Witzig, Thomas E.

Abstract Abstract 2738 Background: Mantle cell lymphoma (MCL) is an uncommon type of non-Hodgkin's lymphoma (NHL) with poor prognosis that necessitates the development of new treatments. Lenalidomide is a unique immunomodulatory agent with antiproliferative and tumoricidal effects on MCL cells. NHL-003 was a phase II, open-label, multicenter trial for subjects with relapsed aggressive NHL that tested single-agent lenalidomide 25 mg PO days 1–21 every 28 days. The primary endpoint was overall response rate (ORR); secondary endpoints included complete response (CR) rate, duration of response (DOR), survival, and safety. At the time of the initial publication (Witzig et al. Ann Oncol.2011;22:1622–1627), MCL subgroup analysis showed an ORR of 42%; the median DOR had not been reached. The purpose of this report is to provide long-term efficacy and safety results for the MCL subgroup from NHL-003. Results: Subjects with MCL (N=57) had a median age of 68 y (range, 33–82), were predominantly male (77%) with good ECOG performance status (89% PS 0–1) and advanced-stage disease (88% stage III/IV). Subjects had received a median of 3 (range, 1–13) prior systemic therapies. According to the current central review at a median follow-up of 12.4 mo, subjects achieved an ORR of 35% (CR/CRu 12%) following lenalidomide, including a median DOR of 16.3 mo (Table 1). The ORR to single-agent lenalidomide was 44% (CR/CRu 21%) by independent assessment, with a median DOR not yet reached. Median PFS was 8.8 mo by central review and 5.7 mo according to investigators. Subjects responded quickly, with a median time to first response of 1.9 mo (central and investigator). Median DOR for subjects in CR and overall survival for all subjects have not yet been reached. The most common grade 3/4 adverse events (AEs) were neutropenia (46%), thrombocytopenia (30%), fatigue (9%), and diarrhea (5%). Other AEs included one subject with grade 1 to 2 tumor flare reaction, one subject with grade 3 deep vein thrombosis, and two subjects with second primary malignancies suspected of being related to treatment (one grade 3 squamous cell carcinoma of the skin that resolved and one grade 4 AML in a heavily pretreated individual with 5 prior cancer therapies). Conclusions: This subset analysis from a phase II study further confirms the efficacy of lenalidomide in subjects with relapsed MCL. Responders have a long DOR with manageable side effects. These results support continued investigation of lenalidomide alone or in combination for the treatment of MCL. Disclosures: Zinzani: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millenium: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mundipharma: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees. Off Label Use: This is a phase 2 clinical study of safety and efficacy for lenalidomide in patients with MCL. Czuczman:Celgene: Consultancy, Consultant Celgene Advisory Board Other. Reeder:Celgene: Mayo Clinic receives funding from Celgene to support clinical trials Other, Research Funding. Haioun:Celgene: Celgene Advisory Board Consultant Other, Consultancy. Tilly:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Pietronigro:Celgene: Employment. Ervin-Haynes:Celgene: Employment. Li:Celgene: Employment. Witzig:Celgene: Research Funding.

