Abstract: Acquired hemophilia A (AHA) is a rare autoimmune disorder caused by neutralizing autoantibodies against coagulation factor VIII (FVIII:C). Immunosuppressive treatment may result in remission of disease over a period of days to months. Until remission, patients are at high risk of bleeding and complications from immunosuppression. Prognostic parameters to predict remission and the time needed to achieve remission could be helpful to guide treatment intensity, but have not been established so far. GTH-AH01/2010 was a prospective multicenter cohort study using a standardized immunosuppressive treatment protocol. The primary study endpoint was time to achieve partial remission (PR, defined as FVIII:C activity 〉 50 IU/dl after cessation of any hemotherapy for 〉 24h, and no active bleeding). Secondary endpoints were time to achieve complete remission (CR, defined as PR plus negative FVIII:C inhibitor, steroid tapered to 〈 15 mg/d prednisolone, and cessation of any other immunosuppressive treatment), and overall survival (OS). Enrolment was strictly prospective and only allowed within 7 days of starting immunosuppression. Outcome data were recorded in all patients enrolled. The treatment protocol consisted of prednisolone (100 mg/d from day 1 to the day of PR, then tapered down to 〈 15 mg/d over 5 weeks), oral cyclophosphamide (150 mg/d, from day 21-42, unless PR was achieved), and rituximab (375 mg/m2 weekly for 4 weeks starting on day 43, unless PR was achieved). If AHA was first diagnosed in patients previously on prednisolone 〉 15 mg/d, or equivalent, they received prednisolone (100 mg/d) and rituximab from day 1. If cyclophosphamide was contraindicated, patients received prednisolone (100 mg/d) and rituximab from day 21. One hundred twenty-four patients from 21 treatment centers in Germany and Austria were enrolled between April 2010 and April 2013 (36 months). The patients from two centers not compliant with the treatment protocol were excluded (N=18), as were patients in whom AHA was not confirmed (N=2) or follow-up was too short at the time of this analysis (N=7). The remaining 97 patients from 17 centers were followed for a median of 256 days (interquartile range [IQR] 84-561). Median age was 74 years (IQR 64-82). AHA was associated with other autoimmune disorders (19%), malignancy (12%), pregnancy or puerperium (5%), but was most often idiopathic (66%). The median FVIII:C activity at baseline was 1 IU/dl (IQR 〈 1-3), and the median inhibitor titer was 20 BU/ml (IQR 7.7-78). PR and CR were achieved after a median time of 35 and 102 days, respectively. Patients achieving PR prior to day 21 (N=22) compared with patients not achieving PR within 21 days (N=75) had a higher baseline FVIII:C activity (median 3 vs. 〈 1 IU/dl, p 〈 0.01) and a lower FVIII:C inhibitor (median 12 vs. 29 BU/ml, p 〈 0.05). Multivariate analysis with adjustment for age, sex, underlying disorder, and WHO performance status on admission demonstrated that baseline FVIII:C activity ( 〈 1 IU/dl vs. 〉 =1 IU/dl) had a strong impact on the time to achieve PR (HR 2.76 [95% confidence interval 1.73-4.42] , p 〈 0.001) and CR (HR 2.36 [1.34-4.14], p 〈 0.01). Baseline FVIII:C activity was also a predictor of PR and CR when other cutoffs were used (2 or 3 IU/dl instead of 1 IU/dl), or when it was analyzed as a continuous variable in Cox regression analysis. In contrast, FVIII:C inhibitor titer assessed by the local laboratory did not affect time to PR or CR significantly. OS after 300 days, estimated by the Kaplan Meier method, was 69%. Age, WHO performance status, and FVIII:C activity at baseline were independent predictors of OS. In summary, GTH-AH 01/2010 is the largest prospective study of patients with AHA treated according to a standardized protocol. The study demonstrated a robust effect of baseline FVIII:C activity on the time needed to achieve PR and CR. Baseline FVIII:C activity, together with age and performance status, also affected OS. Therefore, baseline FVIII:C activity may be considered to guide individually tailored immunosuppression in future studies. Disclosures: Tiede: Baxter: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Biotest: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novo Nordisk: Consultancy, Honoraria, Research Funding; Biogen Idec: Consultancy; CSL Behring: Consultancy, Honoraria, Research Funding. Off Label Use: Prednisolone, cyclophosphamid, and rituximab for immunosuppression in acquired hemophilia. Klamroth:Bayer: Honoraria, Research Funding; Baxter: Honoraria, Research Funding; CSL Behring: Honoraria, Research Funding; Novo Nordisk: Honoraria, Research Funding. Gottstein:Novo Nordisk: Honoraria; Baxter: Honoraria. Holstein:Baxter: Honoraria, Speakers Bureau. Scharf:CSL Behring: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Biotest: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria; Baxter: Consultancy, Honoraria, Research Funding. Huth-Kühne:SRH Kurpfalz Hospital and Hemophilia Center: Consultancy, Employment, Honoraria, Membership on an entity’s Board of Directors or advisory committees. Greil:Roche: Consultancy, Honoraria, Research Funding. Miesbach:Novo Nordisk: Consultancy, Honoraria, Research Funding; Baxter: Consultancy, Honoraria, Research Funding. Trappe:Roche: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau, Travel Other; AMGEN: Research Funding, Travel, Travel Other; CSL Behring: Honoraria, Research Funding, Speakers Bureau, Travel, Travel Other; Mundipharma: Research Funding, Travel, Travel Other; Takeda: Consultancy, Research Funding, Travel Other; Novartis: Consultancy, Research Funding, Travel, Travel Other; Novartis: Research Funding, Travel Other; Cellgen: Travel, Travel Other. Knoebl:Novo Nordisk: Consultancy, Honoraria; Baxter: Consultancy, Honoraria.

