Ansell, Stephen M.

Abstract Background: The pivotal phase 3 ECHELON-1 study demonstrated superior efficacy of brentuximab vedotin plus doxorubicin, vinblastine and dacarbazine (A+AVD) versus doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) in patients with previously untreated advanced stage classical Hodgkin lymphoma (cHL) with a 2-year modified progression-free survival (mPFS) of 82.1% in the A+AVD group versus 77.2% in the ABVD group (Hazard Ratio=0.77; 95% confidence interval [CI] 0.60, 0.98; p=0.04). PN is a known toxicity associated with anti-mitotic agents, including vinblastine and the MMAE component of brentuximab vedotin. In the ECHELON-1 study, the incidence of any-grade PN events was 67% (442 of 662 patients) and 43% (286 of 659 patients) in the A+AVD and ABVD arms, respectively; the incidence of grade ≥3 PN was 11% and 2%, respectively. At the time of the initial analysis, 67% of A+AVD-treated patients had either resolution (43%) or improvement (24%) of PN events. A total of the 92% of ongoing PN events were grade 1 (64%) or grade 2 (29%). Here, we report rates of PN resolution and improvement in patients participating in the ECHELON-1 study after long-term follow-up. Methods: Patients with Stage III or IV cHL were randomized 1:1 to receive up to six cycles of A+AVD (n=664) or ABVD (n=670). Pre-existing PN was an exclusion factor at study entry. Peripheral neuropathy was determined on the basis of a standardized MedDRA query; patients who developed PN were monitored throughout the study and those with ongoing PN at end of treatment were followed for resolution or improvement during the post-treatment follow-up period; follow-up visits were scheduled for every 12 weeks ±1 week until 36 months, then every 6 months until study closure. PN resolution was defined as completely resolved and improvement was defined as improved by ≥1 grade from worst grade as of the latest assessment. Results: At the time of the primary analysis, 51% (226/442) and 61% (174/286) of patients in the A+AVD and ABVD arms, respectively, had resolution or improvement of PN events at EOT. Upon continued follow-up (~10 additional months) for approximately 30 months (range 0-78.5) after end of treatment, 76% (335/442) of patients with PN in the A+AVD arm had either complete resolution (59%, 260/442) or improvement (17%, 75/442) of their PN events compared with 82% (234/286) with either resolution (72%) or improvement (10%) in the ABVD arm. In the A+AVD arm, 90% of ongoing PN cases (n=182) were grade 1/2; grade 1=58% (n=106), grade 2=32% (n=58). Residual grade 3 PN was reported in 9% (n=17) of patients (1 patient with grade 4 PN died before resolution). In the ABVD arm, residual PN (n=81) was grade 1 (65%; n=53), grade 2 (30%; n=24), and grade 3 (5%; n=4). For the subset of patients with PN that had not resolved by end of treatment, the median time to resolution of all PN events from AE start date was 28 weeks for A+AVD and 14 weeks for ABVD, the median time to improvement of PN was 39 weeks for A+AVD and 18.5 weeks for ABVD. Conclusions: After approximately 2.5 years of continued follow-up, PN continues to resolve and improve for patients who were treated with A+AVD or ABVD in the ECHELON-1 study. In both study arms, the majority of ongoing PN cases are grade 1 or grade 2. Further follow-up is ongoing. Disclosures Radford: Celgene: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy, Speakers Bureau; GlaxoSmithKline: Equity Ownership; Takeda: Consultancy, Research Funding, Speakers Bureau; Pfizer: Research Funding; BMS: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; AstraZeneca: Equity Ownership. Connors:Takeda: Research Funding; Seattle Genetics: Honoraria, Research Funding; Roche Canada: Research Funding; Genentech: Research Funding; Cephalon: Research Funding; Bristol Myers-Squibb: Research Funding; Janssen: Research Funding; Bayer Healthcare: Research Funding; NanoString Technologies: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Merck: Research Funding; F Hoffmann-La Roche: Research Funding; Amgen: Research Funding; Lilly: Research Funding. Younes:Astra Zeneca: Research Funding; J&J: Research Funding; Curis: Research Funding; BMS: Honoraria, Research Funding; Bayer: Honoraria; Takeda: Honoraria; Sanofi: Honoraria; Roche: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Merck: Honoraria; Seattle Genetics: Honoraria; Celgene: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Novartis: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding. Gallamini:Takeda: Consultancy, Speakers Bureau. Ansell:Affimed: Research Funding; Merck & Co: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; Seattle Genetics: Research Funding. Gopal:Aptevo: Consultancy; Janssen: Consultancy, Research Funding; Merck: Research Funding; Gilead: Consultancy, Research Funding; Brim: Consultancy; Spectrum: Research Funding; Takeda: Research Funding; BMS: Research Funding; Pfizer: Research Funding; Seattle Genetics: Consultancy, Research Funding; Incyte: Consultancy; Teva: Research Funding; Asana: Consultancy. Flinn:Trillium: Research Funding; Calithera: Research Funding; Forma: Research Funding; Portola: Research Funding; Verastem: Research Funding; Janssen: Research Funding; Infinity: Research Funding; Genentech: Research Funding; Forty Seven: Research Funding; Constellation: Research Funding; Merck: Research Funding; Curis: Research Funding; Takeda: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Incyte: Research Funding; ArQule: Research Funding; Verastem: Consultancy, Research Funding; Celgene: Research Funding; Agios: Research Funding; Novartis: Research Funding; Gilead: Research Funding; Pfizer: Research Funding; TG Therapeutics: Research Funding; Kite: Research Funding; BeiGene: Research Funding. Pettengell:CTI: Honoraria; Pfizer: Honoraria; Roche: Honoraria; Servier: Honoraria; Takeda: Honoraria. Dlugosz-Danecka:Servier: Consultancy; Roche: Consultancy. Engley:Seattle Genetics: Employment. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Liu:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Purevjal:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Miao:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Gautam:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Kuruvilla:Janssen: Consultancy, Honoraria, Research Funding; Princess Margaret Cancer Foundation: Research Funding; BMS: Consultancy, Honoraria; Abbvie: Consultancy; Karyopharm: Honoraria; Celgene: Honoraria; Seattle Genetics: Consultancy, Honoraria; Lundbeck: Honoraria; Merck: Consultancy, Honoraria; Amgen: Honoraria; Roche: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria; Leukemia and Lymphoma Society Canada: Research Funding.

