ALBERT

Description: Introduction. Fli1 (Friend leukemia virus integration 1) together with other transcription factors induces the megakaryocytic differentiation of MEP (megakarycytic and erythroid progenitor). Refractory anemia and thrombocythemia is typical for 5q- syndrome. We found increased mRNA level of Fli1 in mononuclear bone marrow cells of 5q- syndrome patients in comparison with healthy controls (Neuwirtova et al., Ann Hematol 2013). The reason of the elevated Fli1 in 5q- syndrome is haploinsufficiency of microRNA-145, which targets Fli1 mRNA (Kumar et al., Blood 2011). Due to haploinsufficiency of RPS14 in 5q- syndrome non-consumed ribosomal proteins cause ribosomal stress and inactivate HDM2 in erythroblasts. E3 ubiquitin ligase HDM2 regulates p53 level by p53 degradation in proteasome. Inactivated HDM2 in erythroid precursors of 5q- syndrome leads to apoptosis of erythroblasts and to anemia. Why ribosomal stress does not cause thrombocytopenia and ineffective megakaryopoiesis as well? Our previous results support significant role of Fli1 in this process. Fli1 binds to promoter of the HDM2 gene and increases its transcription (Truong et al., Oncogene 2005). The increased activity of HDM2 in megakaryocytes inspite of ribosomal stress maintains p53 regulation and its degradation in proteasome. Megakaryopoiesis remains effective. Why it is not the case in erythroid precursors? To answer this question it was necessary to detect Fli1 as the protein and to determine in which cells Fli1 is present. Material and Methods. Twenty-three control representative bone marrow trephine biopsies of patients from controls (8 negative staging biopsies in lymphoma) and of patients with various hematological diagnoses (7 MDS with normal chromosome 5, 4 MPN, 3 AML and 1 RARS-T) and from 15 patients with 5q- syndrome were examined. In 13 patients with 5q- syndrome, samples taken before and 6 months after lenalidomide (Revlimid) therapy were available. The expression of Fli1 protein was investigated by immunohistochemistry (IHC). Expression of Fli1 on erythroid precursors was studied by double staining IHC procedure utilizing antibodies against Fli1 and either glycophorin A or E-cadherin known as reliable markers for erythroid precursors. Results. Nuclear expression of Fli1 was demonstrated in normal as well as in dysplastic megakaryocytes, in most cells of granulocytic series and lymphocytes. No staining for Fli1 was seen in erythroblasts and proerythroblasts visualized by expression of either glycophorin A or E-cadherin both in 5q- syndrome and controls. There were no significant differences in Fli1 expression between samples taken before and after lenalidomide treatment.The used IHC technique does not permit quantitative analysis of Fli1 protein levels. This fact could explain why we did not find any difference in Fli1 protein labeling in megakaryocytes before and after lenalidomide treatment while Fli1 mRNA level was decreased in majority of 5q- syndrome patients after six months of this therapy. Conclusion. Fli1 expression was found in normal as well as in dysplastic megakaryocytes. However, no Fli1 positivity was found in erythroid precursors in both 5q- syndrome and controls. Negativity of Fli1 expression in erythroid precursors in 5q- syndrome support our hypothesis of protective role of Fli1 against apoptosis under ribosomal stress in megakaryocytes in contrast to erythroblasts lacking Fli1. This protective role of Fli1 in megakaryocytes consists in Fli1 potentiation of expression of the E3 ubiquitine ligase HDM2 (Truong et al., Oncogene 2005). The presence of increased Fli1 in megakaryocytes helps to explain effective megakaryopoiesis in 5q- syndrome and is the answer to the question in the title of our abstract. Supported by Ministry of Health, Czech Republic-conceptual development of research organization Institute of Hematology and Blood Transfusion 00023736, RVO-VFN64165 and PRVOUK P-27/LF1/2. Disclosures No relevant conflicts of interest to declare.

