ALBERT

Description: Despite the advances in the treatment of pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL), infiltration of the central nervous system (CNS) remains a clinical challenge. Certain cytogenetic subtypes such as E2A-PBX1-and BCR-ABL-positive BCP-ALL confer a higher risk for CNS involvement initially and for CNS relapse. Novel strategies to predict CNS and to eradicate leukemic cells from the CNS are subjects of ongoing research. In order to identify targets with diagnostic and therapeutic relevance, comparative RNA-sequencing was performed with patient derived xenograft (PDX) blasts from 5 E2A-PBX1-positive patients, recovered from the bone marrow (BM) and from the CNS of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Differential gene expression analysis revealed the upregulation of various genes of the pre-B cell receptor complex, particularly the signaling component CD79a (Igα) in blasts recovered from the CNS as compared to blasts from the BM. We then investigated the impact of CD79a on CNS infiltration in vivo and in patients. CD79a was downregulated by short-hairpin RNA (shRNA) mediated knockdown in the E2A-PBX1 positive cell line 697. Proliferation rates of 697-shCD79a cells and control-transfected 697 cells (697-shCtrl) in vitro were similar. Furthermore, NSG mice injected with 697-shCD79a cells showed comparable survival times, as well as similar blast infiltration in spleen and BM as animals injected with 697-shCtrl cells. However, downregulation of CD79a led to a significantly lower number of CNS-positive mice (4/15, 26%) as compared to control animals (7/10, 70%) (p=0.0486, Figure A). This indicates that CD79a is not critically involved in proliferation and peripheral engraftment, but in CNS infiltration of E2A-PBX1 positive 697 cells in vivo. To test if CD79a also affects CNS involvement in BCR-ABL-positive leukemia, a murine/murine transplantation model was used. B-cells isolated from CD79a-knockout (CD79a-KO) or wildtype mice (CD79a-Ctrl) were stably transfected with a BCR-ABL fusion gene and cultured independent of cytokines, thereby inducing malignant transformation. Both cell lines were subsequently injected into recipient NSG mice (n=8/group) and leukemic development was followed. The experiment was terminated when all control mice had developed leukemic symptoms and mice were analyzed for leukemic engraftment. A further CD79a-KO group was included for survival analysis. Median spleen volume as a surrogate of leukemic infiltration was significantly lower in mice injected with CD79a-KO as compared to CD79a-Ctrl cells (0.35 cm³ vs. 0.06 cm³; p=0.0001). Median blast percentages in spleens and BM were also markedly reduced (75.3% vs. 5.8%; p=0.0001 and 61.0% vs. 4.5%; p=0.0001, respectively). Importantly, none of the animals in the CD79a-KO group showed blasts in the CNS as assessed by histology whereas blasts were present in all of the animals in the CD79a-Ctrl group. Finally and most importantly, NSG-mice injected with CD79a-KO cells showed a highly significant prolongation in median survival as compared to mice with CD79a-Ctrl cells (29 days vs. 95 days; p=0.0001, Figure B). Altogether, these data suggest that in a model of BCR-ABL-positive leukemia, absence of CD79a impacts the engraftment of blasts in vivo, in the CNS and other leukemic niches. To further validate our findings in patient material, we measured CD79a protein expression in PDX cells from an E2A-PBX1- and a BCR-ABL-positive patient serially transplanted into NSG mice for three passages. For both entities and in all passages, CNS blasts showed a higher CD79a expression than blasts isolated from the bone marrow. In order to assess if CD79a can be used as a marker to predict CNS involvement in patients, CD79a mRNA levels were measured in a selected cohort of 98 pediatric BCP-ALL patients, which contained 26 CNS-positive patients matched to 72 CNS-negative patients. CNS-positive patients showed significantly higher mRNA levels of CD79a than CNS-negative patients (p=0.0225, unpaired t-test, Figure C) suggesting that CD79a may be of value as a potential diagnostic marker for initial CNS involvement in BCP-ALL. Our results indicate a role of CD79a in proliferation and CNS infiltration of BCP-ALL blasts in experimental settings and patients. We intend to prospectively evaluate CD79a as a prognostic marker, which may also be a therapeutic target in CNS-positive BCP-ALL. Disclosures No relevant conflicts of interest to declare.