Abstract: Background: The PTLD-1 trial has demonstrated the efficacy and safety of 4 cycles of weekly rituximab followed by 4 cycles of CHOP-21 + G-CSF in CD20-positive PTLD after solid organ transplantation. Median overall survival (OS) was 6.6 years, a clear improvement over the preceding rituximab monotherapy trials (2.4 years). However, response to rituximab induction predicted OS after completion of therapy. Based on the hypothesis that rituximab consolidation might be sufficient treatment for patients already in a complete response (CR) after rituximab induction, trial treatment was changed in 2007 through a protocol amendment introducing risk-stratified sequential treatment (RSST): rituximab consolidation for patients in CR after rituximab induction and R-CHOP-21 consolidation for all others. Methods: In this international, multicenter phase II trial (PTLD-1, 3rd amendment; NCT00590447), treatment-naïve adult solid organ transplant recipients diagnosed with CD20-positive PTLD were treated with rituximab (375 mg/m2 IV) on days 1, 8, 15 and 22. After restaging, patients in CR continued with four three-weekly courses of rituximab monotherapy while all others received 4 cycles of R-CHOP-21 + G-CSF. In case of disease progression during rituximab monotherapy R-CHOP was commenced immediately. The primary endpoint was treatment efficacy measured as response rates and response duration. Analysis was by intention to treat. This is the final analysis of 152 patients treated with RSST from 2007 to 2014 at centers in Germany (72), Belgium (36), France (24), Australia (7), Poland (7) and Italy (6) with a median follow-up of 4.5 years. The 70 patients treated with rituximab followed by CHOP-21 in the original PTLD-1 trial (median follow-up 5.1 years) served as a control population. Inclusion criteria and follow-up schedule were identical; there were no significant differences in the transplant- and lymphoma-related baseline factors listed below. Results: 115/152 patients were male. 69/152 were kidney, 40 liver, 18 lung, 15 heart, 5 heart/kidney, 3 kidney/pancreas and 2 heart/lung transplant recipients. Median age at diagnosis was 56 years. PTLD was late ( 〉 1 year after transplantation) in 120/152 (79%) of patients. 67/145 (46%) PTLD were EBV-associated. 130/152 patients had monomorphic, 20 polymorphic and 2 early lesion PTLD. The overall response rate (ORR) was 111/126 (88%, CR: 88/126 [70%]). Median duration of remission (DR) was not reached; the 3-year Kaplan-Meier estimate was 82% (compared to 71% in PTLD-1). In the intention-to-treat population (152 patients), the median time to progression (TTP) was not reached either. The 3-year Kaplan-Meier estimate was 78% (69% in PTLD-1). Median OS by intention-to-treat was 6.6 years (95% CI 5.5 - 7.6) with a 3-year estimate of 70% in comparison to 61% in PTLD-1. There was no significant difference in ORR, DR, TTP or OS between EBV-positive and EBV-negative PTLD. On the other hand, response to 4 applications of rituximab was a highly significant predictor of OS, TTP and progression-free survival (PFS) despite treatment stratification (all p 〈 0.001). 37/148 patients (25%) achieved CR with 4 cycles of rituximab and were allocated to rituximab consolidation. In this group, TTP in the intention-to-treat population was significantly longer than in the corresponding group in the PTLD-1 trial (37 patients versus 14 patients, p 〈 0.05). In the 111 patients allocated to R-CHOP consolidation, ORR was 78/92 (85%) with 55/92 (60%) complete remissions (89% and 60%, respectively, in PTLD-1). Median TTP was not reached, the 3-year estimate was 73% (69% in PTLD-1). In patients refractory to rituximab induction, the CR rate was 22/38 (58%) with R-CHOP compared to 3/11 (27%) in PTLD-1 with CHOP (p=0.07); median PFS was 1.4 years versus 0.3 years in PTLD-1, p 〈 0.05. The frequency of grade 3/4 leukopenia and infections was 63% and 34%, respectively. Treatment-related mortality occurred in 7%. Conclusions: This largest trial cohort in PTLD to date demonstrates for the first time that treatment stratification by response to rituximab induction is feasible, safe and effective. Rituximab consolidation in early rituximab responders results in significantly better disease control compared to CHOP consolidation. The addition of rituximab to CHOP chemotherapy improves outcome in patients refractory to rituximab monotherapy. Disclosures Trappe: Mundipharma: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Research Funding, Speakers Bureau; CSL Behring: Research Funding, Speakers Bureau. Zimmermann:Roche: Honoraria; Celgene: Other: Travel support. Morschhauser:Genentech Inc./Roche: Other: Advisory boards. Mollee:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Zaucha:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau. Dührsen:Roche: Honoraria, Research Funding; Alexion Pharmaceuticals: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Hüttmann:Amgen: Research Funding; Roche: Research Funding. Salles:Calistoga Pharmaceuticals, Inc.; Celgene Corporation; Genentech, Inc.; Janssen Pharmaceutica Products, L.P.; Roche: Consultancy; Celgene Corporation; Roche and Gilead Sciences: Research Funding; Celgene Corporation; Roche: Speakers Bureau. Kliem:Astellas: Honoraria; Fresenius: Honoraria; Genzyme: Honoraria; Novartis: Honoraria; Roche: Honoraria; Raptor: Honoraria. Leblond:Janssen: Consultancy, Honoraria, Speakers Bureau; Mundipharma: Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; GSK: Consultancy, Honoraria, Speakers Bureau. Choquet:Janssen: Consultancy; Roche: Consultancy.

