Abstract: BACKGROUND: Short telomere length has been described in CLL as independent adverse prognostic factor in multivariate analyses of several single centre series and clinical trial cohorts. However, the clinical impact of short telomeres has not been studied in the context of allogeneic stem cell transplantation (allo-SCT) in CLL. METHODS: Here, we studied telomere length, its associations and impact on outcome in the multicentre CLL3X trial evaluating efficacy of allo-SCT after reduced intensity conditioning in patients with poor-risk CLL (Table 1). Telomere length was analyzed using quantitative PCR on DNA from peripheral blood mononuclear cells (PBMCs) of 69 patients and this cohort was representative of the full trial population. The technique was validated using terminal restriction fragment length analysis (TRF) (R2=0.859, P 〈 0.001) in an independent control sample set (n=18) and 6 of these samples were included in every batch as controls. RESULTS: Telomere length in the CLL3X cohort was found to be highly variable (1.9 kb – 21 kb). Correlation of telomere length with disease characteristics was performed by defining short and long telomere subgroups, based on median telomere length (median=5.35kb). In contrast to several reports on untreated CLL cohorts, telomere length showed no significant associations with age (P=0.400), sex (P=0.306), presence of high leukocyte count (P=0.765), ECOG status (P=1.000), and prior resistance to fludarabine-based therapy (P=0.955) or other clinical characteristics. Analysis of telomere length association with genetic characteristics showed a trend towards association with del(17p) (P=0.088) while no association was observed with del(11q) (P=0.834), 12q trisomy (P=0.650), normal karyotype (P=0.450) and del(13q) (P=0.792). Also, no association of telomere length with mutations of TP53 (P=0.280), NOTCH1 (P=0.2470) and SF3B1 (P=0.819) was observed. With a median observation time of 6 years, analysis of the impact of telomere length below the median on outcome showed no significant association with non-relapse mortality (HR 2.11, P=0.199), event-free survival (EFS) (HR=1.22, P=0.53, Fig.1a) and time to relapse (HR=0.92, P=0.82). Nevertheless, patients with short telomere length tended to have inferior overall survival (OS) (HR=2.04, 95%CI 0.92 - 4.5, P=0.079, Fig. 1b). The OS benefit associated with long telomeres could be largely explained by superior survival after relapse in this subset (HR=3.04, 95%CI 0.96 - 9.57, P=0.058) indicative of better efficacy of salvage treatment. CONCLUSION: In contrast to several reports on treatment naïve CLL cohorts, telomere length in the poor-risk patient selection of the CLL3X trial was not significantly associated with any known clinical and genetic baseline disease characteristics. While EFS was unaffected by telomere length, short telomeres were associated with poor OS, largely due to inferior survival after CLL relapse, suggesting that rescue treatment after post-transplant disease recurrence was less effective in the presence of short telomeres. Table 1: Patient Characteristics N % Unmutated IGHV 60/65 92.3 Presence of 11q or 17p- 38/64 59.4 Fludarabine refractory 30/45 66.7 Early relapse 26/63 41.3 Previous regimens 〉 1 (Mean = 4 regimens/patient) 57/63 90.5 Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract: The objective of this trial was to evaluate safety and efficacy of bendamustine combined with rituximab (BR) in patients with relapsed and/or refractory chronic lymphocytic leukemia (CLL). Patients and Methods Seventy-eight patients, including 22 patients with fludarabine-refractory disease (28.2%) and 14 patients (17.9%) with deletion of 17p, received BR chemoimmunotherapy. Bendamustine was administered at a dose of 70 mg/m 2 on days 1 and 2 combined with rituximab 375 mg/m 2 on day 0 of the first course and 500 mg/m 2 on day 1 during subsequent courses for up to six courses. Results On the basis of intent-to-treat analysis, the overall response rate was 59.0% (95% CI, 47.3% to 70.0%). Complete response, partial response, and nodular partial response were achieved in 9.0%, 47.4%, and 2.6% of patients, respectively. Overall response rate was 45.5% in fludarabine-refractory patients and 60.5% in fludarabine-sensitive patients. Among genetic subgroups, 92.3% of patients with del(11q), 100% with trisomy 12, 7.1% with del(17p), and 58.7% with unmutated IGHV status responded to treatment. After a median follow-up time of 24 months, the median event-free survival was 14.7 months. Severe infections occurred in 12.8% of patients. Grade 3 or 4 neutropenia, thrombocytopenia, and anemia were documented in 23.1%, 28.2%, and 16.6% of patients, respectively. Conclusion Chemoimmunotherapy with BR is effective and safe in patients with relapsed CLL and has notable activity in fludarabine-refractory disease. Major but tolerable toxicities were myelosuppression and infections. These promising results encouraged us to initiate a further phase II trial evaluating the BR regimen in patients with previously untreated CLL.

