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Purpose: With the advent of highly efficacious time-limited combination treatments of targeted agents in chronic lymphocytic leukemia (CLL), minimal residual disease (MRD) assessment has gained importance as a measure for therapeutic success and as a surrogate for progression-free survival. The currently most widely used method is multicolor flow cytometry, which detects circulating CLL cells in the peripheral blood. However, it seems to be less sensitive for the detection of MRD in the lymph node compartment. Patients and Methods: To evaluate whether a cell-free approach can overcome this limitation, we performed serial assessments of circulating tumor DNA (ctDNA) in patients with CLL treated with obinutuzumab, acalabrutinib, and venetoclax in the phase II CLL2-BAAG trial. Patient-specific variability, diversity, joining (VDJ) rearrangements as well as somatic driver mutations were tracked before, during and after treatment by digital droplet PCR in blood plasma. Furthermore, these were systematically compared to matched flow cytometry data. Results: In the 381 sample pairs, ctDNA and flow cytometry yielded highly concordant results. However, clone-specific ctDNA was detected in 44 of 152 samples (29%) that were assessed as undetectable MRD (uMRD) by flow cytometry (defined as less than one CLL cell in 10,000 normal leukocytes). 29 ctDNA-negative samples showed detectable MRD >10–4 by flow cytometry. Also, somatic driver mutations were detected with a similar sensitivity compared with patient-specific VDJ rearrangements in plasma. In patients with predominantly nodal residual disease, ctDNA compared favorably with 4-color flow cytometry and seemed to more accurately reflect the entire disease burden across compartments. Conclusions: On the basis of these findings, ctDNA-based MRD assessment appears to be a promising method to complement cell-based MRD approaches like flow cytometry that focus on circulating CLL cells in the peripheral blood.

Patients aged 80 years and older make up a fifth of patients with CLL but are underrepresented in clinical trials. We analyzed the outcomes of these patients treated with targeted agents in the front-line setting in six trials of the German CLL Study Group. Targeted agents included venetoclax, ibrutinib, and idelalisib, mainly used in combination with anti-CD20 antibodies. Among 716 patients, 33 matched the selection criteria (5%). Of those, the majority had relevant comorbidity, organ dysfunctions, and/or high-/very high-risk disease. The overall response rate was 73%. The median progression-free survival was 49.2 months compared with those not reached in younger patients. There were 11 documented deaths of which two were deemed related to therapy. Additional results including 40 patients treated with BTK-inhibitors from the GCLLSG registry suggest that treatment with targeted agents is feasible and effective. Dedicated studies are warranted for this particular subgroup of patients.

The placebo controlled CLLM1 trial evaluated the efficacy of lenalidomide maintenance treatment in patients with high-risk chronic lymphocytic leukemia (CLL) in first remission after chemoimmunotherapy (CIT). Upon observation of three cases with acute lymphoblastic leukemia (ALL) in overall 56 lenalidomide treated patients (5.4%), the study treatment was prematurely stopped. Using next generation sequencing of B cell and T cell receptor (TR) rearrangements, we here report common clonal B cell ancestry between CLL and ALL in one of those three patients, in whom both diseases shared the same VDJ- as well as crosslineage TR rearrangements. Chromosomal/mutation analyses indicated that in this patient the ALL developed from a common B cell precursor which lacks genomic lesions acquired in the CLL subclone, but shares a BIRC3 frameshift deletion (p.L421fs*). In two cases we found independent IGH rearrangements indicating de novo ALL development from a different B cell clone. A retrospective cohort analysis of >1600 CLL patients treated with first-line CIT in previously reported phase 2-3 studies of the German CLL study group, yielded a significantly lower cumulative incidence of ALL at 12.6 cases/100,000 patient years, compared to 1345.5 cases/100,000 patient-years observed in the lenalidomide arm of the CLLM1 study. Given our results and increasing knowledge on the biological effects of lenalidomide in bone marrow precursor cells, we discuss the potential involvement of lenalidomide in the pathogenesis of ALL in CLL patients.