Abstract: Background: The PTLD-1 trials established 1 st-line risk-stratified sequential treatment (RSST) of CD20-positive B-cell PTLD in adult solid organ transplant recipients. After rituximab induction, patients (pts) in complete remission (CR) continue with 4 three-weekly courses of rituximab, while all others receive 4 cycles of R-CHOP-21 (Trappe RU et al., JCO 2017;35:536-43). Analyses of the initial PTLD-1 sequential treatment cohort uniformly treated with rituximab followed by CHOP identified the prognostic value of response to rituximab induction, international prognostic index (IPI) risk factors (≥ 3 vs & lt; 3) and thoracic SOT (Trappe RU et al., Am J Transplant 2015;15:1091-100). The PTLD-2 trial therefore tested modified risk-stratification based on these three risk factors. The key hypothesis was that rituximab SC monotherapy consolidation in an expanded low-risk group would be superior to CHOP consolidation in comparable pts of the PTLD-1 trial by demonstrating an improved event-free survival (EFS) at 2 years, based on a lower rate of grade 3/4 infections and similar efficacy. Methods: The prospective, multicenter phase II PTLD-2 trial (NCT02042391) enrolled treatment-naïve adult SOT recipients with CD20-positive PTLD. Key exclusion criteria were CNS involvement, ECOG & gt; 2, pregnancy, severe organ dysfunction or severe, active infection. Treatment consisted of rituximab SC on days (d) 1, 8, 15 and 22. After restaging on d50, pts in CR as well as those in partial remission with & lt; 3 IPI risk factors at diagnosis (low-risk group) continued with rituximab SC monotherapy. Most other pts (high-risk group) received 4 cycles of R SC-CHOP-21 chemotherapy, while thoracic SOT recipients who progressed under rituximab (very-high-risk group) received six cycles of alternating R SC-CHOP-21 and modified R SC-DHAOx. In case of progression before d50, subsequent treatment started immediately. The primary endpoint was EFS (event: infections grade 3/4 from d50 to d143, treatment discontinuation, progression, death) in the low-risk group. Secondary endpoints were response and overall response rate (ORR) by computed tomography at interim and final staging, overall survival (OS), time to progression (TTP), progression-free survival (PFS), response duration and treatment-related mortality (TRM) overall and by risk group. Results: 60 pts were recruited at 15 centers (2015 - 2020). 29/60 were kidney, 14 lung, 9 liver, 4 heart transplant recipients (4 others). Median age was 54 years. 58/60 PTLD were monomorphic and 23/60 EBV-associated. 26/58 pts (45%, 95% CI 33-58) responded at interim staging. 21 were allocated to the low-risk, 28 to the high-risk and 9 to the very-high-risk group. ORR at final staging was 45/48 (94 %, 95% CI 83-98). Grade 3/4 infections were reported in 25/59 pts who started treatment (42%, 95% CI 31-55). TRM occurred in 4/59 pts (7 %, 95 % CI 2-17). With a median follow-up of 2.8 years, the 2-year Kaplan-Meier (KM) estimates of TTP and OS in the intention-to-treat population (60 pts) were 78 % (95% CI 65-90, median not reached) and 68 % (95% CI 55-80, median OS 5.1 years), and thus in the range reported in the PTLD-1 trials. The prognostic value of response to rituximab induction, IPI risk factors (≥ 3 vs & lt; 3) and thoracic SOT was confirmed. The primary endpoint, 2-year EFS in the low-risk group, was 66 % (95% CI 45-86). Events were 4 grade 3 infections (19 %) and 5 relapses (24 %). There was no significant difference to the prespecified comparator group from the PTLD-1 ST trial cohort (52 % [95% CI 32-72]). The 3-year KM estimate of OS in the low-risk group was 100 %. Intensified chemotherapy in the very-high-risk group did not improve outcomes (median OS 7.4 months [95% CI 2.2-12.7] ) compared to PTLD 1 RSST (10.1 months). Conclusions: Overall efficacy and safety outcomes of the trial were comparable to the PTLD-1 trial despite the enrollment of 23% lung transplant recipients, who historically have poor outcomes (Zimmermann H et al. Transplantation Journal 2013;96:e18-9). 32 % of patients were treated with rituximab monotherapy in the low-risk group. The primary endpoint (improved EFS in this group vs. historical control) was not met. However, the observed 100% 3-year OS estimate in this population is an excellent outcome. The trial confirmed the poor prognosis of thoracic SOT recipients with progressive disease after rituximab induction. Intensified chemotherapy did not improve this outcome. Disclosures Zimmermann: Roche Germany: Research Funding; Atara Biotherapeutics: Other: Travel support, Research Funding; Janssen: Other: Travel support. Koenecke: Novartis: Consultancy; Janssen: Consultancy; BMS/Celgene: Consultancy; Kite/Gilead: Consultancy; EUSA Pharm: Consultancy. Dreyling: Bayer HealthCare Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau; Astra Zeneca: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; BeiGene: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Speakers Bureau; Abbvie: Research Funding; Roche: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Genmab: Consultancy; Gilead/Kite: Consultancy, Research Funding, Speakers Bureau. Dührsen: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; CPT Cellex Patient Treatment: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hahn: BMS: Consultancy, Honoraria; Merck: Consultancy, Honoraria; MSD: Consultancy, Other: Travel support, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Celgene: Other: Travel support. Hauser: Roche: Honoraria; Astellas: Honoraria, Other: Travel Support; Biotest: Honoraria, Other: Travel support; Hexal: Other: Travel support; Neovii: Other: Travel support; Novartis: Consultancy, Honoraria. Wolf: Novartis: Honoraria, Research Funding; BMS-Celgene: Honoraria, Research Funding; MSD: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Gilead: Honoraria; Incyte: Honoraria; GEMOAB: Honoraria. Heuser: Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Research Funding; BergenBio: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer Pharma AG: Research Funding; Novartis: Consultancy, Honoraria, 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; Tolremo: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Research Funding. Schmidt: Novartis: Consultancy, Honoraria, Other: Travel support; Kite/Gilead: Consultancy, Honoraria, Other: Travel support, Research Funding; Takeda: Consultancy, Other: Travel support; BMS: Consultancy, Other: Travel support; Janssen: Other: Travel support. Ritgen: MSD: Consultancy, Other: Travel support; Chugai: Consultancy; Abbvie: Consultancy, Other: Travel support, Research Funding; Roche: Consultancy, Other: Travel support, Research Funding; Celgene: Other: Travel support. Siebert: AstraZeneca: Speakers Bureau. Anagnostopoulos: BMS: Consultancy, Honoraria, Other: Travel support; MSD: Consultancy, Honoraria, Other: Travel support. Trappe: Atara Biotherapeutics: Consultancy, Other: Travel support, Research Funding; Celgene: Other: Travel support; Jansen: Other: Travel support; AbbVie: Other: Travel support; GSK: Other: Travel support; Roche: Other: Travel support. OffLabel Disclosure: Rituximab is FDA-approved for the treatment of adult patients with CD20-positive, B-cell NHL, but not explicitly for PTLD, particularly as single agent treatment in DLBCL-PTLD.