Abstract: Introduction FCR is the current standard first line treatment regimen in advanced CLL (Hallek et al., Lancet, 2010), but is associated with significant side effects. The GCCLSG initiated an international phase III study in order to test the non-inferiority regarding efficacy and potentially better tolerability of BR compared to FCR in first-line therapy of physically fit pts without del(17p). Methods and Patients 688 CLL pts from 158 sites in five countries (Germany, Austria, Switzerland, Denmark and Czech Republic) were screened centrally for immunophenotype, genomic aberrations by FISH, IGHV sequenzing, comorbidity burden and renal function. 564 CLL pts with CIRS score ≤ 6, creatinine clearance 〉 70 ml/min and without del(17p) were enrolled between October 2008 and June 2011. Pts were randomly assigned to receive 6 courses of either FCR (N= 284; F 25mg/m2 i.v. d1–3, C 250 mg/m2 i.v. d1–3, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent courses; q 28 days) or BR (N=280; B 90mg/m2 i.v. d1+2, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent courses; q 28 days). The intent-to-treat population consisted of 561 pts, because three patients were excluded due to deferred treatment (1 pt decision, 1 treatment before randomization, 1 misdiagnosis). 22 % were Binet A, 38 % Binet B and 40 % Binet C. The median age was 62 years (yrs) (range 33 to 82), median CIRS score 2 (range 0-6). There were significantly more pts with unmutated IGVH in the BR arm (68%) in comparison to the FCR arm (55%; p=0.003). All other characteristics including median age were well balanced. A mean number of 5.27 courses was given in the FCR arm versus 5.41 courses in the BR arm (p=0.022). 70.6% (FCR) and 80.3% (BR) of pts received 6 courses (p=0.008). Dose was reduced by more than 10% in 27.3% (FCR) and 31.6% (BR) of all courses given (p = 0.012). Results The median observation time was 27.9 months (mo) in all pts alive. While response evaluation was missing in 14 pts, 547 pts (274 FCR; BR 273) were evaluable for response and all 561 pts (282 FCR; 279 BR) for progression-free survival (PFS), event-free survival (EFS) and OS. The overall response rate was identical in both arms with 97.8% (p=1.0). The complete response rate (CRR) (confirmed by central immunhistology) with FCR was 47.4% as compared to 38.1% with BR (p=0.031). MRD data were available at interim analysis from 192 pts (99 FCR; 93 BR) of the first 300pts. 71.7% of pts in the FCR and 66.7% in the BR arms achieved MRD-levels below 10-4 in peripheral blood at final staging (p=0.448). The complete MRD data set will be available by November. PFS was 85.0% at 2 yrs in the FCR arm and 78.2% in the BR arm (p=0.041). EFS was 82.6% at 2 yrs in the FCR arm and 75.7% in the BR arm (p=0.037).There was no difference in OS rate for the FCR vs BR arm (94.2% vs 95.8% at 2 years p=0.593). Hazard Ratio for PFS, EFS and OS was 1.385, 1.375 and 0.842 respectively. PFS was assessed in pts 〈 65 yrs and ≥ 65 yrs. While there was a significant difference in pts 〈 65 yrs between both treatment arm (median PFS for BR 36.5 mo vs not reached for FCR; p=0.016), the difference disappeared in elderly pts (not reached vs. 45.6 mo; p=0.757). A multivariate analysis including treatment arm, Binet stage, age, sex, comorbidity, serum TK, serum beta2-microglobulin (Beta2M), del(11q) and IGHV status identified treatment arm, Beta2M, del(11q) and IGHV as independent prognostic factors for PFS and EFS. FCR treated pts had significantly