ALBERT

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: Introduction: Mantle cell lymphoma (MCL) is considered to be an incurable disease with a poor prognosis, but the prognosis can be significantly different among the patients. The new prognostic index MIPI (MCL International Prognostic Index) has been proposed recently (Hoster ASH 2006, Blood 2008). Three prognostic groups with different survival (low-risk, intermediate-risk and high-risk) can been identified, based on four variables: WBC count, ECOG performance status, LDH and age. Aim: To validate MIPI on an independent unselected cohort of newly diagnosed patients with MCL in the Czech Lymphoma Study Group (CLSG) registry. Methods and patients: Out of 293 patients with MCL diagnosed and registered in the period 1999–2007, 149 patients had central pathology review and confirmation of MCL diagnosis and were eligible for the analysis. The age median was 65 year (24–86), 63% were male (M:F ratio 1,7:1). Most of patients were diagnosed in advanced Ann Arbor stage IV (82%), limited stages I+II formed only 10,5%. The bone marrow was involved in 75% of cases. B-symptoms were present in 45% patients, LDH level elevated in 51%, poor performance status (ECOG 2–4) in 21% and the median leukocyte count was 7,9 ×109/L. A chemotherapy was used as a first line treatment in 144 patients, the combination with rituximab (R) in 106 ones (73%). The most used regimens were hyperCVAD/MTX-HDaraC (30x), R-CHOP (30x), CHOP (19x), R-FC (13x), then R-maxiCHOP/HDaraC (12x), R-CHOP/HDaraC (9x), COP (8x) and others. A consolidation of the first remission with high-dose chemotherapy and autologous stem cell transplantation was used in 12 patients, and an allogeneic transplantation in 2 patients. A first-line radiotherapy was used in 14 patients. Median follow-up is 31 months. Results: Median overall survival (OS) in the whole group of confirmed MCL patients was 58 months, median progression-free survival (PFS) was 24 months. The MIPI index can be calculated for 148 patients, 28% of them belong to low-risk (LR), 35% to intermediate-risk (IR) and 37% to high risk (HR) group. All clinical stages were included. Our comparison of survival curves according to MIPI risk groups confirms a different prognosis – the median OS in the LR group was not reached, in the IR group is the median OS 58 months, and in the HR group 25 months (p 〈 0,0001). The 3-year OS probability for LR, IR and HR group is 82%, 62% and 31%, resp. Similarly, median PFS in the LR, IR and HR group is 45, 24 and 13 months, resp. (p 〈 0,0001). The analysis of rituximab-treated subgroup was performed as well, with a significant difference between the three groups regarding to OS and PFS. The 3y OS probability for LR, IR and HR group is 82%, 63% and 37%, the median OS for LR and IR was not reached, for HR is 31 months (p

Description: The optimal schedule of G-CSF given after autologous peripheral stem cell transplantation (ASCT) has not been defined yet. Here we present results of the third interim analysis of randomized multicentre trial comparing standard application of G-CSF from day +5 (arm A) with delayed dosing (G-CSF was started when WBC reached 0,5x109/l and neutrophil count 0,1x109/l; arm B) and placebo (arm C). In order to eliminate the influence of diagnosis and conditioning and to minimize the impact of graft quality only patients with malignant lymphoma conditioned by BEAM and with graft harvested in maximum 3 aphereses containing at least 5,0x106 CD 34+cells/kg were included. Patients signed informed consent before registration into the study that had been approved by local ethical and national health care authorities. 115 patients at median age 45 (range 21 – 64) were randomized by July 15th, 2004. The data of 97 patients were analysed. There was no difference in age, lymphoma bone marrow involvement at diagnosis, number of chemotherapy cycles and the use of radiotherapy before transplantation and CD 34+ cells content in graft between any two of the three arms. Duration of neutropenia below 0,5x109/l and 1,0x109/l and number of days to neutrophil engraftment over 0,5x109/l and 1,0x109/l are listed in the table. A significant difference in duration of neutropenia and time to neutrophil engraftment was found between the arms A and B (p=0,002 – 0,005), the arms A and C (p20x109/l (day +) 12 (2–33)* 12 (7–30)* 11 (7–24)* Platelet engraftment 〉50x109/l (day +) 17,5 (8–100)* 16,5 (9–115)* 13 (8–32)*

