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Despite their unprecedented success in relapsed/refractory (R/R) large B-cell lymphoma (LBCL), anti-CD19 CAR T cells are associated with significant toxicity, and more than half of patients relapse. As monocytes emerged as key players in CAR therapy, we sought to evaluate the evolution of HLA-DR expression on monocytes (mHLA-DR) before and after commercial anti-CD19 CAR T-cell infusion in a large cohort (n = 103) of patients with R/R LBCL and its association with adverse events and treatment response. Cy-Flu-based lymphodepletion (LD) upregulated mHLA-DR in 79% of the cases, whereas in 2l% of cases (15 patients), the mHLA-DR level decreased after LD, and this decrease was associated with poorer outcome. Low mHLA-DR at day minus 7 (D−7) (

In this retrospective study, we report 70 cases of Epstein-Barr virus (EBV)+ diffuse large B-cell lymphoma not otherwise specified (DLBCL-NOS) among 1696 DLBCL-NOS cases diagnosed between 2006 and 2019 (prevalence of 4.1%). At diagnosis, median age was 68.5 years; 79% of the cases presented with an advanced-stage disease (III-IV), 48% with extranodal lesions, and 14% with an hemophagocytic lymphohistiocytosis (HLH) (8 at diagnosis and 1 on therapy). A total of 46 cases presented a polymorphic pattern, and 21 were monomorphic. All had a non-germinal center B phenotype, with the majority of tumor cells expressing CD30 and programmed death ligand 1 (98% and 95%, respectively). Type II and III EBV latency was seen in 88% and 12% of the cases, respectively. Patients were treated with immunochemotherapy (59%) or chemotherapy (22%), and 19% received palliative care due to advanced age and altered performance status. After a median follow-up of 48 months, progression-free survival (PFS) and overall survival (OS) at 5 years were 52.7% and 54.8%, respectively. Older age (>50 years) and HLH were associated with shorter PFS and OS in multivariate analysis (PFS: hazard ratio [HR], 14.01; 95% confidence interval [CI], 2.34-83.97; and HR, 5.78; 95% CI, 2.35-14.23; OS: HR, 12.41; 95% CI, 1.65-93.53; and HR, 6.09; 95% CI, 2.42-15.30, respectively). Finally, using a control cohort of 425 EBV− DLBCL-NOS, EBV positivity was associated with a shorter OS outcome within patients >50 years (5-year OS, 53% [95% CI, 38.2-74] vs 60.8% [95% CI, 55.4-69.3], P = .038), but not in younger patients.

Background: Diagnostic-to-treatment interval (DTI) was recently described as a strong prognostic factor for newly diagnosed systemic diffuse large B-cell lymphoma patients (DLBCL) with an improvement of event-free survival (EFS) for patients with a longer DTI. These results have some implications for patient selection and result interpretations in clinical trials. This association has not been previously evaluated in DLBCL Primary CNS Lymphoma (PCNSL) patients who also present a clinically aggressive disease. Patients and Methods: The cohort constited of all consecutive DLBCL PCNSL patients treated in two Hematology Departments of the University of Lyon between 1984 and 2018 (N=244). All patients had DLBCL histology at diagnosis, obtained by brain biopsy (N=235, 96%), vitrectomy (N=4, 2%) or CSF evaluation (N=5, 2%). As first line treatments, all patients but 5 (2%) received high-dose (HD) methotrexate-based chemotherapy, associated with intra-venous rituximab for 154 patients (63%) and HD cytarabine for 182 patients (75%). Consolidation treatment by whole-brain radiotherapy was performed in seventy-six patients (31%). DTI was defined as the number of days between the date of diagnosis (i.e. biopsy) and the date of treatment initiation. Association between DTI and patient characteristics was assessed by chi-square tests or Student t-tests. EFS was defined from the start of therapy to progression, relapse, or death from any cause. As we previously described, prognostic factors such as age and performance status (PS) demonstrate a time-dependent effect on overall survival (OS) in PCNSL limiting the validity of traditional Cox proportional hazard models. We thus used a piecewise Cox model to allow assessment of prognostic effect over different time periods. All survival analyses were done in univariate and multivariate settings and stratified on rituximab use during first-line therapy. Results: With a median follow-up of 73.5 months, the 5-year EFS and OS rates were 31.6% and 48.4% for whole cohort, respectively. Median DTI was 16 days (range, 1 