Description: Systemic mastocytosis with an associated hematologic neoplasm (SM-AHN) is the most common subtype of advanced SM (advSM), diagnosed in up to 80% of patients. The AHN is most frequently diagnosed as a myeloid neoplasm, e.g., SM-MDS/MPNu or SM-CMML. Acquired mutations in KIT (usually KIT D816, KIT D816mut) are detectable in 〉90% of patients. The basis for the SM-AHN phenotype is usually the multi-lineage involvement, e.g. monocytes, eosinophils and other non-mast cell lineages, of KIT mutations. Core binding factor (CBF) positive AML (CBFpos AML) represents a distinct subtype and is identified in 5-8% of all AMLs. KIT mutations, most frequently KITD816mut, are detectable in up to 45% of CBFpos AML patients and are associated with an adverse prognosis. There is, however, only little information on KIT D816mut/CBFneg AML. We therefore evaluated a) clinical and molecular characteristics, b) response to treatment and, c) survival and prognostic factors in 40 KIT D816mut/CBFneg patients with histologically proven SM and associated AML (SM-AML), collected at 4 centers of the European Competence Network on Mastocytosis (ECNM). Molecular analyses (n=32) revealed at least one additional somatic mutation (median, n=3) apart from KIT D816, most frequently SRSF2 (n=12, 38%), RUNX1 (n=11, 34%), TET2 (n=11, 34%), ASXL1 (n=10, 31%), or NPM1 (n=7, 22%). At least one mutation in SRSF2, ASXL1 or, RUNX1 (S/A/Rpos) was identified in 21/32 (66%) patients. At diagnosis of SM-AML 21/40 (52%) patients had an aberrant karyotype. Secondary AML evolved in 29/40 (73%) patients from SM ± associated myeloid neoplasm and longitudinal molecular analyses revealed acquisition of new somatic mutations (TP53, n=2; NPM1, n=1; RUNX1, n=1, ASXL1, n=1; BCOR, n=1; IDH1/2, n=1) and/or karyotype evolution in 15/16 (94%) patients at the time of SM-AML. Thirty-one of 40 (78%) patients were treated with intensive chemotherapy (ICT) with a complete response (CR) rate of 40%. Allogeneic stem cell transplantation (SCT) was performed in 12/40 (30%) patients with durable CR in 6/12 (50%) patients. S/A/Rpos and/or the presence of a poor-risk karyotype were adverse predictive markers for response to treatment. To further investigate whether KITD816mut/CBFneg AMLdefines a distinct AML subtype associated with SM, two independent AML databases (AMLdatabases) were retrospectively screened and 69 KIT D816mut/CBFneg AML patients identified. The comparison between KIT D816mut/CBFneg SM-AML from ECNM (n=40) centers with KIT D816mut/CBFneg AMLdatabases(n=69) revealed remarkable similarities: a) a high KIT D816 variant allele frequency (VAF) (median 34% vs. 29%), b) with the exception of SRSF2 (38 vs. 18%), a highly similar mutation landscape, rather comparable to that of advSM (Jawhar et al., Blood 2017) than to that of de novo AML, c) in contrast to de novo AML, a low frequency of FLT3 mutations (3 vs. 7%), and d) a high frequency of an aberrant karyotype (52 vs. 42%). The median overall survival (OS) of 40 KIT D816mut/CBFneg SM-AML and 17 evaluable KIT D816mut/CBFneg AMLdatabases was 5.4 (95% confidence interval, CI [1.7-9.1]) and 26.4 (95% CI [0-61.0]) (P=0.015) months, respectively (Figure 1). However, if only the patients with ICT ± allogeneic SCT were compared, median OS between the two groupswas not different (16.7 vs. 26.4 months, P=0.4). In multivariate analyses, S/A/Rpos and a poor-risk karyotype remained the only independent poor-risk factors with regard to OS. These results were independent of treatment modalities. We conclude that KIT D816mut/CBFneg AML is a new poor-risk subtype associated with SM (SM-AML). The remarkable clinical, genetic and prognostic similarities between SM-AML and AMLdatabases suggest that a significant proportion of the AMLdatabases patients may in fact have SM-AML. We therefore strongly recommend to determine serum tryptase and KIT D816 mutation status in all AML patients, and to perform bone marrow histology in KIT D816mut patients. These simple diagnostic measures would allow reclassification to SM-AML and inclusion of KIT inhibitors in established treatment modalities of AML. Disclosures Meggendorfer: MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Döhner:Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Celator: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Astellas: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Jazz: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Pfizer: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding. Sperr:Novartis: Honoraria; Pfizer: Honoraria; Daiichi Sankyo: Honoraria. Valent:Incyte: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Reiter:Incyte: Consultancy, Honoraria.

