Kurzfassung: Background In contrast to the high cure rates in young patients (pts) treated with anthracycline-based chemotherapy, classical Hodgkin lymphoma (cHL) prognosis is poor in elderly pts, and very few data exist for pts considered too frail to receive standard-dose chemotherapy. In those patients, limited therapeutic options are available. Among the new immune-oncology drugs, Nivolumab, an anti-PD1 antibody, has demonstrated high response rate and very good tolerance, and is now approved in relapse and refractory (R/R) cHL. However, data on its use in the frontline setting are scarce. Material and methods We designed a prospective, open-label, multi-centric phase II study, to assess the efficacy and safety of nivolumab alone, or in combination with vinblastine in naive pts aged 61 years and older, with cHL and coexisting medical conditions. Pts were eligible if they had a Cumulative Illness Rating Scale-Geriatric (CIRS-G) score of 6 or more. Treatment consisted in an induction phase of 6 nivolumab injections, delivered at a flat dose of 240 mg every 14 days. Early assessment was done at 12 weeks by PET-CT and CT-scan. Pts who achieved complete metabolic response (CMR) at early assessment completed treatment with nivolumab monotherapy for 18 additional cycles (consolidation phase). Pts who obtained partial metabolic response (PMR) or non metabolic response (NMR, stable disease) received a combination of 18 cycles of nivolumab plus vinblastine, administered intravenously. The primary objective of the study was to assess the CMR rate based on central review at the end of treatment (EOT). Results From August 30th, 2018 to April 28 th, 2020, 64 pts were included in 31 centers, which composed the full analysis set (FAS), used for safety evaluation. Among these 64 pts, 56 pts were fully evaluable and constituted the efficacy set (ES) used for the efficacy analysis (8 pts progressed early or were not assessed by PET-CT). The median age at inclusion in the ES was 75 years [range: 62-91]. Patients had a median CIRS-G score of 10 [range: 6-18] at baseline, and a median G8 score of 12.5 [range: 6-17]. Seventy-three percent of pts had a stage III-IV disease and 42.9% of pts had B symptoms. At EOT, 16 pts (28.6%) achieved CMR according to central PET-CT review. Ten pts (17.9%) achieved PMR, 10 pts were in NMR (17.9%) and progressive metabolic disease was observed in 17 pts (30.4%). Three pts were not evaluated. The overall response rate at end of induction was 51.9%, (9 CMR and 18 PMR). 23 pts received a consolidation with nivolumab and vinblastine. With a median follow-up of 20.1 months, median PFS was 9.8 months [95% CI: 4.2;12] . 15/64 pts of the FAS died during treatment (23.4%): 6 pts from lymphoma, 2 pts from toxicity of study treatment and 2 pts from concurrent illness. One patient died from toxicity of additional treatment after progression, and 4 pts from other causes. The 2-year overall survival was 76.7% [95% CI: 59.6;87.3]. 49/64 pts (76.6%) experienced at least one AE, among which 32 pts experienced grade 3-4 AEs. The 3 more frequent grade 3-4 AEs were neutropenia (8 pts), sepsis (7 pts) and respiratory tract infection (5 pts). Adverse events were related to nivolumab in 36 pts and led to treatment discontinuation in 19 pts (29.7%). Adverse events of special interest i.e., immune-related AEs, were recorded in 22 pts, including 3 pneumonitis, 1 myocarditis, 1 encephalitis and 1 colitis. Among the 64 pts of the FAS, 34% of pts completed the treatment. The median number of cycles administered was 7 [range: 1-24] for nivolumab and 17 [range: 1-18] for vinblastine. Conclusion The NIVINIHO study is the first study to assess the efficacy and safety of an immune checkpoint inhibitor for first line therapy in elderly, frail patients with cHL. The results suggest that in this setting, a nivolumab-based therapy is active in a subset of pts. Further studies and biological analysis are planned to determine which patients may benefit from this approach. Figure 1 Figure 1. Disclosures Lazarovici: Mundipharma: Other: Travel grant. Bouabdallah: Takeda: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Sandoz: Consultancy, Honoraria; Abbvie: Honoraria; Kite/Gilead: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses. Morschhauser: Roche: Consultancy, Speakers Bureau; Chugai: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZenenca: Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy; Genmab: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Laribi: Takeda: Other: Personal Fees, Research Funding; Novartis: Other: Personal Fees, Research Funding; AbbVie: Other: Personal Fees, Research Funding; BeiGene: Other: Personal Fees; Le Mans Hospital: Research Funding; IQONE: Other: Personal Fees; Astellas Phama, Inc.: Other: Personal Fees; AstraZeneca: Other: Personal Fees; Jansen: Research Funding. Feugier: Abbvie: Consultancy, Honoraria; Amgen: Honoraria; Janssen: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Astrazeneca: Consultancy, Honoraria. Sibon: iQone: Consultancy; Takeda: Consultancy; Abbvie: Consultancy; Roche: Consultancy; Janssen: Consultancy. Ribrag: Gilead: Membership on an entity's Board of Directors or advisory committees; PharmaMar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Nanostring: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Argen-X: Research Funding; MSD Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Epizyme: Honoraria, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Astex Pharmaceuticals: Research Funding; GSK: Research Funding; Infinity Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Nivolumab. Presently labelled for relapse and refractory classical Hodgkin lymphoma and other malignancies

Kurzfassung: Background: The prognostic value of COO classification by immunohistochemistry (IHC) for de novo untreated advanced DLBCL remains controversial after Rituximab-based frontline therapy. Other biomarkers such as BCL2 or MYC protein expression have been proposed to predict survival. IHC characteristics were investigated in a large multicenter randomized study. Methods: Three hundred twenty-three patients (pts) younger than 60 years with de novo untreated advanced DLBCL were randomized in the french prospective multicenter trial GOELAMS-075 to receive either 8 courses of RCHOP14 (n=161) or 2 courses of RCEEP (Rituximab, Cyclophosphamide, Eldisine, Epirubicine, Prednisone) and 1 course of Rituximab-Methotrexate-Cytarabine (RMC) followed by intensive BEAM conditionning with autologous transplant (ASCT) (n=162) upon negative interim PET-CT (visual analysis). In case of positivity, salvage regimen followed by ASCT was applied. Three years Event-free-survival (3y-EFS) was the primary endpoint. Event was defined by interim PET-CT positivity, progression or relapse, or death from any cause. Central pathology review confirmed de novo DLBCL diagnosis for 300 pts (93%). COO determination using Hans algorithm, BCL2 protein expression (clone 124, Dako) and MYC protein expression (clone Y69, Abcam) were recorded. Cut-off values were 70% for BCL2, and 40% for MYC. Results: COO analysis could be performed for 125/161 pts in RCHOP arm and 134/162 pts in intensive regimen arm including 36 and 34 Primary-Mediastinal-B-Cell subtype (PMBL) respectively. Repartition of non-PMBL was: 33/89 (37%) Germinal-Center subtype (GC), 56/89 (63%) Non-Germinal-Center subtype (NGC) in R-CHOP arm; 48/100 (48%) GC, 52/100 (52%) NGC in intensive regimen arm. Of 70 PMBL there were 50 NGC, 4 GC and 16 NE equally distributed in both arms. Clinical characteristics were similar in both GC and NGC subtypes, whereas PMBL presented with more frequent bulky disease and predominantly female gender. BCL2 ≥70% and MYC ≥40% were found in 147/285 (55%) and 85/185 (46%) of available samples, without difference between two arms. No correlation was found between BCL2 or MYC protein expression and GC or NGC subtype, however there were seen in a significantly lower proportion of PMBL (34% and 17% respectively). Coexpression of BCL2≥70% and MYC≥40% (MYC+/BCL2+) occurred in 52/184 (28%) cases, without difference between two arms or COO subtypes. By contrast, PMBL subtype displayed an extremely low rate of MYC+/BCL2+ cases (1/49, 2%). 