more frequent severe, CTC grade 3 to 5, adverse events during the whole observation period (90.8% vs 78.5%; p 〈 0.001). Especially severe hematotoxicity was more frequent in the FCR arm (90.0% vs 66.9%, p 〈 0.001). The higher rate of severe neutropenia (81.7% vs 56.8%, p 〈 0.001) resulted in a significantly higher rate of severe infections (39.0% vs 25.4%, p=0.001) in the FCR arm, especially in the elderly (FCR: 47.4% vs BR: 26.5%; p=0.002). Treatment related mortality occurred in 3.9% (n=11) in the FCR and 2.1% (n=6) in the BR arm. Conclusion The results of this planned interim analysis show that FCR seems more efficient than BR in the first-line treatment of fit CLL pts with regard to higher CRR, as well as longer PFS and EFS. These advantages might be balanced by a higher rate of severe adverse events, in particular neutropenia and infections, associated with FCR. In light of these results, no firm recommendation of one regimen over the other can be given at the present time regarding the first-line use in CLL pts with good physical fitness. Disclosures: Eichhorst: Roche: Consultancy, Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding. Gregor:Roche: Consultancy, Honoraria, Travel Support Other; Mundipharma: Travel Support, Travel Support Other. Plesner:Mundipharma: Research Funding. Trneny:Roche: Honoraria, Research Funding. Fischer:Roche: Travel grants Other; Mundipharma: Travel grants, Travel grants Other. Kneba:Roche: Consultancy, Research Funding. Wendtner:Roche: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding. Kreuzer:Roche: Honoraria; Mundipharma: Honoraria. Stilgenbauer:Roche: Consultancy, Research Funding, Travel grants Other; Mundipharma: Consultancy, Research Funding. Böttcher:Roche: Honoraria, Research Funding. Hallek:Janssen: Research Funding; Gilead: Research Funding; Roche: Research Funding.

Abstract: Introduction: Bendamustine has shown considerable activity in monotherapy for solid and lymphoid malignancies including CLL and has been used for more than 30 years in anti-cancer treatment. In vitro and ex vivo studies have demonstrated synergistic pro-apoptotic effects of bendamustine and the CD20 antibody rituximab (BR) in primary B-CLL cells. Encouraging clinical results have been obtained using BR combination treatment in relapsed/refractory NHL or mantle cell lymphoma. The present phase II trial represents the first study assessing efficacy and toxicity of bendamustine in combination with rituximab in pts with relapsed/refractory B-CLL. Patients and Methods: Between March 2006 and June 2007 81 pts with relapsed/refractory B-CLL and a median number of 2 pretreatments were enrolled into this trial. Bendamustine was given at a dose of 70 mg/m2 on day 1 and 2, combined with 375mg/m2 rituximab for the first cycle and 500 mg/m2 for the second and subsequent cycles. BR treatment was administered every 28 days up to 6 courses. Blood samples were taken for molecular cytogenetics by fluorescence in situ hybridization (FISH), analysis of the IgVH mutational status and expression of ZAP70/CD38. Assessment of minimal residual disease (MRD) was evaluated in peripheral blood and bone marrow by 4-colour flow cytometry. Results: So far data of 31 pts (median age 66 years) with a total of 126 treatment cycles are available for analysis. There was notable toxicity with 48 reported CTC grade 3/4 adverse events, particularly myelosuppression and infections: grade 3/4 anemia occurred in 6.3.