Description: We aimed at understanding the relapse-driving processes in pediatric T-ALL and performed an integrated longitudinal multi-level omics analysis of 13 T-ALL patients at initial diagnosis (INI) and relapse (REL). We compared the mutation (SNV/InDels) and copy number alteration (CNA) patterns as well as gene expression, methylation levels and chromatin accessibility by ATAC-Seq. Aberrant expression of T-ALL transcription factors (TAL1, TAL2,LMO2, TLX1, TLX3, NKX2.4 and NKX2.5) was preserved from initial presentation to relapse in all patients. These leukemia-driving events defined the expression patterns, methylation profiles and the chromatin accessibility landscapes. A global differential analysis of the RNA-Seq data (DESeq2, padj

Description: Purpose: To investigate the prognostic impact of the coexpression of the natural killer cell marker CD56 / neural-cell adhesion molecule NCAM and to compare it to the immunophenotype subgroups according to the EGIL/WHO 2008 classification and to the early T-cell precursor (ETP) subtype for patients with T-ALL treated in the ALL-BFM 2000 protocol. Patients and Methods: The immunophenotype of 493 children with T-ALL was analyzed centrally at diagnosis with a four-color antibody panel consisting of 28 different antibodies for the detection of antigen expression in the cytoplasm and on the surface of the blast cell population. The frequency of immunophenotypic subtypes and their correlation with event-free survival (EFS) and cumulative incidence of relapse (CIR) were investigated. Results: The frequencies of T-ALL subtypes according to the EGIL/WHO classification were 0.4% for pro-T-ALL, 19.9% for pre-T-ALL, 64.7% for cortical T-ALL and 15% for mature T-ALL. The frequency of the ETP subtype according to the ETP-Score published by Inukai T. et al. (Br J Haematol. 2012) was 6.7% (surface CD3 negative) or 7.5% (with surface CD3 positivity) of all the patients with T-ALL. This is a lower frequency compared to the findings in the St. Jude and AIEOP patients published by Coustan-Smith E. et al. (Lancet Oncology 2009), but similar to what has been reported for the Tokyo Children's Cancer Study Group Study L99-15 by Inukai T. et al. (Br J Haematol. 2012). Coexpression of CD56 was detected in 7.2% of all T-ALL patients. The percentage of ETP in the CD56+ T-ALL cohort was 4-fold increased (30%) as compared to all T-ALL patients (7.2%). The 5-year EFS rates for the EGIL/WHO subgroups pre-T-ALL (n=57), cortical-T-ALL (n=310), and mature T-ALL (n=66) were not statistically different (0.72, SE=0.06, 0.83, SE=0.02, and 0.74, SE=0.06, respectively, Fig. 1). Also the 5-year EFS for the ETP (n=23) did not statistically differ from the non-ETP T-ALL cohort (Fig.1). By contrast, patients with CD56 coexpression (n=35) had a significantly lower 5-year EFS and a higher CIR at 5 years than patients without CD56-expression (EFS: 0.56, SE=0.09 vs. 0.80, SE=0.02, log-rank p = 0.001; CIR: 0.25, SE=0.8 vs. 0.14, SE=0.02, p(Gray) = 0.08), (Fig. 2). In the multivariate analysis, considering other risk parameters like age older than 10 years, WBC greater than 100,000 and prednisone response, CD56 coexpression was an independent prognostic marker for 5-year-EFS with a hazard ratio (HR) of 2.50 (p = 0.002). CD56 coexpression lost significant prognostic impact with the addition of the MRD risk groups to the multivariate model (HR=1.45, n.s.). Conclusion: In the ALL-BFM 2000 trial the prognostic significance of the ETP-phenotype, which has been previously demonstrated as being prognostically unfavorable in several ALL clinical trials, could not be confirmed. The CD56-coexpression, although not superior to the MRD risk assignment, warrants further investigation as an additional independent prognostic indicator at diagnosis for unfavorable clinical outcome in childhood T-ALL. Figure 1. T2=pre-T-ALL, T3=cortical, T4=mature, TNKP=CD56+ Figure 1. T2=pre-T-ALL, T3=cortical, T4=mature, TNKP=CD56+ Figure 2 T-ALL and CD56 coexpression Figure 2. T-ALL and CD56 coexpression Disclosures Moricke: JazzPharma: Honoraria, Other: financial support of travel costs.