Description: Introduction Results of randomized studies showed benefit of maintenance therapy with monoclonal anti-CD20 antibody (rituximab) in terms of time to progression (PFS) and overall survival (OS) in follicular lymphoma (FL). General recommendation, based on large clinical trial, is to give 2 years of rituximab maintenance á 375mg/m2every 2 months (12 doses) in first line setting. On the other hand, there are various rituximab maintenance schedules; however, the clear comparison of clinical efficacy is missing. Our retrospective analysis compared two different schedule of rituximab maintenance in first-line treatment of FL used in university centers participating on CLG registry. Methods Data were recruited from 1702 FL patients registered in the prospectively maintained multicentric database (Czech Lymphoma Group; CLG). For the analysis, patients with stage II-IV of new diagnosed FL (grade 1-3a) responding (complete or partial remission) to 6-8 cycles first-line RCHOP (rituximab, cyclophosphamide, doxorubicine, vincristine and prednisone) followed with rituximab maintenance (RM) were included. Completed planned maintenance was inclusion criterion. Patients with previous watch and wait or additional first line therapy (radiotherapy, other chemotherapy, transplant therapy) were excluded. Results Totally, 168 evaluable FL patients with median age 57ys (range 28-82) including 70 (41.7%) men treated with RCHOP + RM were found in CLG database. 52/168 patients received totaly 8 doses of rituximab maintenance every 3 months for 2 years (RM8 arm), whereas 47/168 patients were treated with totaly 12 doses (RM12 arm) of rituximab maintenance every 2 months for 2 years. All patients in both subgroups completed planned RM therapy. There was no difference in distribution of age, gender, FLIPI, grade, B-symptoms, bone marrow involvement, performance status, LDH and beta2microglobuline level between both arms. Induction treatment in terms of administered cycles CHOP (6xCHOP in 41/52 and 35/45 pts., for RM8 and RM12 arm) and rituximab doses (8xR in 48/52 and 41/45 pts., for RM8 and RM12 arm) was similar between arms (ns). There were 4/52 (7.7%) and 5/47 (10.6%) relapses in subgroups RM8 and RM12, with no statistical significance. Median PFS was 3.8 (2.1-5.8) years vs. 3.9 (2.4-7.8) years in RM8 and RM12 arms (not significant), and median OS 3.91 (2.2-6.94) years vs. 3.1 (2.48-8.6) years also with no statistical significance. Conclusion Our results show, that rituximab maintenance given every 2 or every 3 months for two years in first line treatment brings similar benefit to the FL patients in terms of remission duration and overall survival. Despite the fact, that presented data are retrospective observation, this is the first report comparing two different rituximab maintenance regimens in FL. Further prospective study and longer follow up are needed to confirm our preliminary data. This work was supported by grant NT/12193-5 and MHCZ-DRO (FNBr 65269705) Disclosures: Mayer: Roche: Consultancy, Research Funding; Glaxo: Consultancy, Research Funding. Trneny:Roche: Honoraria, Research Funding.

Description: Background: MCL is a distinct lymphoma entity with improved outcome achieved by the introduction of rituximab, high dose Ara-C and autologous stem cell transplantation (ASCT) into the first line therapy. The outcome of the relapsed patients (pts) remain however poor and there is little data on the outcome after subsequent relapses and there is no information on secondary MIPI prognostic value. Aim: To analyze the outcome of the MCL patients after first line treatment failure and to evaluate the prognostic role of the sec MIPI which is MIPI calculated at the time of relapse/progression. Methods: This analysis is a part of the Lymphoma project in which consecutive lymphoma patients are registered since the year 1999. Altogether 519 newly diagnosed MCL patients were registered in 5 university centers and 9 regional departments between 1999 and 2011. Patients who were treated with rituximab as part of the first line treatment (n=388) were included into the analysis. The diagnoses were confirmed according to WHO classification in the reference pathology centers. The median follow up is 4.5 years. Results: The whole cohort consists of 261 males and 127 females (2.1:1) with median age 65 y (28-87), the majority of pts had advanced disease (CS IV in 81.6% pts), PS ECOG ≥ 2 in 23.6% pts, elevated LDH in 52.5% of pts. The MIPI risk profile was as follows: low risk 21.7%, intermediate risk 27.2% and high risk in 51.1%. All pts received rituximab as part of the induction, 48.7% pts received CHOP, 5.7% alternation of CHOP and HD Ara-C, 26.2% intensive induction with HD Ara-C, 10.3% CVP, 6.4% FC. High dose therapy with ASCT was performed in 23.9% of pts. The ORR was 89.0% with 63.8 CR/CRu, 6.3% had stable disease and 4.9% were primary progressive. The PFS and OS were 2.9 y and 5.5 y with significant impact of MIPI risk (p