Abstract Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin Lymphoma and is characterized by deregulation of several signal transduction pathways. Approximately 50% patients with DLBCL are shown to have aberrant activation of the signal transducer and activator of transcription (STAT) pathway. However, mechanism of aberrant STAT3 signaling in DLBCL is not well understood. Protein tyrosine phosphatases (PTPs) are important enzymes that control the activity of multiple signaling pathways downstream of tyrosine kinases; mutations in PTPN11 have been found associated with the development of myeloproliferative disorder. In the current study, we sequenced a set of 38 DLBCL tumor samples for genetic mutations of PTPN6. Bi-directional sequencing reactions were performed on genomic DNA, and all exons of PTPN6 were amplified and analyzed by Sanger sequencing. We identified 2 novel heterozygous missense mutations in PTPN6 gene in 2 separate patients (2/38; 5.2%). The first missense mutation occurred in the exon 7, resulted in an Asp226 to lysine substitution (N226K), while other missense mutation found on exon 15 resulted in an Ala552 to valine substitution (A552V). In order to elucidate the functional significance of these mutations, we performed site directed mutagenesis to mutate wild type (WT) PTPN6 at codon 226 and 552. Both, wild-type PTPN6 (PTPN6WT) or those containing the N226K (PTPN6N226K) and A552V (PTPN6A552V) mutations were cloned and stably expressed in the HEK-293T cells with a lentiviral expression vector and PTPN6 phosphatase activity was measured. Our results showed marked reduction (70%) in the PTPN6 phosphatase activity in both the PTPN6 mutants as compared to the WT control. Interestingly both the PTPN6 mutants (PTPN6N226K and PTPN6A552V) promoted cell proliferation of HEK-293 cells as compared to WT PTPN6. In order to evaluate that whether or not PTPN6 mutations modulate STATs signaling, we analyzed STAT1, STAT3, STAT5 and STAT6 phosphorylation at tyrosine residue in cells stably transfected with WT or mutant PTPN6. While overexpression of WT PTPN6 reduced STAT3 phosphorylation, however no effect was observed on STAT1, STAT5 and STAT6 phosphorylation. Unlike WT-PTPN6, none of the PTPN6 mutants was able to dephosphorylate STAT3. In addition, PTPN6 A552V mutation was found to decrease the ability of PTPN6 to dephosphorylate STAT3 after induction with interleukin-10. Furthermore JAK2/JAK1 inhibition through the pharmacological inhibitor ruxolitinib (5μM) dephosphorylated STAT3 in WT PTPN6 as well as in PTPN6 mutants within 4 hours. Inhibition of JAK3 through a pharmacological inhibitor WHI-P154 (5μM) was able to completely dephosphorylated STAT3, however both the PTPN6 mutants were found resistant to JAK3 inhibition. Moreover, in a luciferase reporter assay compared to WT PTPN6, expressing either of the PTPN6 mutants (N226K and A552V) enhanced transcriptional activity of STAT3. To determine the effect of the PTPN6 mutations on the downstream targets of the JAK/STAT pathway, we demonstrated that Mcl-1, survivin and Bcl-2 protein level was significantly elevated in both mutant cells than that seen in the WT PTPN6 cells. Overall these results demonstrate that the N226K and A552V PTPN6 mutations occur in 5% of DLBCL tumors. Mutations we have found are both able to cause loss-of-function of PTPN6 that leads to increased STAT3 phosphorylation and increased transcriptional activity resulting in accumulation of Mcl-1, Bcl-2 and survivin proteins. Our data suggest that clinical trials of JAK1/JAK2 inhibitors need not be restricted to tumors with PTPN6 mutations but rather should focus on tumors with demonstrated aberrant STAT3 activation. Taken together, our data suggest that PTPN6 mutations may guide the clinical use of inhibitors of JAK3 kinase in DLBCL. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 1638 Introduction: Hodgkin lymphoma (HL) represents the most common subtype of malignant lymphoma in young people in the Western world. Most of the patients can be cured with modern treatment strategies. However, about 20% of patients still die due to relapse or progressive disease. Recently, elevated numbers of tumor-associated macrophages in diagnostic pretreatment and relapse biopsies have been associated with poor long-term outcomes. Furthermore, high expression of CSF1R on the malignant Hodgkin Reed Sternberg cells has been linked to shorter progression-free survival, providing the rationale to test PLX3397, a highly selective inhibitor of CSF1R (also known as Fms) and Kit receptor tyrosine kinases, in HL patients. Patients and Methods: Patients with relapsed or refractory HL were enrolled in this single-agent multicenter trial. All patients had progressed after or were ineligible for autologous stem cell transplantation, had radiographically measurable disease, and had discontinued all previous HL therapy. Patients were treated with oral PLX3397 at a dose of 900 mg/day continuously until occurrence of unacceptable toxicity or disease progression. The primary endpoint was the objective response rate according to the 2007 consensus criteria. Results: A total of 20 patients were enrolled (9 male, 11 female, median age 36 years). Six patients had tumor reduction ranging between 3% and 54% including one partial remission (overall response rate of 5%) (Figure). The median duration of progression-free survival was 56 days. The most common drug-related adverse effects were asthenia, fatigue, hair