Background: The introduction of targeted agents has revolutionized the treatment of CLL but only few patients achieve complete remissions and minimal residual disease negativity with ibrutinib monotherapy. Methods: This multicentre, investigator-initiated phase-II study evaluates a sequential treatment with two cycles of bendamustine debulking for patients with a higher tumour load, followed by ofatumumab and ibrutinib induction and maintenance treatment. An all-comer population, irrespective of prior treatment, physical fitness and genetic factors was included. The primary endpoint was the investigator assessed overall response rate at the end of induction treatment. Findings: Of 66 patients enrolled, one patient with early treatment discontinuation was excluded from the efficacy analysis as predefined by the protocol. Thirty-nine patients (60%) were treatment-naive and 26 patients (40%) had relapsed/refractory CLL, 21 patients (32%) had a del(17p) and/or TP53 mutation and 45 patients (69%) had an unmutated IGHV status. At the end of the induction, 60 of 65 patients (92%) responded and 9 (14%) achieved minimal residual disease (MRD) negativity (

Patients with chronic lymphocytic leukemia (CLL) may be more susceptible to Coronavirus disease 2019 (COVID-19) due to age, disease, and treatment-related immunosuppression. We aimed to assess risk factors of outcome and elucidate the impact of CLL-directed treatments on the course of COVID-19. We conducted a retrospective, international study, collectively including 941 patients with CLL and confirmed COVID-19. Data from the beginning of the pandemic until March 16, 2021, were collected from 91 centers. The risk factors of case fatality rate (CFR), disease severity, and overall survival (OS) were investigated. OS analysis was restricted to patients with severe COVID-19 (definition: hospitalization with need of oxygen or admission into an intensive care unit). CFR in patients with severe COVID-19 was 38.4%. OS was inferior for patients in all treatment categories compared to untreated (p

Background: For fit CLL patients (pts), continuous BTK inhibitor treatment is replacing CIT as standard of care in frontline setting, particularly in pts with unfavorable prognostic factors. The time limited combinations venetoclax plus obinutuzumab (GVe) and venetoclax plus rituximab (RVe) have produced high rates of undetectable minimal residual disease (uMRD), which strongly associates with long progression-free survival (PFS) both in frontline and relapsed setting. For frontline therapy GVe is approved in this setting based on data from the CLL14 trial in an unfit population. However, data from a fit cohort are not yet available. The GAIA (CLL13) trial evaluated the efficacy and safety of three Ven+CD20 antibody-based regimens in comparison to CIT as a frontline treatment for fit pts with CLL and without TP53 mutation/deletion. Methods: Treatment-naïve fit (CIRS ≤6, normal creatinine clearance with ≥ 70ml/min) CLL pts requiring therapy were eligible. Based on known poor response to CIT, pts with TP53 aberrations were excluded. Pts were randomized in a 1:1:1:1 ratio to receive six courses of CIT (FCR for pt ≤65 years: fludarabine 25 mg/m² d1-3, cyclophosphamide 250 mg/m² d1-3, rituximab 375 mg/m² d1 cycle 1 and 500 mg/m² d1 cycle 2-6; BR for pt >65 years: bendamustine 90mg/m² d1-2, rituximab) or one of three venetoclax (V) combinations (standard ramp-up from cycle 1 d22, 400 mg/d cycle 2-12): V and rituximab (375/500mg/m² d1 cycle 1-6) [RVe], V and obinutuzumab (1000 mg d1, 8, 15 cycle 1 and d1 cycle 2-6) [GVe], or V, obinutuzumab and ibrutinib (420 mg/d cycle 1-12, if MRD-detectable continued until cycle 36) [GIVe] . Pts were stratified according to country, Binet stage and age (≤ 65/> 65 years). The co-primary endpoints of the trial are (1) the rate of uMRD ( Trial is registered at ClinicalTrials.gov (NCT02950051). Results: A total of 926 pts (CIT: 229 (150 FCR, 79 BR), RVe: 237, GVe: 229, GIVe: 231) with a median age of 61 years (range 27-84) were accrued between 12/2016 and 09/2019. The majority of pts were in advanced Binet stage (B: 37.8%, C: 35.6%) and unmutated IGHV status was present in 56%. Fourteen pts did not receive study treatment (13 FCR, 1 GVe) and were not included in the safety population. The data cut for the first co-primary endpoint analysis was February 28, 2021. The median observation time was 27.9 months. The co-primary endpoint uMRD in PB at MO15 was met as the rate of uMRD in ITT population was significantly higher in GVe compared to CIT: 86.5% (97.5% CI 80.6-91.1) vs 52.0% (CI 44.4-59.5; p The most common grade 3-5 treatment-emergent AE were neutropenia (50.5% of all pts), thrombocytopenia (12.2%), tumor lysis syndrome (7.5%), infusion-related reaction (7.2%), febrile neutropenia (6.5%) and pneumonia (5.3%)). Atrial fibrillation and bleeding