to 67 days). Short DTI (≤16 days) was associated with a poor PS (ECOG PS 2-4, 53.3% versus 38.5%), altered Karnofsky score ( 16 days, respectively (Figure 1). Using a standard cox model, in univariate analyses, PS (2-4 vs. 0-1) (HR: 1.40, 95%CI, 1.00 - 1.94, P=0.045) and age (per 10-year increase) (HR: 1.19, 95%CI, 1.05-1.36, P=0.006) were associated with EFS but not DTI (≤ or > 16 days) (HR: 0.80, P=0.19), deep involvement (HR: 0.97, P=0.85) and LDH level (HR=1.02, P=0.91). In multivariate analysis, only age was associated with EFS (HR: 1.27, 95%CI, 1.11-1.46, P=0.001). Using a piecewise Cox model over two periods of time (before and after 12 months), we confirmed in multivariate analyses, the time varying effect of PS and age on EFS with a high-risk period before 12 months and no prognostic effect after 12 months (Table 1). We also observed a time-dependent effect for DTI as shown by a significant interaction with time (P=0.02) (Table 1). Indeed, longer DTI was not associated with EFS before 12 months (HR: 1.14, 95%CI, 0.74-1.76, P=0.56) however, it had a strong protective effect after 12 months (HR: 0.44, 95%CI, 0.24-0.86, P=0.02). Conclusions: In this large cohort of DLBCL PCNSL, a short DTI was mainly associated with poor PS at diagnosis. We confirmed that prognostic factors for PCNSL outcome such as age and PS had time-varying effects with a good predictability of EFS only before 12 months. However, DTI allows prediction of long-term EFS (>12 months) after first line treatment. These results could be related to different biological patterns of tumor aggressiveness. If confirmed in independent PCNSL cohorts, DTI should also be taken in consideration for patient selection and the interpretation of clinical trial results especially for long-term outcome. Disclosures Karlin: Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Sanofi: Honoraria; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: Personal fees. Salles:Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Other: Educational events; BMS: Honoraria; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Novartis, Servier, AbbVie, Karyopharm, Kite, MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Roche, Janssen, Gilead, Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Epizyme: Consultancy, Honoraria. Bachy:Amgen: Research Funding; Roche, Gilead: Consultancy; Beigene: Membership on an entity's Board of Directors or advisory committees; Roche, Celgene, Amgen, Janssen, Gilead, Novartis, Sanofi: Honoraria.

Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies. acceptedVersion

Two autologous anti-CD19 chimeric antigen receptors (CAR) T cells (axicabtagene ciloleucel [axi-cel] and tisagenlecleucel [tisa-cel]) are commercially approved in Europe for relapsed/refractory (R/R) diffuse large B cell lymphoma (DLBCL). We performed a retrospective study to evaluate patterns of use, efficacy and safety for axi-cel and tisa-cel. Data from 70 patients who underwent apheresis for commercial CAR T cells between January 2018 and November 2019 in our institution were retrospectively collected. Sixty-one patients were infused. The median age at infusion was 59 years old (range 27-75 years). The median number of prior therapies was 3 (range, 2-6). The overall response rates (ORRs) at 1 month and 3 months were 63% and 45%, respectively, with 48% and 39% achieving a complete response (CR), respectively. After a median follow-up after infusion of 5.7 months, the median progression-free survival (PFS) was 3.0 months (95% CI, 2.8-8.8 months), and the median overall survival (OS) was 11.8 months (95% CI, 6.0-12.6 months). In multivariate analysis, factors associated with poor PFS were the number of previous lines of treatment before CAR T cells (≥4) (P = .010) and a C reactive protein (CRP) value30 mg/L at the time of lymphodepletion (P .001). Likewise, the only factor associated with a shorter OS was CRP30 mg/L (P = .009). Cytokine release syndrome (CRS) of any grade occurred in 85% of patients, including 8% of patients with CRS of grade 3 or higher. Immune cell-associated neurotoxicity syndrome (ICANS) of any grade occurred in 28% of patients, including 10% of patients with ICANS of grade 3 or higher. Regarding efficacy and safety, no significant difference was found between axi-cel and tisa-cel. This analysis describes one of the largest real-life cohorts of patients treated with axi-cel and tisa-cel for R/R aggressive B cell lymphoma in Europe.