depigmentation, anemia, leukopenia, and increased LDH, all of which were grade 1 or 2 except for one grade 3 neutropenia. CD14dim/16+ labeled peripheral blood monocytes were markedly reduced in all patients at 4 weeks vs. Baseline (median=83% reduction, range of 44%-96% reduction), confirming inhibition of CSF1R signaling. Increases were observed for adiponectin in 82% of patients (median=2.6-fold, range 1.2 to 12-fold) and for CSF-1 in 94% of patients (median=4.0-fold, range 1.4 to 16.5-fold), also consistent with CSF1R inhibition. Archival formalin-fixed paraffin-embedded lymphoma tissues of sufficient quality were available for 12 patients. Biopsy material was obtained from either initial diagnosis or after relapse. CD68+ and CD163+ macrophages were highly elevated (>25% cellularity) in 42% and 58% of patients, respectively. The number of tumor-associated macrophages was not significantly associated with a reduction in lesion size after PLX3397 treatment in this small study cohort. Discussion: In this phase 2 clinical trial, PLX3397 at a dose of 900 mg/day showed limited activity in this heavily pretreated patient cohort. However, target inhibition of both Fms and Kit was clearly demonstrated. Although the efficacy of single agent PLX3397 in this study population was modest, the manageable safety profile and evidence of target inhibition may warrant further testing in combination therapy trials. Disclosures: Younes: Seattle Genetics, Inc.: Consultancy, Research Funding; Millennium: Honoraria; Novartis: Honoraria, Research Funding; Celgene: Honoraria; Affimed: Research Funding; Gilead: Research Funding; Johnson & Johnson: Research Funding. Gascoyne:Plexxikon Inc.: Consultancy, Research Funding. West:Plexxikon Inc.: Employment. Nolop:Plexxikon Inc.: Employment. Steidl:Plexxikon Inc.: Research Funding.

Abstract Abstract 1527 Interim Positron-Emission Tomography (PET-scan), as a functional imaging test for tumor activity, has been shown to be a predictor for progression-free survival (PFS) and time to progression (TTP) in classical Hodgkin lymphoma (HL). The peripheral blood absolute lymphocyte/monocyte ratio (ALC/AMC) at diagnosis, as a surrogate marker of host immunity (i.e., ALC) and tumor microenvironment (i.e., AMC), has been recently reported [Porrata et al, Hematologica 2012; 97(2): 262–9] and confirmed [Koh et al, Oncologist 2012; 17(6): 871–80] to be also a predictor for PFS and TTP in classical HL. Therefore, we evaluated the combination of ALC/AMC ratio at diagnosis and the interim PET-scan to further stratify the clinical outcomes of PFS and TTP in patients with classical HL. To participate in the studies, patients were required to be diagnosed, treated, and followed at Mayo Clinic, Rochester, Minnesota. The treatment consisted of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) with or without radiation therapy. Patients were required to have an interim PET-scan performed. An ALC/AMC ratio ≥1.1 cut-off was used in the study based on our previous publication [Porrata et al, Hematologica 2012; 97(2): 262–9]. From 2000 until 2008, 111 classical HL patients qualified for the study. The cohort included 54% males and 46% females. The median age at diagnosis was 37 years (range: 18–83 years). The median follow-up was 2.8 years (range: 0.3–10.4 years). Patients with a negative interim PET-scan (N=98) presented with a higher ALC/AMC ratio at diagnosis (median of 2.32, range: 0.26–37.5) compared with patients with a positive interim PET-scan (N = 13) (median of 0.9, range: 0.29–3.10), p < 0.004. By univariate analysis, the ALC/AMC ratio at diagnosis and the interim PET-scan were predictors for PFS [ ALC/AMC ratio, R =0.13, 95% CI (0.05–0.35), p < 0.0002; and interim PET-scan, HR = 0.13, 95% CI (0.05–0.37), p < 0.0003] and TTP [ALC/AMC ratio, R =0.07, 95% CI (0.02–0.24), p < 0.0001; and interim PET-scan, HR = 0.05, 95% CI (0.01–0.18), p < 0.0003]. By multivariate analysis, ALC/AMC ratio at diagnosis and the interim PET-scan were independent predictors for PFS [ ALC/AMC ratio, R =0.13, 95% CI (0.07–0.63), p < 0.006; and interim PET-scan, HR = 0.11, 95%CI (0.02–0.47), p < 0.003] and TTP [ALC/AMC ratio, R =0.11, 95% CI (0.02–0.71), p < 0.02; and interim PET-scan, HR = 0.10, 95% CI (0.02–0.46), p < 0.003] when compared to the International Prognostic Score, limited versus advanced stage, and radiation. Patients were stratified into four groups: group 1 included patients with a negative interim PET-scan and ALC/AMC ratio at diagnosis ≥1.1 (N = 88); group 2 included positive interim PET-scan and ALC/AMC ratio at diagnosis ≥1.1 (N = 5); group 3 included negative PET-scan and ALC/AMC ratio at diagnosis < 1.1 (N = 10); and group 4 included positive PET-scan and ALC/AMC ratio at diagnosis <1.1 (N = 8). The three year PFS rates for each group were for goup1 95% (Events = 6); group 2 40% (Events = 3); group 3 56% (Events = 4); and group 4 50% (events = 4), p < 0.0001. The three year TTP rates for each group were: for group1 was 100% (Events = 0); for group 2 of 40% (Events = 3); for group 3 of 65% (Events = 3); and group 4 of 50% (events = 4), p < 0.0001. In conclusion, the ALC/AMC ratio at diagnosis is independent of the interim PET-scan to predict PFS and TTP in classical HL. Further studies are warranted to confirm our findings and to assess if the combination of the ALC/AMC ratio at diagnosis and interim PET can be use for planning of risk-adapted treatment. Disclosures: Ansell: Seattle Genetics, Inc.: Research Funding.