events occurred more frequently in GIVe while infusion-related reactions were most common in the GVe arm (Table 1). The absolute numbers of second malignancies were 33, 19, 22 and 21 for CIT, RVe, GVe and GIVe. Fatal AEs occurred in 5, 7, 6 and 9 of the patients. Conclusions: The time-limited therapies of GVe and GIVe provided superior uMRD rates in PB at MO 15 compared to CIT. In addition, uMRD rates in BM and CRR were higher in GVe and GIVe in particular than in CIT. All arms showed a good safety profile in this fit pt population. Figure 1 Figure 1. Disclosures Eichhorst: AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Adaptive Biotechnologies: Speakers Bureau; Hexal: Speakers Bureau; ArQule: Membership on an entity's Board of Directors or advisory committees; Oxford Biomedica (UK): Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Consultant Department I for Internal Medicine: Consultancy; University Hospital of Cologne: Current Employment. Kater: Genmab, LAVA: Other: Ad Board, Steering Committee; Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; Abbvie: Honoraria, Other: Ad Board, Research Funding; BMS, Roche/Genentech: Other: Ad Board, , Research Funding. Von Tresckow: Celgene: Other: travel grant; AstraZeneca: Honoraria, Other; Roche: Honoraria, Other: Reasearch support, travel grant; Janssen: Honoraria, Other: Reasearch support, travel grant; AbbVie: Honoraria, Other: advisory board, travel grant. Staber: Roche: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; Takeda: Consultancy, Research Funding; MSD: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria. Tadmor: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Poulsen: Janssen: Consultancy; Abbvie: Consultancy. Janssens: Sanofi: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Beigene, AstraZeneca: Consultancy, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Trael Grant, Speakers Bureau; Abbvie, Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Noesslinger: Roche: Speakers Bureau; Abbvie,: Speakers Bureau; Janssen: Speakers Bureau; AstraZeneca: Honoraria; Gilead: Honoraria; Celgene: Honoraria. Jaeger: Norvartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Frederiksen: Abbvie: Research Funding; Gilead: Research Funding; Alexion: Research Funding; Novartis: Research Funding; Janssen Pharmaceuticals: Research Funding. Hebart: Roche: Honoraria; BMS: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria; Janssen: Honoraria. Simon: Gilead: Other: Travel support. Fink: AbbVie: Other: travel grant; Janssen: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Celgene: Research Funding. Fischer: Abbvie: Honoraria; Roche: Honoraria, Other: Travel Grants. Kreuzer: Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Abbvie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Mundipharma: Consultancy, Honoraria, Research Funding, Speakers Bureau. Ritgen: Abbvie: Consultancy, Other: Travel support, Research Funding; Chugai: Consultancy; MSD: Consultancy, Other: Travel support; Roche: Consultancy, Other: Travel support, Research Funding; Celgene: Other: Travel support. Brüggemann: Amgen: Other: Advisory Board, Travel support, Research Funding, Speakers Bureau; Incyte: Other: Advisory Board; Janssen: Speakers Bureau. Levin: Roche, Janssen, Abbvie: Other: Travel Expenses, Ad-Board. Stilgenbauer: AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Other: Research Support; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Consultancy; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Honoraria; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Research Funding. Hallek: Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Abbvie: Consultancy, Research Funding, Speakers Bureau. OffLabel Disclosure: Ibrutinib in combaintion with Venetoclax + Obinutuzumab is not approved.

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Chemoimmunotherapy has been the standard of care for patients with chronic lymphocytic leukemia for a long time. However, over the last few years, novel agents have produced unprecedented outcomes in treatment-naïve and relapsed/refractory chronic lymphocytic leukemia. With the advent of these targeted agents, treatment options have diversified very considerably and new questions have emerged. For example, it is unclear whether these novel agents should be used as sequential monotherapies until disease progression or whether they should preferably be combined in time-limited treatment regimens aimed at achieving deep and durable remissions. While both approaches yield high response rates and long progression-free and overall survival, it remains challenging to identify patients individually for the optimal concept. This review provides guidance in this decision process by presenting evidence on sequential and combined use of novel agents and discussing the advantages and drawbacks of these two approaches.