Description: Introduction Germline mutations in GATA2 were recently identified as causative for several overlapping syndromes: MonoMAC (monocytopenia, mycobacterial infections), DCML (dendritic cells, monocytes, B and NK cells deficiency), Emberger syndrome (lymphedema, sensorineural deafness, multiple warts) and familiar myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML). Of note, GATA2 mutations were also found in children and young adults with “primary” MDS. Aplastic anemia (AA) constitutes an important differential diagnosis to pediatric MDS, particularly in patients with normal cytogenetics. Because of heterogeneous phenotype of GATA2 mutated patients, defining a set of typical findings would help in their earlier identification and understanding the natural course of the disease. Therefore we aimed to analyze monocytes and lymphocyte subpopulations with the emphasis on B cell lineage by flow cytometry (FC) and polymerase chain reaction (PCR) in all pediatric patients with GATA2 mutation diagnosed in the Czech Republic. Patients and methods Eleven pediatric patients were found to harbor GATA2 mutations in the Czech Republic so far. Three mutations were intronic. There was a clear male predominance (9/11). In 7 patients the disease manifested with MDS in childhood, 2 female patients were followed for immunodeficiency and developed MDS in adulthood. One another patient was diagnosed with interstitial lung disease and chronic EBV infection. His brother, carrying the same mutation, has mild neutropenia. Bone marrow (BM) and peripheral blood (PB) samples were analyzed by FC. The level of intronRSS-Kde recombination excision circles (KREC) and T-cell receptor excision circles (TREC) for assessment of proliferation history of B and T cells was examined by PCR. The control group comprised 26 GATA2 wild-type MDS (“other MDS”) patients and 36 AA patients. Results Disturbance of B cell compartment was the most frequently observed anomaly in the patients with GATA2 mutation. We observed a decrease of absolute and relative B cell numbers in PB and BM (n=9/11). In BM there was a decrease of immature CD10pos B cells (n=10) with proportional increase of plasma cells. Peripheral blood B cell immunophenotype was shifted towards memory B cells (n=5/7). Presence of normal B cell precursors CD19pos10pos34pos in BM was observed only in 1 patient in part of follow-up samples. Atypical malignant B lymphoblasts were present in another patient, whose MDS quickly progressed to AML with a clear switch to B lymphoid phenotype. Despite significantly reduced number of B cells the levels of IgG were normal in majority of patients. Only 2 patients had IgG hypogammaglobuliemia, in one patient with chronic active EBV infection IgG hypergammaglobulinemia was present. Slightly decreased IgA level was present in 6 patients. Although B cell numbers in other MDS control patients were significantly lower compared to AA, still the decrease was less prominent in comparison with GATA2. The decrease of immature and naive B cells in patients with GATA2 mutation was reflected in very low level of KREC in PB and BM. Stored newborn dry blood spots from 4 patients were evaluated for TREC and KREC numbers. Strikingly, only one patient had negative KREC levels (the youngest patient from our cohort with MDS diagnosed at age 4). The remaining 3 patients had normal TREC and KREC levels at birth. Thus, the deterioration of de novo production of B cells occurred supposedly postnatally in most patients. Low KREC levels were also present in some patients with other MDS (n=5). Relative monocytopenia was found in 2 patients, low NK cells were present in 6 patients. T cells were mostly of naive non-activated phenotype. Conclusions Changes in B cell compartment are the most characteristic feature in patients with GATA2 mutation. Decreased number of B cells together with a shift towards mature phenotype and decreased level of KREC reflect history of substantial B cell proliferation in an environment of impaired production. This process appears to happen postnatally and resemble normal ageing process, which is accelerated due to progenitor cell impairment. Immunophenotyping is a useful tool in identifying patients for GATA2 sequencing. Supported by GAUK 802214, IGA NT/14534-3, NT/13462-4, UNCE 204012, GAČR P301/10/1877 Disclosures No relevant conflicts of interest to declare.