Introduction Primary cerebral lymphoma (PCNSL) is an uncommon subtype of diffused large B-cell lymphoma (DLBCL) with a particular poor outcome as compared to systemic DLBCL, especially in elderly. For patients older than 60 years, standard treatment consists of high-dose methotrexate (HD-MTX) chemotherapy without consolidation brain radiotherapy to reduce the risk of leukoencephalopathy. Rituximab in combination with HD-MTX, procarbazine, vincristine followed by HD-cytarabine consolidation is one of standard of treatments for PCNSL patients with a 2-year PFS rate of 47% for patients aged of 60 or older in prospective trial (Morris JCO 2013). Etoposide and Ifosfamide are two drugs that can diffuse across blood-brain barrier and commonly used for relapsed/refractory PCNSL. To improve efficacy of R-MPVA protocol, we developed a new regimen which consisted in adding etoposide and ifosfamide for patients with a newly diagnosed PCNSL aged between 60 and 75 years old. Patients & Methods The protocol consisted of 3 cycles every 28 days of rituximab (375mg/m2, J1 and J15), MTX (3.5 g/m2, J1 and J15), vincristine (1.4 mg/m2, J1 and J15), vepeside (100mg/m2, J2) and procarbazine (100mg/m2, J1-7). Consolidation therapy consisted of 2 cycles every 21 days rituximab (375mg/m2, J1) in combination with cytarabine (3g/m2, J1-2) with ifosfamide (1.5 g/m2, J1-3). Response evaluations were planned after the 3 cycles of induction (R-MPV-VP16) and after consolidation (R-AraC-Ifo). We retrospectively reviewed treatment modalities, toxicities, response and outcome with this protocol and compared results with a matched group of patients with the same range age (60 - 75 years) treated with R-MPVA. Results Between 2013 and 2018, 28 PCNSL patients were treated with this protocol. The median age was 67.5 years old (range, 61-74). Poor performance status (PS 3-4) was presented in 9 patients (32%). As compared to 31 patients treated between 2007 and 2018 with R-MPVA, patients treated with intensive protocol were younger (66 vs. 69 years, P=0.01) and had less frequently a poor PS 3-4 (32% vs. 61%, P=0.04). In intent-to-treat analysis, 27 patients received 3 cycles of R-MPV-VP16 but one received only 2. Among them, five patients achieved PR and then received 1 to 2 additional cycles of R-MPV-VP16. Following this induction, 25 patients underwent 2 cycles R-AraC-ifo consolidation, 3 of them did not received ifosfamide for the second cycle because of hematological toxicity and poor PS. One patient in complete response (CR) after whole treatment received high-dose therapy followed by autologous stem cell transplantation. After R-MPV-VP16, 10 patients (36%) achieved CR and 14 partial responses (50%) (PR) as compared to 12 CR (39%) and 12 PR (39%) for patients treated with R-MPVA. After consolidation phase, 23 patients (82%) achieved CR after R-AraC-Ifo as compared to 21 CR (68%) after R-AraC in the historical arm. Differences were not statistically significant. R-MPV-VP16 regimen was associated with favorable toxicity profile with 13 (46%) grade 4 hematological toxicity, 8 (28%) grade 3 and one grade 4 (3%) renal toxicity, 3 (10%) grade 3 and one grade 4 (3%) hepatic toxicity, 6 (21%) grade 3 and 4 grade 4 (14%) and infectious toxicity. With a median follow-up of 46.5 months, patients treated with R-MPV-VP16 followed by R-AraC-ifo had a median event-free survival (EFS) of 33.2 months (95%CI, 17.6 - not reached [NR]) with a 2-year EFS rate of 52%; the median overall survival (OS) was not reached (95%CI, 58.6-NR) with a 2-year OS rate of 70%. With a median follow-up of 94.2 months, patients treated with R-MPVA had a median EFS of 18.3 months with a 2-year EFS rate of 39% (P=0.14, Fig 1); the median OS was 65.9 months with 2-year OS rate of 64% (P=0.33, Fig 1). Conclusions In this retrospective analysis of two HD-MTX and HD-AraC based regimens for PCNSL patients aged between 60 and 75 years performed in real-life setting, R-MPVA was more frequently proposed for older patients with a poorer PS. Combination of vepeside to R-MPV and ifosfamide to R-AraC was feasible with a favorable toxicity profile. Despite not statistically different, we observed a trend for an improvement of response rate at the end of treatment (82% vs. 68% of CR) and reduced rate of relapses (2-year EFS rates: 52% vs. 39%) with the intensified protocol. These first results deserve a confirmative larger prospective study of R-MPV-VP16 followed by R-AraC-ifosfamide for elderly PCNSL patients. Disclosures Ferrant: AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Karlin:Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Celgene: Other: Personal fees; Sanofi: Honoraria; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, personal fees; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support. Bachy:Beigene: Membership on an entity's Board of Directors or advisory committees; Roche, Celgene, Amgen, Janssen, Gilead, Novartis, Sanofi: Honoraria; Amgen: Research Funding; Roche, Gilead: Consultancy.