Fifty-one of 189 evaluable patients from 3 prospective phase 2 trials evaluating a sequential targeted treatment had high-risk chronic lymphocytic leukemia (CLL) with a 17p deletion, TP53 mutation, or both. Twenty-seven patients started treatment with bendamustine debulking before induction and maintenance treatment, which was ibrutinib/ofatumumab (IO) in 21 patients, ibrutinib/obinutuzumab (IG) in 13, and venetoclax/obinutuzumab (AG) in 17. The primary end point was overall response rate after 8 months of induction treatment, which was 81%, 100%, and 94% for IO, IG, and AG, respectively. Minimal residual disease (MRD) was undetectable (uMRD) in peripheral blood (

Background: Patients (pts) aged 80 years or older, albeit making up ≥ 20% of CLL pts, are still underrepresented in clinical trials and treatment outcomes in this cohort remain understudied. We conducted an analysis of pts aged 80 years or older in 6 phase II and III studies of the German CLL Study Group (GCLLSG) in the frontline-setting to elucidate outcomes of targeted treatments with regard to relevant clinical endpoints including overall survival and causes of death. Methods: We pooled data of pts aged 80 years or older at the time of first-line treatment, with at least one administration of a targeted agent as first-line treatment (ibrutinib, idelalisib, or venetoclax) within the following GCLLSG trials: CLL14 (treatment with venetoclax + obinutzumab [GVe]), CLL2-GIVe (venetoclax + obinutuzumab + ibrutinib) and the so-called BXX-studies (CLL2-BIG, CLL2-BAG, CLL2-BIO, CLL2-BCG; treatment with optional bendamustine debulking and either ibrutinib + obinutuzumab, venetoclax + obinutuzumab, ibrutinib + ofatumumab or idelalisib + obinutuzumab). Demographic, laboratory, and genetic data were pooled. Data on treatment exposure and safety (standardized mortality ratios and secondary malignancies) were analyzed accordingly. Kaplan-Meier curves for progression free survival (PFS), overall survival (OS) and time to next treatment (TTNT) were plotted. Results: A total of 716 pts (66 pts each from CLL2-BIG, CLL2-BAG, CLL2-BIO, 45 from CLL2-BCG, 41 from CLL2-GIVe and 432 from CLL14) were analyzed. Of these, 33 (5%) matched the selection criteria for our analysis. The median observation time was 51.8 months. Median age of pts at the time of treatment initiation was 82 years (range 80-89), 18 (55%) pts were male (Table 1). 22 (71%) pts had relevant comorbidities with a cumulative illness rating scale (CIRS) of >6 and 30 (91%) pts having impaired renal function with a GFR The type of first-line treatment received was GVe in 27 (82%), bendamustine + ibrutinib + obinutuzumab in 3 (9%), bendamustine + ibrutinib + ofatumumab in 1 (3%) and GIVe in 2 (6%) of pts. 16 pts (48%) discontinued treatment prematurely, in 4 cases because of pts wish, 3 because of progressive disease, 7 pts died (5 due to adverse event, 1 due to cardiac failure and for 1 pt the cause of death is unknown) and 2 discontinued because of reasons classified as "other". The overall response rate was 73%, with 36% CR and 36% PR. Within our sub-cohort, undetectable minimal residual disease (uMRD) rate was 73% in peripheral blood and 39% in bone marrow. Time-to-event analyses showed a median PFS of 49 months (pts There were 11 documented deaths (33%) in our analysis, with adverse events being the most frequent cause of death in 5 cases. Of these, 2 were due to sepsis and 1 each due to heart failure, pulmonary embolism and renal failure. Other reasons not attributed to AEs were progressive disease, infection, respiratory insufficiency and cardiac arrest as well as cardiac failure in 1 case each. For one pt the cause of death is unknown. There were 9 secondary malignancies in 7 pts reported with basal cell carcinoma being the most frequent in 44% of cases. The standardized mortality ratio was 0.78 (95% CI 0.39-1.4) with 11 observed deaths vs. 14 expected deaths compared to the average mortality in this age group. Conclusions: Our analysis demonstrates that this patient population is indeed underrepresented in clinical trials, but anti-leukemic treatment with targeted agents appears feasible and effective in ≥80-year-old pts with CLL, even in presence of coexisting conditions or organ function impairment. Very old pts treated with targeted agents have a comparable survival to an age- and sex-matched population, suggesting that initiating treatment in elderly and potentially frail pts is beneficial. Dedicated studies are warranted for this clinical setting. Hence, our ongoing phase II CLL-Frail trial is evaluating BTK-inhibition for very old (≥80y) or frail pts with CLL (NCT04883749). Figure 1 Figure 1. Disclosures Simon: Gilead: Other: Travel support. Fink: Celgene: Research Funding; AbbVie: Other: travel grant; AstraZeneca: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees. Cramer: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees, Research Funding; Beigene: Research Funding; F. Hoffmann-LaRoche: Honoraria, Other: Travel support, Research Funding; AbbVie: Honoraria, Other: Travel support; Gilead: Other: Travel support, Research Funding. Von Tresckow: AbbVie: Honoraria, Other: advisory board, travel grant; Celgene: Other: travel grant; AstraZeneca: Honoraria, Other; Janssen: Honoraria, Other: Reasearch support, travel grant; Roche: Honoraria, Other: Reasearch support, travel grant. Goede: Roche: Honoraria; AbbVie: Honoraria; Janssen: Honoraria; Gilead: Honoraria; AstraZeneca: Honoraria. Stilgenbauer: AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Consultancy; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Research Funding; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Honoraria; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Other: Research Support. Wendtner: Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; F. Hoffmann-LaRoche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Janssen Cilag: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding. Eichhorst: University Hospital of Cologne: Current Employment; Consultant Department I for Internal Medicine: Consultancy; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Adaptive Biotechnologies: Speakers Bureau; Hexal: Speakers Bureau; ArQule: Membership on an entity's Board of Directors or advisory committees; Oxford Biomedica (UK): Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees. Fischer: Roche: Honoraria, Other: Travel Grants; Abbvie: Honoraria. Hallek: Abbvie: Consultancy, Research Funding, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau. Al-Sawaf: Janssen: Honoraria, Research Funding; Gilead: Honoraria; Beigene: Honoraria, Research Funding; AstraZeneca: Honoraria; Adaptive: Honoraria; AbbVie: Honoraria, Research Funding; Roche: Honoraria, Research Funding.