3y-EFS rates were 52% ± 6% for GC, 58% ± 5% for NGC and 49% ± 6% for PMBL (p= 0,42) with no significant difference according to treatment arm. Of note, in PMBL, the majority of events was positive interim PET-CT. Worse EFS was seen in BCL2≥70% cases (3y-EFS: 47% ± 4% vs 60% ± 4%, p= 0,05) but this difference was erased in RCHOP arm (3y-EFS: 52% ± 6% vs 58% ± 6%). 3y-Progression Free Survival (PFS) rates were 73% ± 6% for GC, 76% ± 6% for NGC and 94% ± 4% for PMBL (p=0,03) with no difference between the two arms (Fig 1). There was no PFS difference in BCL2≥70% vs 〈 70% cases (3y-PFS: 71% ± 4% vs 82% ± 4%, p= 0,11). EFS and PFS rates were similar between MYC≥40% and 〈 40% cases (3y-EFS: 56% vs 59%; 3y-PFS: 78% vs 84%) without further advantage of one arm compared to another. Same results were obtained for MYC+/BCL2+ vs non MYC+/BCL2+ cases (3y-EFS: 53% vs 58%; 3y-PFS: 78% vs 81%). After a median follow-up of 71 months, PMBL was associated with significant better overall survival (OS) whereas no difference was observed between GC and NGC subtypes (5y-OS : 96% vs 75% and 78% respectively, p= 0,002) (Fig 2). OS rates were similar for BCL2 positive and BCL2 negative cases after exclusion of PMBL (5y-OS: 75% vs 78%, p=0,65). There was no significant impact of IHC MYC positivity (5y-OS : 80% vs 86% for MYC negative cases, p=0,29) or MYC+/BCL2+ coexpression (5y-OS : 80% vs 85% for negative cases, p=0,50) on outcome. There was no significant impact of treatment on OS of MYC and/or BCL2 positive cases. Conclusion: In younger patients, outcome of IHC defined GC and NGC subtype of non-PMBL DLBCL was not different following R-CHOP14 or intensive treatment including ASCT. Similarly, regardless of treatment arm, BCL2 or MYC or both overexpression did not impair significantly the prognosis. IHC defined COO or BCL2/MYC overexpression could not identify DLBCL in need of intensive therapy with ASCT. Finally the good prognosis of PMBL subtype with excellent PFS and OS was confirmed. Disclosures Cartron: Sanofi: Honoraria; Celgene: Honoraria; Gilead: Honoraria; Roche: Consultancy, Honoraria; GSK: Honoraria.

Kurzfassung: Introduction: Older patients with an age above 60 years with classical Hodgkin lymphoma (cHL) represent a proportion of 20% to 30% of all cHL. Older cHL patients are characterized by unfavorable prognostic factors with an aggressive disease, a poor tolerance to chemotherapy resulting to a significant reduced survival as compared to younger patients. In relapsed and refractory HL, prospective and retrospective studies showed that bendamustine in monotherapy provided interesting efficacy with 30% of complete response with an acceptable toxicity profile. We developed the PVAB (Prednisone, Vinblastine, Doxorubicin and Bendamustine) regimen in first line therapy to improve prognosis of older HL with advanced stage. Methods: In this prospective phase II, we recruited newly diagnosed classical HL patients age of 61 years or older with an advanced stage (Ann Arbor stage III, IV, IIB with risk factors). Inclusion criteria were: baseline 18-FDG PET scan performed before any treatment with at least one hypermetabolic lesion; ECOG performance status 0-2; adequate cardio-pulmonary function with LVEF ≥ 50%; adequate renal function with creatinine clearance ≥ 40 mL/min; HIV negative; For patients aged 70 years old and more, a Mini Nutritional Assessment (MNA) ≥ 17. Treatment consisted of 6 cycles of prednisone (40mg/m2 D1-5), vinblastine (6mg/m2, D1), doxorubicin (40mg/m2, D1) and bendamustine (120mg/m2, D1) every 21 days. A first evaluation was performed after 4 cycles by CT scan and a final evaluation by PET scan after 6 cycles. No radiotherapy was applied in this protocol. The primary endpoint was the complete metabolic response (CMR) rate after 6 cycles of study treatment or at premature treatment discontinuation according to Lugano Classification. The main analysis for the CMR rate was based on a Simon's phase II design. We selected P0 and P1 to be 70% and 85%, respectively for CMR rate. A total of 79 patients provided