Abstract: Introduction: Post-transplant lymphoproliferative disorder (PTLD) is a rare and often aggressive disease in the setting of immunosuppression following solid organ transplant (SOT). Epstein-Barr virus (EBV) infection of B cells is responsible for about 50% of cases, either due to reactivation of the virus after transplantation or primary EBV infection. Although there is no approved therapy for patients (pts) with PTLD, guidelines include reduction of immunosuppression (RIS) as a part of initial treatment and may be sufficient for pts with early lesions. Rituximab, either as monotherapy or in combination with chemotherapy (CT), is used in addition to RIS as initial treatment. Pts with EBV + PTLD following SOT who fail rituximab plus CT have poor outcomes with limited treatment options. There are ongoing clinical studies investigating innovative therapies to address unmet needs in these pts. Published data on clinical outcomes of these pts remain limited and not well documented. We aimed to characterize the outcomes for pts diagnosed with EBV + PTLD following SOT who fail initial rituximab plus CT in a multi-national real-world setting. Methods: We conducted a large multinational, multicenter, retrospective chart review study of pts with EBV + PTLD following allogeneic hematopoietic cell transplantation (HCT) or SOT who received rituximab or rituximab plus CT between January 2000‒December 2018 and were refractory (failed to achieve complete response [CR] or partial response [PR] ) or relapsed at any point after such therapy. Treatment response was assessed either by clinical diagnosis, radiographic/imaging, biopsy/cytology, or a combination of such assessments. Data were collected from 29 centers across North America (United States and Canada) and the European Union. Study population was aligned to the ongoing investigational trial (Clinicaltrials.gov Identifier: NCT03394365). This analysis includes pts with EBV + PTLD following SOT who were refractory/relapsed to rituximab plus CT. The Kaplan-Meier method was utilized to estimate the overall survival (OS). Results: A total of 86 pts with EBV + PTLD following SOT who failed rituximab plus CT were included in the analysis; 65 (75.6%) pts were refractory while 21 (24.4%) relapsed after initial response of CR or PR. Median age at PTLD diagnosis was 43 years (range 1‒78) and median time to PTLD onset from transplant was 1.7 years (range 0.1‒27.9). Median follow up time was 12.9 months from the date of PTLD diagnosis. PTLD histological subtypes were 66 (76.7%) monomorphic, 18 (20.9%) polymorphic, and 2 (2.3%) early lesions. The most common PTLD subtype was diffuse large B-cell lymphoma (DLBCL) (58, 67.4%). Of the 86 pts, 49 (57%) received CT following rituximab monotherapy while 37 (43%) pts received CT concurrently with rituximab. Overall, 63 (73.3%) pts died. PTLD-specific mortality was observed in 41 (65.1%) pts, treatment-related mortality in 10 (15.9%) pts, mortality due to organ rejection/failure in 2 (3.2%) pts, mortality due to other causes in 7 (11.1%) pts, and mortality due to unknown causes in 3 (4.8%) pts. Median OS was 15.5 months (95% confidence interval [CI]: 8.3‒22.9) from PTLD diagnosis, and was 4.1 months (95%CI: 1.9‒8.5) from the earliest date when pts became refractory or relapsed following rituximab plus CT. Conclusions: The prognosis for pts with EBV + PTLD following SOT who fail rituximab plus CT remains poor, with an estimated median OS of about 4 months and a majority of pts dying from PTLD and related treatment. In this specific population, there remains a significant unmet medical need for effective and well-tolerated therapies. Figure 1 Figure 1. Disclosures Dharnidharka: Merck, Pfizer, Medronic, Cardinal Health: Current holder of stock options in a privately-held company; CareDx: Honoraria, Research Funding; Atara Bio, MedinCell: Consultancy. Thirumalai: Atara Biotherapeutics: Current Employment. Jaeger: Roche: 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; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Norvartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Zhao: Atara Biotherapeutics: Current Employment. Dierickx: Roche: Consultancy, Research Funding; Novartis: Consultancy; Sanofi: Consultancy; Sandoz: Consultancy; Takeda, Incyte, Atara: Consultancy. Xun: Atara Biotherapeutics: Current Employment. Sawas: Flat Iron Health: Current Employment; Roche: Current holder of stock options in a privately-held company; Seattle Genetics, Acrotech: Consultancy; Daiichi-Sankyo, Seattle Genetics, Gilead: Other: Travel, accommodation, expenses, Speakers Bureau; Affimed, Trillium: Research Funding. Sadetsky: Atara Biotherapeutics: Current Employment. Barlev: Atara Biotherapeutics: Current Employment. Zimmermann: Roche, Atara: Research Funding; Celgene, Roche, Atara, Jansen: Other: Travel accomodations. Trappe: Celgene: Other: Travel support; Roche: Other: Travel support; Atara Biotherapeutics: Consultancy, Other: Travel support, Research Funding; Jansen: Other: Travel support; GSK: Other: Travel support; AbbVie: Other: Travel support.