Background: In early studies of venetoclax (ven) in CLL, severe tumor lysis syndromes (TLS) were observed leading to the implementation of multiple safety measures including a 5-week ramp up schedule. Since then, studies have consistently reported low rates of TLS in ven-treated patients (pts), most likely as a result of strict prophylactic and laboratory monitoring measures. Various lead-in regimens prior to the administration of ven were shown to be feasible and effective in reducing the risk of TLS in pts with CLL. However, no comparison of different pretreatment regimens has been performed so far in a prospective randomized trial. Using the set-up of the GAIA trial, we compared TLS incidence and formal TLS risk reduction between 3 different ven-based combinations. Methods: The phase 3 GAIA (CLL13) trial compared 3 different time-limited ven-based combinations against standard chemoimmunotherapy (CIT) in fit, treatment-naïve pts with CLL. Pts were randomized to receive CIT (FCR in pts ≤65 years; BR in pts >65 years), ven and rituximab (RVe), ven and obinutuzumab (GVe), or ven, obinutuzumab and ibrutinib (GIVe). In RVe, GVe and GIVe, ven was added at cycle 1 day 22 (ramp up day 1) after a 21-day pretreatment with rituximab (1 dose), obinutuzumab (3 doses) or obinutuzumab (3 doses) plus ibrutinib (continuous) (Figure 1A). The safety population (i.e. all pts who received study treatment) of the ven-containing arms was used for this analysis. TLS was reported according to Cairo-Bishop criteria (Cairo M, Bishop M. Br J Haematol. 2004). For TLS risk evaluation, the most recent available CT/MRI and absolute lymphocyte count (ALC) were used. TLS risk was evaluated at baseline and at ramp up day 1, before the first dose of ven. The patients were categorized retrospectively according to the following TLS risk categories: high (any lymph node [LN] with largest diameter ≥10 cm or any LN with largest diameter ≥5 cm and ALC ≥25 G/L), intermediate (any LN ≥5 cm to Results: The safety population of all ven-containing arms comprised of 696 pts (RVe: 237, GVe: 228, GIVe: 231). Baseline TLS risk was high in 22%, 23% and 19% of pts in the RVe, GVe and GIVe arm, intermediate in 62%, 65%, 67% and low in 10.5%, 14.7% and 12.4% of pts, respectively. After the first 21 days of treatment (i.e. at ramp up day 1), the fraction of pts with a reduction in TLS risk varied between the treatment arms with 31.7% (RVe), 71.4% (GVe) and 47.3% (GIVe) of pts decreasing by at least one TLS risk category (Figure 1B). With regard to TLS risk reduction, GVe was superior to RVe (p In total, 36, 30 and 19 cases of TLS occurred in 29 (12.2%), 26 (11.4%) and 19 (8.2%) pts in the RVe, GVe and GIVe arm. The majority of TLS cases were categorized as CTC grade 3 (28 [RVe], 19 [GVe], 12 [GIVe]), only few CTC grade 4 TLS were reported (1 [RVe], 2 [GVe], 3 [GIVe]). There were no cases of fatal TLS and no pts requiring dialysis due to TLS. In the obinutuzumab arms the majority of TLS cases occurred before ramp up day 1 (GVe: 76.7%, GIVe: 68.4%), i.e. before any venetoclax intake, in contrast 80.6% of TLS cases in the RVe arm were reported during ven ramp up (Figure 2). While there was no significant difference in the cumulative TLS incidence between the treatment arms (p=0.334), there was an increase in TLS occurring after ramp up day 1 in the RVe arm compared to GVe (p Conclusions: This analysis represents the first comparison of the formal TLS risk reduction and actual TLS incidence of different ven-based combinations in a randomized trial. GVe led to the highest TLS risk reduction, while the lowest number of TLS cases occurred in the GIVe arm. Most TLS cases in the GVe and GIVe arms occurred before the start of ven. RVe was least effective in reducing TLS risk and in contrast to the obinutuzumab-containing arms, the vast majority of TLS cases was reported during the ven ramp up. The relatively high incidence of TLS in comparison to other trials might partly be a consequence of using different reporting criteria (Cairo-Bishop vs Howard criteria). No fatal TLS occurred in any of the treatment arms. Figure 1 Figure 1. Disclosures Von Tresckow: AbbVie: Honoraria, Other: advisory board, travel grant; Celgene: Other: travel grant; AstraZeneca: Honoraria, Other; Roche: Honoraria, Other: Reasearch support, travel grant; Janssen: Honoraria, Other: Reasearch support, travel grant. Niemann: Novo Nordisk Foundation: Research Funding; CSL Behring, Genmab, Takeda, Octapharma: Consultancy; Abbvie, AstraZeneca, Janssen: Consultancy, Research Funding. Kater: Abbvie: Honoraria, Other: Ad Board, Research Funding; Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; Genmab, LAVA: Other: Ad Board, Steering Committee; BMS, Roche/Genentech: Other: Ad