nominal power of 80% at the nominal one-sided 5% significance level. Using a drop-out rate of 10%, 90 patients should be included in this trial. Results: Between July 2015 and July 2018, 89 patients who signed the consent form and received at least one PVAB cycle corresponding to intention to treat (ITT) group were included in 34 LYSA centers. Among them, four patients did not respected major inclusion criteria (one patient had a nodular lymphocyte predominant subtype after histological review and three patients ≥ 70 years had no MNA evaluation at inclusion) corresponding to the modified ITT group (N=85). The median age of the 89 patients was 68 years (range, 61-88) with 35 patients ≥70 years old (39%) and 58 male (65%). According to the central review, the main histological subtype was nodular sclerosis cHL (66%). Ann Arbor stages were as follows: II (n=3, 3%), III (n=30, 34%), IV (n=56, 63%). B symptoms were present in 57% of patients and 70 patients (80%) had IPS≥3. 78 patients (88%) completed the 6 cycles of PVAB. In ITT, the CMR rate corresponding to the primary endpoint of the study was 77.5% (95%CI, 67-86) with 69 patients in CMR; 8 patients were in partial metabolic response; 2 and 5 patients had a stable and progressive disease, respectively and 5 were not evaluable. In the modified ITT group, the CMR rate at this end of treatment was 77.6% (95%CI, 67-86). With a median follow-up of 23 months (0.5-40.3), 25 patients relapsed or progressed (28%). The 2-year progression survival rate (PFS) rate was 61.3% (95%CI, 49-72). For the 69 patients achieving CMR, the 2-year disease free survival (DFS) rate was 73.3% (95%CI, 61-82). At the date of analysis (December 2018), 17 patients (19%) died: 7 cHL, 4 treatment toxicity, 3 second cancers, 3 other causes. The 2-year overall survival rate was 84.1% (95%CI, 73-91). For toxicity, 4 patients presented toxic death during treatment: one cardiogenic shock (71y, 〉 cycle 1) one septic shock (70y, 〉 cycle 1), one brain hematoma with grade 4 thrombocytopenia (76y, 〉 cycle 1), one fungal infection (86y, 〉 cycle 4). At least one serious adverse events (SAE) were presented by 28 patients (31.5%) mainly infections (13 patients, 15%), blood (11 patients, 12%) and cardiac disorders (4 patients, 4.5%). Conclusions: Six cycles of PVAB regimen provided high CMR (77.5%) with acceptable toxicity in older cHL patients with advanced stage. Patients with CMR at the end of treatment had a particular favorable outcome but long term follow-up is needed for a better evaluation of survival endpoints. Disclosures Morschhauser: Roche/Genentech: Consultancy; Celgene: Honoraria; Servier: Consultancy; Gilead: Consultancy; Janssen: Honoraria; BMS: Honoraria. André:Celgene: Other: Travel grants, Research Funding; Chugai: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers-Squibb: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Novartis: 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; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Other: Travel grants, Research Funding; Amgen: Other: Travel grants, Research Funding; Johnson & Johnson: Research Funding; Takeda Millenium: Research Funding. Quittet:Novartis: Honoraria, Speakers Bureau. Brice:Takeda France: Consultancy, Honoraria; Millennium Takeda: Research Funding; BMS: Honoraria. OffLabel Disclosure: Bendamustine is off-label drug use in Hodgkin lymphoma

Kurzfassung: Introduction: Older classical Hodgkin lymphoma (cHL) patients are characterized by a significant reduced survival as compared to younger patients. In relapsed and refractory HL, prospective and retrospective studies showed that bendamustine monotherapy provided interesting efficacy with 30% of complete response with an acceptable toxicity profile. We developed the PVAB (Prednisone, Vinblastine, Doxorubicin, Bendamustine) regimen in first line therapy to improve prognosis of older HL with advanced stage. Methods: In this prospective phase II, we recruited newly diagnosed classical HL patients age of 61 years or older with an advanced stage (Ann Arbor stage III, IV, IIB with risk factors). Inclusion