Abstract Background Peripheral T-cell lymphomas (PTCLs) are aggressive non-Hodgkin lymphomas with poor overall survival rates. The genetics of PTCLs are poorly understood. We have described t(6;14)(p25.3;q11.2) translocations in PTCLs involving the T-cell receptor-alpha (TRA@) and interferon regulatory factor-4 (IRF4) genes and overexpressing IRF4 protein (also called MUM1). IRF4/MUM1 is a lymphoid transcription factor involved in differentiation and growth, the expression of which is tightly regulated in normal T cells. However, nearly half of PTCLs constitutively express IRF4/MUM1 and this expression is associated with adverse overall survival in several PTCL subtypes. Because IRF4/TRA@ translocations are rare among PTCLs (<1%), we investigated the presence of other genetic abnormalities of IRF4 in PTCLs and examined their association with IRF4/MUM1 protein expression. Methods Studies were performed on paraffin tissue sections of PTCL specimens diagnosed by standard WHO criteria. IRF4/MUM1 immunohistochemical staining (IHC) was performed using the MUM1p antibody and considered positive if nuclear staining was present in >30% of tumor cell nuclei. Fluorescence in situ hybridization (FISH) was performed using breakapart probes constructed from bacterial artificial chromosome DNA that hybridized to loci flanking the IRF4 locus on 6p25.3. Cases with 3 or more fusion signals were considered to have extra copies of the IRF4 gene. In a subset of cases, PCR and Sanger sequencing was performed on DNA extracted from frozen PTCL tumor tissue with primer sets that amplified exons 1 to 10 of the IRF4 gene. Data were analyzed using the chi-square test or t test. Results PTCLs from 277 patients (175 M:102 F; median age, 61 y) were examined by both IHC and FISH. The subtype distribution was: PTCL, not otherwise specified (NOS), 93; anaplastic large cell lymphoma (ALCL), 89; angioimmunoblastic T-cell lymphoma (AITL), 27; cutaneous T-cell lymphoma (CTCL), 43; and cytotoxic PTCL, 25. IRF4/MUM1 was positive in 116 cases (42%). Extra copies of IRF4 were identified in 18 PTCLs (7%), 83% of which were IRF4/MUM1 protein-positive. In contrast, 39% of cases without extra copies of IRF4 were IRF4/MUM1 protein-positive (p=0.0002). The mean percentage of tumor cells with IRF4/MUM1 staining was 69% in cases with extra copies of IRF4, compared to 30% in cases without extra copies (p=0.0001). Extra copies of IRF4 were seen in 13% of ALCLs, 4% each of PTCLs, NOS and cytotoxic PTCLs, 2% of CTCLs, and 0% of AITLs (p=0.02). Two IRF4/MUM1-positive cases had an IRF4/TRA@ translocation (1%). We selected 30 IRF4/MUM1-positive PTCLs for Sanger sequencing. In this subset, we identified a previously undescribed non-synonymous variant in exon 5 (S309R) in 1 case (3%) without an extra copy of IRF4. Conclusions Extra copies of IRF4 are seen in ∼7% of PTCLs, are significantly associated with IRF4/MUM1 expression, and are preferentially observed in ALCLs. Both IRF4/TRA@ translocations and IRF4 mutations are rare in PTCLs. These data suggest that genetic abnormalities of the IRF4 gene – specifically extra copies of IRF4 – may contribute to IRF4/MUM1 expression in some PTCLs. Since IRF4/MUM1 expression is seen in ∼42% of PTCLs, these data also imply the existence of other regulatory mechanisms. Characterizing these mechanisms may be important clinically, since IRF4/MUM1 has been proposed as a therapeutic target in human cancers but drugs that directly inhibit its function are currently not available. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction Recent advances in the understanding of the WM pathobiology led to the expansion of our therapeutic options in this disease. A number of targeted drugs are either available or under investigation and are poised to change the chemo-immunotherapy paradigm in the treatment of WM. Now more than ever, an individualized treatment approach for patients with WM is possible, where patient characteristics and preferences can be matched by different treatment goals and side effect profiles. While deep responses have been associated with longer disease-free survival in other hematologic malignancies, data on patients with WM are sparse. We report the impact of depth of response in disease-free and overall survival (OS) in WM. Methods WM patients consecutively seen at Mayo Clinic between 01/1998 and 12/2016 were reviewed for response to therapy and disease burden. The best response achieved after the treatment of interest (TOI) was classified using the IWWM-7 Response Criteria. The included TOI were: BR, DRC, BDR and high-dose chemotherapy followed by ASCT. All time-to-event analyses were performed from the TOI initiation date using the Kaplan-Meier method and the log-rank test. A landmark analysis from the date-of-best response was also performed for OS to prevent immortal-time bias. Univariate and multivariate analyses of progression-free survival (PFS) and time-to-next therapy (TTNT) were performed using the Cox regression method. Results A total of 181 patients had disease response assessed after the TOI. Baseline characteristics at time of diagnosis are summarized in table 1. The median follow up from TOI was 3.8 years (95% CI: 3-4), the majority of patients received TOI as salvage therapy [n=112 (63%); median 2nd line (rage 1-11)]. Best response rates with the corresponding 5-year PFS and TTNT are summarized in table 2. The median OS from TOI was longer in patients who achieved at least a PR [median 7.2 years (95% CI: 5-NR) vs 3.7 years (95% CI: 1.6-NR), p=0.01]. A trend towards a longer OS was also seen with deeper responses (PR or better) achieved with frontline therapy [median 5.8 years (95% CI: 5.8-NR) vs 3.4 years (95% CI: 1.6-NR), p=0.24]. Figure 1 shows the correlation between deeper responses with PFS and TTNT. Among patients achieving a PR or VGPR, those with a normal FLC ratio post TOI demonstrated a longer PFS and TTNT [PFS: median NR (95% CI: 3.4-NR) vs 4.9 years (95% CI: 2.8-8.7), p=0.01; TTNT: median NR (95% CI: 3.5-NR) vs 5.2 years (95% CI: 4.2-9.4), p=0.04], figure 2. In a multivariate analysis including normal FLC ratio, normal IgM level and minimal BM involvement (<5%) post TOI, normal FLC ratio remained an independent prognostic factor for longer PFS and TTNT. Similar trends were seen when considering treatment naïve and relapsed/refractory patients independently (data not shown). Discussion Our results not only suggest an association between depth of response with PFS and TTNT, but also with OS in patients with WM. A normal FLC ratio (not part of the IWWM-7 response criteria) seems to predict a longer disease-free interval in patients achieving a PR or VGPR. Disclosures Gertz: Ionis: Honoraria; Apellis: Consultancy; annexon: Consultancy; Prothena: Honoraria; janssen: Consultancy; Physicians Education Resource: Consultancy; Alnylam: Honoraria; Teva: Consultancy; spectrum: Consultancy, Honoraria; Medscape: Consultancy; celgene: Consultancy; Research to Practice: Consultancy; Amgen: Consultancy; Abbvie: Consultancy. Kapoor:Takeda: Research Funding; Celgene: Research Funding. Ailawadhi:Amgen: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding; Celgene: Consultancy. Reeder:Affimed: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Lacy:Celgene: Research Funding. Kumar:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Seattle Genetics: Research Funding; Celldex: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Regeneron: Research Funding.

