Witzig, Thomas E.

Abstract Abstract 4168 Background: Primary Pulmonary MALT lymphoma represents 15–20% of Extranodal Marginal Zone Lymphomas of Mucosa Associated Lymphoid Tissue (MALT). In contrast to the more common gastric MALT lymphoma, natural history, prognosis and treatment outcomes for primary pulmonary MALT lymphoma are not well defined. Herein, we report a single institution experience. Methods: Consecutive patients with primary pulmonary MALT lymphoma registered in the Mayo Clinic Lymphoma Database, which includes all consenting patients with lymphoma seen at Mayo Clinic Rochester, were reviewed for clinical features, treatment outcome progression free survival (PFS) and overall survival (OS). The pathology for all patients was centrally reviewed by hematopathologist and the diagnoses were based on WHO lymphoma classification criteria. PFS and OS were assessed using the Kaplan–Meier method and the Cox proportional hazard model was used to assess the impact of variables on PFS and OS. Results: Between December 1986 and June of 2009, ninety-seven patients with primary pulmonary MALT lymphoma were enrolled. The median age at diagnosis was 63 years (range 31–87). There were 43 (44%) males. The initial presentation was a unilateral pulmonary lesion (n=47, 48%), bilateral pulmonary lesions (n=41, 42%), and pulmonary lesion with intrathoracic lymphadenopathy (n= 4, 4%). Bone marrow involvement and presence of B symptoms were 4, 4% and 5, 5%, respectively. International Prognostic Index (IPI) was 0–1, 2–3 and 4–5 in 69, 25 and 1 patient(s) respectively. The median follow-up was 10.4 years. The estimated median OS was 13. 6 years and the median PFS was 5.5 years (Figure). In a multivariate analysis, age >60 (p=0.02) and ECOG PS>2 (p=0.01) were associated with shortened survival. The IPI and age adjusted IPI were not predictive of overall survival. The treatment outcomes for the most common treatment modalities are summarized in the Table below. The median PFS of the 38% of patients who had a complete surgical resection was excellent at 11.2 years; whereas for observed patients with residual disease after biopsy was 3.2 years. Only 8 patients received single agent rituximan with relatively low response rate. Summary: The prognosis of primary pulmonary MALT lymphoma is favorable, with a median survival of over 13 years. In patients with resectable disease, surgery alone is associated with excellent disease control. Further prospective studies are needed to define the optimal treatment of primary pulmonary MALT lymphoma. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Ixazomib is an experimental, orally bioavailable, proteasome inhibitor that has demonstrated anti-tumor activity in relapsed multiple myeloma (MM). In the dose escalation studies, ixazomib was tolerated up to a dose of 5.5 mg given every week as a single agent, while a dose of 4 mg was utilized in the combination studies with lenalidomide. We undertook this study to examine the efficacy and tolerability of the two doses of ixazomib in combination with dexamethasone in patients with relapsed MM. Patients and methods: This was a randomized phase 2 study of two doses of ixazomib (4mg; Arm A or 5.5 mg; Arm B) given weekly for three weeks with a week off along with weekly dexamethasone (40 mg) in patients with relapsed MM, who are proteasome inhibitor na•ve (including bortezomib) or have received less than 6 cycles of therapy with bortezomib and had a PR or better with no progression at the time of discontinuation. The primary objective was to determine the confirmed overall response rate (>=PR); secondary objectives included progression free and overall survival. A total of 71 patients were accrued from February 2013 to April 2015; one patient was ineligible. Results: Baseline characteristics were similar in the two arms; median age across the study was 70 years (46-84); 53% were male. Median number of prior therapies was 4 (range 2-6); 90% of the patients had prior IMiDs, 70% had prior transplant and 29% had prior bortezomib. At a median follow up of 10 months, 17 (49%) and 19 (54%) of patients had disease progression in arms A and B respectively with 12 (34%) patients in each arm still continuing on treatment. All patients in each arm were evaluable for response; the overall response rates were 31% in arm A (95%CI: 17-49) and 51% (95%CI: 34-69) in Arm B. The depth of response, event free survival and overall survival are outlined in Table 1. Among the patients with no prior bortezomib exposure the