%, leukopenia/neutropenia in 10.8% and thrombocytopenia in 11.9% of all courses. 6 episodes of CTC grade 3/4 infections were documented: 1 sinusitis maxillaris, 1 FUO and 1 abscess, all of them being reversible after antibiotics. However, 3 pts died due to severe infections including 2 fatal pneumonias and 1 urosepsis. One pt died due to myocardial infarction. Regarding efficacy, 23 pts were evaluable for response: The overall response rate (ORR) was 65.2% with a CR rate of 13.0% (3 pts) and a PR rate of 52.2% (12 pts). No molecular remission was observed by 4-colour cytometry. Stable disease (SD) was achieved in 26.1% (6 pts) whereas 2 pts had progressive CLL (PD, 8.7%). Responses were observed in the majority of pts with genomic aberrations 11q deletion (ORR: 4/5) and trisomy 12 (ORR: 2/3), while none of the pts with 17p deletion (ORR: 0/4) was responsive (P=0.006). Conclusion: Bendamustine plus rituximab is an effective regimen in refractory/relapsed B-CLL. Major treatment toxicities were myelosuppression and infections. Updated data with respect to toxicity and efficacy based on the entire study population will be available for the Meeting.

Abstract: Introduction: For physically fit CLL pts with low comorbidity burden FCR is the standard frontline regimen in advanced CLL. The CLL10 study, an international phase III study evaluated the efficacy and tolerance of BR in comparison to FCR in frontline therapy of fit pts without del(17p). Methods and Patients: 158 sites in five countries (Germany, Austria, Switzerland, Denmark and Czech Republic) registered 688 CLL pts for central screening including immunophenotyping, FISH, comorbidity burden and renal function. 564 CLL pts with CIRS score ≤ 6, creatinine clearance 〉 70 ml/min and without del(17p) were enrolled between 10/2008 and 6/2011. Pts were randomly assigned 1:1 to receive 6 courses of FCR (N= 284; F 25mg/m2 i.v. d1–3, C 250 mg/m2 i.v. d1–3, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent cycles; q 28 days) or BR (N=280; B 90mg/m² i.v. d1+2, R 375 mg/m2 i.v. d 0 at first cycle and 500 mg/m2 d1 all subsequent cycles; q 28 days). A general prophylactic use of antibiotics or growth factors was not recommended. Three patients (2 FCR, 1 BR) were excluded because of deferred treatment. The median CIRS score was 2. There was no difference in median age (61.6 years (yrs) for all pts), but a significantly higher proportion of pts ≥ 70 yrs was included in the BR arm (22% vs 14%, p=0.020). Binet A was present in 22%, Binet B in 38 % and Binet C in 40 %. Unmutated IGHV status was not balanced between both groups (68% in BR versus 55% in FCR arm; p=0.003). All other characteristics showed no differences. The mean number of administered FCR courses was 5.27 courses vs 5.41 BR course (p=0.017). Results: The median observation time for all patients was 35.9 months (mo). 547 pts (FCR 274 ; BR 273) were evaluable for response and all pts (282 FCR ; 279 BR) included for progression-free survival (PFS) and overall survival (OS) analysis. The overall response rate in both arms was 97.8% (p=1.0). The complete response (CR) rate according to IWCLL and confirmed by central bone marrow immunohistology was 40.7% with FCR compared to 31.5% with BR (p=0.026). Four-colour-flow MRD data from peripheral blood (sensitivity 10-4) were available from 355 pts (185 FCR; 170 BR) at final staging. In the FCR arm 74.1% and 62.9% in the BR arm respectively of all evaluated pts were MRD negative (p=0.024). Bone marrow samples, available in 129 