Abstract Introduction Immunoglobulin M monoclonal gammopathy of undetermined significance (IgM MGUS) is a relatively common pre-malignant condition that may progress to Waldenstrom macroglobulinemia (WM), an incurable low-grade non-Hodgkin lymphoma. The acquisition of genomic alterations in a multistep process of progression is likely a central mechanism responsible for the progression of IgM MGUS to WM, leading to increased tumor burden and end-organ damage. The exact role of the immune system in this process is still poorly characterized. The modulation of the immune system by malignant cells leading to anti-lymphoma immunity or immune evasion is a well-stablished principle associated with lymphoma survival and progression, respectively. The understanding of the pathobiology of IgM MGUS and WM has grown significantly over the last few years; however, most of the past research has focused on genetics and flow cytometric analysis of malignant cells. The introduction of CyTOF, a novel platform coupling mass spectometry with single-cell flow cytometry using antibody-metal isotope pairs, has allowed a broader single-cell analysis and the study of functional profiles. We here report the use of CyTOF technology to comprehensively profile the immune system of patients with IgM MGUS and WM. Methods Viably-cryopreserved (DMSO 10%) single-cell suspensions containing peripheral blood mononuclear cells from 15 patients (WM n=9 and IgM MGUS n=6) were used in this study. Recovered cells (1-3 x 106 per sample) were stained with a 30-parameter surface protein CyTOF panel designed to characterize multiple cell types and profile the immune system. Nucleated cellular events were identified using a DNA intercalator conjugated to natural abundance iridium (191Ir and 193Ir). Cisplatin (195Pt) was used for dead-live cell discrimination and calibration beads containing natural abundance cerium (140/142Ce), europium (151/153Eu), holmium (165Ho), and lutetium (175/176Lu) were used for normalization of the instrument signal. CyTOF analysis of normalized files was carried out using the Astrolabe Diagnostics platform. Cell clusters were assigned using the FlowSOM package and differential abundance analysis was performed using the edgeR package. Analysis is adjusted for multiple comparisons. Results The median live single-cell count for the entire cohort was 573,300 (range 50,681 to 869,727), representing a median of 81% (range 39% to 87%) of the total event counts [median 820,800 (range 130,452 to 1,000,000]. The cell count and the proportion of event count was similar in patients with WM or IgM MGUS. T cells represented 45.8% of the total events; granulocytes represented 31.3%; NK cells represented 8.6%; monocytes represented 8.1%; B cells represented 2.4% of the total events for the entire cohort. Figure 1 shows a heat map of different immune cell sub-types proportion per patient sample. A difference was noted in the proportion of monocytes (CD14+, CD16+) and B-cells when comparing patients with IgM MGUS and WM (figure 2). Patients with WM had a higher proportion of monocytes compared to IgM MGUS patients (p=0.05). A higher proportion of B-cells was noted in patients with IgM MGUS when compared to WM (4.2% vs 0.6%, p=0.01). When B-cells were sub-classified as naïve, transitional, non-switched memory, switched memory, and plasmablasts, the proportion of non-switched memory B-cells was higher in IgM MGUS compared to WM (p=0.05). While the results of this pilot study suggest important differences between IgM MGUS and WM as regards the immune repertoire, confirmatory studies are in progress in a larger cohort of patients. Conclusion To our knowledge, this is the first study of mass cytometry in patients with WM and IgM MGUS patients. A higher proportion of monocytes and lower proportion of memory B-cells was noted in patients with WM compared to IgM MGUS. CyTOF study of the immune profile in these patients is feasible and can potentially uncover relationships between cell types not typically associated with the disease progression continuum (IgM MGUS to WM). While definitive conclusion cannot be made using this dataset due to the small sample size, CyTOF is a powerful tool in the study of the immune profile of WM patients. Disclosures Gertz: Amgen: Consultancy; Abbvie: Consultancy; Apellis: Consultancy; annexon: Consultancy; spectrum: Consultancy, Honoraria; Teva: Consultancy; Alnylam: Honoraria; Physicians Education Resource: Consultancy; Ionis: Honoraria; janssen: Consultancy; celgene: Consultancy; Prothena: Honoraria; Research to Practice: Consultancy; Medscape: Consultancy. Kapoor:Celgene: Research Funding; Takeda: Research Funding. Ailawadhi:Takeda: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Pharmacyclics: Research Funding. Reeder:Affimed: Research Funding. Ansell:Seattle Genetics: Research Funding; Regeneron: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Merck & Co: Research Funding; Trillium: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Celldex: Research Funding; Bristol-Myers Squibb: Research Funding.