response rates were 38% for Arm A and 52% for Arm B. The treatment was well tolerated with 2 patients in each arm discontinuing treatment for adverse events; there were no on study deaths. A grade 3 or higher AE that was at least possibly related to treatment was seen in 21% and 54% in Arms A and B respectively; with 15% and 37% hematologic and 6% and 29% non-hematologic AEs. The most common attributable toxicities encountered included fatigue, thrombocytopenia, diarrhea and nausea with more grade 3 toxicities among Arm B. Peripheral neuropathy, possibly related to ixazomib, was seen in 55% (only grade 1 or 2) in arm A and 43% (2 patients with grade 3) in Arm B. Toxicities led to dose reduction of ixazomib in 17% and 43% of patients in Arm A and B respectively; the median number of cycles administered were 5 (1-24) and 5 (1-22) respectively. Conclusions: Ixazomib in combination with dexamethasone was well tolerated with significant anti-myeloma activity in this group of patients with relapsed MM. Deep responses including stringent CR were observed. The higher dose of ixazomib appears to be associated with a higher response rate but with higher rate of adverse events requiring dose reductions. Table 1. Treatment outcome in all patients Arm B (4 mg) (N=35) Arm C (5.5 mg) (N=35) Response Rate 31% (95%CI: 17-49) 51% (95%CI: 34-69) No. of Responders 11 18 sCR 0 1 CR 1 0 VGPR 7 8 PR 3 9 MR 5 1 Median Overall Survival1 NA NA 6 Months 100% 100% Median Event Free Survival1,2 8.4 mos (95%CI: 4.3-13.2) 8.2 mos (95%CI: 3.8-16.3) %Event Free at 6 Months 60% (95%CI: 45-81) 60% (95%CI: 45-81) Median Duration of Response1 16.7 mos (95%CI: 9.3-22.0) 16.3 mos (95%CI: 7.0-20.1) Median Time to Response 1.1 mos (range: 0.8-3.6) 1.0 mos (range: 0.8-7.5) CI: confidence interval; mo: month; NA: not attained 1Kaplan Meier 2Event-free survival time is defined as the time from registration to the first of disease progression, death due to any cause, or subsequent treatment for multiple myeloma. Disclosures Kumar: Celgene: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Skyline: Consultancy, Honoraria; Onyx: Consultancy, Research Funding; Novartis: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy.

Abstract Abstract 2692 Background: Massive splenomegaly is occasionally encountered in patients with Non-Hodgkin's Lymphoma (NHL) and can be associated with abdominal symptoms, anemia and thrombocytopenia. The spleen may also be a primary focus of the disease itself. Splenectomy offers the benefit of localized treatment of the disease as well as relief of symptoms from splenomegaly and associated cytopenias. The safety and long term clinical outcomes of splenectomy for massive splenomegaly (>1500 gm) in patients with various histologies of NHL was analyzed. Methods: Data was obtained from clinical records of 90 patients with a diagnosis of NHL who underwent a splenectomy at Mayo Clinic Rochester from January 1998 to December 2007. Demographics, previous treatments, histology, post- surgical complications were collected and analyzed for the entire cohort. Additionally, median overall survival, improvement in symptoms, anemia and thrombocytopenia were analyzed by NHL type. Results: Median age at splenectomy was 67 years (range 42–84 yrs.) and 56 (62%) of patients were male. Average time from diagnosis to splenectomy was 3 months (range 0–217 months). Splenectomy was the first treatment in 56 (62%) patients; the other 34 patients were treated with chemotherapy with an average of two previous regimens. Most patients had involvement outside of the spleen, 65 (72%) with concurrent bone marrow involvement and 35 (50%) with lymph node involvement. Various different NHL histologies were represented: marginal zone (MZ) (34%), mantle cell (MC) (26%), diffuse large B-cell lymphoma (DLBCL) (10%), follicular (FL) (11%), lymphoplasmacytic (LP) (6%) and T cell NOS (4%). With a median follow-up time of 25 months, the median overall survival differed by histology type of NHL (Table 1). Indolent lymphomas such as FL, LP and MZ had more favorable survival compared with more aggressive lymphomas such as DLBCL and T cell NOS. Splenectomy was safe and well tolerated with only one treatment related death. There were no reported post-splenectomy septic events. Two patients did develop a portal vein thrombosis. 