Board, , Research Funding. Staber: Roche: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria; Takeda: Consultancy, Research Funding; MSD: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria. Tadmor: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Levin: Roche, Janssen, Abbvie: Other: Travel Expenses, Ad-Board. Poulsen: Janssen: Consultancy; Abbvie: Consultancy. Janssens: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Trael Grant, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Beigene, AstraZeneca: Consultancy, Speakers Bureau; Abbvie, Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Noesslinger: AbbVie: Honoraria; Celgene: Honoraria; Roche: Honoraria; Jansen: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria. Simon: Gilead: Other: Travel support. Fink: AbbVie: Other: travel grant; Janssen: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Celgene: Research Funding. Fischer: Abbvie: Honoraria; Roche: Honoraria, Other: Travel Grants. Wendtner: Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; F. Hoffmann-LaRoche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Janssen Cilag: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding. Ritgen: MSD: Consultancy, Other: Travel support; Chugai: Consultancy; Abbvie: Consultancy, Other: Travel support, Research Funding; Roche: Consultancy, Other: Travel support, Research Funding; Celgene: Other: Travel support. Brüggemann: Amgen: Other: Advisory Board, Travel support, Research Funding, Speakers Bureau; Incyte: Other: Advisory Board; Janssen: Speakers Bureau. Stilgenbauer: AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Honoraria; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Other: Research Support; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Research Funding; AbbVie, Amgen, AstraZeneca, Celgene, Gilead, GSK, Hoffmann-La Roche, Janssen, Novartis, Sunesis: Consultancy. Hallek: Roche: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Mundipharma: Honoraria, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Pharmacyclics: Honoraria, Speakers Bureau. Eichhorst: Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Speakers Bureau; Adaptive Biotechnologies: Speakers Bureau; Hexal: Speakers Bureau; ArQule: Membership on an entity's Board of Directors or advisory committees; Oxford Biomedica (UK): Membership on an entity's Board of Directors or advisory committees; MSD: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel, accomodation, expenses, Research Funding, Speakers Bureau; Consultant Department I for Internal Medicine: Consultancy; University Hospital of Cologne: Current Employment. OffLabel Disclosure: The combination of obinutuzumab, venetoclax and ibrutinib is not approved for the treatment of CLL

Continuous treatment vs fixed duration of monotherapies and combinations of targeted agents are treatment options in relapsed chronic lymphocytic leukemia. The optimal choice of relapse treatment is dependent on the prior frontline therapy, duration of remission after frontline, genetic markers, and patients’ condition, including age and comorbidities. Combination therapies may result in deep responses with undetectable minimal residual disease (uMRD). Although uMRD is an excellent predictive marker for disease progression, it is rarely used in clinical practice and needs additional evaluation in clinical trials before discontinuation of therapy should be guided according to uMRD.

Simple Summary Nowadays, many patients with chronic lymphocytic leukemia (CLL) are treated with so-called novel agents, including BTK inhibitors, Bcl-2 inhibitors and PI3K inhibitors. As CLL is a chronic disease, most patients will relapse on or after treatment with these drugs and various mechanisms behind this resistance to novel agents have been described. In this review, we present the current evidence on resistance to novel agents, discuss approaches to prevent its development and provide guidance on the treatment of patients who have already acquired resistance. Abstract The approval of Bruton’s tyrosine kinase (BTK) inhibitors such as ibrutinib and acalabrutinib and the Bcl-2 inhibitor venetoclax have revolutionized the treatment of chronic lymphocytic leukemia (CLL). While these novel agents alone or in combination induce long lasting and deep remissions in most patients with CLL, their use may be associated with the development of clinical resistance. In this review, we elucidate the genetic basis of acquired resistance to BTK and Bcl-2 inhibition and present evidence on resistance mechanisms that are not linked to single genomic alterations affecting these target proteins. Strategies to prevent resistance to novel agents are discussed in this review with a special focus on new combination therapies.