FCR and 98 BR pts, were MRD negative in 58.1% and 31.6% of pts, respectively (p 〈 0.001). At 12 mo follow-up 58.2% of the pts in the FCR arm (46/79) were still MRD negative in comparison to 26.3% (20/76) after BR (p 〈 0.001). At 18 mo there were 53.8% (35/65) MRD negative cases versus 24.6% (16/65; p=0.006). Median PFS was 53.7 mo in the FCR arm and 43.2 mo in the BR arm (HR=1.589, 95% CI 1.25-2.079; p=0.001). While PFS was statistically not significant different between both arm in pts with mutated IGHV, pts with unmutated IGHV status had a median time to progression of 43.9 mo after FCR compared to 34.0 mo after BR (p=0.015). Physically fit subgroups (CIRS max 3, only one CIRS item, age 〈 65 yrs) benefited most from FCR therapy. The difference in PFS was statistically not significant between both arms in pts ≥ 65 years, CIRS 4-6 or 〉 1 CIRS item. Multivariate analysis identified treatment arm, age ≥ 65 yrs, male sex, high serum TK, del(11q), absence of del(13q) and IGHV status as independent prognostic factors for PFS. No difference in OS was observed (at 36 mo 90.6% for FCR vs 92.2% for BR; HR=1.030, 95% CI 0.618-1.717; p=0.910). For OS male gender, age ≥ 60 yrs, high serum TK and IGHV status were assessed as independent prognostic factors. Severe neutropenia was more often observed in the FCR arm (87.7% vs 67.8%, p 〈 0.001), but no significant difference in the incidence of anemia (14.2% vs. 12.0%; p=0.46) or thrombocytopenia (22.4% vs 16.5%; p=0.096) was documented. Severe infections occurred significantly more frequent (39.8% vs 25.4%, p=0.001) in the FCR arm during treatment phase until 6 months follow-up, especially in older pts (48.4% vs 26.8%; p=0.001). Treatment related mortality was 3.9% (FCR) and 2.1% (BR), respectively. Conclusion: The final analysis of the CLL10 study shows that FCR remains the standard therapy in very fit CLL patients, because it yields higher CR rates, more MRD negativity and longer PFS in comparison to BR. However, in elderly fit pts high toxicity rates and infection rates result into dose reductions leading to similar efficacy between both arms. Elderly fit pts or pts with previous infections might benefit from BR as alternative regimen. Disclosures Eichhorst: Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding, Travel grant Other; Mundipharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Travel grant, Travel grant Other; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy. Off Label Use: The Combination of Bendamustine and Rituximab is not approved for frontline chemoimmunotherapy of CLL. Fink:Celgene: Other. Maurer:Mundipharma: Travel grant Other. Kiehl:Roche: Membership on an entity's Board of Directors or advisory committees. Gregor:Roche: Consultancy, Honoraria; Mundipharma: Consultancy, Honoraria. Trneny:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fischer:Roche: Other. Döhner:Roche: Research Funding. Kneba:Roche: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding. Wendtner:Mundipharma: Consultancy, Honoraria, Research Funding; Hoffmann-La Roche: Consultancy, Honoraria, Research Funding. Klapper:Hoffmann-La Roche: Research Funding; Takeda/Millenium: Research Funding. Kreuzer:Roche: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding. Stilgenbauer:Roche: Consultancy, Honoraria, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding. Böttcher:Roche: Honoraria, Research Funding, Travel grant Other. Hallek:Roche: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding.