95% of patients had relief in pressure and abdominal symptoms post-splenectomy. With the exception of patients with DLBCL and T-cell NHL, a majority of patients had improvement in anemia and thrombocytopenia related to splenomegaly (Table 2). Conclusions: This represents the largest reported series of patients with lymphoma treated with splenectomy. Our results indicate that median overall survival after splenectomy is determined by the underlying type of NHL. Patients with LP, FL, MZ and MCL have a favorable outcomes following splenectomy. Splenectomy remains a safe and effective treatment option for massive splenomegaly in selected patients during the course of their disease management. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 4127 Introduction: Mantle cell lymphoma (MCL) is an aggressive lymphoma. NF-κB has been shown to be constitutively activated in MCL cell lines and patient biopsy samples and may play a key role in the growth and survival of MCL cells. We previously reported in a pilot study of 39 MCL patients from the NCI-SEER Survival Study that host genetic variation in candidate TNF and NF-κB genes was associated with overall survival after accounting for clinical variables (Blood 2007;110(11):472a). Here, we attempt to replicate the top 8 genes (NFKB1, IRF4, TNFSF13B, TNFRSF25, NFKBIA, LTA/TNF, TRAF5, RELB) and associated single nucleotide polymorphisms (SNPs) in an independent sample of MCL patients. Methods: We genotyped 71 SNPs from 8 genes in a prospective cohort of newly diagnosed MCL patients with germline DNA enrolled at the Mayo Clinic and University of Iowa from 2002–2008 as part of the Molecular Epidemiology Resource of the Iowa/Mayo Lymphoma SPORE. All patients were systematically followed through 2009 for overall survival (OS) and event-free survival (EFS, defined as disease progression, retreatment or death due to any cause). Genotyping was performed on an Illumina Golden-Gate platform. Cox regression was used to estimate Hazard Ratios (HRs) and 95% confidence intervals (CI) for individual SNPs with OS and EFS. Each SNP was modeled with the most prevalent homozygous genotype used as the reference group. An ordinal test was used to assess the trend across genotype. A principal components methodology was used for gene-level analyses. All Cox models were adjusted for MIPI and treatment. We compared our results to the previously reported NCI-SEER study that included MCL patients diagnosed from 1998–2000. The NCI-SEER study had a median age at diagnosis of 64 years (range 38–74), 27 deaths (69%), and a median follow-up for living patients of 47 months (23-85 months). Replication was declared based on a p-trend<0.10 in the gene-level test or p-trend<0.10 in the SNP-level ordinal trend test and a HR of similar direction and magnitude to the NCI-SEER study result. Results: The median age at diagnosis of the 101 patients in the SPORE was 64 years (range 42–88), and by simplified MIPI score there were 38% low risk, 37% intermediate risk, and 26% high risk patients. The most common initial therapy was anthracycline-based chemotherapy ± rituximab (59%) with or without stem cell transplantation. Through 2009, there were 61 events (60%) and 31 (31%) deaths, with a median follow-up for living patients of 59 months (range 29–90). At the gene-level, none of the 8 genes replicated at p<0.10. However, at the SNP level, the genes with SNPs that replicated for OS included TRAF5 (rs3738199, rs6684874, rs12569232), TNFRSF25 (rs3138156), and RELB (rs10424046, rs1560725). The strongest TRAF5 SNP was rs3738199 which had a minor allele frequency (MAF) of 0.35. Compared to patients with the AA genotype, those with the AG (HR=2.14, 95% CI 0.91–5.01) or GG (HR=3.72, 95% CI 1.34–10.3) genotypes had inferior survival (p-trend=0.0092). The TNFRSF25 SNP rs3138156 had a MAF of 0.054; compared to patients with the AA genotype, those with the AG or GG genotype (HR=2.46, 95% CI 0.88–6.89) had inferior survival (p=0.087). Finally, the strongest RELB SNP was rs10424046, and had a MAF of 0.54. Compared to patients with the GG genotype, those with the GC (HR=0.57, 95% CI 0.25–1.28) or CC (HR=0.39, 95% CI 0.14–1.12) genotypes had superior survival (p-trend=0.065). Similar results for EFS were observed for the TRAF5 and RELB SNPs. Discussion: Germline genetic variation in the TNF and NF-κB pathway genes TRAF5, RELB, and TNFRSF25 were associated with prognosis in MCL after adjustment for clinical and treatment factors, and this result replicates findings from an independent dataset. TRAF5 is one of the components of a multiple protein complex which binds to TNF receptor cytoplasmic domains and mediates TNF-induced activation; RELB is part of the NF-κB complex; and TNF super family receptor member 25 stimulates NF-κB activity and regulates apoptosis through signal transduction that is mediated by various death domain containing adaptor proteins. In summary, genetic variation in TNF and NF-κB pathway genes may play a role in disease progression and overall survival in MCL, supporting further targeting of this pathway for therapy. Support: Lymphoma Research Foundation, P50 CA97274, R01 CA129539. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2690 Diffuse large B cell lymphoma (DLBCL) is the most common type of adult non-Hodgkin lymphoma. Aberrant gene expression and mutations are involved in the pathogenesis of DLBCL and may have prognostic and therapeutic relevance. We have shown that STAT3 (by immunohistochemistry) is constitutively activated in approximately 50% of new untreated DLBCL cases. To investigate whether genetic mutations play a role in the activation of JAK2/STAT3 signaling pathway in DLBCL, we sequenced the coding regions of the JAK2 gene and found no novel missense mutations. Since we did not find any missense mutations in the JAK2 gene, we proceeded to bi-directionally sequence all the 24 exons of the STAT3 gene in the same DLBCL patient tumors (n=40). We discovered mutations in 2 patients, one in exon 7 (T>A) and the other at the stop codon in exon 24 (G>A). While the G to A mutation in exon 24 was a silent mutation, the T to A mutation in exon 7 led to methionine substitution by lysine at codon 206 (M206K). Codon 206 is located in the coil-coiled domain of STAT3, which is a conserved amino acid in STAT3 from many different species. In order to delineate the functional significance of this STAT3 M206K mutation we generated STAT3 expression plasmids with the lentiviral expression vector pLEX-MCS. STAT3 constructs carrying the M206K mutation were generated by site directed mutagenesis of wild type STAT3. Since there are two STAT3 isoforms in humans, full-length STAT3α and the splicing variant STAT3β (which lacks the C-terminal transactivation domain), we constructed stable cell lines containing mutant and wild type gene of both STAT3α and STAT3β in HEK-293T cells. The mutation was found to increase the phosphorylation of Tyr705 in STAT3α mutant cell lines with no effect on STAT3β mutant cell line. Moreover the mutant STAT3α cell line was more sensitive to IL-10 in the activation of Tyr705 compared to its wild type while STAT3β mutant cell line was insensitive to IL-10. Both the STAT3 mutants (STAT3α and STAT3β) were insensitive to IL-6, which suggests that the mutant can sense the signal specifically from IL-10. Furthermore JAK2 inhibition through the pharmacological inhibitor TG 101348 dephosphorylated STAT3 in WT cells; however, had minimal effect in both the STAT3 mutants. Immunofluorescence staining showed that the M206K mutation did not affect the nuclear translocation of both STAT3α and STAT3β, which was confirmed by immuno-blotting on the cytosol and nucleus of the cells. Interestingly, the mutation activated the transcriptional activation activity of both STAT3α and STAT3β by luciferase reporter assay. Overall these results suggest that the M206K STAT3 gene mutation is rare (2.5%) in DLBCL tumors, leads to STAT3 activation, and enhances STAT3 transcriptional activation activity. Thus, STAT3 mutations in addition to cytokines can produce STAT3 pathway activation in DLBCL. Our data suggest that clinical trials of novel STAT3 inhibitors need not be restricted to tumors with STAT3 mutations but rather should focus on tumors with demonstrated aberrant STAT3 activation. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 468 The requirement for BAFF and BAFF-R in normal human and murine B cells is well studied, but there is also significant evidence to suggest that BAFF plays an important role in malignant B cell proliferation and survival. Serum BAFF levels are elevated in patients with non-Hodgkin lymphoma (NHL) and high BAFF levels correlate with aggressive disease and a poor response to therapy. There is also increasing genetic evidence suggesting an association between the development of human disease and genetic variation in genes encoding BAFF and its receptors. Mutations in TNFRSF13B (TACI) were identified in patients with familial common variable immunodeficiency (CVID) and IgA deficiency and we have found that single nucleotide polymorphisms (SNP) in TNFSF13B (BAFF) are associated with elevated BAFF levels and risk for developing NHL. To build upon these findings we sequenced BAFF and its