criteria were: ECOG performance status 0-2; adequate cardio-pulmonary function with LVEF ≥ 50%; adequate renal function with creatinine clearance ≥ 40 mL/min; HIV negative; For patients aged 70 years old and more, a Mini Nutritional Assessment (MNA) ≥ 17. Treatment consisted of 6 cycles of prednisone (40mg/m 2 D1-5), vinblastine (6mg/m 2, D1), doxorubicin (40mg/m 2, D1) and bendamustine (120mg/m 2, D1) every 21 days. The primary endpoint was the complete metabolic response (CMR) rate according to local review after 6 cycles of study treatment or at premature treatment discontinuation according to Lugano Classification. We presented the final analysis of the study with a median follow-up of 42 months (range, 0.5-63.8), with prognostic analyses for progression free survival (PFS) measured from the date of inclusion to the date of progression, relapse or death from any cause. Prognostic factors included baseline clinical and biological characteristics, geriatric assessments and 18F-FDG PET/CT metabolic parameters especially baseline total metabolic tumor volume (TMTV). Optimal thresholds for some parameters were calculated using X-Tile approach. Results: Between July 2015 and July 2018, 89 patients were included in 34 LYSA centers. The median age was 68 years (range, 61-88) with 35 patients ≥70 years old (39%). The main histological subtype was nodular sclerosis cHL (n=56, 63%) with 26 EBV associated cases (LMP1 staining). Ann Arbor stages were as follows: II (n=3, 3%), III (n=30, 34%), IV (n=56, 63%). B symptoms were present in 57% of patients; 70 patients (80%) had IPS≥3. The median of CIRS-G score was 3 (range, 0-12). Seventy-eight patients (88%) completed the 6 cycles of PVAB. Update results for toxicity showed that 28 patients (32%) presented at least one serious adverse event (SAE) in particular infections (n=13, 15%), blood (n=11, 12%) and cardiac disorders (n=4, 4.5%). The CMR rate according to local review corresponding to the primary endpoint of the study was 77.5% (95%CI, 67-86) with 69 patients in CMR. After central review of 79 available PET/CT images, the CMR rate was 78.5%. Thirty-one patients relapsed or progressed (35%). The 4-year PFS rate was 50% (95%CI, 39-61). For the 69 patients achieving CMR, the 4-year disease free survival (DFS) rate was 62.8% (95%CI, 49-74). Twenty-four patients (27%) died: 11 cHL (46%), 4 treatment toxicity (17%), 6 second cancers (25%), 3 other causes after treatment (infection, cardiac insufficiency, pulmonary embolism, 12%). The 4-year overall survival rate was 69% (95%CI, 57-79). In univariate analysis, altered ECOG PS, Ann Arbor stage IV, bulky disease ( & gt;7cm), B-symptoms, extra-nodal involvement ( & gt;1), bone or medullar involvement, liver involvement, albumin (≤30g/l), hemoglobin level ( & lt;10.5g/dl), lymphocyte count ( & lt;0.8 G/L), leucocyte count (≥12G/L), CD4+ lymphocyte count ( & lt;0.41G/L), B2 microglobuline level (3 mg/l), CRP level ( & gt;88mg/l), TMTV ( & gt;450ml) and number of medications non-related to HL ( & gt;5) were associated with PFS. In multivariate analysis, liver involvement (HR: 3.79; 95%CI,1.71-8.43; P=0.001), lymphopenia (HR: 3.04; 95%CI,1.54-6.01; P=0.001), CRP (HR: 3.37; 95%CI, 1.69-6.69; P=0.0005) and co-medications (HR: 2.85; 95%CI,1.44-5.66; P=0.003) were independently associated with PFS. Conclusions: PVAB regimen provided high CMR (77.5%) with acceptable toxicity for advanced stage cHL patient over 60 years. The 4-year PFS and OS rates were 50% and 69% respectively, these survival endpoints were influenced by not related-lymphoma events. Prognostic analyses showed that specific involved site (liver), biological parameters (lymphocyte count and CRP) and patient's comorbidity (co-medications) influenced independently PFS. Disclosures Ghesquieres: Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Roche: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Gilead Sciences: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Mundipharma Research Limited: Consultancy, Honoraria; Takeda: Other: Travel, accommodation, expenses. Casasnovas: Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead Kite: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Jaccard: Janssen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Abbvie: Honoraria. Laribi: Jansen: Research Funding; Novartis: Other: Personal Fees, Research Funding; Takeda: Other: Personal Fees, Research Funding; AbbVie: Other: Personal Fees, Research Funding; IQONE: Other: Personal Fees; Astellas Phama, Inc.: Other: Personal Fees; BeiGene: Other: Personal Fees; AstraZeneca: Other: Personal Fees; Le Mans Hospital: Research Funding. Morschhauser: BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy; Incyte: Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy; Genmab: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZenenca: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Speakers Bureau; Janssen: Honoraria; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Brice: Takeda: Consultancy, Honoraria, Research Funding; BMS: Honoraria; MSD: Honoraria. OffLabel Disclosure: Bendamustine is off-label drug use in Hodgkin lymphoma

Kurzfassung: Background and aim of the study Primary mediastinal B-cell lymphoma (PMBL) is an entity of aggressive B-cell lymphoma that is clinically and biologically distinct from the other molecular subtypes of diffuse large B-cell lymphoma (DLBCL). We recently detected by Whole exome sequencing a recurrent point mutation in the XPO1 (exportin 1) gene (also referred to as chromosome region maintenance 1; CRM1), which resulted in the Glu571Lys (p.E571K) missense substitution in 2 refractory/relapsed PMBL (Dubois et al., ICML 2015; Mareschal et al. AACR 2015). XPO1 is a member of the Karyopherin-b superfamily of nuclear transport proteins. XPO1 mediates the nuclear export of numerous RNAs and cellular regulatory proteins, including tumor suppressor proteins. This mutation is in the hydrophobic groove of XPO1 that binds to the leucine-rich nuclear export signal (NES) of cargo proteins. In this study, we investigated the prevalence, specificity, and biological / clinical relevance of XPO1 mutations in PMBL. Patients and methods High-throughput targeted or Sanger sequencing of 117 PMBL patients and 3 PMBL cell lines were performed. PMBL cases were defined either molecularly by gene expression profile (mPMBL cohort) or by standard histological method (hPMBL cohort) and enrolled in various LYSA (LYmphoma Study Association) clinical trials. To assess the frequency and specificity of XPO1 mutations, cases of classical Hodgkin lymphoma (cHL) and primary mediastinal grey zone lymphoma (MGZL) were analysed. Cell experiments were performed to assess the impact of the E571 mutation on the activity of selective inhibitor of nuclear export (SINE) molecules. Results XPO1 mutations were present in 28/117 (24%) PMBL cases but were rare in cHL cases (1/19, 5%) and absent from MGZL cases (0/20). A higher prevalence (50%) of the recurrent codon 571 variant (p.E571K) was observed in PMBL cases defined by gene expression profiling (n = 32), as compared to hPMBL cases (n = 85, 13%). No difference in age, International Prognostic Index (IPI) or bulky mass was observed between the PMBL patients harboring mutant and wild-type XPO1 in the overall cohort whereas a female predominance was noticed in the mPMBL cohort. Based on a median follow-up duration of 42 months, XPO1 mutant patients exhibited significantly decreased PFS (3y PFS = 74% [CI95% 55-100]) compared to wild-type patients (3y PFS = 94% [CI95% 83-100] , p=0.049) in the mPMBL cohort. In 4/4 tested cases, the E571K variant was also detected in cell-free circulating plasmatic DNA, suggesting that the mutation can be used as a biomarker at the time of diagnosis and during follow-up. Importantly, the E571K variant was detected as a heterozygous mutation in MedB-1, a PMBL-derived cell line, whereas the two other PMBL cell lines tested, Karpas1106 and U-2940, did not display any variants in XPO1 exon 15. KPT-185, the SINE compound that blocks XPO1-dependent nuclear export, induced a dose-dependent decrease in cell proliferation and increased cell death in the PMBL cell lines harbouring wild type