Introduction: The GCLLSG has demonstrated the efficacy of a sequential therapy with bendamustine followed by obinutuzumab (or GA101; G) and ibrutinib (I) according to a "sequential triple-T" concept [Hallek M., Blood 2013] using a tailored and targeted treatment aiming at total eradication of minimal residual disease (MRD) in CLL [von Tresckow J, Leukemia 2019]. Here we present the results of the final analysis of the CLL2-BIG trial after the end of maintenance therapy. Methods: This phase-II trial investigated the efficacy and safety of a novel regimen for physically fit and unfit CLL patients (pts) requiring treatment, irrespective of high-risk genetics. 62 pts were to be recruited according to a predefined allocation for the two strata of first-line (1L) and relapse/refractory (RR) treatment. Six cycles of induction therapy with G and I were administered followed by maintenance therapy with continuous I and G every three months until achievement of an MRD-negative complete remission or up to 24 months. Pts with an absolute lymphocyte count ≥ 25.000/µl and/or lymph nodes ≥ 5cm were scheduled to receive two cycles of bendamustine before start of induction. The primary endpoint was the overall response rate 3 months after the start of last induction cycle administered; secondary endpoints included the best response rate, MRD evaluations as well as survival and safety parameters (graded per the NCI CTCAE v.4 criteria). Results: 66 pts were enrolled. Five pts completed less than two cycles of induction therapy and were therefore excluded from the full analysis set as defined by study protocol. Patient characteristics are shown in Table 1. Of note, half of the pts had received prior therapies and two thirds had a high/very-high CLL-IPI. At the end of induction, ORR was 100% and 29 pts (47.5%) achieved MRD-negativity ( 11 pts discontinued maintenance therapy early due to AE (6 pts (10.2%)), progressive disease (PD), refusal of further treatment (2 pts (3.4%) each) or physician´s decision (1 pt (1.7%)). 15 pts (25.4%) completed 24 months and 33 pts (55.9%) stopped due to MRD negativity after a median time of 15.6 months on study. PFS and OS are shown in Figures 2 and 3. In 1L pts 4 PD (13.3%) and no deaths occurred while among RR pts 8 PD (25.8%) and 7 deaths were reported (3 due to infections, 2 due to progression of CLL, 1 due to comorbidity and 1 due to infection and unknown cause). Among pts who stopped treatment due to MRD negativity, 5 pts relapsed after a median duration of 16.4 months off treatment and 1 pt died after 8.7 months, respectively. During maintenance therapy, no grade 5 AE occurred. 151 (45.5%) of 332 CTC grades 1 - 4 AE were deemed as related to study drugs. Due to AE, I was dose modified in 26 pts (44.1%), G in 1 pt (1.7%). All grade 3-4 toxicities observed are shown in Table 2. Conclusion: The depth of response of the BIG regimen can be improved by maintenance therapy with I and G, leading to a rate of undetectable MRD in the PB in 71.2% of pts. Among 33 pts who discontinued treatment due to MRD negativity only 5 pts relapsed and 1 pt died so far. The data demonstrate that the BIG protocol using an MRD guided concept for treatment discontinuation yields very good results, in particular in 1L CLL pts. Disclosures Von Tresckow: Celgene: Other: Travel support; AbbVie: Consultancy, Honoraria, Other: Travel support; Roche: Consultancy, Honoraria, Other: Travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel support, Research Funding. Cramer:Acerta: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Other: travel support, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding; Roche: Honoraria, Other: travel support, Research Funding; mundipharma: Other: travel support. Langerbeins:Mundipharma: Other: travel support; Roche: Honoraria, Other: travel support; Janssen: Honoraria, Other: travel support, Research Funding; AbbVie: Honoraria, Other: travel support; Sunesis: Honoraria. Fink:Celgene: Research Funding; Roche: Other: travel grants; Janssen: Membership on an entity's Board of Directors or advisory committees. Al-Sawaf:Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: travel support; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support. Illmer:Roche: Other: travel support. Tausch:AbbVie: Consultancy, Honoraria, Other: travel support, Speakers Bureau; Roche: Consultancy, Honoraria, Speakers Bureau. Ritgen:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding. Fischer:Roche: Other: travel grants; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Wendtner:Gilead Sciences, Inc.: Consultancy, Honoraria, Research Funding, Speakers Bureau; MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Hoffman-La Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen-Cilag: Consultancy, Honoraria, Research Funding, Speakers Bureau. Kreuzer:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Mundipharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Stilgenbauer:Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pharmacyclics: Other: Travel support; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; Hoffmann La-Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau. Böttcher:AbbVie: Honoraria, Other: travel support; Becton Dickinson: Honoraria; Celgene: Other: tavel support; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support. Eichhorst:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; ArQule: Membership on an entity's Board of Directors or advisory committees; BeiGene: Research Funding; Gilead Sciences, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hallek:AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. OffLabel Disclosure: Obinutuzumab (GA101) is not registered for Treatment of relapsed/rferactory CLL