Abstract Introduction: The addition of Rituximab to chemotherapy has significantly improved the outcome of patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL). Patients treated with immunochemotherapy for DLBCL who achieve EFS24 (event-free for 2 years after diagnosis) have an overall survival equivalent to that of the age- and sex-matched general population. Relapses after achieving EFS24 have been considered to be unusual but have been understudied. We sought to define the rate, clinical characteristics, treatment pattern, and outcomes of such relapses. Methods: 1448 patients with newly diagnosed DLBCL from March 2002 to June 2015 were included. Patients were enrolled in the Molecular Epidemiology Resource (MER) of the University of Iowa/Mayo Clinic Lymphoma SPORE, treated per physician choice (predominantly R-CHOP immunochemotherapy) and followed prospectively. An event was defined as progression or relapse, unplanned re-treatment after initial therapy, or death from any cause. Cumulative incidence of relapse and non-relapse mortality after achieving EFS24 were analyzed as competing events using Gray's test in the EZR software. Post-relapse survival was defined as time from relapse to death from any cause and analyzed using Kaplan-Meier method in SPSS (V22). Results: Among the 1448 patients, 1260 (87%) had DLBCL alone at diagnosis, and 188 (13%) had concurrent indolent lymphoma (follicular lymphoma 115, marginal zone lymphoma 18, chronic lymphocytic leukemia 14, lymphoplasmacytic lymphoma 4, unspecified 37) at diagnosis. After a median follow-up of 83.9 months, 896 patients achieved EFS24. For all 896 patients who achieved EFS24, the cumulative incidence of relapse (CIR) was 5.7%, 9.3% and 13.2%, respectively, at 2, 5 and 10 years after achieving EFS24. Patients with concurrent indolent lymphoma at diagnosis had a higher CIR compared to those with DLBCL alone at diagnosis (10.2 vs 4.8% at 2 years, 15.7 vs 8.0% at 5 years, 28.8 vs 9.7% at 10 years, P<0.001; Figure 1). There were a total of 84 patients who relapsed after achieving EFS24. The median age at initial diagnosis was 66 years (range 35-92), and 48 (57%) were male. At diagnosis, 11 (13%) had ECOG PS >1, 37 (50%) had LDH elevation, 62 (74%) were stage III-IV, 14 (17%) had more than 1 extranodal site, and 26 (31%) were poor risk by R-IPI score. There were 58 patients with DLBCL alone at diagnosis who relapsed after achieving EFS24, and 38 (75%) relapsed with DLBCL, 13 (25%) relapsed with indolent lymphoma (predominantly follicular lymphoma), and pathology was unknown in 7 patients. In contrast, there were 26 patients with concurrent indolent lymphoma at diagnosis who relapsed after achieving EFS24, and 9 (41%) relapsed with DLBCL, 13 (59%) relapsed with indolent lymphoma, and pathology was unknown in 4 patients. In the 47 patients who relapsed with DLBCL after achieving EFS24, 45% received intensive salvage chemotherapy, 19% received regular intensity chemotherapy, 9% received CNS directed chemotherapy, and 36% went on to receive autologous stem cell transplant (ASCT). In the 26 patients who relapsed with indolent lymphoma after achieving EFS24, 27% were initially observed, 54% received regular intensity chemotherapy, 4% received intensive salvage chemotherapy, and 19% received ASCT after subsequent progression. The median post-relapse survival (PRS) for all patients with a relapse after achieving EFS24 was 38.0 months (95% CI 27.5-48.5). The median PRS for patients who relapsed with DLBCL and indolent lymphoma after achieving EFS24 were 29.9 (19.9-39.9) and 89.9 (NR-NR) months, respectively (P=0.002; Figure 2). Conclusions: Relapses after achieving EFS24 in patients with DLBCL were uncommon in the rituximab era. Patient with DLBCL alone at diagnosis can relapse with either DLBCL or indolent lymphoma (3:1 ratio). Patients with concurrent DLBCL and indolent lymphoma at diagnosis had a significantly higher CIR, and relapses with DLBCL and indolent lymphoma were similar (2:3 ratio). Even with high intensity salvage chemotherapy and consolidative ASCT, patients who relapsed with DLBCL had a significantly worse survival compared to those who relapsed with indolent lymphoma. Late relapses with DLBCL remain clinically challenging, with a median survival of 2.5 years after relapse. Figure 1. Figure 1. Disclosures Maurer: Celgene: Research Funding; Nanostring: Research Funding; Morphosys: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Takeda: Research Funding; Pfizer: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Celldex: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Merck & Co: Research Funding; Bristol-Myers Squibb: Research Funding. Cerhan:Celgene: Research Funding; Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding.

Abstract Background An association has been identified between the diagnosis-to-treatment interval (DTI) and prognostic clinical factors and outcomes in patients with previously untreated diffuse large B-cell lymphoma (DLBCL) (Maurer et al, JCO 2018). This association can result in inadvertent selection bias in clinical trials to exclude patients with aggressive disease due to the inability to delay treatment long enough to fulfill enrollment criteria, compromising the validity of clinical trial study results to the general population. A similar concern exists in the relapsed/refractory (r/r) DLBCL setting regarding patient selection bias against patients with aggressive disease requiring immediate treatment following relapse or progression. Here we examine the time from progression after immunochemotherapy (IC) to the initiation of first salvage chemotherapy and its association with outcome. Patients and Methods: Newly diagnosed patients were prospectively enrolled within 9 months of diagnosis in the University of Iowa/Mayo Clinic Lymphoma SPORE Molecular Epidemiology Resource (MER), now a subcohort of the Lymphoma Epidemiology of Outcomes (LEO) Cohort Study, and followed for progression/relapse, retreatment, and death. This analysis includes patients with their first r/r DLBCL following frontline IC who initiated aggressive salvage chemotherapy as identified and included in a previous publication (Farooq et al, BJH 2017). The progression-to-treatment interval (PTI) was defined as the time in days from date of progression from IC to initiation of salvage therapy. The date of progression was defined as either a) the date biopsy was obtained for patients who had a biopsy to confirm progressive disease or b) the date of the scan or clinical examination indicating progression in patients who did not have a biopsy performed. Event-free survival (EFS) was defined as time from initiation of first salvage therapy to progression or relapse, initiation of new anti-lymphoma therapy, or death due to any cause; overall survival (OS) was defined as time from initiation of salvage therapy until death due to any cause. Results: 162 patients with r/r DLBCL enrolled in the MER from 2002-2012 who initiated aggressive salvage chemotherapy with intent to transplant and had confirmed dates for both progression after IC and start of salvage therapy were evaluated. Median age at first progression for these patients was 64 years (range 36-76) and 104 (64%) were male. Median time from diagnosis to first progression on IC was 6.7 months (IQR: 4.6-12.7). Initial salvage therapy was R-ICE (80%), R-DHAP (8%), rituximab, oxaliplatin, cytosine arabinoside, and dexamethasone (ROAD) (6%), and other (7%). At a median follow-up of 49 months from initiation of salvage therapy (IQR: 33-74), 116 patients had died (72%). Median PTI was 6 days (IQR: 2-13). 