or mutated alleles. To test directly if XPO1 mutation from E571 to E571K alters XPO1 inhibition by SINE compounds, the mutated protein was tested in vitro. The E571XPO1 mutated allele was transiently transfected into osteosarcoma U2OS cells which stably express the fluorescently labelled XPO1 cargo REV. Cells were treated with the clinical SINE compound selinexor, which is currently in phase I/II clinical trials and nuclear localization of REV-GFP was analysed in red transfected cells. The results showed that the nuclear export of the mutated XPO1 protein was inhibited by selinexor similarly to the wild-type XPO1 protein (Figure 1). Conclusion Although the oncogenic properties of XPO1 mutations remain to be determined, their recurrent selection in PMBL strongly supports their involvement in the pathogenesis of this curable aggressive B-cell lymphoma. XPO1 mutations were primarily observed in young female patients who displayed a typical PMBL molecular signature. The E571K XPO1 mutation represents a novel hallmark of PMBL but does not seem to interfere with SINE activity. Rev-GFP (green fluorescent) expressing U2OS cells were transfected with wild type XPO1-RFP (red fluorescent protein), XPO1-C528S-RFP, XPO1-E571K-mCherry, and XPO1-E571G-mCherry. The cells were then treated with 1µM KPT-330 for 8 hours. Figure 1. Rev-GFP expressing U2OS cells transfected with XPO1 variants. Figure 1. Rev-GFP expressing U2OS cells transfected with XPO1 variants. Disclosures Landesman: Karyopharm Therapeutics: Employment. Senapedis:Karyopharm Therapeutics, Inc.: Employment, Patents & Royalties. Argueta:Karyopharm Therapeutics: Employment. Milpied:Celgene: Honoraria, Research Funding.

Kurzfassung: Introduction We (Bobée et al, 2020) have recently described a new molecular classifier combining gene expression profiling of 137 genes and machine learning able to diagnose B-cell lymphomas. As this tool can be easily performed from formalin fixed paraffin embedded tissue, we proposed to evaluate how it may be useful after the process of central review by expert pathologists in a LYSA diffuse large B-cell lymphoma (DLBCL) clinical trial, the GAINED trial (Le Gouill et al, 2021). Methods The GAINED trial was a multicenter randomized phase 3 trial comparing obinutuzumab to rituximab followed by a PET-driven consolidation in patients with DLBCL. Histological inclusion criteria were : DLBCL, high grade B-cell lymphoma double/triple hit (DH/TH) or high grade NOS. 670 patients were included and 646 underwent a central review of the biopsy by at least two LYSA pathologists. The central review performed immunostaining of full slides by anti-CD20, CD5, CD10, BCL6, MUM1, MYC, BCL2 if sufficient material was available as well as RNA extraction for the molecular classifier, the nanostring Lymph2CX and DNA extraction for targeted NGS. The molecular classifier was able to deliver 8 different signatures: DLBCL GCB, DLBCL ABC, primary mediastinal large B-cell lymphoma (PMBL), follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma/lymphoplasmacytic lymphoma, CLL/lymphocytic Lymphoma, T-cell rich signature. We compared classification by the histopathology review and by the molecular classifier. Discordant cases were reviewed both by two histopathologists (JB, TJM) and the molecular biologist (PR) and a reconciliation diagnosis was proposed Results The central histopathological review alone identified 580 patients with DLBCL or high grade B-cell lymphoma and 40 patients with a lymphoma subtype not eligible for the trial. Among the 470 patients evaluated by the molecular classifier, the reconciliation diagnosis identified 292 DLBCL NOS with 40 associated with a small B-cell component, 13 High grade DH/TH, 9 high grade NOS, 109 PMBL, 16 T-cell rich large B-cell Lymphoma (TCRBCL), 5 DLBCL EBV+ NOS. 29 cases did not fit with inclusion criteria and were mainly FL (3A or 3B), MCL, Nodular lymphocyte Predominant Hodgkin Lymphoma (NLPHL). Among them, the classifier helped to identify one case of CD5- MCL initially diagnosed as DLBCL with CD5- marginal zone lymphoma as well as one case of