B-cells are under intense selective pressure to eliminate autoreactive or premalignant clones. B-cell receptor (BCR) signals are required for survival, however, BCR-signaling exceeding maximum thresholds often reflects signaling from an autoreactive BCR or a transforming oncogene and triggers negative selection and cell death. The tyrosine kinase SYK initiates BCR-downstream signaling in B-cells while its close relative ZAP70 is almost exclusively expressed in T-cells. Interestingly, the segregation of SYK to B-cells and ZAP70 to T-cells is less confined in malignant lymphopoiesis suggesting that the balance of these related kinases may alter signaling output in disease and contribute to development of leukemia. As previously shown in B-cell chronic lymphocytic leukemia (B-CLL), we identified aberrant ZAP70 expression as a frequent feature in multiple other B-cell malignancies that depend on survival signals from a functional (pre-) BCR (E2A-PBX1+ pre-B ALL, and mantle cell lymphoma) or harbor oncogenic mimics of the BCR (BCR-ABL1+ B-ALL). Studying SYK and ZAP70 expression by single-cell Western blot, co-expression of the two tyrosine kinases was extremely rare in normal B- and T-cell populations. In contrast, >50% of tumor B-cells in mantle cell lymphoma, pre-B ALL and CLL co-expressed SYK and ZAP70. Despite their structural similarities, genetic deletion and engineered reconstitution of SYK and ZAP70 in human B-cell lymphoma cells revealed striking functional differences. Proximity-dependent biotin identification (BioID) analyses identified that SYK, but not ZAP70, engaged the PI3K pathway via interaction with CD19. Consistent with this, reconstitution with SYK and SYK-ZAP70 but not ZAP70 alone promoted survival and proliferation. Detailed analysis of BCR-mediated cascades in lymphoma cells expressing SYK, ZAP70 or SYK-ZAP70 established that ZAP70 is only weakly efficient at propagating BCR-mediated calcium and downstream pathway activation in B-cells. Strikingly, co-expression of ZAP70 with SYK resulted in re-wired BCR-signaling of intermediate strength: compared to cells expressing only SYK, SYK-ZAP70 co-expressing cells had markedly reduced activation of the BLNK-BTK-PLCγ pathway, further reflected in BCR-induced Ca2+ signaling with delayed onset, lower amplitude but longer duration. In this way, we speculated that SYK and ZAP70 may be present within close proximity at the apex of BCR-initiated interactions, and hence compete for downstream substrates resulting in a re-wiring of classic signaling programs propagated normally by SYK. To explore this, we utilized proximity ligation assays (PLA) to monitor the proximity of SYK and ZAP70 in resting or BCR-stimulated B-cells, and found that SYK and ZAP70 co-exist within close proximity consistent with the view that varying levels of these kinases may alter B-cell signaling output. Functional experiments further showed that phosphomimetic activation of SYK, but not ZAP70, induced hyperactivation of PI3K-signaling and acute BTK-mediated cell death in pre-B ALL cells. In line with altered BCR-signaling strength and quality in SYK and ZAP70 co-expressing cells, over-expression of Zap70 in pre-B ALL cells rescued auto-immune checkpoint activation induced by hyper-activation of BCR-associated signaling. To study functional consequences of SYK-ZAP70 co-expression during normal B-cell development, we generated a novel knock in Zap-70+/Mb1-Cre+mouse model, to induce conditional expression of Zap70 in the B cell compartment from the proB stage. Consistent with compromised central tolerance checkpoints, Syk-Zap70 co-expressing pro/pre-B and immature B-cells had reduced spontaneous apoptosis rates and gave rise to autoantibody production against multiple self-antigens. Importantly, our findings highlight a previously unrecognized role for ZAP70 in oncogenic BCR-signaling and we conclude that the co-expression of ZAP70 mitigates the ability of SYK, downstream of an autoreactive BCR or a transforming oncogene, to trigger negative B-cell selection and cell death (Figure 1). Disclosures Weinstock: Celgene: Research Funding. Meffre:AbbVie: Consultancy, Other: Grant.