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: Background Waldenström's macroglobulinemia (WM) is a rare B-cell neoplasm defined as lymphoplasmacytic lymphoma with bone marrow infiltration and monoclonal IgM in the serum. More than 90% of WM patients carry a point mutation L265P in the MYD88 gene and concurrently, almost one third of MYD88L265P-positive patients harbor frameshift (WHIM-FS) or non-sense (WHIM-NS) mutation in gene CXCR4. The mutations in CXCR4 result in premature stop codons and in shortening of CXCR4 protein product. Incomplete C-terminal domain of CXCR4 chemokine receptor is known to hyperactivate CXCR4-mediated signalization. The presence and type of mutation in genes MYD88 and CXCR4 appears to be significant in diagnostics and prognostic stratification of WM patients and it also influences the clinical manifestation of the disease. Aims To analyze mutational status of MYD88 and CXCR4 genes in patients with WM, to compare our results with laboratory parameters and to evaluate the prognostic stratification of the patients according to MYD88 and CXCR4 mutational status. Methods Analyzed DNA was isolated from mononuclear fraction of bone marrow or peripheral blood cells at the time of diagnosis. Mutational status of analyzed genes was determined using allele-specific PCR (in the case of MYD88) and using direct Sanger sequencing (in the case of CXCR4). All found mutations were confirmed by specific cleavage with restriction endonucleases at defined conditions. Results We analyzed 23 patients with WM. All patients were MYD88L265P-positive (100 %), and 7 of them (30,4%) were also CXCR4 mutants (1 patient harbored WHIM-FS mutation and 6 harbored WHIM-NS mutation). CXCR4 mutations were associated with more aggressive disease: higher ISSWM score (low 0/intermediate 1/ high 6 risk), anemia (7/7), hyperviscosity syndrome (2/7) at time of diagnosis. CXCR4WHIM-WT patients were often asymptomatic (5/16) with lower ISSWM score (low 5/intermediate 5/ high 6 risk) but with common adenopathy (11/16). CXCR4 mutations were also associated with worse treatment response (2 CXCR4WHIM-MUT patients were refractory to initial therapy and needed 2nd line treatment, 3 patients had only partial response to first-line therapy, one patient died after 2nd cycle due to abdominal septic complication and only one patient reached VGPR). Progression-free survival in treated patients was 32 vs. 8 months in CXCR4 mutants. Conclusion/summary The mutational analysis of MYD88 and CXCR4 genes is essential for the diagnostics and prognostic stratification of patients with WM and it allows a deeper understanding of the molecular pathogenesis of the diseases. CXCR4 mutations were found in nearly one third of WM patients. In accordance with published data, we confirmed that CXCR4 mutations are associated with more aggressive disease presentation and thus affect treatment outcome. On the contrary CXCR4WHIM-WT patients have more indolent course of the disease. This work was supported by grant IGA-LF-2018-004 and MH CR - RVO (FNOL, 00098892). Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Mantle cell lymphoma (MCL) is rare B-cell lymphoma subtype with usually aggressive behavior. Mutations of TP53 gene and complex karyotype (CK) were described to be poor prognostic factors (Obr A et al, 2018), but their impact on primary resistance to induction has not been investigated. Methods: We analyzed 115 MCL patients (pts) treated in two Czech university centers from 4/2006 to 10/2016. Both classical cytogenetics and next generation sequencing (NGS, MiSeq, Illumina) for TP53 mutation detection were performed on tumoral tissue (peripheral blood, bone marrow) in all patients. Cut-off for TP53 mutation was 1% variant allele frequency (VAF). CK was defined as 3 and more cytogenetic aberrations in one cell population. Pts with stable or progressive disease (SD/PD) during induction or with relapse within 6 months after induction completion were considered as primary refractory (PrR). Variables were compared by chi-squared test. T-test was used to compare the difference between means of TP53 mutation load in PrR+ and PrR- subgroup. Cut-off for TP53 mutation load (27%) was established as median VAF. Overall and progression free survival (OS, PFS) were calculated from the date of diagnosis. Results: The median age at diagnosis was 66 (40-87) years. Ninety-six percent of pts had advanced disease (III and IV). MIPI score was low, intermediate and high in 19.1%, 27.8% and 53.0% pts, respectively. Induction regimens used were as follows: R-CHOP/R-CHOP-like in 47.8%, intensive R-HDAC-containing in 38.3% and non-anthracycline regimen in 9.6% pts. Complete and partial response was achieved in 53.0% and 27.0% pts, resp. SD/PD was observed in 11.3% pts. Overall, 27 (23.5%) pts were considered as primary refractory. TP53 mutation and CK were present in 37 (32.3%) and 15 (13.0%) pts, respectively. Age, disease stage, ECOG score, MIPI, HDAC therapy and CK did not correlate with PrR status. Significantly higher TP53 mutation load was observed in the PrR+ (42%), compared to PrR- subgroup (25%, p=0.03). After median follow-up of 4.6 years, 3-year overall survival (3-y OS) and 3-year progression free survival (3-y PFS) in all pts was 65.8% and 50.9%, resp. Median OS in PrR+ and PrR- pts was 9.2 months, and 4.5 years, resp. Survival analysis stratified according to the TP53 mutation status/mutation load showed 3-y OS and 3-y PFS for wild type (TP53-WT), low mutation load (TP53-low load), high mutation load (TP53-high load) 74.2%, 47.6%, 33.3% and 56.0%, 37.0%, 27.8%, respectively (p=0.001 both). Conclusions: High TP53 mutation load (〉27% VAF), but not CK, has significantly correlated with refractory disease in MCL pts. Pts with high mutation load of TP53 gene should be considered to an innovative treatment. Acknowledgement: Supported by IGA_LF_2019_001, MH CZ - DRO (FNOl, 00098892), AZV16-32339A and AZV16-31092A grants Figure Disclosures Trneny: Morphosys: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Gilead sciences: Consultancy, Honoraria; Takeda: Consultancy, Honoraria.

Description: Background: Frontline therapy of Hodgkin lymphoma (HL) is strictly stage-adapted. Staging systems used are based on historical variables which only indirectly reflects tumor load (Ann Arbor stage) or lymphoma cytokine activity (systemic symptoms, erytrocyte sedimentation rate). With new, abbreviated interim PET-tailored chemotherapy schemes (2+2) and reduced radiotherapy protocols, there is a clinical need for precise staging tools. Last years have brought new insight into the prognostic role of metabolic quantitative PET parameters and HL-associated biomarkers. Total metabolic tumor volume (TMTV) measured using fluoro-deoxyglucose PET (FDG-PET) was found to be a predictor of therapy failure after frontline treatment (Kanoun 2014). Interestingly, TMTV was found capable of identifying poor responders within one (intermediate) staging group (Akhtari, 2018; Cottereau 2018). Serum concentrations of thymus and activation-regulated chemokine (TARC) and other cytokines have been proved to have prognostic significance in the patients treated both in the frontline and relapse setting (Moskowitz, 2015; Guidetti 2017). A relationship between pretreatment TMTV, baseline cytokines levels, and current staging systems has not been analyzed yet. Aim: To analyzed quantitative metabolic PET parameters and selected soluble biomarkers in the context of the staging systems used in the U.S. and Europe Methods: We have analyzed a prospectively enrolled cohort of forty-eight patients with HL who were diagnosed in two large university medical centers from 5/2015 to 2/2018. All pts have undergone pretreatment FDG-PET/CT with quantitative analysis of TMTV, Total Lesion Glycolysis (TLG), Maximum Standardized Uptake Volume (SUVmax.) and the Largest Tumor Diameter (LD) and were sampled for cytokine analysis within 16 (median) days from the PET/CT. We have analyzed a set of four serum biomarkers: CD30 (sCD30), CD163 (sCD163), TARC, and interleukin 6 (sIL6), which were measured using ELISA assays. Results: A cohort consisted of 22 males and 26 females with median age of 42 years (range 21-75). Histology subtype was known in all but one case: nodular sclerosis in 23, mixed cellularity 15, lymphocyte-rich in 5 and nodular-lymphocyte predominant (NLPHL) in four. Ann Arbor stages were as follows: I in 5, II in 20, III in 13 and IV in 10 of the pts with systemic symptoms in 20 (42%) of them. All pts were classified according to the German Hodgkin Study Group (GHSG) and NCCN staging systems. GHSG stages - limited, intermediate and advanced were seen in 8 (17%), 10 (21%) and 30 (62%) pts, respectively. NCCN stages were distributed into early favorable in 8 (17%), early unfavorable in 17 (35%) and advanced in 23 (48%) of the pts. Chemotherapy was applied in all but four pts using: BEACOPPesc, combined BEACOPP+ABVD, ABVD and ABV/COPP protocols in 7, 15, 16 and six pts respectively. Of four pts without chemo one case was treated with local