Abstract: Introduction The antibody-drug conjugate polatuzumab vedotin (Pola) has recently been approved in combination with bendamustine and rituximab (Pola-BR) for patients with r/r diffuse LBCL (DLBCL). Methods To characterize the efficacy of Pola-BR in a real-world setting, we retrospectively analyzed data from 97 patients with r/r LBCL who were treated with Pola in 24 German centers within the national CUP. Clinical baseline and follow-up (FU) data were collected by chart review and summarized descriptively. Progression-free survival (PFS) and overall survival (OS) were analyzed using Kaplan-Meier and Cox regression methods. Fisher's exact test was used to compare categorical factors between groups of patients. Results 97 patients with LBCL (DLBCL n=90, High-grade B-cell lymphoma n=6, Primary mediastinal B-cell lymphoma n=1) were included as of July 22nd, 2020. 49 patients were treated with Pola as bridging concept to immunotherapies (bridging cohort: chimeric antigen receptor T-cells (CART) n=39, allogeneic stem cell transplantation (alloSCT) n=9, bispecific antibodies n=1), and 48 patients were treated with Pola in palliative intention (palliative cohort). Within the bridging cohort the median age was 61 years (range: 22-82). Patients were heavily pretreated with a median of 3 treatment lines (range: 2-6). 84% (41/49 patients) had been refractory to their last treatment line, and 31% had failed an autologous stem cell transplantation. Notably, 14% and 10% of patients had failed prior CART and alloSCT, respectively, and were planned for the alternate cellular immunotherapy. Based on an individual decision, patients were treated with Pola-Rituximab (Pola-R, n=20), Pola-chemotherapy (Pola-chemo, BR n=25; R-CHP n=1) or Pola-monotherapy (Pola-mono, n=3). With a median of 2 Pola cycles (range 1-6), overall response rate (ORR) of all evaluable patients was 33% (15/46 patients) including patients with complete response (CR n=1), partial response (PR n=9) and clinical response (n=5). Although not significant, ORR tended to be better in patients treated with Pola-chemo versus Pola-R/Pola-mono (ORR: 42% versus 20%, Fishers test p=0.1). 11 of these 15 responders (24% of the entire bridging cohort) proceeded to CART or alloSCT, while 4 responders (8% of entire bridging cohort) experienced fast progression after their initial response and were referred to best supportive care. 15 of 31 non-responders (33% of entire bridging cohort) underwent immunotherapy with either stable disease (n=6), mixed response (n=2), or progression on Pola (n=7). The remaining 16 patients (35% of entire bridging cohort) were all refractory to Pola and either received alternative salvage treatments which enabled 8 further patients to proceed to the intended immunotherapy, or best supportive care. Taking the effects of CART or alloSCT into account, median OS from initiation of Pola treatment was 8.2 months (median FU 7.2 months, Fig. 1A). The palliative cohort tended to be older than the bridging cohort with a median age of 73.5 years (range: 37-86, p & lt;0.001). Patients were pretreated with a median of 3 treatment lines (range: 2-8), and 85% (41/48 patients) had been refractory to their last treatment line. Patients in the palliative cohort were treated with a median of 4 Pola cycles (range: 1-9). 65% received Pola-chemo (BR, n=30; R-Gemcitabine, n=1) and 35% Pola-R. The CR rate and ORR was 19% (9/48) and 56% (27/48), respectively. The 6-month PFS and OS from initiation of Pola was 36% and 51%, respectively (median FU of 9.7 months, Fig. 1B). Again, ORR and OS tended to be better in patients treated with Pola-chemo versus Pola-R (ORR: 61% versus 47%, Fishers test p=0.4; median OS 7.2 versus 4 months, HR 0.8, 95%CI 0.4-1.9, p=0.7). In univariate analysis, failure to respond to the last treatment line predicted inferior PFS (HR 2.4, 95%CI 1.2-5.0 p=0.02) and OS (HR 2.5, 95%CI 1.2-5.4 p=0.02). Patients with more than two prior treatment lines in total tended to have a shorter PFS (HR 2.0, 95% CI 0.9-4.5, p=0.1) and OS (HR 1.8, 95% CI 0.8-4.0, p=0.2), although significance was not reached. Conclusion Pola permits effective bridging to CART and alloSCT in r/r LBCL. In the palliative setting, Pola represents an effective salvage option for patients with transplantation-ineligible r/r LBCL. Compared to the approval study, the inferior outcome of the patients of this real-world analysis might be explained by their more advanced disease course. Disclosures Duell: Morphosys: Research Funding. Kerkhoff:BMS: Honoraria. Leng:Roche: Other: lecture fee; Celgene: Other: traveling expenses and congress attendance fee. Holtick:Miltenyi Biotec B.V. & Co. KG: Honoraria. Mayer:Amgen: Honoraria, Other: travel grants; Abbvie: Other: travel grants; Novartis: Honoraria; Roche: Honoraria. Hüttmann:Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Gilead: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Roche: Other: Travel expenses; Seattle Genetics: Research Funding; University Hospital Essen, University of Duisburg-Essen, Essen, Germany: Current Employment; Lead Discovery Center GmbH: Consultancy. Brunnberg:Gilead: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: travel grants; MSD: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Amgen: Other: Travel grants. Bullinger:Menarini: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Celgene: 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. Hess:Roche: Research Funding; Celgene: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Genmab: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Morphosys: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mueller-Tidow:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Deutsche Krebshilfe: Research Funding; BMBF: Research Funding; Wilhelm-Sander-Stiftung: Research Funding; Jose-Carreras-Siftung: Research Funding; Bayer AG: Research Funding; Daiichi Sankyo: Research Funding; BiolineRx: Research Funding; Janssen-Cilag Gmbh: Membership on an entity's Board of Directors or advisory committees; Deutsche Forschungsgemeinschaft: Research Funding. Lenz:Verastem: Research Funding; AQUINOX: Research Funding; BMS: Consultancy; AstraZeneca: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Agios: Research Funding; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Dreger:Roche: Consultancy, Speakers Bureau; Neovii: Research Funding; AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Consultancy; Gilead: Consultancy, Speakers Bureau; Janssen: Consultancy; Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau. Dietrich:Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: 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; KITE: Membership on an entity's Board of Directors or advisory committees.