receptors; TNFSF13B, TNFRSF13B, TNFRSF17(BCMA), and TNFRSF13C (BAFF-R) in NHL patients to identify novel genetic variants that may be associated with NHL risk. Among 40 individual samples (20 controls and 20 follicular lymphoma (FL) cases) that were bi-directionally sequenced we identified a heterozygous cytosine to thymidine transition in 1 patient specimen at position 475 (C475T) of TNFRSF13C. The C475T transition encodes a missense substitution of tyrosine for histidine in codon 159 (H159Y) in the highly conserved cytoplasmic tail of BAFF-R, adjacent to the TRAF3 binding motif PVPAT. We next expanded our analysis of BAFF-R H159Y and analyzed NHL tumor biopsies for the presence of the mutation. 4/41 (10%) follicular lymphomas (FL), 2/42 (5%) diffuse large B cell lymphomas, 1/22 (5%) lymphoplasmacytic lymphomas (LPL), and 1/24 (4%) mucosal associate lymphoid tissue lymphomas carried the heterozygous mutation. The BAFF-R H159Y mutation was not detected in any of the normal control DNA from healthy donors (n=100). Given its close proximity to the TRAF3 binding site in the cytoplasmic domain of BAFF-R we first wanted to determine if the H159Y mutation altered BAFF induced signaling. We generated cell lines that express HA-tagged wildtype BAFF-R, BAFF-R with the H159Y mutation, or BAFF-R with an ablated TRAF3 binding site as a negative control. Analysis of cells expressing H159Y BAFF-R demonstrates that this mutation results in increased BAFF-R-mediated NFκB1 and NF-κB2 activation. The enhanced signal activated by BAFF-R H159Y is coupled with a several fold increase in TRAF3, TRAF2, and TRAF6 recruitment to BAFF-R and increased IgM production. We further demonstrate that recruitment of TRAF6 to BAFF-R is not unique to the mutant H159Y BAFF-R, but is also an important and necessary feature of BAFF-R signaling in normal B cells. Collectively, our data identify a novel lymphoma-associated mutation in BAFF-R and describe exciting new aspects of BAFF-R signaling that are important for understanding normal B cell homeostasis and function, as well as pathogenic BAFF-R contributions to human disease. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: The clinical impact of ibrutinib is irrefutable and has been hailed as a revolutionary treatment for several cancers, including mantle cell lymphoma (MCL). Despite high response rates noted with ibrutinib therapy in MCL (ORR, 68%), complete responses are low and durability of remission is suboptimal in MCL vs. CLL or Waldenstrom macroglobulinemia (WM) patients (Cheah et al Ann Oncol 2015). This relative lack of efficacy may be due to MCL cells having a higher proliferation rate and being less indolent in nature than CLL or WM cells. Tumor cells with a high proliferation index rely on optimally functioning protein metabolism/homeostasis systems. In MCL, this observation has been fortuitously exploited with the use of bortezomib, a 20S proteasome inhibitor. Indeed the ubiquitin proteasome system is a validated target and consists of several individual components whose function in MCL has yet to be mapped out. We have recently reported that inhibition of the 19S proteasomal deubiquitinating enzymes (DUBs), USP14 and UCHL5; with the small molecule inhibitor b-AP15 is lethal to drug-resistant WM tumor cells. This intriguing observation, prompted us to define the role of USP14/UCHL5 and their inhibition in a diverse panel of B-cell lymphoma cell lines, including MCL models as well as ibrutinib-resistant MCL cells. Materials: b-AP15 (and its clinical grade analog, VLX1570) was obtained from Vivolux AB and bortezomib from Sellekchem. Human NHL (DLBCL, MCL, Burkitt), Hodgkin lymphoma (HL), multiple myeloma (MM) cell lines as well as established drug-resistant subclones were used in drug-sensitivity screening experiments (total n=25). Results: USP14 and UCHL5 mRNA expression was queried in the CCLE database (Broad-Novartis) and showed highest expression in plasma cell and B-lymphoid tumor cell types. This was also observed at the protein level, wherein analysis of The Human Protein Atlas database revealed moderate to high intensity staining for USP14 and UCHL5 localizing to the cytoplasmic/membranous and nuclear compartments in high-grade NHL tissues. Next, we examined B-lymphoid tumor cell sensitivity to pharmacologic inhibition of USP14/UCHL5 with either b-AP15 or VLX1570 (72hr fluorescein diacetate hydrolysis assay or CellTiter Glo). We observed that MCL cells, including those resistant to ibrutinib (Jeko/IR cell line) were highly sensitive to VLX1570 (median