Description: Childhood myelodysplastic syndromes (MDS) belong to a rare group of disorders of aberrant clonal hematopoiesis manifesting throughout entire childhood and adolescence. We had previously established that GATA2 germline mutations can be considered the most common "first hit" in pediatric MDS seen in 7% of primary MDS. However the secondary somatic aberrations facilitating leukemogenesis are not elucidated in children. Previous sequencing efforts established that most somatic mutations very frequently encountered in adults, i.e. affecting TET2, DNMT3a, and the spliceosome genes, do not play a role in the pathogenesis of childhood MDS. Here we aim to define the global mutational landscape in childhood MDS using targeted next-generation sequencing (NGS) approaches. We investigated children and adolescents enrolled in the prospective studies of the European Working Group of Childhood MDS. Diverse target enrichment and NGS strategies were established including hybridization capture and Ampliseq PCR, Illumina Miseq/Hiseq and Iontorrent PGM. We first examined a pilot cohort of 68 patients for mutations in 138 myeloid leukemia genes. This allowed for the identification of recurrently mutated genes that were selected to be included in a pediatric MDS panel encompassing 28 genes. Targeted NGS using the Iontorrent PGM identified known recurrent mutations. However, the high indel error rate and coverage gaps in homopolymeric regions i.e. in ASXL1 precluded further studies. Using inhouse-adapted Ampliseq-Miseq approach we then sequenced DNA from bone marrow of 586 MDS patients (469 primary and 117 secondary MDS after radio/chemotherapy or inherited bone marrow failure syndromes) at an average depth exceeding 700 reads per amplicon. Somatic mutations were identified in 22% of primary MDS patients, with 1, 2 and 3 genes affected in 16%, 4.5%, and 1.5% of cases, respectively. In secondary MDS twice as many patients (46%) carried mutations; 1, 2, and 3 genes were concurrently mutated in 32.5%, 9.5%, and 4% of patients, respectively. Longitudinal NGS analyses and single CFU colony sequencing confirmed the presence of multiple somatic clones evolving in a hierarchical manner throughout disease course. Most frequent mutations identified in more than 1% of our study cohort of primary MDS were: SETBP1 (7%), ASXL1 (6%), NRAS/KRAS (5%), RUNX1 (3%), PTPN11 (3%) and BCOR/BCORL (1.5%); and in secondary MDS: RUNX1 (14.5%), TP53 (9%), NRAS/KRAS (8.5%), ASXL1 (8%), SETBP1 (6%), PTPN11 (6%), CBL (5%), BCOR/BCORL1 (3.4%). Other genes mutated at very low frequency of

Description: Background: Follicular lymphoma (FL) is an indolent lymphoma with chronically relapsing disease course. Treatment of relapses with 2nd line regimens such as salvage and autologous stem cell transplant (ASCT) is considered successful, i.e. the relapse itself does not shorten life expectancy. However, LymphoCare registry study (Casulo et al., JCO 2015) identified an early progression of the disease (POD24, i.e. progression within 24 months after R-CHOP commencement) to be a strong unfavorable event. Early progressors experienced only 50% 5-year OS compared to 90% in the control group) irrespective of the salvage treatment delivered. It is unclear whether post R-CHOP maintenance immunotherapy (MAINT) decreases POD24 incidence. Potential predictors identifying patients at risk of POD24 have not been analyzed yet. Aims: (1) To analyze the impact of MAINT on POD24 occurrence, (2) to find clinically applicable predictors of POD24 at the time of FL diagnosis. Methods: The Czech Lymphoma Study Group (CLSG) database was searched using the LymfoCare (LC) study methodology for previously untreated FL grade I-IIIa patients (pts), CS II-IV (Ann Arbor), no watch-and-wait before R-CHOP. Early progressors were defined as pts with progression or relapse within 24 months after FL diagnosis. OS was calculated both from diagnosis and from the Risk-defining event (rdOS) - it means from the date of early progression (POD group) or 24 months after diagnosis (non POD group). We have identified 821 FL pts, who met the inclusion criteria above and were diagnosed before DEC-2014. Median age of the CLSG group (58 years; range 26-82 years) was identical to the LC group (58 years; 22-88). Fifty-eight percent were females (46% in LC) and 50.5 % had high risk FLIPI (44% in LC). 80.8% of our pts had FL grade I-II and 19.2% had FL grade IIIa (62% and 38% in LC, respectively) Results: Treatment response was available in all but 15 pts (99.9%): CR/CRu, PR and SD/PD was achieved in 70.0%, 25.5% and 4.5%, respectively. After median follow up of 5.02 years 244 (29.7%) pts relapsed or progressed and 101 (12.3%) of the pts died. Five year OS and progression-free survival (PFS) was 90.1% (95% CI 0.88-0.92) and 63.7% (95% CI 0.60-0.68), respectively. In total, 99 POD24 (12.3%) were identified in the whole cohort of 821 patients. Five-year OS without POD24 (93.8%) was superior to 5-year OS in the POD24 group (64.3%, p