Abstract Abstract 1546 Background: Follicular lymphoma (FL) is an incurable disease with an undefined optimal management strategy. Global priorities in goals of care are avoidance of death and transformation to aggressive subtypes. Retrospective series, – most including patients diagnosed before ubiquitous rituximab use, - describe diverse rates of transformation with a common consensus of 3% per year, and with a median survival post transformation of less than 2 years. This study sought to characterize transformation events in a prospective observational series begun after diffusion of early rituximab use in FL. Methods: Newly diagnosed FL patients were prospectively enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) from 2002–2009. Clinical data were abstracted from medical records using a standard protocol. Patients were actively followed for retreatment, transformation, and death. Inclusion criteria for this analysis were initial diagnosis of grade I-IIIa FL. Exclusion criteria for this cohort include composite diffuse large B-cell lymphoma (DLBCL), FL grade IIIb, or evidence of clinical or pathological transformation at the time of FL diagnosis. Transformation was defined as refractory/recurrent disease with either a) biopsy confirmed subtype of FLIIIb, DLBCL or higher grade B-cell lymphoma; or b) clinical indication of transformation (sudden rise in LDH, rapid discordant localized nodal growth, new involvement of unusual extranodal sites, new B symptoms or hypercalcemia). Risk of transformation was analyzed via time to transformation using a death as a competing risk. Time to transformation was defined as the date of initial FL diagnosis to date of transformation. Overall survival was defined as the date of initial diagnosis to date of death or last known follow-up for patients still alive. Results: There were 631 newly diagnosed grade I-IIIa FL patients with a median age at enrollment of 60 years (range 23–93). 54% were male. The most common types of initial therapy were observation (33%), rituximab (R) monotherapy (12%), alkylator based chemotherapy +/− R (22%), and anthracycline based chemotherapy +/− R (20%). At a median follow-up of 60 months (range 11–110), 79 patients had died, 311 patients had an event (death, progression, or retreatment), and 60 patients (9.5%) had transformed. Transformation was biopsy proven in 48 of the 60 patients (80%). The overall transformation rate at 5 years (TX5) was 10.7% (95% CI: 8.3%–13.8%) (Figure 1). Time to transformation was associated with a FLIPI score of 3–5 (HR=2.37, 95% CI 1.28–4.39, p=0.006), but was not significantly associated with other standard clinical characteristics. Risk of transformation was different in the common initial treatment groups with the highest rate in patients who were initially observed (TX5=14.4%) and lowest rate in patients who initially received R monotherapy (TX5=3.2%)(p=0.058). Outcome after transformation was inferior to MER subjects with de-novo diagnosed DLBCL (p<0.0001). The median overall survival from date of transformation was 44 months (95% CI: 22-NA). Survival after transformation was superior in patients who transformed greater than 18 months after FL diagnosis compared to patients who transformed earlier (5 yr OS =70% vs 20%) (p=7 ×10−5), and for those initially observed (median unreached) versus those patients who were initially treated with alkylator or anthracycline based chemotherapy (median survival of 11 months)( p=0.016). Conclusions: Follicular transformation rates in this modern large prospective observational study are similar to risk of death without transformation and slightly lower at 5 years than most previous reports. Post-transformation prognosis is substantially better than described in older series. These observed differences may be a function of the prospective nature of the study design, modern management strategies, or patient selection factors. Initial management strategies may influence the risk of transformation. Marked survival differences following early vs. late transformation suggest that these may be different biologic events. Disclosures: Link: Genentech: Consultancy, Research Funding; Celgene: Consultancy; Millenium: Consultancy. Johnston:Novartis: Consultancy.