IC50 12 - 25nM). In contrast, MM cells were not as sensitive (IC50's ranging between 58 - 90nM). Nine DLBCL cell lines exposed to equivalent time/concentrations of b-AP15 showed a median IC50 of 311nM (range, 70 - 910nM) and 3 HL models exhibited an IC50 of 531nM (range, 420 - 783nM). No difference in sensitivity to VLX1570 was noted between ABC-type vs. GCB-type DLBCL models. These functional results aligned with prior genomic inquiry where USP14 and UCHL5 gene expression was noted to be higher in MCL cell lines compared to DLBCL and non-hematologic cancer models analyzed (FDR=0.0019, p=0.001), suggesting their more central role in maintaining MCL tumor viability. Indeed MCL tumor survival (particularly ibrutinib-resistant cells) appears linked to USP14/UCHL5 function as treatment of Jeko/IR cells with VLX1570 (250nM, 12hrs) caused marked apoptosis (71.8% annexin-V+ staining) and cleavage of PARP-1. Moreover, the combination of ibrutinib and VLX1570 synergistically induced MCL cell death (median CI: 0.3). Mechanistic studies demonstrated that VLX1570 modulates several proteins critical for MCL survival including cyclin-D1, Myc and CXCR4/CD184. Reduction in cyclin-D1 was also noted to coincide with cell cycle arrest of VLX1570-treated MCL cells. Altogether, these findings suggest that VLX1570 modulates critical cellular signaling pathways utilized by MCL tumor cells, particularly those that are involved in resistance to ibrutinib. Conclusions: MCL remains a challenging malignancy to treat with no effective treatments for ibrutinib-relapsed disease. Our data supports the role of the proteasome-associated DUBs, USP14 and UCHL5, as critical factors involved in ibrutinib-resistant MCL tumor survival. VLX1570 is a potentially effective agent for the treatment of ibrutinib-resistant MCL. Disclosures Gullbo: Vivolux AB: Other: Shareholder. Linder:Vivolux AB: Other: Shareholder.

Abstract Abstract 3088 Background: Despite the use of modern immunochemotherapy (R-CHOP) regimens, almost 50% of patients with diffuse large-B-cell lymphoma (DLBCL) will relapse. Current prognostic models, most notably the International Prognostic Index, are comprised of patient and tumor characteristics and are unable to identify patients with less than a 50% chance of long-term survival. However, recent observations demonstrate that factors related to host adaptive immunity and the tumor microenvironment are powerful prognostic variables in non-Hodgkin lymphoma Methods: We retrospectively examined the absolute neutrophil count (ANC), monocyte count (AMC) and lymphocyte count (ALC), obtained from an automated complete blood count with differential, as prognostic variables in a cohort of 255 consecutive DLBCL patients that were uniformly treated with R-CHOP between 2000 and 2007 at a single institution. The primary study objective was to assess if ANC, AMC, and ALC at diagnosis were predictors of overall survival (OS) in DLBCL. Results: At diagnosis, the median ANC was 4720/uL (range 1190–17690), the median AMC was 610/uL (range 30–4040), and the median ALC was 1220/uL (range 140–5410). The median follow-up for these patients was 48 months. In the univariate analysis, each of these variables predicted OS as continuous variables. As dichotomized variables, an elevated ANC (≥5500/μL; hazard ratio 1.75, 95% confidence interval 1.14–2.60, p=0.01) and AMC (≥610/μL; hazard ratio 3.36, 95% confidence interval 2.10–5.59, p<0.0001) were each associated with inferior OS. In contrast, the presence of lymphopenia, defined as an ALC ≤1000/uL, was associated with inferior OS (hazard ratio 2.21, 95% confidence interval 1.43–3.39, p=0.0004). When components of the IPI were included on multivariate analysis only the AMC and ALC were independently significant prognostic factors for OS, with hazard ratios of 3.37 (95% confidence interval 2.05–5.74, p<0.0001) and 2.19 (95% confidence interval 1.38–3.44, p=0.0009), respectively. The dichotomized AMC and ALC generated the AMC/ALC prognostic index (PI) and stratified patients into 3 risk groups: very good (AMC <610/uL and ALC >1000/uL), good (AMC ≥610/uL or ALC ≤1000/uL), and poor-risk (AMC ≥610/uL and ALC ≤1000/uL) populations. For both the very good (n=79) and good-risk (n=134) groups median OS has not been reached with estimated 5-year overall survival of 88% and 69%, respectively. Median OS for poor-risk (n=42) patients was 1.7 years (95% confidence interval 1.1–2.7 years) with an estimated 5-year overall survival of 28% (p<0.0001). By comparison, the R-IPI was