Description: Abstract 2882 Absolute lymphocyte count (ALC) at time of diagnosis has been documented as an independent predictor of survival in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL). The optimal cut-off values of ALC are still a matter of debate. An extensive analysis of the prognostic impact of ALC in the elderly population treated with rituximab has not yet been carried out. Thus, we assessed the prognostic significance of different ALCs in unselected, newly diagnosed elderly patients with DLBCL in the population of the Central European region (the Czech Lymphoma Project registry). We analyzed data of 651 patients with confirmed DLBCL older than 59 years. Those with CNS involvement were excluded. The median age at diagnosis was 69 years (range, 60–97); the Ann Arbor stages were as follows: I (16.5%), II (26.1%), III (15.9%), and IV (41.5%). The IPI scores were: low (L) 19.8%, low-intermediate (LI) 26.6%, intermediate-high (IH) 24.3%, and high (H) 29.3%. We analyzed the prognostic value of lymphopenia with 3 different cut-off values. Values of ALC 〈 1.0 × 109/L and ALC 〈 0.84 × 109/L were chosen according to the previously published data, the third value was the median ALC at diagnosis (ALC 1.35 × 109/L). ALC 〈 1.0 × 109/L was observed in 201 (31%) and ALC 〈 0.84 × 109/L in 159 (24%) patients. ALCs below predefined levels were associated with higher (IH, H) IPI scores: ALC 〈 0.84 × 109/L (78% vs 46%, p 〈 0.001), ALC 〈 1.0 × 109/L (77% vs 43%, p 〈 0.001), and ALC 〈 1.35 × 109/L (68% vs 38%, p 〈 0.001); advanced disease (stages III/IV): ALC 〈 0.84 × 109/L (72% vs 53%, p 〈 0.001), ALC 〈 1.0 × 109/L (72% vs 51%, p 〈 0.001), and ALC 〈 1.35 × 109/L (66% vs 48%, p 〈 0.001); and low performance status (ECOG ≥ 2): ALC 〈 0.84 × 109/L (52% vs 27%, p 〈 0.001), ALC 〈 1.0 × 109/L (50% vs 25%, p 〈 0.001), and ALC 〈 1.35 × 109/L (43% vs 22%, p 〈 0.001). In 85% of patients, treatment was initiated with an anthracycline-containing regimen (CHOP), i.e. only 15% of patients recieved a non-anthracycline-based regimen (COP). The median number of chemotherapy cycles was 6. Chemotherapy was combined with rituximab in all patients (a median of 6 doses). Generally, treatment response was assessed in 544 (83.6%) patients. Complete remission (CR) or unconfirmed CR was achieved in 79.8% and partial remission in 12.5% of patients, with 7.7% of patients being classified as having stable disease or disease progression. CR rates were significantly higher in patients with higher lymphocyte counts: ALC 〉 0.84 × 109/L (82% vs 71%, p = 0.006), ALC 〉1.0 × 109/L (83.1% vs 71.7%, p = 0.008), and ALC 〉 1.35 × 109/L (85% vs 75%, p = 0.027). The overall survival (OS) and event-free survival (EFS) rates were superior in all subgroups of patients with higher ALC levels. The 3-year OS rates stratified by lymphocyte count: ALC 〉 0.84 × 109/L (67% vs 51%, p = 0.0002), ALC 〉 1.0 × 109/L (67% vs 52%, p = 0.0017), and ALC 〉 1.35 × 109/L (71% vs 55%, p = 0.0001). The 3-year EFS rates stratified by lymphocyte count: ALC 〉 0.84 × 109/L (61% vs 44%, p = 0.0002), ALC 〉 1.0 × 109/L (62% vs 44%, p = 0.0002), and ALC 〉 1.35 × 109/L (66% vs 47%, p 〈 0.0001). Only ALC 〈 1.35 × 109/L was found to be an independent negative prognostic factor for the OS (RR = 1.53, p = 0.006) and EFS (RR = 1.43, p = 0.013) in a multivariate analysis when compared with the LDH level, clinical stage, performance status and age (above median). In summary, the data support the hypothesis that host innate immunity is critical in tumor growth control and is a limiting factor for the efficacy of immunochemotherapy in elderly patients with DLBCL. The optimal cut-off levels of ALC may be different in various populations. This fact should be taken into account when designing new ALC-based prognostic schemes. Disclosures: Prochazka: ROCHE: Honoraria. Pytlik:ROCHE: Honoraria.