Abstract: Introduction: FCR is still the standard frontline regimen for physically fit CLL pts without TP53 alteration. The international phase III CLL10 study demonstrated the inferiority of BR in comparison to FCR in this population. In order to evaluate long-term outcome and toxicity we performed an updated analysis after extended observation time. Methods and Patients: 561 pts were randomized as previously published (Eichhorst B et al., Lancet Oncol 2016). 282 and 279 pts were randomized to receive either 6 courses of FCR or BR respectively. After the end of treatment pts were followed 3-monthly for 2 years (yrs) and 6-monthly for 3 yrs, and afterwards annually until progressive disease (PD). After PD annual visits were documented either within the study or within the registry of the GCLLSG. Health related quality of life (HRQOL) was evaluated by using the EORTC C30 questionnaire, which was completed at baseline, after 3, 6 and 12 months and then annually until year 5. Results: After a median observation time of 58.2 months (mo) (range, 0 - 88 mo), the median progression-free survival (PFS) for FCR was 57.6 mo versus (vs) 42.3 mo for the BR arm [Hazard ratio (HR)=1.593 (95% confidence interval (CI), 1.271-1.996); p 〈 0.0001]. While PFS was statistically significant different in younger pts [≤ 65 years (yrs)] (median PFS 57.6 vs 38.2 mo.; p 〈 0.0001), the difference was statistically not significant in elderly pts [ 〉 65 yrs] (57.6 vs 42.3; p=0.134). Richter transformation (RT) was assessed as PD and occurred in 5 pts (1.8%) after FCR and 8 pts (2.9%) after BR. 77 (27.3%) pts following FCR and 108 (38.7%) following BR treatment received at least one subsequent therapy. BR was the most common second line therapy after prior FCR (42 pts), while BR re-exposure after frontline BR was performed in 31 pts. 33pts switched to FCR after BR first line therapy. So far, only 3 pts after FCR and 2 pts after BR received kinase inhibitors. 51 pts (18.1%) of the FCR arm and 54 (19.4%) pts of the BR arm deceased so far. Main cause of death in the FCR arm were secondary malignancies (14 pts; 5.0%), followed by CLL including RT (11 pts incl. 2 RT; 3.9%), infections (7 pts; 2.5%) and concomitant diseases (6 pts; 2.1%). In the BR arm CLL was the most common cause of death (15 pts incl. 6 pts with RT; 5.4%) followed by infections (12 pts; 4.3%) and concomitant disease and secondary malignancies (10 pts each; 4.3% each). Other causes of deaths were distributed similarly (incl. adverse events to frontline or relapse treatment or unknown). No differences in overall survival (OS) were observed (OS at 5 yrs, 80.9% for FCR vs 80.1% for BR; HR=1.108, 95% CI 0.755-1.627; p=0.599). The difference in OS for younger pts was statistically not significant (OS at 5-yrs 85.6% for FCR vs 81.1% for BR; p=0.119). Otherwise, 5-yrs OS was 78.8% for pts 〉 65 yrs receiving BR and 70.9% for those receiving FCR (p=0.238). Multivariate analysis identified treatment arm, male sex, high serum thymidine kinase (TK), del(11q) and unmuated IGHV status, but not age as independent prognostic factors for PFS. For OS only high serum TK and unmutated IGHV status were assessed as independent prognostic factors. Secondary neoplasia was documented in 49 (17.6%) of 279 FCR treated pts and 35 (12.5%) of 278 BR treated pts. No difference in the incidence rate of secondary solid tumors was observed between both arms (for FCR 28 (10.0%) and for BR 25 (9.1%)). Secondary MDS and/or AML occurred more frequently after FCR therapy (12 [4.3%] vs 2 [0.7%] ), particularly in pts 〉 65 yrs (6 [7.0%] vs 1 [0.9%] ). 