Abstract: Background: Post-transplant lymphoproliferative disorder (PTLD) is a rare and often aggressive disease in the setting of immunosuppression following solid organ transplant (post-SOT). About 50% of cases are associated with Epstein-Barr virus (EBV) infection of B cells, either due to reactivation of the virus after transplantation, or from primary EBV infection. Data remain very limited with respect to overall clinical and economic burden among EBV+PTLD patients (pts), particularly in the setting of pts who fail first line therapy. This retrospective chart review aimed to quantify the burden of hospitalization due to EBV+PTLD in post-SOT pts who failed first-line therapy in the real-world setting in Germany. Study Design and Methods: The German PTLD registry database was screened for pts with EBV+PTLD post-SOT who were refractory (failed to achieve complete [CR] or partial remission [PR] ) to rituximab or rituximab plus chemotherapy (CT) or relapsed at any point after such therapy between 2000 to 2015. Pts with primary CNS PTLD were excluded. Pts without any outpatient visit or hospitalization record were excluded from the analysis (n of pts=1). Hospitalization data were reviewed by an experienced physician and adjudicated as PTLD relevant; details on diagnoses and procedures performed during hospitalization were collected from the first diagnosis of PTLD to the earliest of the following: death, loss to follow up or end of study period (Sep 1st, 2018). We estimated the mean number of hospitalizations, average length of inpatient stay per admission and the percentages of time spent in the hospital out of the total time following PTLD index date or treatment failure index date. The PTLD index date was defined as the first date of EBV+PTLD diagnosis; and the treatment failure index date was defined as the earliest date of pts who became refractory or relapsed to first-line therapy of rituximab or rituximab plus CT. Results: A total of 35 EBV+PTLD pts were analyzed. All had failed first line rituximab monotherapy. Median follow up time was 24.8 months from the PTLD index date. Median age at PTLD diagnosis was 47 years (range 18-75). Of these, 6 (17.1%) were polymorphic, 21 (60%) were diffuse large B cell lymphoma, 3 (8.6%) were Burkitt lymphoma, and 5 (14.3%) were other B-cell lymphoma. Among the 35 pts, 23 (65.7%) died: 12 from PTLD, 6 treatment-related, 1 from organ failure, and 4 from other causes. The vast majority of pts (29 out of 35) received CHOP-based CT following rituximab failure (2 other CT, 4 did not receive CT). All pts (100%) had at least one inpatient hospitalization after PTLD diagnosis and 16 (45.7%) pts had at least one ICU admission following PTLD index date. The mean number of PTLD hospitalizations following PTLD index date was 4 (SD 3.2, range 1-12) and the mean average length of stay per hospitalization was 23.8 days (SD 22.6, range 2-94). The mean proportion of time spent in the hospital out of total time at risk from PTLD index date was 20.5% (SD 27.6, range 0.1-100) with an average of 9.5% of time spent in the ICU setting during hospitalization stay (SD 22, range 0-99.5). The mean number of PTLD hospitalizations (n of pts=19) following first course CT failure index date was 2.1 (SD 1.9, range 0-7) and the mean average length of stay per hospitalization was 14.8 days (SD 8.6, range 6-31.6). The mean proportion of time spent in the hospital out of total time at risk from CT failure index date was 41.8% (SD 39.6, range 0-100) with an average of 26% time spent in the ICU setting (SD 39, range 0-100). Conclusions: This is the first study to quantify the hospitalization burden directly related to EBV+PTLD post-SOT in Germany. The results show that hospitalization burden in EBV+PTLD post-SOT pts failing first line rituximab monotherapy is substantial accounting for approximately 20% of patient's time after initial diagnosis of PTLD with around 10% spent in the ICU setting. This hospitalization burden is even higher and accounts for over 40% of time in pts after additional treatment failure to first CT with 26% spent in the ICU setting. Disclosures Zimmermann: Roche: Research Funding; Janssen: Other: Travel, accomodations expenses; Atara Biotherapeutics: Other: Travel, accomodations expenses, Research Funding; Celgene: Other: Travel, accomodations expenses. Xu:Atara Biotherapeutics: Employment, Equity Ownership. Barlev:Atara Biotherapeutics: Employment, Equity Ownership. Zhang:Atara Biotherapeutics: Employment, Equity Ownership. Thirumalai:Atara Biotherapeutics: Employment. Watson:Atara Biotherapeutics: Employment, Equity Ownership. Trappe:Atara Biotherapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Other: Congress related travel support; Roche: Consultancy, Honoraria, Other: Congress related travel support, Research Funding; AbbVie: Consultancy, Other: Congress related travel support; Celgene: Other: Congress related travel support.

Abstract: Introduction: In CLL, numerous new therapeutic options have been introduced recently, without establishing a definitive standard therapy or cure for most patients (pts). An advantage of targeted therapies is the avoidance of toxicities associated with chemotherapy. However, all new kinase inhibitors used for treatment of CLL have low rates of complete remission (CR). Combinations of targeted agents have the potential to improve outcomes, shorten treatment duration, and reduce toxicity. Tirabrutinib (a BTK inhibitor), and entospletinib (a SYK inhibitor), both show significant single-agent clinical activity in pts with CLL. In this study, we evaluated tirabrutinib and entospletinib as dual therapy (TE), and as triple therapy in combination with obinutuzumab (TEO). Methods: This is a prospective, open-label, phase 2 protocol (NCT02983617) at 15 clinical centers in Germany that recruited pts with relapsed or refractory CLL between April 2017 and September 2018. As of amendment 3, pts who did not progress while on an inhibitor of BTK, SYK, PI3K, BCL-2 or on obinutuzumab were also included. Pts received the TE regimen with tirabrutinib 80 mg once daily (QD) + entospletinib 400 mg QD for up to 104 weeks, or the TEO regimen adding obinutuzumab at standard dosing for a total of 8 doses of 1000 mg over 21 weeks. After the implementation of protocol amendment 3, randomization was discontinued and all subsequently enrolled pts received the TEO regimen. Response was measured by modified iwCLL 2008 criteria. The primary endpoint was the CR rate at week 25. Results: Thirty-six pts were treated, 6 with TE and 30 with TEO. Median (range) age was 68 (45-82) years, with a median of 1 (1-2) and 2 (1-8) prior anticancer therapies in those assigned to TE and TEO, respectively. As of 16 May 2019, 29 of all 36 pts (81%) continue to receive tirabrutinib and entospletinib on study; 2 (6%) pts completed study drug dosing as specified per protocol at week 104. Twenty-eight of 30 pts (93%) in the TEO arm completed obinutuzumab dosing as specified per protocol. Of the 36 pts, 34 (94%) continued the study and 2 (6%) discontinued the study due to adverse events (AEs) or death, both were in the TEO group. Median duration (range) of exposure to tirabrutinib and entospletinib was 99 (90-105) weeks on TE and 50 (4-104) weeks on TEO, including 20 (2-35) weeks for obinutuzumab. At week 25, CR rate was 0% (90% confidence interval [CI] 0-39.3) with TE and 7% (90% CI 1.2-19.5) with TEO (Table 1). Overall response rates at week 25 were 100% (90% CI 60.7-100) and 90% (90% CI 76.1-97.2) for TE and TEO.One pt on the TEO regimen experienced disease progression (per clinical response assessment) after 3.75 months of therapy. Three (10%) pts on TEO were minimal residual disease (MRD) negative in peripheral blood (PB MRD-) at week 25; one (3%) pt was also MRD negative in bone marrow (BM MRD-).No pts showed MRD negativity with TE therapy. Best rate of CR/PB MRD- was 7% (90% CI 1.2-19.5) and for CR/BM MRD- was 3% (90% CI 0.2-14.9) with