Abstract Abstract 2741 Background: The novel agent lenalidomide (LEN) has shown significant single-agent activity in patients with relapsed lymphoma through anti-proliferative and immunomodulatory mechanisms. In combination LEN may synergistically improve the efficacy of rituximab. However, there is limited data on the efficacy and safety of LEN in multi-drug combination regimens for treatment-naïve patients. We designed a phase II single arm trial to evaluate tumor response, toxicity (AE) and survival with a combination of LEN, rituximab, cyclophosphamide (CTX) and dexamethasone (DEX) (LR-CD) in symptomatic untreated patients with indolent B-cell lymphoma. (NCT00784927). Methods: Eligibility required age ≥18, ECOG PS ≤2, confirmed diagnosis of indolent B-cell lymphoma (FL1–2, SLL, MZL or LPL/WM), measurable nodes ≥2cm or IgM ≥400mg/dL (LPL/WM), ANC ≥1400/mm3, platelets ≥100,000/mm3, creatinine ≤2mg/dL, and signed informed consent. Only patients needing therapy were considered eligible. Treatment consisted of IV rituximab 375mg/m2 D1, oral LEN 20mg D1–21, CTX 250mg/m2 D1, 8, 15, DEX 40mg D1, 8, 15, 22 and ASA 325 mg daily in a 28 day cycle. Treatment continued 2 cycles beyond best response up to a maximum of 12 cycles. Toxicity was assessed by NCI CTCAE v3.0. Results: Thirty-one patients have enrolled at Mayo Clinic with 28 evaluable for toxicity and response (1 deemed ineligible, 1 withdrew before treatment, 1 treatment violation). Four patients continue on study at this time. Patient characteristics: median age 68.5(43–83), 71% male, stage IV 86%, FL 28%, MZL 25%, LPL/WM 39%, and SLL 4%. Median number of cycles given was 6 and 71% completed the study per protocol. The best overall response is 89% with 32% CR and 57% PR. In subgroup analysis, the response rates for LPL/WM was 91% (all PR) and for FL 88% (CR 63%, PR 25%). The most common grade ≥3 AEs were neutropenia (35.7%), leukopenia (17.8%), anemia (14.3%) and thrombosis (14.3%). The LPL/WM subgroup experienced more grade ≥3 anemia (36%) compared to the group as a whole. Patients (57%) required at least one dose reduction of LEN (n =10), CTX (n = 9) or DEX (n = 7). At a median f/u of 14.5 (1.8–36.5) months 86% are progression free (fig. 1) and the OS is 96% (fig. 2). One death unrelated to treatment occurred 7.7 months after completing 12 cycles of treatment. Conclusion: Lenalidomide can be safely combined with other active agents and in the combination LR-CD produces high response rates in symptomatic patients with indolent B-cell lymphoma. The regimen is well tolerated with manageable toxicities which are similar to that seen with single agent LEN. The encouraging results seen in patients with LPL/WM have led to expansion of this cohort for additional study. Disclosures: Reeder: Celgene: Research Funding. Off Label Use: lenalidomide use in non-Hodgkin lymphoma. Stewart:Celgene: Consultancy, Honoraria.