Introduction: standard treatment for relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) is high-dose chemotherapy followed by autologous stem-cell transplantation (ASCT) but this strategy is not appropriate for elderly DLBCL patients (pts) related to a high risk of toxicities. Multiple chemotherapy regimens had been developed for heavily pretreated elderly DLBCL patients such as R-bendamustine, R-gemcitabine-oxaliplatin (R-GEMOX) and pixantrone; the median progression free survival (PFS) of these regimens were 2, 4 and 3.5 months, respectively in prospective phase II studies for patients previously treated with R (Sehn 2017, Mounier 2013, Pettengel 2016). Adapted dose of ifosfamide and etoposide was firstly developed as sequential consolidation regimen after high-dose CHOP (ACVBP regimen) in first line therapy of young DLBCL patients (Tilly 2003). This regimen with a safe toxicity profile was then used in combination with R in Lyon University Hospital in elderly R/R DLBCL ineligible to intensive strategy. Methods: we retrospectively reviewed the efficacy and the safety profile of this regimen performed in two Lyon University Hospitals (Centre Hospitalier Lyon Sud and Leon Berard Cancer Center). Between June 2004 and March 2017, 75 pts with R/R DLBCL (63 de novo DLBCL, 12 transformed DLBCL) received R (375 mg/m2) in combination etoposide (300 mg/m2) and ifosfamide (1500 mg/m2) on day 1 (N=72, 96%) and on days 1-2 (N=3, 4%) at 2 (N=46, 61%) or 3-week (N=29, 39%) intervals. All medical records were reviewed for clinical and biological characteristics, modality of treatment and supportive care, toxicities, responses and outcome. Results: the median age was 79 years (range, 64-92) at the beginning of R-ifosfamide/VP16 treatment with 46% of the patients over 80 years. 13% of pts had a CIRS-G grade 3 or 4 >2 categories and 35% had a cumulative CIRS-G score more than 6. The performance status according to EORTC scale was 2-4 in 37% of the pts and 93% had III-IV Ann Arbor stages. Age-adjusted IPI were 0-1 in 20 pts (27%) and 2-3 in 55 pts (73%). All patients were previously treated in first-line therapy by R in combination with chemotherapy (CHOP, N=56, 75%, low-dose CHOP, N=14, 19%, other, N=5, 6%). The patients received a median number of 1 previous line (range, 1-8) and no patient was previously treated by ASCT. The median time between initial diagnosis and R-ifosfamide/VP16 was 20 months (range 4-187). The median time between the last treatment and R-ifosfamide/VP16 was 5 months (range 0-181). A refractory disease to first-line treatment was showed in 14 pts (19%). 31% of the patients had a refractory disease to the last regimen performed before R-ifosfamide/VP16. Patients received a median of 6 cycles (1-12). At the end of treatment, the overall response rate (ORR), defined by the rate of complete response (CR) and partial response (PR) was 37%, with 18% of CR. Evaluations were assessed for 29% of the pts by TEP scanner. For toxicity, among the 387 cycles, 10 patients developed febrile neutropenia (2.6%); 15 (20%) a grade 3-4 neutropenia; 7 (9%) a grade 3-4 thrombocytopenia; 5 patients needed platelet units and 16 patients received packed red blood cell units. No grade 3-4 non-hematological toxicity was observed and no toxic death occurred. With a median follow up of 31.3 months (range, 5.0-202.8), the median progression-free survival (PFS) was 4.3 months with a 1-year PFS rate of 26.0% (95%CI, 17.7-38.3) (Figure 1A). The median overall survival (OS) was 8.2 months with a 1-year OS rate of 40.8% (95%CI, 30.9-54.0) (Figure 1B). The median duration of response was 4 months (range 1-97). The median PFS was adversely affected by response (refractory versus CR/PR) to the last treatment (3.0 months versus 5.5 months, P=0.001) (Figure 1C). Conclusions: in this retrospective study, R-Ifosfamide/VP16 regimen provided effective results in R/R DLBCL transplant-ineligible pts with 37% of ORR and a median of PFS of 4.3 months with a safe toxicity profile. This regimen could also be considered as a platform for combinations with novel targeted agents in these categories of patients. Disclosures Karlin: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sarkozy:ROCHE: Consultancy. Bachy:Gilead Sciences: Honoraria; Takeda: Research Funding; Sandoz: Consultancy; Amgen: Honoraria; Roche: Research Funding; Celgene: Consultancy; Janssen: Honoraria. Salles:Abbvie: Honoraria; Epizyme: Honoraria; Amgen: Honoraria; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Gilead: Honoraria, Other: Advisory Board; Acerta: Honoraria; Novartis: Consultancy, Honoraria; Servier: Honoraria; Servier: Honoraria, Other: Advisory Board; Takeda: Honoraria; BMS: Honoraria, Other: Advisory Board; Celgene: Honoraria, Other: Advisory Board, Research Funding; Janssen: Honoraria, Other: Advisory Board; Merck: Honoraria; Morphosys: Honoraria; Pfizer: Honoraria. Ghesquieres:Sanofi: Consultancy; Gilead: Consultancy; Celgene: Consultancy.

Purpose International Prognostic Index (IPS) is the most widely used risk stratification index for advanced stage Hodgkin's lymphoma (HL). The use of (18F)-fluorodeoxyglucose PET/CT at diagnosis allows a better characterization of extra-nodal involvement (ENI). We investigated if the type of ENI could affect the prognosis of stage IV HL patients diagnosed with PET/CT and if a specific prognostic index could be defined for these patients (pts). Patients and methods We retrospectively analyzed 220 stage IV HL patients treated from 2005 to 2015 in three LYSA centers. We considered the local investigator interpretation based on the nuclear medicine physician PET/CT report. Regarding ENI, six subgroups were identified: involvement of lung and/or pericard and/or pleural, liver, diffuse and/or focal bone involvement, digestive system, and other involvements; we also considered bone marrow involvement based on the results of bone marrow biopsy. The main outcome was event free survival (EFS) defined by relapse, progression, death from any cause and initiation of a new therapy. For prognostication, we first evaluated the six variables of IPS-6 (corresponding to IPS without "stage IV" item) in this population. ENI was tested adjusted on the retained IPS variables. Univariate and multivariate Cox models were used to assess their prognostic ability for EFS. Cross-validation (10-fold) was used to select the more robust variables avoiding optimism. The finally selected variables constituted a score that was tested on overall survival (OS). Results Among the 220 stage IV patients, 135 (61%) were male. Median age was 33 years (range, 16-86) and 72 pts (33%) were ≥45 years. 130 pts (59%) presented constitutional symptoms. Nodular sclerosis subtype was observed in 163 pts (74%), mixed cellularity subtype in 25 pts (11%) and 47/157 pts (30%) presented EBV-positive HL. For biological parameters of IPS, 158 pts (80%) had low albumin level 15G/L in 42pts (19%) and lymphocyte count Conclusions: For stage IV HL defined by PET/CT, we developed a simple prognostic score based on age (≥45y) and liver involvement that identify a subgroup of patients with a poor outcome. These findings need to be validated in independent cohorts. Based on these results, whether HL pathogenesis differs by ENI sites should be investigated. Disclosures Bachy: Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Beigene: Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria; Amgen: Honoraria. Karlin:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support. Sarkozy:ROCHE: Consultancy. Traverse-Glehen:Takeda: Research Funding; Astra Zeneca: Other: Travel. Salles:F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Servier: Honoraria, Other: Advisory Board; Novartis: Consultancy, Honoraria; BMS: Honoraria, Other: Advisory Board; Morphosys: Honoraria; Janssen: Honoraria, Other: Advisory Board; Abbvie: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Celgene: Honoraria, Other: Advisory Board, Research Funding; Epizyme: Honoraria; Gilead: Honoraria, Other: Advisory Board; Acerta: Honoraria; Merck: Honoraria; Servier: Honoraria; Takeda: Honoraria. Casasnovas:Takeda: Consultancy; Gilead: Consultancy, Research Funding; AbbVie: Consultancy; Roche: Consultancy, Research Funding; Bristol-Meyers Squibb: Consultancy; Merck: Consultancy. Ghesquieres:Celgene: Consultancy; Gilead: Consultancy; Sanofi: Consultancy.