radiotherapy and three with WaW (all of them with NLPHL). Treatment response was known in 41 (85%) of the cases with CR, PR, and PD in 33 (80.5%), 6 (14.6%) and two (4.9%) pts, respectively. Relationships between disease stages and PET-parameters are summarized in Table 1. Briefly, metabolic tumor burden (TMTV, TLG) identified two markedly different groups: low and intermediate/high risk. Similarly, cytokines levels were significantly lower in low-risk patients compared to those with intermediate-high risk (Table 2). Treatment outcome did not correlate either with GHSG nor NCCN stage. We found correlation of sIL-6 (p=0.03) but not sCD30 (p=0.09), sCD163 (p=0.14) and TARC (p=0.57) with CR achievement. In terms of PET-parameters the high TMTV〉104 cm3 (P=0.046) and TLG〉798 (P=0.003) were associated with not achieving of CR with NPV, PPV and test accuracy of 94.4, 22.0, 58.5 for TMTV and 100%, 36,4%, 66% for TLG, respectively. Conclusion: Adequate frontline treatment policy is vital for achieving an optimal balance between efficacy and toxicity. Current staging systems have a weak correlation with metabolic tumor burden: one-third of those recognized as advanced stage have the low burden, and vice versa about a half of intermediate-risk pts have high tumor burden. Combination of TMTV/TLG and cytokines can be currently used for decision making in borderline stage cases and probably could serve as a backbone for a new staging system in the future. Acknowledgment: IGA_LF_2018_004, MH CZ-DRO (FNOL, 00098892) Disclosures No relevant conflicts of interest to declare.

Description: Background: Early events within 24 months (POD24) of initial immunochemotherapy (IC) were repeatedly confirmed to be associated with poor survival in follicular lymphoma (FL). Rituximab maintenance (RM) given to responding patients after IC is effective strategy to reduce relapse incidence and improve survival (Salles, Lancet 2011; Hill, BJH 2019). There is little known about the POD24 incidence pattern in chemosensitive patients, and the impact of subsequent RM application for POD24 reduction has not been studied yet. Aim: To (1) analyze the role of POD24 events in patients with responding FL and (2) describe whether post-induction RM changes the pattern of POD24 incidence and possibly post-POD24 outcome of the patients. Methods: The study comprised patients prospectively enrolled in the Czech Lymphoma Study Group network (ClinicalTrials.gov: NCT03199066) in 2000-2015, with grade 1-3A FL and treated with frontline R-CHOP/R-CHOP-like or R-bendamustine or R-CVP IC. Cases with previous WaW were not enrolled. No frontline stem cell (auto/allo) transplant was allowed. Only patients who achieved complete (CR/CRu) or partial remission (PR) at the end of induction (EOI) and were thus potential candidates for RM were included. Early event was defined as progression, relapse or death within 24 months after the date of EOI response assessment. Overall (OS) and progression-free survival (PFS) were calculated from the date of diagnosis and date of EOI response (OS-EOI). Patients who experienced an event before the median time to RM initiation were excluded from POD24 survival analyses to avoid overestimation of the RM group results. Results: A total of 1089 patients were identified, of whom 729 (67%) received RM (maintenance group) and 360 (33%) were followed without RM (observation group; OBS). When comparing both groups, we found no differences in age (median age 59 yrs for both; P=0.54), sex distribution (males 39% vs. 41% in OBS vs. RM, respectively; P=0.37) and ECOG 0-1 (90% vs. 93% in OBS vs. RM; P=0.10). There was a slightly lower proportion of advanced FL (Ann Arbor III-IV) in OBS (80%) as compared to RM (87%, P=0.01), which translated into a lower proportion of high FLIPI patients (46% vs. 52% in OBS vs. RM, respectively; P=0.003). The induction regimens were as follows: R-CHOP in 70% and 83%, R-COP in 18.6% and 10.7%, R-bendamustine 1% and 4%, R-fludarabine-based in 4% and 1% and others in 5% and 1% in RM and OBS, respectively. The EOI remission status was assessed 61 days (median) after the last IC dose with CR/CRu/PR rates of 65%/9%/26% and 65%/6%/29% in OBS and RM, respectively (P=0.14). The median time from EOI response to the first RM dose was 48 days (range 0-371 days), 89% of the pts have started RM within 120 days. The median number of RM doses given was 8 (range, 1-36), with 85% of patients receiving 8-12 doses of RM. After a median follow-up of 10.4 yrs (OBS) vs. 6.0 yrs (RM); P