Abstract Background: CLL patients (pts) treated with novel targeted therapies continue to experience disease progression. Approximately 7-15% of relapsed CLL treated with ibrutinib or venetoclax developed Richter's syndrome (RS), an aggressive high grade lymphoma transformation. Standard chemotherapy has limited efficacy in RS. We hypothesized that checkpoint blockade would re-establish anti-tumor immune response in progressive CLL/RS and here we aim to update the clinical data and correlative analysis of MC1485: a phase 2 study of PD-1 blocking antibody pembrolizumab in relapsed/refractory CLL and RS. Methods: Relapsed/refractory CLL including RS enrolled in the CLL arm of MC1485 trial was reported here. The primary end point of this study is overall response rate (ORR). Pts with prior allogeneic stem cell transplant were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks. NCI CTCAE v4.0 and IWCLL 2008 criteria were used for non-hematological adverse events (AE) and for CLL grade hematological AE. Tumor expression of PD-1 and PD-L1 were assessed with standard immunohistochemical (IHC) staining. Percentage expressions of individual antigens were analyzed with whole-slide scanning followed by image analysis with Image-Pro software (Media Cybernetics). Fluorescence in situ hybridization (FISH) was performed on available CLL/RS tissue sections to assess copy number of chromosome 9p region that contains PD-L1 and PD-L2. Results: 25 pts including 16 CLL and 9 RS (biopsy-proven large cell lymphoma) were enrolled in CLL arm. The median age was 69 years (46-81). Twelve (48%) pts had del(17p) or monosomy 17 or TP53 mutation. The median number of prior therapies was 4 (1-10). 96%, 72% or 48% of pts had received alkylator and anti-CD20 antibody, purine analog or anthracycline. Fifteen (60%) pts had prior ibrutinib and 12 (48%) progressed clinically while receiving ibrutinib, including 6 who progressed to RS and 6 who developed progressive CLL. The median number of pembrolizumab doses that pts received was 3 (1 to 21), administered over a median treatment duration of 11 weeks (1 to 56). Drug-related AE occurred in 21 pts (88%) with the most common ones being neutropenia in 9 (37%), cough in 7 (29%) and dyspnea in 6 (25%) pts. Drug-related grade 3 or above AE occurred in 9 (38%) pts with most common ones being thrombocytopenia (5, 21%), dyspnea (2, 8%), and fatigue (2, 8%). The most common immune-related AE was liver enzyme elevation (12%, 8% G3) and was reversible with therapy interruption or steroid therapy. Based on investigator assessment using the Revised Response Criteria for Lymphomas and IWCLL 2008 criteria, one RS pt had complete response (CR, 4%), 3 RS had partial responses (PR, 12%). Among 9 RS pts, 1 CR (11%), 3 PR (33%), 3 SD (33%) and 2 PD (22%) were observed. Thus the ORR in RS was 44%. No CLL pts achieved a CR/PR, 3 had SD and 9 had progressive disease (PD). The ORR of all pts was 16%. Of the 4 RS who had CR/PR, responses occurred early after 2 cycles of therapy and median duration of therapy for CR/PR pts was 8.3 months with data cut-off by June 30th 2016 (Figure 1A). The causes for therapy discontinuation in RS were PD (3, 33%), alternate therapy (2, 22%), and thrombocytopenia due to increased marrow CLL (1, 11%). Increased marrow CLL was observed in 2 RS pts with PR to RS phase of disease assessed by PET, thus the protocol was amended to allow addition of idelalisib/ibrutinib to control the underlying marrow CLL. For RS pts who had a CR/PR or SD, variable nodal responses were observed (Figure 1B). In particular, 6 RS who had prior ibrutinib experienced CR or PR or SD with nodal responses. After a median follow-up of 10.2 (1.9 to 16.1) months, the median overall survival (OS) for all pts was 10.7 months (95% confidence interval [CI], 5.4 to not reached). The 6 month OS rate for RS and CLL pts were 73% and 59%, respectively. Biomarker assessment using IHC analysis on 10 pts with available tumor/nodal tissues (6 RS and 4 CLL) showed an increased expression of PD-L1 (p = 0.02) and a trend for an increased expression of PD-1 (p = 0.1) in the group of pts with CR/ PR versus pts in the group with no clinical response. One out of 10 tested showed polysomic for chromosome 9p. Conclusion: Pembrolizumab had an acceptable safety profile in CLL and RS patients. We confirmed that pembrolizumab has substantial therapeutic activity in RS. Single-agent pembrolizumab does not appear to have clear activity in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding. Shanafelt:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Abstract 1858 Systemic light chain amyloidosis (AL amyloidosis) is a condition where clonal plasma cells produce misfolded insoluble immunoglobulin light chains that deposit in various organs causing progressive organ dysfunction. Chemotherapy and autologous stem cell transplant (ASCT) when eligible is the standard treatment