110 patients (68%) had biopsy confirmation of disease prior to initiating salvage therapy; median PTI was 2 days (IQR: 1-7) for patients who had biopsy confirmation vs. 7 days (IQR: 3-16) in patients without biopsy confirmation, Wilcoxon p=<0.0001. There was no difference in OS from initial salvage therapy between patients who did not have biopsy confirmation (HR=1.09, 95% CI: 0.74-1.60, p=0.68) compared to patients with biopsy confirmation. Patients with short PTI (0-6 days) had significantly worse overall survival from initiation of salvage therapy (median OS = 7.6 months, HR=2.10 (95% CI: 1.43-3.08) compared to patients who initiated therapy 7 or more days from progression (median OS = 29.7 months), logrank p<0.0001. This association remained consistent (HR=2.20, 95% CI: 1.48-3.26, p<0.0001) after adjusting for age and biopsy confirmation of progression. Short PTI was also associated with inferior response rate to initial salvage therapy (51% vs. 65%, p=0.058), lower rate of proceeding to transplant after initial salvage therapy (33% vs. 55%, p=0.0063), lower rate of being event-free 24 months from initial salvage therapy (16% vs 33%, p=0.011) and lower rate of ever proceeding to transplant (44% vs. 59%, p=0.057). Conclusions: A short progression-to-treatment interval is strongly associated with inability to proceed to transplant and inferior overall survival in r/r DLBCL. These results have implications for the design and interpretation of clinical trials in the relapsed/refractory setting. Figure. Figure. Disclosures Maurer: Celgene: Research Funding; Nanostring: Research Funding; Morphosys: Research Funding. Ansell:Trillium: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Pfizer: Research Funding; Celldex: Research Funding; Takeda: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cerhan:Nanostring: Research Funding; Celgene: Research Funding; Jannsen: Other: Scientific Advisory Board.

Abstract Background: The oral BTK inhibitor ibrutinib is the only approved therapy for patients with symptomatic Waldenström macroglobulinemia (WM). Bing-Neel syndrome (BNS) is a rare complication of WM that results from infiltration of malignant lymphoplasmacytic cells into the central nervous system (CNS) causing neurological deficits. Treatment options in patients with BNS are limited to agents with CNS penetration. Ibrutinib can penetrate into the CNS, but data on its efficacy in BNS is lacking outside case reports. Methods: We performed a multicenter retrospective study evaluating the efficacy of ibrutinib in patients with BNS. The diagnosis of BNS was established in patients with a clinicopathological diagnosis of WM by radiological and/or cytological evidence of CNS involvement by WM, and response was assessed based on recently published criteria. Ibrutinib was given orally at doses of 420-560 mg PO once daily until disease progression or intolerable toxicity. Response was assessed using criteria from the 8th International Workshop for WM (Minnema et al. Haematologica 2017). Events were defined as death from any cause, progression of disease and stopping ibrutinib from any reason. Time to events was estimated using the Kaplan-Meier method. Results: We present data on 24 patients with BNS treated with ibrutinib. The median age at diagnosis of WM was 60 years (range 38-76 years) and 14 patients (58%) were men. The median lines of therapy for WM prior to BNS diagnosis was 1 (range 0-7 lines), and 9 patients (38%) were untreated for WM at the time of BNS diagnosis. Previous WM therapies included anti-CD20 antibodies (n=15), alkylators (n=13), nucleoside analogues (n=8), proteasome inhibitors (n=3), immunomodulators (n=2), and autologous transplant (n=1). The median age at BNS diagnosis was 65 years (range 38-80). The median time from WM to BNS diagnosis was 4 years (range 0-27 years). In 2 patients, the diagnosis of BNS was made concurrently with WM diagnosis. The median number of BNS lines prior to ibrutinib was 1 (range 0-5 lines). Previous BNS therapies included intrathecal chemotherapy (n=9), high-dose methotrexate (n=6), bendamustine (n=3) and radiation therapy (n=3). In 7 patients (29%), ibrutinib was the first line of treatment for BNS. The most common symptoms at BNS presentation were cognitive deficits (n=10), sensory deficits (n=8), ataxia/falls (n=8), motor deficits (n=6), headache (n=5) and seizures (n=5). MRI findings included leptomeningeal enhancement (n=16) and brain masses (n=5). Cerebrospinal fluid (CSF) flow cytometry confirmed the presence of clonal CD19+ in 19 patients (79%). Biopsies were performed in 5 patients (21%) and confirmed presence of WM cells. 4 patients had normal MRI but had abnormal CSF cytology and/or flow cytometry. Tissue was not obtained in 1 patient in whom MRI showed leptomeningeal enhancement. Interestingly, 2 patients were diagnosed with lymphoplasmacytic lymphoma secreting IgG paraprotein. The median serum IgM (n=20) prior to ibrutinib initiation was 1,294 mg/dl (range 125-5,938 mg/dl), and the median hemoglobin level was 11.9 g/dl (7.7-15.2 g/dl). Ten patients (42%) received ibrutinib 560 mg PO once daily, and 14 (58%) received ibrutinib 420 mg PO once daily. At best response, median serum IgM and hemoglobin levels were 340 mg/dl (82-3,330 mg/dl) and 14.6 g/dl (range 9.2-16.0 g/dl). Based on consensus BNS response criteria, complete response was attained in 2 patients (8%), partial response in 14 (58%) and clinical improvement in 3 patients (13%). With a median follow-up time of 13 months (95% CI 8-21 months), 5 patients have stopped ibrutinib, 3 due to BNS progression, 1 due to grade 3 muscle cramps and 1 due to arrhythmia, and 3 patients have died, 2 from infection and 1 from BNS progression. The median event-free survival (EFS) from ibrutinib initiation was not yet reached. The 1-year and 2-year EFS rates were 71% (95% CI 46-86%) and 52% (23-75%), respectively. Conclusion: Ibrutinib is a safe and effective treatment option for patients with BNS. Disclosures Palomba: Pharmacyclics: Consultancy; Celgene: Consultancy. Talaulikar:Amgen: Consultancy, Honoraria; Takeda: Research Funding; Janssen: Honoraria, Speakers Bureau; Roche: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Buske:Janssen: Honoraria, Research Funding; Bayer: Research Funding; Roche: Honoraria, Research Funding. Tedeschi:Gilead: Consultancy; AbbVie: Consultancy; Janssen: Consultancy, Speakers Bureau. Simpson:Pharmacyclics LLC, an AbbVie Company: Research Funding; Acerta: Research Funding; Merck: Honoraria, Research Funding; BeiGene: Research Funding; Sanofi: Research Funding; Bristol-Myers Squibb: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Novartis: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; MSD: Honoraria; Roche: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Amgen: Research Funding, TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen: Honoraria, Research Funding. Tam:Janssen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BeiGene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Ansell:Affimed: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Pfizer: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Celldex: Research Funding; LAM Therapeutics: Research Funding. Treon:Johnson & Johnson: Consultancy; BMS: Research Funding; Pharmacyclics: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding; Janssen: Consultancy, Other: Travel, Accommodations, Expenses. Castillo:Millennium: Research Funding; Genentech: Consultancy; Abbvie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Beigene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.