CD10+ follicular T-cell lymphoma (T-cell rich signature with Rho A mutation) initally diagnosed as FL 3B. Among 235 patients with GCB/ ABC subtyping, the correlation with Nanostring was 97.4% for the molecular classifier and 86,4% for the Hans algorithm. Although the main aim of the pathology review was not dedicated to differentiate DLBCL NOS from PMBL but to validate histological inclusion criteria, after reconciliation 22 DLBCL NOS were reclassified as PMBL. Overall, among the 109 PMBL , PET-CT at baseline in 108 cases evaluable found in 93 cases (86%) a mediastinal mass unique (37) or with satellite lymph nodes(56), in 12 cases (11%) a mediastinal mass with extramediastinal localization and in only 3 cases (3%) the absence of mediastinal mass. This observation fits well with the known anatomical distribution of PMBL and with the rare non mediastinal lymphomas with a PMBL signature. However, the molecular classifier was able to identify 8 signatures and could not recognize other lymphoma subtypes such as High grade B-cell Lymphomas NOS or DH/TH. In addition, 14 follicular lymphomas in our series comprising 5 grade 3A and 6 grade 3B were diagnosed molecularly mainly as DLBCL GC or rarely ABC . Although the TCRBCL were all included in the T-cell signature lymphoma, this signature included high grade B-cell lymphoma, DLBCL NOS, PMBL, DLBCL EBV+, NLPHL. Conclusion Overall, the molecular classifier in addition to the expert pathologic review increased accuracy of diagnostic by the pathologists particularly for difficult or rare cases, as well as it strongly helped to identify PMBL and GC/ABC DLCBL. However, the pathologist should be aware of the limit of the tool when dealing with DLBCL differential diagnosis, particularly for the identification of FL3A, FL3B or for cases with a T-cell rich microenvironment such as TCRBCL. Disclosures Bobée: Genexpath: Patents & Royalties: The author is a potential inventor on a patent application for the LymphoSign, which has been licensed for by Genexpath Patents & Royalties. . Drieux: Genexpath: Patents & Royalties: The author is a potential inventor on a patent application for the LymphoSign, which has been licensed for by Genexpath Patents & Royalties.. Casasnovas: ROCHE: Consultancy, Research Funding; TAKEDA: Consultancy, Research Funding; Gilead/Kite: Consultancy, Research Funding; BMS: Consultancy; Janssen: Consultancy; Amgen: Consultancy. Ghesquieres: Mundipharma Research Limited: Consultancy, Honoraria; Gilead Sciences: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Roche: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Takeda: Other: Travel, accommodation, expenses. Morschhauser: abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; epizyme: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; jannssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation. Thieblemont: Cellectis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Hospira: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: travel compensation, Research Funding; Kite: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel compensation. Ribrag: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Epizyme: Honoraria, Research Funding; Servier: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; PharmaMar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nanostring: Membership on an entity's Board of Directors or advisory committees; Argen-X: Research Funding; Astex Pharmaceuticals: Research Funding; Infinity Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; MSD Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees. Haioun: Takeda: Honoraria, Research Funding; Servier: Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Miltenyi: Honoraria, Research Funding. Jardin: Genexpath: Patents & Royalties: The author is a potential inventor on a patent application for the LymphoSign, which has been licensed for by Genexpath Patents & Royalties. . Ruminy: Genexpath: Patents & Royalties: The author is a potential inventor on a patent application for the LymphoSign, which has been licensed for by Genexpath Patents & Royalties. .