Abnormal expression of the tyrosine kinase ZAP-70 by tumoral B cells in chronic lymphocytic leukemia (CLL) is associated with bad prognosis, related to B cell receptor (BCR) hypersignalling, clonal expansion and autoimmune cytopenia (AIC) occurrence, these latter being mostly induced by polyclonal IgG from the residual non tumoral B cells. We previously shown that ZAP-70 is expressed by these non tumoral B cells in CLL, positively associated with its expression in CLL B cells and with AIC occurrence (Ghergus et al. Poster ASH 2017). Here, we show for the first time a potential role of ZAP-70 expression in tolerance breakdown in CLL and in an original knock in mouse model overexpressing ZAP-70 conditionally in B cells. First, to assess a potential molecular link between ZAP-70+ CLL and non tumoral B cells, an analysis of their BCR repertoire has performed on FACS-sorting CD19+CD5-IgM-IgD- (non tumoral) and CD19+CD5+IgM-IgD- (tumoral) single B cells from blood samples of CLL patients with AIC. ZAP-70 positivity was screened by RT-PCR, and variable regions of heavy (IGVH) and light (IGVK/VL) immunoglobulin genes amplified by RT-PCR on ZAP-70+ cells. To date, analysis of 24 BCR sequences from 7 patients showed that non tumoral ZAP-70+ B cells were polyclonal, without stereotypy, using different V(D)J and CDR3 in comparison with those of the corresponding CLL B cells. IGVH of non tumoral ZAP-70+ B were mostly mutated, of replacement type, suggesting antigenic contact, contrary to CLL B cells. To determine potential autoreactivity of the non-tumoral ZAP-70+ B cells, IGVH and corresponding IGVK/VL were amplified for production of recombinant antibodies (rAb). To date, among 17 rAB from 7 different patients, 2/13 (15.4%) have an antinuclear autoreactivity on HEp-2 cells and 4/17 (23.5%) were polyreactive on ELISA (DNA, lipopolysaccharide, insulin), compared respectively to 6% and 4,3% of control B cells (Wardemann et al., Science 2003). Production of 7 additional rAb and tests for anti-erythrocytes and anti-platelets reactivity are in process. To study functional consequences of early ZAP-70 expression in B cells in vivo, we generated a knock in Zap-70+/Mb1-Cre+mouse model (KI ZAP), to induce conditional expression of ZAP-70 in the B cell compartment from the proB stage, with KI Zap-70+/Mb1-Cre-mice as controls (CTRL). The ZAP-70 mRNAs levels in B cells from KI ZAP mice were on average 20 times higher than that in CTRL B cells. Up to 20 months-old, KI ZAP mice did not develop signs of lymphoproliferation. KI ZAP mice had hypo-IgG since 16 weeks-old (p After immunization by ovalbumin + Freund's adjuvant, a reduced production of specific IgG and IgM was observed (p=0.01 and p=0.03 respectively) with a trend in decreased number of antibody-secreting cells (p=0.07). KI ZAP B cells shown increased spontaneous activation and proliferation levels holding after BCR stimulation (p Our findings highlight for the first time that non tumoral B cells ZAP-70+ are distinct from CLL cells at cellular level, but probably enriched in autoreactive cells. Moreover, we shown that early ZAP-70 expression in normal B cells in vivois associated with autoimmune characteristics, together with partial block in B cells peripheral maturation, and a conversely early increased activation and proliferation status. ZAP-70 could interfere early with SYK leading to an altered BCR signaling responsible for defect in normal B maturation promoting emergence of autoreactive B cells. Mechanistic role of ZAP-70 in BCR signaling has to be further analyzed but our data open new opportunities involving ZAP-70 in the understanding of B cell development and physiopathology of tolerance breakdown. Disclosures No relevant conflicts of interest to declare.