Description: Background Follicular lymphoma (FL) is a disease with very heterogeneous course ranging from the indolent forms to rapidly progressive cases with poor outcome. Optimal therapy in FL patients with high tumor burden is immunochemotherapy (R-CHOP is the most frequent regimen used), followed by maintenance treatment. Data from randomized prospective studies (PRIMA) showed poorer outcome in those with high risk disease in terms of lower CR rate, higher risk of relapse and lower efficacy of maintenance therapy. Data comparing up-front intensive approach in younger fit patients and R-CHOP are limited. Aim To analyze long term results of intensive treatment protocol (R-sequential chemotherapy) in comparison with age, FLIPI and maintenance delivery matched (R-CHOP) controls. Methods Here we analyzed data of 48 prospectively enrolled FL patients who were treated by sequential (R-SQ) chemotherapy with or without up-front autologous stem cell transplant (ASCT) as a part of stratified risk adapted treatment in one institution. For R-SQ regimen were indicated patients3mg/L and/or thymidine kinase〉15 IU/L) or HIGH-FLIPI patients (irrespective of additional risk factors). R-SQ protocol consists of alternating three cycles of etoposide-doxorubicine regimen (PACEBO), one methotrexate-ifosfamide regimen (IVAM), and one cycle of high dose cytarabine regimen (HAM). Remission was consolidated with 6th cycle of chemotherapy (PACEBO) in INT-FLIPI patients (n=22, 46%) or with ASCT with BEAM-200 conditioning (n=26, 54%) in HIGH-FLIPI patients. Maintenance immunotherapy was applied for historical reasons in 24 patients (50%). Controls were randomly selected from the Czech Lymphoma Study Group (CLSG) database from 626 cases with confirmed FL grade I to IIIa, treated with R-CHOP. Pair matching was performed on 1:3 basis, controls were matched by age, FLIPI and rituximab maintenance application. In the end, we analyzed intensive SQ-group (n=44) and standard control R-CHOP-group (n=144). Maintenance therapy was delivered to 24 patients (50%) in R-SQ group and to 72 patients (50%) in R-CHOP-group (P=1.00). Results Median age of SQ-group was 47.6 years compared to 48.7 years in R-CHOP (P=0.44), FLIPI index was equally distributed: INT-FLIPI (43% vs 43%), HIGH-FLIPI (57% vs 57%, P=1.00). Treatment response quality was higher in SQ-group than in R-CHOP-group: CR/CRu 93.8% vs 70%, PR 6.2% vs 23% and SD/PD 0% vs 8% respectively (P=0.01). During the follow-up, (median 3.5 and 6.1 years in R-CHOP and SQ-group respectively, P

Description: Introduction Localized stages of follicular lymphoma (I-II) have been traditionally treated with involved field radiotherapy (IF-RT), which seems to be able to cure a significant proportion of patients. On the other hand, nearly half of patients relapse within 10 years. The late distant relapses remain the problem. Rituximab (anti CD20 antibody) is low-toxic, efficient systemic therapy for follicular lymphoma (FL). In vitro models bring the evidence of significant synergism between rituximab and radiotherapy. Up to now, there are no clinical data about clinical benefit of rituximab addition to the IF-RT. This study compares IF-RT alone vs. IF-RT with rituximab in early-stages of FL. Methods Between 2005-2012, through the prospectively maintained multicentric database (Czech Lymphoma Group; CLG), we identified patients with stage I-II FL treated with IF-RT (dose ≥ 24Gy) or IF-RT (dose ≥ 24Gy) with rituximab or rituximab alone. Patients receiving IF-RT with chemotherapy were not included. Complete staging including CT (neck, thorax, abdomen and pelvis) and bone marrow biopsy was performed at diagnosis. We compared EFS and OS between these three treatment arms. Rituximab (4 doses á 375mg/m2) was administered prior start of radiotherapy in combined arm. The total doses of rituximab varied between 4-8 doses á 375mg/m2 in rituximab monotherapy subgroup as well as in combined arm. Response to treatment was evaluated with CT 6-12 weeks after last dose of therapy. Results For the study period, approximately 1700 pts. of FL were identified in CLG database; 101pts with stage I-II FL (grade 1-3A) were included in the analysis. 