lymphoma.

Abstract Background: Indolent non-Hodgkin’s lymphoma (NHL) has a median survival as long as 10 years but is rarely cured. Lenalidomide (Revlimid®), an immunomodulatory drug, is approved in the US for treatment of myelodysplastic syndromes associated with a del[q5] cytogenetic abnormality and is approved both in the US and the EU for the treatment of relapsed/refractory multiple myeloma. Lenalidomide also has activity in chronic lymphocytic leukemia and cutaneous T-cell lymphoma. Aim: This study was designed to assess the safety and efficacy of lenalidomide monotherapy in patients with relapsed/refractory indolent NHL. Methods: Patients with relapsed/refractory indolent NHL with measurable disease ≥ 2cm after at least 1 prior treatment regimen were eligible. Patients received 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continued therapy for 52 weeks as tolerated or until disease progression. Response and progression were evaluated using the IWLRC methodology. Results: Forty-three patients were enrolled in the study and included in this analysis. The median age was 63 (43–89) and 17 were female. Histology was small lymphocytic lymphoma [SLL] (n=18), follicular center lymphoma grades 1, 2 [FCL] (n=22), nodal marginal B-cell lymphoma (n=2) and extranodal marginal zone B-cell lymphoma of MALT type (n=1). Median time from diagnosis to lenalidomide treatment was 4.5 (0.4–24) years and median number of prior treatment regimens was 3 (1–15). Eleven of the 43 patients (26%) exhibited an objective response (2 complete responses (CR), 1 complete response unconfirmed (CRu), 8 partial responses (PR)), 15 had stable disease (SD), 13 had progressive disease (PD) and 4 were not evaluated. Responses included 4/18 SLL (22%) and 7/22 FCL (32%). Median time to response was 3.6 months (range 1.7–4.1). Progression free survival is 4.6 months for all patients, > 7.7 months (range 4.4 - > 13.5) for responding patients and ongoing. Sixteen patients (37%) required at least one dose reduction with a median time to first dose reduction of 2 months (0.5–9.6). The most common Grade 4 adverse event was neutropenia (14%) and the most common Grade 3 adverse events were neutropenia (21%) and thrombocytopenia (12%). Conclusion: Lenalidomide oral monotherapy is active with manageable side effects in relapsed/refractory indolent NHL.