Abstract Background: The phase 3 ECHELON-1 study assessed frontline brentuximab vedotin administered with doxorubicin, vinblastine, and dacarbazine (A+AVD) vs doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) in patients (pts) with advanced cHL (NCT01712490). The primary endpoint of ECHELON-1, modified PFS (mPFS) per independent review facility (IRF), is defined as (1) progressive disease, (2) death, or (3) subsequent anticancer therapy (chemotherapy [chemo] and/or radiotherapy [RT]) following detection of a non-complete response (non-CR = Deauville score 3-5) at end of frontline therapy. A+AVD was superior to ABVD (hazard ratio [HR]=0.77; p=0.035) with 2-year mPFS rates of 82.1% and 77.2%; as previously reported. In pts with newly diagnosed cHL, the aim of frontline therapy is curative. Pts who do not achieve a satisfactory response to frontline therapy may initiate subsequent anticancer therapy prior to response criteria-defined progression. The measurement of traditional PFS becomes confounded, as pts may effectively be rescued from criteria-defined progression by subsequent treatment, resulting in an overestimation of PFS with frontline therapy (Connors et al. Haematologica 2016;101[s5]:22-3[P007]). To further evaluate modified and traditional PFS in the ECHELON-1 study, two sensitivity analyses were conducted. Methods: 1334 pts with Stage III (36%) or IV (64%) cHL were randomized 1:1 to receive A+AVD (n=664) or ABVD (n=670) on days 1 and 15, for up to six 28-day cycles. In addition to mPFS per IRF, mPFS per investigator (INV) was collected. A sensitivity analysis (mPFS-chemo) was performed in which RT following a non-CR at the completion of frontline therapy was not counted as an event: in this case, mPFS-chemo was defined as (1) progression, (2) death, or (3) receipt of additional anticancer chemo excluding RT for pts who are not in CR after completion of frontline therapy. A second sensitivity analysis of traditional PFS (PFS-traditional), defined as (1) progression or (2) death, was also performed. All analyses were performed per INV as, per protocol, IRF follow up of pts was not conducted after the initiation of subsequent therapy. Results: At 2 years, the rates of mPFS per INV (95% CI) for A+AVD vs ABVD were 81.0% (77.6-83.9%) vs 74.4% (70.7-77.7%), respectively; HR=0.72 (95% CI: 0.573, 0.914; p=0.006). Concordance between IRF and INV mPFS assessments was high among all pts in both arms, at 91%. A total of 123 mPFS events per INV were observed among pts treated with A+AVD, including 73 pts with PD, 15 deaths, and 35 who received additional anticancer therapy following evidence of non-CR at the end of frontline therapy, vs 164 per INV mPFS events among pts treated with ABVD, of which 103 were PD, 22 were deaths, and 39 were additional anticancer therapy following evidence of non-CR at the end of frontline therapy. Of the 35 (A+AVD) and 39 (ABVD) additional anticancer therapy events, chemo/RT following evidence of non-CR at the end of frontline therapy accounted for 11/24 and 17/22 of these events, respectively. For mPFS-chemo, a larger benefit in favor of A+AVD vs ABVD, with a HR=0.687 (95% CI: 0.534, 0.885; p=0.003), was observed. The 2-year mPFS-chemo (95% CI) was estimated as 84.0% (80.9-86.7%) for pts treated with A+AVD vs 77.3% (73.7-80.4%) for pts treated with ABVD. A total of 103 events were observed among pts in the A+AVD arm, including 78 pts with PD, 15 deaths, and 10 who received additional chemo following evidence of a non-CR at the end of frontline therapy, vs 145 events among pts treated with ABVD, of which 106 were PD, 22 were deaths, and 17 were additional chemo following evidence of non-CR at the end of frontline therapy. For PFS-traditional, an advantage in favor of A+AVD vs ABVD was also observed: HR=0.70 (95% CI: 0.54-0.91; p=0.006). The 2-year PFS estimate (95% CI) was 84.2% (81.1-86.9%) for A+AVD vs 78.0% (74.4-81.1%) for ABVD. In total, there were 101 PFS events in the A+AVD arm, including 86 pts with PD and 15 deaths; vs 140 PFS events in the ABVD arm, including 118 pts with PD and 22 deaths. Conclusions: Consistent with the primary outcome of ECHELON-1, a benefit in favor of A+AVD vs ABVD was observed independent of the inclusion of additional anticancer RT or chemo as survival events, in addition to progression or death. A traditional PFS assessment including only progression or death events demonstrated that A+AVD resulted in a 30% reduction in the risk of progression or death compared to ABVD. Figure. Figure. Disclosures Connors: Lilly: Research Funding; Bayer Healthcare: Research Funding; Janssen: Research Funding; Bristol Myers-Squibb: Research Funding; Merck: Research Funding; NanoString Technologies: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Seattle Genetics: Honoraria, Research Funding; Roche Canada: Research Funding; Amgen: Research Funding; Genentech: Research Funding; F Hoffmann-La Roche: Research Funding; Cephalon: Research Funding; Takeda: Research Funding. Younes:J&J: Research Funding; Celgene: Honoraria; BMS: Honoraria, Research Funding; Sanofi: Honoraria; Abbvie: Honoraria; Curis: Research Funding; Genentech: Research Funding; Merck: Honoraria; Bayer: Honoraria; Pharmacyclics: Research Funding; Janssen: Honoraria, Research Funding; Novartis: Research Funding; Incyte: Honoraria; Seattle Genetics: Honoraria; Roche: Honoraria, Research Funding; Astra Zeneca: Research Funding; Takeda: Honoraria. Gallamini:Takeda: Consultancy, Speakers Bureau. Ansell:Pfizer: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Celldex: Research Funding; Seattle Genetics: Research Funding. Kim:J&J: Research Funding; Kyowa-Kirin: Research Funding; Mundipharma: Research Funding; Celltrion: Honoraria, Research Funding; Novartis: Research Funding; Takeda: Research Funding; Roche: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Celgene: Research Funding; Merck: Research Funding. Advani:Janssen: Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Cell Medica: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Forty Seven Inc.: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Kura: Research Funding; Kyowa: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Merck: Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Celgene: Research Funding; Autolus: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Millenium: Research Funding; Agensys: Research Funding; Infinity: Research Funding; Regeneron: Research Funding; Celgene: Research Funding; Gilead/Kite: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board. Bartlett:KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; ImaginAB: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding; Pharmacyclics: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Millennium: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Meyers Squibb: Research Funding; Immune Design: Research Funding; Astra Zeneca: Research Funding; Forty Seven: Research Funding; Affimed: Research Funding; Genentech: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Merck & Co: Research Funding; Janssen: Research Funding. Straus:Onco Tracker: Consultancy; Roch China: Speakers Bureau; Memorial Sloan Kettering Cancer Center: Employment; JUNO: Consultancy; Medical Crossfire: Speakers Bureau; DAVA Oncology: Consultancy, Honoraria; Bayer: Consultancy; InPractice Elselvier: Consultancy; Millenium (Takeda): Consultancy, Research Funding; Seattle Genetics: Consultancy. Sureda:BMS: Consultancy, Honoraria; Sanofi: Honoraria; Roche: Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria. Hutchings:Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Dlugosz-Danecka:Servier: Consultancy; Roche: Consultancy. Engley:Seattle Genetics: Employment. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Liu:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Miao:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Jolin:Takeda Pharmaceuticals International Co.: Employment. Gautam:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Radford:Novartis: Consultancy, Speakers Bureau; Celgene: Research Funding; Pfizer: Research Funding; GlaxoSmithKline: Equity Ownership; Takeda: Consultancy, Research Funding, Speakers Bureau; AstraZeneca: Equity Ownership; Seattle Genetics: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; ADC Therapeutics: Consultancy, Research Funding.

Abstract Background Peripheral T-cell lymphomas (PTCL) are a heterogeneous group of non-Hodgkin’s lymphomas (NHL) characterized by poor treatment outcomes with conventional chemotherapy, including CHOP [complete remission (CR) ∼40%]. Retrospective studies suggest that the incorporation of etoposide into chemotherapy regimens may improve outcomes compared to CHOP. In contrast, anthracyclines appear to have a limited role in PTCL, largely attributed to p-glycoprotein related resistance. Pralatrexate was the first drug approved for patients (pts) with relapsed PTCL, providing a rationale to evaluate it in the front-line setting. Herein, we evaluated the efficacy of a novel combination for the primary therapy of pts with PTCL whereby the anthracycline in CHOP backbone was replaced with etoposide (CEOP) alternating with pralatrexate (P). Methods Pts > 18 years (yrs) with PTCL stages II-IV with no prior therapy and adequate end organ function were eligible. Eligible histologies included, PTCL-NOS, AILT, ALCL (ALK positive pts only allowed if IPI >3). CEOP (Cycle A) was administered as: cyclophosphamide 750 mg/m2 IV d1, etoposide 100 mg/m2 IV d1-3 (or 100 mg/m2 IV d1 and 200 mg/m2 PO days 2-3), vincristine 2 mg IV day 1 and prednisone 100 mg/day X 5 alternating with P (cycle B) 30 mg/m2 IV d 15, 22 and 29 (with vitamin B12 and folate supplementation). Growth factors were used to support both cycles of therapy. Imaging to assess response was done after cycle 2B, 4B and 6B. Pts achieving a remission were eligible for consolidative autologous stem cell transplant (ASCT) after cycle 4B at physician discretion. The primary statistical aim was to improve the CR rate from 40 to 63% with CEOP-P and optional transplant. Secondary objectives included assessment of event free survival (EFS), overall survival (OS) and toxicity of the regimen. A two-stage Simon design (alpha=0.10, 90% power) tested the null hypothesis that the CR rate would be </= to 40%. For the first stage of 20 evaluable pts, the trial would be terminated if 8 or fewer pts experienced a CR after course 2B of chemotherapy. For the second stage, a total of 34 pts were required with at least 17 achieving a CR at the end of therapy to consider the regimen useful. Results 34 pts were enrolled and one withdrew consent before starting therapy, leaving 33 pts enrolled between 7/2011 and 1/2013. Characteristics are shown in Table 1. 27 pts received at least 2 cycles of therapy. 6 pts received only 1 cycle due to early disease progression in 4 and adverse events in 2. Grade 3-4 toxicities attributed to therapy included, anemia (27%), thrombocytopenia (12%), febrile neutropenia (18%), mucositis (18%), sepsis (15%), increased creatinine (12%) and liver transaminases (12%). At the end of stage 1, 10 of 20 pts (50%) achieved a CR; therefore accrual proceeded to stage 2. At the time of this initial analysis, the overall response rate is 70%. To date 15 pts (45%) have achieved a CR with two additional pts pending evaluation. Overall, the 1-yr EFS is 48% (95% CI 28-64), and 1-yr OS 70% (95% CI 47-84) (Figures 1 and 2). 