65 patient were treated with radiotherapy alone (RT), 14 pts. with rituximab alone (R) and 14 pts. received rituximab and radiotherapy (R+RT), 8 pts. were excluded because of incomplete data. Median follow up was 4.57 (2.25- 12.6) years since diagnosis. There were no differences of age, performance status, FLIPI, proportion of bulky or extranodal tumor. In subgroup treated with R+RT was higher proportion of FL grade 3A in comparison with R or RT alone arms (35% vs. 1.5% vs. 7.5%; p.007). Complete response rate was 92% in RT arm, 100% in arm with R+RT and 86% in group treated with R alone, difference did not reach statistical significance. Median of event free survival was 3.35years in RT group, not reached in R+RT arm and 5.1 years in patients treated with R alone. EFS differences are statistically significant (p.035), but with no impact on overall survival. Conclusions In spite of fact, that RT is considered to be a good initial treatment for localized FL, rituximab alone or better in combination with RT seems to give better results in terms of long-term global control of disease. Our preliminary results should be confirmed with other studies and longer follow up is needed to verify or not the impact of rituximab on survival in early stages of FL. The work is support by research grant NT/12193-5 and MHCZ-DRO FNBr65269705. Disclosures: Mayer: Roche: Consultancy, Research Funding; Glaxo: Consultancy, Research Funding. Trneny:Roche: Honoraria, Research Funding.

Description: Background: The outcome of DLBCL patients is improving, it however seems to be very poor for those who are refractory to the therapy. We have decided to analyze this group of patients. Methodology: As part of an observational clinical study NiHiL (GovTrial No NCT03199066) we identified the patients treated in the first line by R-CHOP like immunochemotherapy who met at least one criterium: 1. refractory (stable disease - SD or progression) on 1st line therapy (1st l- R), 2. refractory (SD or progression) on salvage (platinum based regimen) (Salv-R), 3. refractory to or relapse/progression within 12 months after ASCT (ASCT-R/R). There were 210 patients diagnosed in the period 2001-2017 who fulfilled the criteria. Progression-free survival (PSF) and overall survival (OS) were estimated from the time of determination of a refractory disease. Results: The cohort consisted of 163 patients primarily resistant to the first-line therapy, 31 patients were resistant to the salvage therapy and 16 patients progressed within 12 months after ASCT . At the time of the diagnosis, the median age was 65 years (22-91) (the same as at the refractory disease), 54% were males, 74% had advanced clinical stage (III+IV), 68% had IPI 〉3, 77% had above-normal LDH, and 45% had a tumor mass 〉10cm. The OS from the time of determination of refractory disease was 0.53 years, median PFS was 0.29 years. Patients under 65 years had median survival 0.8 years compared to 0.4 years in the group of patients above 65 years of age. The median PFS for 1st l-R, Salv-R and ASCT-R/R resp. was 0.3, 0.26 and 0.35 years resp. and 5y survival 22%, 0% and 6% resp. The median OS for 1st l-R, Salv-R and ASCT-R/R resp. was 0.55, 0.39 and 0.65 y resp. and 5y survival was 28%, 0% and 13% resp. Our results demonstrate that resistant DLBCL has an extremely poor prognosis, clearly new effective therapeutic strategies such as CAR-based therapies or others are required. This work was supported by a research program Progres Q28-9. Disclosures Belada: Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.