540 of 561 pts (96.3%) were evaluable for HRQOL analysis, 272 pts of the FCR and 268 pts of the BR arm. No differences between both arms were detected with respect to global health status or any functional or symptom scale. As compared to an age- and sex-matched normal population functional scale values were impaired mostly during treatment phase and symptom scales also during follow-up. However, after the end of therapy and during follow-up global health status was improved. Conclusion: Long-term follow-up data of the CLL10 study confirm the superiority of FCR regimen in young (≤ 65 yrs) and fit CLL patients. However, importantly these data support the recommendation of using BR in fit elderly pts. This particular group of pts had both a very good outcome after BR and compared to FCR a decreased risk of secondary MDS and/or AML. Disclosures Eichhorst: Novartis: Consultancy; Gilead: Consultancy, Research Funding, Speakers Bureau; Abbvie: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Mundipharma: Consultancy, Research Funding, Speakers Bureau. Bahlo:F. Hoffman-La Roche: Honoraria, Other: Travel grant. Maurer:Mundipharma: Other: Travel grants. Kiehl:Roche: Consultancy, Other: Travel grants, Speakers Bureau. Fischer:Roche: Other: travel grants. Kneba:Amgen: Research Funding; Roche: Consultancy, Honoraria, Other: Travel grants, Research Funding; Gilead: Consultancy, Honoraria, Other: Travel grants, Research Funding; AbbVie: Consultancy, Honoraria, Other: Travel grants; Glaxo-SmithKline: Other: Travel grants; Janssen-Cilag: Consultancy, Honoraria, Other: Travel grants. Wendtner:Hoffmann-La Roche, Mundipharma, Janssen, Gilead, Abbvie, Servier, Morphosys: Consultancy, Other: Travle grants, Research Funding. Klapper:Roche, Novartis, Amgen, Takeda: Research Funding. Kreuzer:Roche Pharma GmbH and Mundipharma GmbH: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Honoraria, Research Funding, Speakers Bureau. Böttcher:Celgene: Research Funding; Hoffmann-LaRoche: Honoraria, Other: Travel grants, Research Funding; AbbVie: Honoraria, Research Funding. Stilgenbauer:GSK: Consultancy, Honoraria, Other: Travel grants , Research Funding; AbbVie: Consultancy, Honoraria, Other: Travel grants, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel grants, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel grants , Research Funding; Genzyme: Consultancy, Honoraria, Other: Travel grants , Research Funding; Gilead: Consultancy, Honoraria, Other: Travel grants , Research Funding; Hoffmann-La Roche: Consultancy, Honoraria, Other: Travel grants , Research Funding; Celgene: Consultancy, Honoraria, Other: Travel grants , Research Funding; Genentech: Consultancy, Honoraria, Other: Travel grants , Research Funding; Mundipharma: Consultancy, Honoraria, Other: Travel grants , Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: Travel grants , Research Funding; Janssen: Consultancy, Honoraria, Other: Travel grants , Research Funding; Sanofi: Consultancy, Honoraria, Other: Travel grants , Research Funding; Boehringer Ingelheim: Consultancy, Honoraria, Other: Travel grants , Research Funding. Fink:Celgene: Research Funding; Roche: Honoraria, Other: Travel grants; Mundipharma: Other: Travel grants; AbbVie: Other: Travel grants. Hallek:Celgene: Research Funding; Roche: Consultancy, Honoraria, Research Funding; Gilead: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria; GSK: Research Funding; Mundipharma: Research Funding; Janssen: Research Funding.

Abstract: Telomeres are sequences at the ends of each chromosome that confer genomic stability. The presence of dysfunctional telomeres is associated with increased genomic abnormalities and tumorigenesis. In CLL, telomere length has been described as an independent prognostic factor (e.g. Roos et al., Blood 2008) but these analyses have been performed on heterogeneous patient cohorts and have not yet been confirmed within clinical trials. Here, we studied the impact of telomere length on outcome in the international CLL8 trial of the GCLLSG evaluating first-line treatment with fludarabine and cyclophosphamide (FC) versus FC with rituximab (Anti-CD20). Telomere length was analyzed using quantitative PCR of DNA (in triplicates) from baseline samples of 620 patients enrolled on CLL8, and this cohort was representative of the full trial population. The technique was validated using terminal restriction fragment length analysis (TRF) (R2=0.859, P 〈 0.001) in an independent control sample set (n=18) and 6 of these samples were included in every batch as controls. Telomere length was found to be highly variable in CLL (1.94 kb – 33.56 kb), whereas normal B-cells from age matched healthy probands (n=20) showed limited variability (5.39 – 9.60 kb; median 7.54 kb). Analysis of paired CD19+ (malignant) and CD19- (non-malignant) fractions (n=48) showed that telomere shortening in CLL was restricted to the malignant cell population (median: CD19+ 3.37 kb vs. CD19- 5.42 kb; P 〈 0.001). Comparison of clinical characteristics between the groups defined by short and long telomeres (cut-off at the median of 4.54 kb) showed no significant associations with age (P=0.931), sex (P=0.116), presence of B-symptoms (P=0.297), ECOG status (P=0.288), CIRS score (P=0.438) and ß2-MG (P=0.586). Short telomeres were significantly associated with high WBC (≥50 Giga/L; P=0.004), high thymidine kinase levels (≥10.0 U/L; P 〈 0.001) and presence of larger lymph nodes ( 〉 5cm; P=0.048). Also, unmutated IGHV (P 〈 0.001), ZAP70+ (≥20%; P=0.005), del(17p) (P 〈 0.001) and del(11q) (P 〈 0.001) were significantly more frequent in the group with short telomeres. Interestingly, cases with Binet C stage were significantly associated with long telomeres (P=0.007). After a median follow up time of 69.97 months, there were 423 events for progression free survival (PFS) and 209 for overall survival (OS). Short telomeres were significantly associated in both treatment arms with poor PFS (FC: median 27.4 vs. 44.0 months, P 〈 0.001; FCR: median 44.3 vs. 70.0 months, P 〈 0.001) (Figure) and OS (FC: median 35.1 vs. 62.5 months, P 〈 0.001; FCR: median 79.5 vs. 86.2 months, P=0.010). Multivariable analysis by Cox regression with backward selection was performed for the identification of independent prognostic factors, including as variables the treatment arms, age, sex, stage, ECOG status, B-symptoms, WBC, thymidine kinase, ß2-MG, CIRS, del(11q), +(12q), del(13q), del(17p), mutation status of IGHV, TP53, NOTCH1, SF3B1 and telomere length. Regarding PFS, we identified the following independent prognostic markers: FCR (HR 0.493; P 〈 0.001), male sex (HR 1.330; P=0.035), ECOG status 〉 0 (HR 1.256; P=0.037), thymidine kinase 〉 10 (HR 1.312; P=0.042), del(11q) (HR 1.378; P=0.012), del(17p) (HR 3.225; P 〈 0.001), unmutated IGVH (HR 1.478; P=0.007), TP53 mutation (HR 2.031; P=0.001) and short telomere length (HR 1.425; 95% CI 1.109-1.832; P=0.006). Regarding OS, the following independent prognostic markers were identified: FCR (HR 0.657; P=0.007), age ≥65 years (HR 1.453; P=0.021), ECOG status 〉 0 (HR 1.617; P=0.003), thymidine kinase 〉 10 (HR 1.850; P=0.007), beta2 microglobulin (HR 1.486; P=0.016), del(17p) (HR 2.716; P 〈 0.001), unmutated IGHV (HR 2.001; P=0.001) and TP53 mutation (HR 3.034; P=0.001). When not including NOTCH1, SF3B1 and TP53 in the multivariable models, short telomeres where identified as independent prognostic markers for PFS (HR 1.543; P 〈 0.001) and OS (HR 1.473; P=0.029). In conclusion, the characterization of telomere length in the CLL8 trial revealed significant associations with other biological high-risk features and an independent prognostic impact on outcome after FC or FCR treatment. This points to a role of telomere dysfunction in CLL pathogenesis, progression and response to therapy. Further study of telomere dysfunction in the evolution of CLL and in the context of novel non-genotoxic treatments is warranted. Disclosures: Wenger: F. Hoffmann-La Roche: Employment, Ownership interests (including stock options) in a start-up company, the stock of which is not publicly traded Other. Fingerle-Rowson:F. Hoffmann-La Roche : Employment. Wendtner:Hoffmann-La Roche: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Fischer:Roche: Travel grants Other; Mundipharma: Travel grants, Travel grants Other. Hallek:Roche: Consultancy, Honoraria, Research Funding. Stilgenbauer:Roche: Consultancy, Honoraria, Research Funding.