TEO. Median time to first PB MRD- was 32 weeks on TEO. Median progression-free survival (PFS) and overall survival have not been reached yet, and 24-month PFS rates were not yet estimable in either treatment group. Treatment-emergent AEs (TEAEs) are listed in Table 2. No pt in the TE and 3 pts (10%) in the TEO group discontinued tirabrutinib and entospletinib due to TEAEs, and no pt discontinued obinutuzumab due to TEAEs. Two (7%) pts in the TEO arm died following a TEAE: an 82-year-old male from subdural hematoma (onset within 30 days of last dosing, and death within 68 days) and a 77-year-old male from syncope (onset on the last dosing date, and death at day 35 after last dosing); both deaths were considered unrelated to study treatment by investigators. Conclusion: A triple combination with tirabrutinib, entospletinib, and obinutuzumab (TEO regimen) was tolerable and demonstrated excellent therapeutic activity in pts with relapsed or refractory CLL, but with limited CR rate. Disclosures Kutsch: Gilead Sciences, Inc.: Research Funding; Mundipharma, AbbVie, Janssen: Other: Travel, accomodation, expenses. Pallasch:Gilead Sciences, Inc.: Honoraria, Research Funding. Tausch:AbbVie: Consultancy, Honoraria, Other: travel support, Speakers Bureau; Roche: Consultancy, Honoraria, Speakers Bureau. Boehme:Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Glenmark Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Helsinn: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; VioPharm: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; InCyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grant. Ritgen:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding. Wacker:Celgene: Consultancy; Roche: Consultancy; BMS: Consultancy; Incyte: Consultancy; Amgen: Consultancy. Trappe:Celgene, Janssen, Takeda, TEVA: Other: Congress related travel support ; Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche Pharma: Consultancy, Honoraria, Other: Congress related travel support , Research Funding; AbbVie: Consultancy, Other: Congress related travel support . Dreger:AbbVie, Gilead, Novartis, Riemser, Roche: Speakers Bureau; AbbVie, AstraZeneca, Gilead, Janssen, Novartis, Riemser, Roche: Consultancy; Neovii, Riemser: Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia. Stilgenbauer:AbbVie, AstraZeneca, Celgene, Gilead Sciences, Inc., GSK, Hoffmann La-Roche, Janssen, Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau. Zhang:Gilead Sciences, Inc.: Employment, Other: Shareholder. Jürgensmeier:Gilead Sciences, Inc.: Employment, Other: Shareholder. Bhargava:Gilead Sciences, Inc.: Employment, Other: Shareholder; Tioma Therapeutics: Membership on an entity's Board of Directors or advisory committees; Dicerna Pharmaceuticals: Consultancy; Sanofi, Aveo Pharma: Patents & Royalties. Hallek:Roche, Gilead Sciences, Inc., Mundipharma, Janssen, Celgene, Pharmacyclics, AbbVie: Honoraria, Research Funding, Speakers Bureau. Eichhorst:ArQule: Membership on an entity's Board of Directors or advisory committees; BeiGene: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead Sciences, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. OffLabel Disclosure: GAZYVA (obinutuzumab) is a CD20-directed cytolytic antibody and is indicated in combination with chlorambucil, for the treatment of patients with previously untreated chronic lymphocytic leukemia.

Abstract: This study is the first to assess prognostic factors in patients with AHA treated according to a uniform immunosuppressive regimen. Residual factor VIII activity and inhibitor concentration at baseline are potentially useful predictors of remission.

Abstract: Purpose: Post transplant lymphoproliferative disorder (PTLD) is a serious and often devastating complication after solid organ transplantation. The initial therapeutic action is reduction of immunosuppression (IR). Patients not responding to IR usually are treated with rituximab monotherapy and/or CHOP-based chemotherapy. The impact of treatment on the renal graft function is to be analyzed. Methods: A retrospective data analysis was performed on adult renal transplant recipients with PTLD requiring further therapy after failing to respond to IR. All patients gave their informed consent to this study and all had been treated within one of the prospective German PTLD Study Group protocols: PT-LPD-1 (rituximab monotherapy), PTLD-1 (sequential treatment with rituximab and CHOP chemotherapy) or PTLD D2006–2012 (different treatment protocols). Renal graft function was analyzed 6 months (6m) before, during and up to 2 years after treatment of PTLD. From our renal transplant database altogether 1075 transplant recipients that had transplantation between January 1998 and June 2008 served as a control. Controls were matched for sex, patient age, transplant age and transplant function at time of diagnosis of PTLD. Results: Median age at diagnosis of PTLD was 49 years. 38/55 pts. were male, 43/55 had late onset PTLD. 53/55 had B-cell PTLD: 2 polymorphic, 37 aggressive B-cell, 3 Hodgkin or Hodgkin-like PTLD and 11 others. 2/55 had T-cell PTLD. 34/55 had an advanced stage of disease and 26/51 had elevated LDH levels. 1 patient had renal graft involvement. Renal transplantation for endstage renal disease was either due to autoimmune disorders (26/55), to diabetes (4/55), to cystic renal degeneration (5/55) or to metabolic dysfunction (1/55, 19 others). At diagnosis of PTLD 10 patients were on calcineurin-inhibitor (CNI) therapy only, 16 were on CNI plus mycophenolate mofetil (MMF), 13 were on CNI plus azathioprin (AZA), 4 were on CNI plus mTor-inhibitor, 4 were on mTor-inhibitor plus MMF or AZA and 7 were on single agent immunosuppression with MMF, AZA or prednisone. Immunosuppression was reduced in all patients immediately after diagnosis of PTLD. 15/55 patients received further therapy with single agent rituximab, 40/55 patients received CHOP or CHOP-like chemotherapy +/− rituximab. 36/53 (68%) patients reached a complete remission (CR). At a median follow up of & gt;2 years 4 patients relapsed and 17 died: 5 from PTLD, 7 from infections, 1 from myocardial infarction and 3 of unknown reason. Matching criteria were equally distributed in the patient and control group. After successful treatment of PTLD 4 of 38 PTLD survivors (10%) had failed renal allografts and recommenced hemodialysis: 1 due to a haemolytic uremic syndrom, 1 due to acute renal failure after a septic complication, 2 due to chronic transplant dysfunction. With a mean transplant age of 6.2 years transplant survival at 1 year after diagnosis of PTLD is 92% in the stable CR group. In a longitudinal analysis in 27 and 44 patient pairs evaluable not requiring hemodialysis we found a drop in eGFR values from 50.9 ml/min 6m before diagnosis of PTLD to 46.8 ml/min at time of diagnosis of PTLD that was statistically significant (p=0.04) suggesting a negative impact of the lymphoma (and/or of IR) to the graft function. With treatment of PTLD the graft function improved up to a mean eGFR of 56.3 ml/min 4 weeks after completing therapy (p=0.014). In subsequent subgroup analyses we found this effect to be restricted to and more durable in patients that had been treated with chemotherapy resulting in an eGFR of 57.6 ml/min, 55.7 ml/min and 58.6 ml/min 4 weeks, 6 months and 12 months after therapy, respectively. The graft function in this subgroup of patients was even superior to controls (p=0.012 at 6m, p=0.004 at 12m), which may result from the immunosuppressive effect of chemotherapy. Conclusion: PTLD may be associated with a worsening of graft function in renal transplant recipients but the graft often ameliorates during therapy. Beside rare acute complications like acute renal failure during septic complications there is no evident negative impact of therapy on renal graft function with rituximab and chemotherapy based 1st-line protocols in PTLD. Transplant survival in the disease free survival group is excellent.