6 pts (18%) to date (n=3 CR, n=2 PR and 1 with stable disease) have received consolidation with ASCT and all are in CR post-transplant. Pts who proceeded to ASCT were younger than the non-transplant cohort (median age 58 versus 64 yrs) with other clinical characteristics being similar. On exploratory bivariate analyses, age <60 yrs, absence of B symptoms, low IPI score (0,1), achieving a CR, and receiving a ASCT were associated with better EFS. Attaining a CR was the only factor associated with better OS and was highest in patients with low IPI (78%) and those with ALCL histology (75%). Conclusions CEOP-P met the pre-defined stage 1 response criteria. Longer follow-up is needed to assess the impact on the final CR rate and secondary objectives of EFS and OS. Defining optimal front line therapy in PTCL continues to be a challenge and an unmet need. Disclosures: Advani: Seattle Genetics: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Spectrum Pharmaceuticals: Research Funding. Off Label Use: Pralatrexate is currently only approved for relapsed/refractory PTCL. Lechowicz:Allos Therapeutics: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Seattle Genetics: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Carson:Spectrum Pharmaceuticals: Honoraria, Research Funding, Speakers Bureau. Foss:merck: Research Funding; spectrum: Research Funding; eisai: Membership on an entity’s Board of Directors or advisory committees; millenium: Honoraria, Membership on an entity’s Board of Directors or advisory committees; celgene: Honoraria, Research Funding; seattle genetics: Research Funding. Horwitz:Celgene : Consultancy, Research Funding; Spectrum Pharamaceuticals: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Infinity Pharmaceuticals: Consultancy; Kyowa Hakko Kirn Pharma: Consultancy; Genzyme : Research Funding; Janssen: Research Funding; Millennium: Consultancy, Research Funding. Pro:Spectrum Pharmaceuticals: Honoraria. Pinter-Brown:Spectrum Pharmaceuticals: Consultancy, Honoraria. Smith:Micromet: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; Allos: Consultancy; Genentech: Consultancy; Onyx: Consultancy. Shustov:Spectrum Pharmaceuticals: Consultancy, Honoraria. Savage:Spectrum Pharmaceuticals: Research Funding. Vose:Spectrum Pharmaceuticals: Research Funding.

Background The ubiquitin proteasome system (UPS) maintains homeostasis in eukaryotic cells by degrading and recycling proteins associated with DNA transcription and cell cycle regulation. In tumor cells with a high protein turnover rate, particularly in immunoglobulin secreting cancers such as Waldenströms Macroglobulinemia (WM), proteasomes are critical for sustained cell proliferation. Proteasome inhibitors (PI) such as bortezomib and carfilzomib target the B5 subunit of the proteasome catalytic core and disrupt its activity leading to accumulation of polyubiquitinated proteins. Although highly effective in WM, persistent use of bortezomib eventually leads to emergence of a bortezomib resistant (BR) subclone. Point mutation in the PSMB5 gene (encoding the B5 subunit) leading to altered binding kinetics is identified as a potential underlying mechanism of PI resistance. Despite these adaptive modifications that support resistance to PI resistance, the UPS as a whole remains a relevant target with vulnerable sites that can be therapeutically exploited. The 19S cap of the proteasome contains deubiquitinating enzymes (DUBS) that function to deubiquitinate proteins prior to their entry into the proteasomal core. Using a novel DUB-inhibitor b-AP15, which blocks the UCHL5 and USP14 DUBS, D’Arcy et al demonstrated that disruption of these DUBS does not alter proteasomal activity yet induces robust tumor cell death in various cancers. Aim Investigation of b-AP15 in preclinical models of BR WM and characterization of associated downstream signaling interactions. Methods For these studies, we developed and used BR variants of the most commonly used WM cell lines (variants termed BCWM.1/BR, RPCI-WM1/BR and MWCL-1/BR). Proteasomal activity was measured in these cells using synthetic fluorogenic peptide substrates and apoptosis was measured by annexin-v/PI staining. For gene expression profiling (GEP), the Nanostring nCounter mRNA quantification assay was utilized. Results We treated all BR WM clones with either single agent bortezomib (10nM), carfilzomib (10nM), b-AP15 (100nM) or all three agents in combination and assessed their effect on chymotrypsin-like, caspase-like and trypsin-like proteasomal activity. b-AP15, either alone or in combination with the other PI, did not alter proteasomal activity, nor did it abrogate the inhibition of chymotrypsin-like activity of other PI. Although proteasomal activity was not disrupted, we observed an increase in high molecular weight ubiquitinated proteins on immunoblot analysis. We hypothesized that despite the BR cells resistance to B5-targeting PI, they would remain sensitive to UPS inhibition if targeted through DUB inhibition. We treated BR cells with b-AP15 at concentrations ranging from 50nM - 1.25uM and observed that b-AP15 induced robust WM cell death in a dose and time dependent manner. Apoptosis was more pronounced in MWCL-1/BR cells and optimal cell death (55%) was observed at 500nM; however a commitment towards cellular demise was evident by PARP-1 and caspase cleavage as early as 3 hrs. Use of a pan-caspase inhibitor resulted in rescuing of the BR WM cells from b-AP15 mediated death and demonstrated a caspase-dependent death process. In order to gain further mechanistic insight into the processes that regulates response to b-AP15, we performed GEP and immunoblot of BR WM cells treated with 50nM of b-AP15. We observed an increase in phospho-p38 protein, which belongs to the MAPK family and regulates IL8 secretion. When BR WM cells were treated with a p38 inhibitor in combination with b-AP15, a significant decrease in cell viability was noted relative to b-AP15 (100nM) alone. Furthermore, GEP and network analysis identified key regulator genes associated with p53, cell cycle and MAPK signaling. Summary We provide first evidence that inhibition of the DUBS, UCHL5 and USP14 with b-AP15 results in caspase-dependent apoptosis of BR WM cells. Our investigation uncovers important molecular interactions that may dictate the BR cells responsiveness to DUB-inhibition by b-AP15. These observations validate the pervasive role of the UPS and confirm alternate therapeutics targets using our unique BR WM models. We are grateful to the Waterfall Waldenström Macroglobulinemia Research Fund, the Leukemia and Lymphoma Society and the International Waldenström Macroglobulinemia Foundation for their continued support. Disclosures: Martin: Teva: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Genentech: Speakers Bureau; Millennium: Research Funding; Seattle Genetics: Consultancy, Speakers Bureau.