options for patients with AL amyloidosis. There are several studies who report long term outcomes of patient post ASCT. However, there is a paucity of literature describing the outcomes of patients who have received ASCT but have relapsed. We performed a retrospective study to assess the outcomes and treatment regimens employed following relapse after ASCT. Between 1996 and 2009, 410 patients received ASCT at the Mayo Clinic as first line therapy. Of those 410 patients 42 patients died within 3 months of transplant, 64 patients died without documented relapse, 158 patients were alive without documented progression, and 146 patients had documented progression. Those 146 patients are the subject of our study. The median time to hematologic relapse was 2 years (range: 0.2–15.5 years). At relapse, 59 patients were treated with IMiD based therapy, 36 with alkylator based therapy, 24 with bortezomib, 15 with steroids, and 5 with second ASCT. The respective hematologic response rates were 58%, 33%, 50%, 53%, and 60%. The remaining six patients were not evaluable for response for one other following reasons: organ transplants; no further therapy; inevaluable disease. With a median post relapse follow up of 3.6 years, the median overall survival (OS) from the first post ASCT relapse was 4.6 years. The median post transplant follow up was 6.1 years, the median OS for these patients was 7.3 years from the time of transplant. These data provide novel information about outcomes after SCT relapse, which should be useful not only for patients and doctors but also for investigators designing studies for salvage therapies post-transplant. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Myeloma remains incurable due to a stem cell/proliferative component that responds poorly to standard treatments. We have shown that aberrant IL-1beta stimulates the generation of paracrine IL-6, a central myeloma growth factor. A Phase II trial was completed using IL-1 receptor antagonist (IL-1Ra/Anakinra), which inhibits paracrine IL-6 production, and low dose Dexamethasone (Dex), which decreases IL-1 levels through myeloma cell apoptosis, in patients with SMM/IMM. SMM/IMM patients are most likely to benefit from anti-cytokine therapy in order to delay/prevent the development of active myeloma. Methods: Patients that had ≥ 10% bone marrow plasma cells and/or an IgG or IgA M-spike ≥ 3 g/dL and did not require immediate chemotherapy were eligible. All patients received 100 mg of IL-1Ra SQ qd for 6 months unless clinical progression occurred. Non-progressors were allowed to continue on therapy with IL-1Ra alone. Low dose Dex (20 mg qweek) was added after 6 months of IL-1Ra or for evidence of clinical progression; the dose was adjusted based on response/toxicity. Results: To investigate the effects of IL-1Ra and Dex alone and in combination in vitro, we co-cultured IL-1beta transduced +/− myeloma cells with stromal cells +/− dexamethasone, IL-1Ra, or both for 48 hours and quantitated the percent apoptotic cells by flow cytometry and IL-6 production by ELISA. The results showed that: 1) IL-1Ra was superior to Dex at inhibition of IL-6 but caused no myeloma apoptosis; 2) Dex induced apoptosis was inhibited by IL-6 3) Dex and IL-1Ra combined induced maximal IL-6 inhibition and apoptosis of myeloma cells. In the clinical trial, data were available on 47 patients; smoldering (79%) / indolent (21%). All patients received IL-1Ra initially and 20/47 subsequently received IL-1Ra/Dex. Seven patients had a decrease in the plasma cell labeling index (PCLI), a marker of cell proliferation, on IL-1Ra alone which paralleled a decrease in the high sensitivity C-reactive protein (CRP). Interestingly, in one patient treated with Dex alone for 6 months, Dex induced a decrease in the M-protein and IL-1 levels, however, the PCLI and CRP values increased. The IL-1Ra/Dex combination has resulted in stability of disease in the majority of the 47 patients; 28 continue on therapy with a median overall progression-free survival (PFS) of 37.5 months. Four of the 47 pts achieved a minor response (MR) with IL-1Ra alone, and an additional 6 pts achieved a MR/PR after addition of dex. The continuous measure of % reduction in CRP was significantly associated with time to progression (p=0.02). Similarly, those patients who had a >5% decrease in serum M protein also had a longer PFS (p<0.001). Of note, 2 patients with high PCLI values of 6.4 and 3.0, characteristic of poor prognosis, responded with a reduction in the PCLI values and continue on combination therapy for 3 and 1.5 years, respectively with stable disease. Conclusion: Agents such as IL-1Ra that specifically inhibit paracrine IL-6 production are more effective at targeting the proliferative component than apoptosis inducing agents such as Dex; the combination may be especially useful in patients that have an elevated PCLI at presentation.