Abstract: Abstract 100 Purpose: This trial aimed to investigate the efficacy and safety of sequential treatment with rituximab and CHOP-21 in patients with PTLD unresponsive to reduction of immunosuppression. Methods: An ongoing prospective, multicenter, international phase II trial was initiated in January 2003. Initially patients were treated with a fixed sequence of rituximab at days 1, 8, 15 and 22 (4R) followed by four cycles of CHOP-21 combined with G-CSF support starting 4 weeks after the last dose of rituximab (sequential treatment, ST). Based on the results of an earlier interim analysis showing that the response to rituximab predicts OS the trial was amended in 2007 introducing risk stratification according to the response to 4R (risk stratified sequential treatment, RSST). In RSST patients achieving a complete remission after 4R (low risk) continue with four 3-weekly courses of rituximab monotherapy while patients in PR, SD or PD (high risk) are followed by four cycles of R-CHOP-21 + G-CSF. Results: This is a scheduled interim analysis after inclusion of a total of 104 patients. The median follow up is 34.0 months for ST (64 pts.) and 9.1 months for RSST (40 pts.). 61 ST and 35 RSST patients were diagnosed with monomorphic PTLD, 3/5 with polymorphic PTLD. 27/23 patients were kidney, 3/0 kidney+pancreas, 15/8 liver, 13/6 heart, 6/3 lung or heart+lung transplant recipients. Median age at diagnosis of PTLD was 53/60 years (mean age: 48/56 years). 59%/58% of patients had an advanced stage of disease (Ann Arbor III/IV) and 49%/47% of tumors were EBV positive. 75%/75% of patients had late PTLD (i.e. later than 1 year after transplantation). LDH was elevated in 71%/64% of patients, respectively. The overall response rate (ORR) to 4 initial courses of rituximab monotherapy (4R, N=104) was 54% with a CR-rate of 32% and the subsequent completion of treatment with CHOP or R-CHOP allowed a clear increase of the response (p 〈 0.0001, Fig. 1). With ST the final ORR was 89% (CR rate: 69%). 86%, 75% and 75% of patients were without disease progression at one, two and three years, respectively (Fig. 2a). Disease free survival was 87%, 78% and 70% at one, two and three years. There were 6 early treatment associated deaths (9%) resulting from infections (1 from CMV-colitis, 1 from PcP-pneumonia, 1 from fulminant hepatitis, 3 from sepsis) and 2/64 patients died from refractory PTLD. Two further patients died due to hemorrhage during treatment. With RSST the ORR was 90% and 73% achieved a complete remission. 90% of patients were without disease progression at one year (Fig. 2a). There was one early treatment related death due to infection (2.5%). This patient died from sepsis secondary to intestinal perforation in response to R-CHOP treatment. 2/40 patients died from refractory PTLD. With 1 event in 16 patients in both, the ST and the RSST-arms, subsequent consolidation with rituximab monotherapy (RSST) seems not to be inferior to consolidation with 4 cycles of CHOP (ST) in patients with a CR after 4R. Up to now there is no difference in toxicity between CHOP and R-CHOP in ST/RSST. Patients failing to achieve a complete remission with 4R (72 patients) seem to benefit from the subsequent escalation from CHOP to R-CHOP (Fig. 2b). Conclusions: This is the largest prospective study in PTLD. Sequential treatment with rituximab and CHOP-21 + G-CSF is well tolerated and highly effective with a treatment related mortality of less than 10% and an efficacy of up to 90%. In comparison to historic series of rituximab monotherapy, significantly more patients achieve a CR with sequential treatment and time to progression (TTP) is very much prolonged. In comparison to historic series of CHOP, sequential treatment is much better tolerated. This may result from a lower tumor burden and a better patient fitness at the time chemotherapy is applied. Introduction of risk stratification according to the response to 4 courses of rituximab monotherapy might further improve these results restricting chemotherapy related toxicity to high risk patients while these data suggest that low risk patients can effectively be treated with extended rituximab monotherapy. Thus, risk stratified sequential treatment (RSST) might further improve OS in this difficult to treat disease. Disclosures: Trappe: Hoffmann La Roche Ltd.: Consultancy, Honoraria, Research Funding; AMGEN GmbH: Research Funding. Choquet:Hoffmann La Roche Ltd.: Consultancy, Honoraria. Oertel:Hoffmann La Roche Ltd.: Employment, Equity Ownership. Leblond:Hoffmann La Roche Ltd.: Consultancy, Honoraria, Research Funding. Ekman:Hoffmann La Roche Ltd.: Honoraria. Dührsen:Hoffmann La Roche Ltd.: Honoraria, Research Funding. Salles:Hoffmann La Roche Ltd.: Consultancy, Honoraria, Research Funding. Morschhauser:Hoffmann La Roche Ltd.: Honoraria. Riess:Hoffmann La Roche Ltd.: Consultancy, Honoraria, Research Funding; AMGEN GmBH: Consultancy, Honoraria, Research Funding.