Description: Human cytomegalovirus (CMV) reactivation and disease is still a frequent complication after allogeneic stem cell transplantation (allo SCT). It is well accepted that T-cell immunity is mandatory to control CMV infection and disease and much effort has been put into the development of cell-based monitoring assays. Nevertheless, no reliable marker for protective immunity has been established to date. Most studies use one CMV model antigen (pp65) to compare the frequencies of cytokine producers (mainly IFNg) or multimer-specific T-cells. Methods: In total, we recruited 16 patients after allo SCT, (7 high risk, 9 standard risk pts.). We used 8-colour flow cytometry to detect degranulation (mobilized CD107a/b), intracellular IFNg, TNFa, IL-2 production and CD28-expression in peptide pool stimulated pp65 and IE-1 specific CD8 T-cells. Results were compared to 7 healthy CMV exposed donors. Results: Degranulation identifies the highest percentage of CMV-specific T-cells in allo-transplanted patients (pp65: 0,94% degranulation and 0,31% IFNg; IE-1: 1,44% degranulation and 0,87% IFNg, mean frequency). These T-cells are relatively cytokine deficient compared to those in healthy donors (cytokine-production/degranulation ratio: SCT=0,42, healthy=0,72 for pp65, p=0,048; SCT=0,61, healthy= 1,00 for IE-1, p=0,133, U-test). The cytokine expression pattern differs between antigens used for stimulation, for example more IL-2-producers could be detected in the pp65 specific compartment (12,5% for pp65 and 4,5% for IE-1 of all activated CD8 T-cells, p=0,015). Conclusion: This study demonstrates that degranulation is the most prominent marker of CMV-specific T-cells (pp65 and IE-1) in allo SCT patients. Looking at IFN-g producers only may underestimate the frequencies of CMV specific T-cells in this setting. Furthermore, these subsets have a divergent functionality in transplant recipients compared to healthy individuals. Our data challenge the concept of enumerating CMV specific T-cells to estimate immunity. We rather propose measuring functional differences in the T-cell response may help to identify patients with a high risk of CMV reactivation. A careful dissection of these differences is a prerequisite for the development of monitoring tools and adoptive T-cell transfer.

Description: Introduction High-dose chemotherapy and stem cell transplant (SCT) remains a standard of care in medically fit patients (pts) with newly diagnosed (ND) MM. Induction triplets with at least one of the newer compounds are recommended. Bortezomib (V), lenalidomide (R) and dexamethasone (D; VRD) ranks among the most effective regimens and VRD/SCT was superior to VRD alone in an RCT. In a phase 2 study, we demonstrated RAD induction (lenalidomide 25 mg d1-21; Adriamycin 9 mg/m2 iv d1-4; dexamethasone 40 mg d 1-4 and 17-20 every 4 weeks) followed by SCT to be safe and effective (Knop et al., Leukemia 2017). Therefore, we decided to compare RAD versus (vs) VRD (lenalidomide 25 mg, d1-14; subcutaneous bortezomib 1.3 mg/m2 d 1, 4, 8, 11; dexamethasone 20 mg d 1+2, 4+5, 8+9, 11+12 every 3 weeks) induction (3 cycles each) in an RCT. MethodsThe current study was set up according to a double 2x2-factorial design to enrol transplant-eligible pts up to 65 years. The post-induction (PI) complete response (CR) rate as per IMWG criteria was the efficacy co-primary endpoint. We hypothesized the CR rate following RAD to be non-inferior to VRD which was estimated to be 20%. The study was powered to confirm non-inferiority of RAD at a margin of 10% with a one-sided alpha level of .05. Cytogenetic characterization was performed by fluorescence in situ hybridization (FISH) from CD138-enriched plasma cells. Minimal residual disease (MRD) was assessed by second-generation eight-color flow cytometry (FC; EuroFlow protocol). Bone marrow (BM) samples from baseline and defined restaging time points were analyzed for an acquisition of ⩾107cells/sample. In a subgroup of 103 pts, we evaluated the applicability of comprehensive immunoglobulin (Ig) amplicon next generation sequencing (NGS) to detect molecular MRD markers and to compare the results with FC. NGS-based marker screening was performed in baseline BM. Sequencing libraries were prepared using 2-step PCR employing multiplex primer sets for IGH V-D-J (FR1, FR2 and FR3), IGH D-J and IGK loci (V-J and KDe). For MRD detection, we used 1-step library preparation with the same primer sets. Results476 pts with a median age of 55 (range, 32-65) years were randomized between 05/2012 and 06/2016 and 469 received at least one dose of study drug. High-risk (HR) FISH abnormalities comprised del17p (11.3% of pts); t(4;14) (11.7%); and t(14;16) (4.5%). 232 pts were randomized to receive RAD, and 237 to VRD, respectively. 