unable to identify a group of patients with a median survival less than 8 years. The estimated 5-year OS was 93%, 71% and 53% for very good, good and poor-risk patients, respectively. We sought to determine whether the AMC/ALC PI may provide additional prognostic information when combined with the R-IPI. To test this possibility, the 171 very good/good risk and 84 poor risk patients identified by the R-IPI were subsequently risk stratified using the AMC/ALC PI. Among R-IPI very good/good risk patients a subset of poor risk patients (n=21) with a median OS of 2.2 years (95% confidence interval 1.1–6.6 years) and 35% 5-year OS could be identified with the AMC/ALC PI. In contrast, 5-year OS ranged from 75%-88% among very good and good risk patients. Similarly, stratification of R-IPI poor risk patients by the AMC/ALC PI identified subsets of very good (n=19) and good risk (n=44) patients with median OS that had not been reached and 86% and 55% 5-year OS, respectively. High risk (n=21) patients had a median OS of 1.4 years (95% confidence interval 0.9–2.2 years) and an estimated 5-year OS of less than 25%. Conclusions: Measurement of AMC and ALC at diagnosis is widely applicable, cost effective, predicts OS, and identifies high-risk patients with DLBCL. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 613 Uncontrolled immunoglobulin (Ig) secretion by malignant cells is a characteristic feature of lymphoplasmacytic malignancies and associates with significant morbidity. IL6 has been shown to promote Ig secretion by malignant B cells, however, the mechanisms mediating this cellular event remain elusive. Here, we identified a CCL5 induced pathway that upregulates IL6 secretion in B cell/plasma cell malignancies including Waldenström macroglobulinemia (WM). Characterization of this mechanism revealed that activation of the CCL5 pathway increases IL6 expression and promoter activity in stromal cells (HS-5, Saka and primary stromal cells from WM patients). Conversely, stable RNAi knockdown of the CCL5 receptor CCR3 in stromal cells led to significantly reduced IL6 promoter activity and expression. Further analysis using a combination of bioinformatics analysis, genetic analysis and chromatin immunoprecipitation assays (ChIP) identified GLI2 as the mediator of this CCL5-IL6 functional interaction. CCL5 induces GLI2 expression via activation of the PI3K/AKT pathway. Constitutively active PI3K and AKT mutants increase expression of GLI2 through the canonical NFkB pathway. ChIP assay showed p65 binds to the GLI2 promoter and increases GLI2 levels in stromal cells. Dominant negative molecules antagonizing these pathways effectively blocked CCR3 induction of GLI2 expression. Interestingly, this CCL5-induced pathway was independent of the Hedgehog signaling. Blockade of this cascade using pharmacological or genetic tools did not affect CCL5 activation of GLI2 in stromal cells. To validate the biological significance of this newly identified CCL5-GLI2-IL6 signaling axis in the regulation of IgM secretion, we used an in vitro coculture system and an in vivo mouse model. Coculture of primary WM stromal cells, HS-5 or Saka cells with primary WM malignant cells or BCWM.1, an IgM producing cell line, led to a significant increase in IL6 and IgM secretion. Similar results were obtained in vivo using athymic nu/nu mice subcutaneously injected with BCWM.1 and HS-5 cells. We then confirmed the requirement of GLI2 in vitro and in vivo. We infected HS-5 cells with a lentivirus containing shRNA targeting GLI2 or a scramble control and cocultured them with BCWM.1 cells. Knockdown of GLI2 decreased IL6 and IgM secretion in coculture. This was confirmed in vivo by infecting HS-5 cells or primary WMsc with lentivirus targeting GLI2 or scrambled shRNA and coinjecting with BCWM.1 cells into athymic nu/nu mice. Mice injected with cells lacking GLI2 had lower IgM levels in the serum and tumors compared with mice injected with HS-5 cells with an intact GLI2, further supporting the hypothesis that CCL5 requires an intact GLI2 to increase IL6 and consequently IgM. Finally, we confirmed the importance of this phenomenon in other B cell/plasma cell malignancies such as MGUS and MM. Primary stromal cultures from these neoplasms were infected with lentivirus targeting GLI2 or scrambled shRNA and cocultured with BCWM.1 cells. Similar to WM, there was a significant decrease in IL6 and IgM secretion in the absence of GLI2 suggesting the role of this molecule is conserved in other B cell/plasma cell malignancies. In summary, our data identifies a novel role for GLI2, an effector of the Hedgehog signaling pathway, in mediating the interaction between CCL5 and IL6 in the tumor microenvironment that modulates Ig secretion by malignant B cells. Therefore therapies targeting this signaling axis in the tumor microenvironment might provide efficacy in patients with Ig-mediated diseases. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 2802 Background: Redundancy of pro-survival signaling pathways promotes survival and drug resistance in lymphoid and plasma cell malignancies. In particular, the PI3K-Akt and the MEK-ERK pathways have been shown to play an important role in the proliferation and survival of these malignant cells induced by various cytokines in the tumor microenvironment. Sorafenib, a Raf kinase and VEGF receptor inhibitor, and everolimus, an mTOR inhibitor, have synergistic cytotoxicity in myeloma and lymphoma cells due to inhibition of multiple signaling pathways. Methods: We designed a Phase 1/2 clinical trial to identify the maximum tolerated doses of the two drugs used in combination and the efficacy of the combination. Patients (Pts) with relapsed myeloma or lymphoma were eligible for enrollment. Pts were required to have an absolute neutrophil count ≥1500 × 10(6)/L, a platelet count ≥75,000, and a serum creatinine 21.5 mg/dL. The study utilized the classic 3+3 design. Extensive pharmacokinetic studies were performed to better delineate potential drug interactions. Results: Twenty-six pts were accrued from August 2007 to February 2009. Four pts discontinued sorafenib during cycle 1 for various reasons (2 patient refusal, 1 unrelated medical condition and 1 physician discretion) and were excluded from MTD determination. An additional pt did not have measurable disease and was ineligible, leaving 19 pts with lymphoma (including 6 with Hodgkin lymphoma) and 2 with myeloma for phase I analysis. The pts had a median age of 56 years (range, 22, 69) and were heavily pretreated with a median of 4 prior therapies (range, 1–10). Eighteen (86%) had received a prior stem cell transplant. Four dose limiting toxicities were seen across all dose levels (Table). These included grade 3 vomiting (level 1), grade 4 thrombocytopenia (level 2 and 3, one each) and grade 2 hand and foot rash leading to treatment delay (level 3). Overall, 13 pts experienced a grade 3 or 4 hematologic toxicity. Grade 3 or 4 anemia, neutropenia, and thrombocytopenia occurred in 19%, 43%, and 38% of pts, respectively. Four pts have experienced a grade 3 non-hematologic toxicity; no grade 4 non-hematologic toxicities were seen. Grade 3 non-hematologic toxicities included hypokalemia, weight loss, vomiting, hand-foot skin reaction, fatigue, and elevated alkaline phosphatase. Dose level 1 (sorafenib 200 mg and everolimus 5 mg daily) was best tolerated and was selected for phase 2 evaluation. The ORR was 33% (7/21;95% CI: 15–57%, Table) with 3 pts at dose level 0 (2 PR, 1 CR), one at level 2 (1 PR) and three at level 3 (2 PR, 1 CR) responding. The responders included 5 pts with Hodgkin's disease and one each with an NK cell and T-cell lymphoma. Pts have received a median of 6 cycles (range: 1–19) of treatment. 16 pts have discontinued treatment due to disease progression (13 pts), non-resolution of cytopenias (1 pt), physician discretion (1 pt), and death on study due to lymphoma (1 pt). Disease progression has been seen in 16 pts; 9 pts have died. Median follow-up for pts still alive is 18.7 months (range: 11.5–29.4). 6 pts died from disease progression, one each due to sepsis unlikely related to treatment, cholecystitis, and unknown causes. Sorafenib is metabolized by the cytochrome P450 CYP3A enzyme and RAD-001 mainly by the CYP3A4 system in the liver, hence there is a potential for interactions. The detailed PK analyses performed as part of this trial showed a decrease in the RAD001 levels following initiation of sorafenib on day 8 of cycle 1 (Figure). Conclusion: The combination of sorafenib and everolimus is safe at a recommended phase 2 dose of sorafenib 200 mg and everolimus 5 mg daily. There is no significant drug interaction seen. Activity has been observed, especially in the setting of Hodgkins Disease. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Off Label Use: Lenalidomide for treatment of newly diagnosed myeloma. Witzig:Novartis and Celgene: Patents & Royalties, Research Funding, Served on advisory boards with Novartis and Celgene – both uncompensated with compensation to Mayo Clinic.