Abstract Abstract 1575 We recently demonstrated in a phase II study that the anti-CD22 monoclonal antibody epratuzumab added to RCHOP improved DLBCL survival parameters. Despite these advances, 30–40% of DLBCL patients still relapse and die of disease. Recent advances have led to the identification of a variety of intracellular oncogenic pathways as potential targets for lymphoma therapy. Specifically, many studies have found that activation of the Signal transducer and activator of transcription 3 (STAT3) pathway promotes tumor cell survival in various types of cancers. STAT3 is a transcription factor and exerts its anti-apoptototic effect through several downstream targets such as MYC. MYC protein can be expressed in lymphoma cells with or without the presence of MYC translocation. The frequency of phosphorylated STAT3 (pSTAT3) and MYC expression and their prognostic relevance are unknown within diffuse large B-cell lymphoma (DLBCL), germinal center B-cell (GCB) and non-GCB subtypes. This study studied the tumor cell expression of pSTAT3 and MYC by IHC paired with serum cytokine levels in a DLBCL patient population uniformly treated on N0489. DLBCL tumor samples (n=38) were stained for detection of nuclear pSTAT3 expression. Using a threshold of ≥30% of tumor nuclei staining positive, 35 % (14/40) of tumors were pSTAT3+. An additional 17% (7/40) had between 10–30% pSTAT3+ cells. Non-malignant tonsil tissues (n=10) were positive for tSTAT3 in all cases but all but one case were pSTAT3 negative. Twenty-four of the same DLBCL tumors used for pSTAT3 expression were stained for MYC and 50% (12/24) were MYC positive (all nuclear) as defined by the criteria of ≥30% of cells staining positive. In cases (n=23) where both MYC and pSTAT3 IHC were performed, a positive pSTAT3 was more likely to have MYC expression whereas a positive MYC stain did not inform pSTAT3. By using a break apart probe for the MYC gene, MYC translocations in the major breakpoint regions were found in 10% (3/29) of cases. When MYC FISH was correlated with MYC IHC in the 24 DLBCL cases that had both techniques performed, all 3 MYC translocation cases were GCB by IHC, two were strongly positive for MYC by IHC, and 1 was negative. Among the 21 MYC FISH negative cases, 10 were MYC positive by IHC. These data suggest that MYC expression in lymphoma is not only controlled by genetic events such as translocations but also by other signaling pathways such as STAT3. pSTAT3 expression was correlated with an elevated serum LDH (p=0.0007). Neither MYC or pSTAT3 tumor expression correlated with other clinical or pathological features. Survival analysis revealed a trend toward shorter EFS for DLBCL patients whose tumors expressed MYC protein by IHC (p=0.2) or had a MYC translocation (p=0.09) by FISH; pSTAT3 expression status did not predict EFS (p=0.9). Within the GCB group 10 cases were MYC negative (10/17; 59%) and 7 cases were MYC positive (7/17; 41%). Among the non-GCB group 83% (5/6) were MYC positive. These data clearly suggest a trend of higher MYC positivity in the non-GCB DLBCL group (p=0.07). MYC positive cases had a clear trend of inferior EFS in both GCB (p=0.2) and in non-GCB (p=0.5) groups. The distribution of pSTAT3 (n=38) expression was also evaluated in the GCB (n=26) and non-GCB (n=12) DLBCL. In the GCB group 27% (7/26) were pSTAT3 positive compared to 58% (7/12) in the non-GCB group. Thus, there was a clear trend toward higher pSTAT3 positivity in non-GCB DLBCL tumors (p=0.06); however, pSTAT3 status did not correlate with EFS in either GCB or non-GCB DLBCL patients. In the present study we correlated pretreatment serum cytokines levels of these patients with pSTAT3 and MYC tumor cell expression. Out of the 30 cytokines tested, the only pre-treatment cytokines that were significantly correlated with pSTAT3 expression were IL-10 (p=0.05), G-CSF (p=0.03) and TNFa (p=0.04); none were correlated with MYC expression. Overall, our data provide evidence that over-expression of pSTAT3 and MYC is common in DLBCL. These biomarkers have potential as prognostic factors in the case of MYC and as a tool for selecting therapy for pSTAT3. MYC may be especially useful to further identify an adverse group of DLBCL patients within the otherwise favorable GCB tumor group. The availability of JAK/STAT and STAT-specific inhibitors provides the rationale to incorporate pSTAT3 staining in tumors from patients who are participating in these trials to learn if this biomarker can predict response Disclosures: No relevant conflicts of interest to declare.