90.5% of RAD vs 93.7% of VRD pts completed all 3 cycles. PI CR rate was 13.5% (95% CI, 9.4%-18.7%) with RAD vs 13.4% (95% CI, 9.3-18.5) with VRD, (P=.971). Rates of ≥VGPR were 40.6% (50% CI, 34.2%-47.3%) with RAD vs 48.9% (95% CI, 42.3-55.6%) with VRD (P=.076). In pts with HR cytogenetics, rates of ≥VGPR were 43.3% (RAD) vs. 59.3% (VRD; P=.096). From 317 pts with paired samples, 33/151 (21.9%) of RAD vs 45/166 (27.1%) of VRD pts were FC MRD negative (P=.169) following induction at a median sensitivity level of 6.73x10-6. 197/239 positive pts (82.4%%) had MRD levels above 0.01%, and 42 (17.6%), between 0.0001 and 0.01%. Flow MRD negativity as per IMWG MRD criteria (Kumar et al, Lancet Oncol 2016) was seen in 8/151 (5.2%) pts with RAD vs 6/166 (3.6%) with VRD (P=.27). The remainder of pts did not (yet) fulfil IMWG CR for various reasons. NGS marker screening identified at least 1 Ig marker in 98/103 evaluable patients. To date, 47/98 pts were analyzed for NGS MRD following induction. Four out of 47 (8.5%) subjects were sequencing negative (3/4 post-VRD) with all of them also being IMWG FC MRD negative. One VRD patient died during induction for a mortality rate of 0.2 %. 62.1% of RAD vs 55.3% of VRD pts experienced at least one serious adverse event (SAE; p=.16). SAEs with relationship to study drugs of at least °3 severity occurred in 26.3% (RAD) vs 23.6% (VRD) pts (p=.523). ConclusionsTo the best of our knowledge, this is the first RCT to compare two R-based triplets in SCT-eligible pts. The co-primary efficacy endpoint was met with identical PI CR rates of around 13% for RAD and VRD, respectively. However, a trend emerges to favor VRD over RAD in terms of at least VGPR including HR FISH subjects. Analysis of MRD by multicolor FC showed 5% of pts to be already IMWG flow MRD-negative. Results for all 98 pts evaluable for NGS MRD will be presented. As of yet, too few progression events have occurred to estimate the second co-primary endpoint, 3-year progression-free survival. Longitudinal response and MRD analysis are ongoing. Disclosures Langer: Celgene: Consultancy. Mügge:Celgene: Honoraria, Research Funding; Janssen: Honoraria; Novartis: Honoraria; Bristol Myers Squibb: Honoraria; Amgen: Honoraria. Blau:Amgen: Other: Advisory board; BMS: Other: Advisory board; Novartis: Other: Advisory boards; Takeda: Other: Advisory board; Janssen: Other: Advisory board, Research Funding; Celgene: Other: Advisory board, Research Funding. Rollig:Janssen: Research Funding; Bayer: Research Funding. Dechow:AMGEN: Consultancy; Celgene: Honoraria. Gramatzki:Affimed: Research Funding. Brümmendorf:Merck: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Schmidt:Gilead: Honoraria, Other: Travel Grants; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Grants; Celgene: Honoraria. Knop:Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding.

Description: Infection and disease with human cytomegalovirus (HCMV) is still an important cause for morbidity and mortality after allogeneic stem cell transplantation (allo SCT). Specific T-cells (CTL) are crucial for the control of CMV infection. In addition to cytokine production, degranulation is an interesting marker of T-cell function. Recent studies in patients after solid organ transplantation revealed that high levels of IE-1-specific CTL correlate with a protection from CMV disease. However, the functionality of these cells is less clear. As demonstrated in AIDS suffering patients, CTL activity is more related to a protection than to a cytokine secretion. Here we address the question, whether CD4 and CD8 T-cells have different abilities to degranulate or to produce cytokines depending on the type of immunosuppression and the CMV target protein. Material and Methods: T-cells from 6 healthy CMV exposed donors and 16 allografted patients (11 AML, 3 ALL, 1 NHL, 1 MPS) were stimulated with peptide pools representing the pp65 (UL83) and IE-1 (UL123) proteins. Mobilized CD107 (marker of CTL activity), TNF, IFN-g, and IL-2 production was analyzed by 8-color flowcytometry. Immunosuppression consisted of CSA/MMF (n=4), CSA alone (n=4) and CSA/MTX (n=8), 4/8 patients additionally received ATG for GvHD-prophylaxis as part of the conditioning regimen. In all transplanted patients CMV antigenemia was assessed twice a week. Results and Conclusion: The responding T-cell population mainly demonstrated an effector phenotype with a low expression of CD28. Frequency of reactive CTL did not correlate with CMV antigenemia. Interestingly, there was no impairment of degranulation or cytokine production found in any of the allogeneic transplanted patients compared with healthy CMV exposed controls, showing that immunosuppression does not target the function of the specific CTL.

Description: 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