Introduction: In CLL, chemoimmunotherapies (CIT) and combinations with novel agents have proven to be highly effective with regard to eradication of minimal residual disease (MRD), while complete remissions (CR) are frequently not achieved due to residual lymphadenopathy. We have previously reported that minimal residual disease (MRD) negativity after CIT is a prognostic factor irrespective of the clinical response (Kovacs et al., JCO 2016). Because inferior outcome was observed in small subgroups of patients (pts) with residual lymphadenopathy, we analyzed the prognostic value of residual lymphadenopathy after CIT in comparison to MRD detection in a larger pt population. Methods: We included 361 pts receiving frontline CIT within 3 prospective clinical trials of the GCLLSG (CLL2M: 23 pts, CLL8: 113 pts, CLL10: 225 pts) with available CT/MRI scans to assess abdominal lymphadenopathy at the final restaging (FR; 2 months after the end of last treatment cycle). Pts with available data on all classical lymph node regions (N=217) were analyzed separately (Figure 1). Enlarged lymph nodes (LN+) were defined as >1.5 cm in the longest diameter according to iwCLL 2008 guidelines regardless of the investigator-assessed response category. MRD levels in peripheral blood (PB) were assessed at FR. PFS and OS was analyzed from time point of radiological assessment. Kaplan-Meier curves were plotted and compared using the log-rank test. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox regression modelling. Results: Of the 361 pts included in this analysis, 227 (62.9%) received fludarabine, cyclophosphamide and rituximab (FCR) and 134 (37.1%) pts received bendamustine and R (BR). Median age was 60 years (range, 34-79); median observation time was 55.8 months (mo) (3.2-85.5). 62 (17.2%) pts had residual abdominal LN+, 299 (82.8%) had no residual abdominal lymphadenopathy (LN-) at FR. Of 217 pts with documented CT/MRI of all LN regions at FR, 48 (22.1%) pts had residual LN+ in at least one LN region and 169 (77.9%) showed no residual LN in any of the regions. Baseline characteristics were equally distributed between pts with and without available radiological assessments, between pts with radiological assessments of all regions or only abdominal and between LN+ and LN- pts. MRD in PB was available for 231 (64.0%) pts in this analysis group; of these, 165 pts (71.4%) showed MRD negativity (MRD-) at FR. PFS and OS were analyzed for different LN size categories (≤1 cm; >1 & ≤2 cm; >2 & ≤3 cm; >3 cm). Patient outcome decreased with larger residual abdominal LN size at FR with regard to PFS (median, 52.9 mo vs. 24.6 mo vs. 30.5 mo vs. 10.6 mo; p1.5 cm in any lymph node region, PFS and OS was significantly worse compared to LN- pts (median PFS: 27.3 mo vs. 60.4 mo; HR 2.409; CI=1.622-3.577; p In the MRD- group, PFS was significantly shorter in MRD-/LN+ pts compared to MRD-/LN- pts (abdominal LN: median, 34.7 mo vs. 75.6 mo; HR 2.150; CI=1.190-3.883; p=0.011; any LN: median, 34.7 mo vs. 75.6 mo; HR 2.343; CI=1.221-4.497; p=0.01). This observation was confirmed for OS (abdominal LN: 5-year survival, 52.9% vs. 88.8%; HR 3.153; CI=1.183-8.407; p=0.022; any LN: 5-year survival, 61.9% vs. 94.3%; HR 4.213; CI=1.179-15.016; p=0.027) (Figures 2 & 3). Conclusions: Residual abdominal lymphadenopathy at FR is an independent prognostic factor for PFS and OS regardless of MRD negativity. It remains to be determined whether these findings can be transferred to novel targeted agents such as kinase inhibitors, venetoclax, novel CD20 antibodies or combinations of these. Residual disease in the lymph node compartment may identify a pt population which might benfit from strategies using consolidation therapies. Disclosures Bahlo: Roche: Honoraria, Other: Travel Grants. Fink:Celgene: Consultancy, Research Funding; AbbVie: Consultancy, Other: travel geants; Roche: Other: travel grants; Mundipharma: Other: travel grants. Dreyling:Roche: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Mundipharma: Consultancy, Research Funding; Bayer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Sandoz: Consultancy; Acerta: Consultancy; Gilead: Consultancy, Honoraria. Hess:CTI: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Other: travel expenses, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Ritgen:Roche: Honoraria, Research Funding; abbvie: Research Funding. Kneba:AbbVie: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Döhner:Bristol Myers Squibb: Research Funding; Jazz: Consultancy, Honoraria; Pfizer: Research Funding; Astellas: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Pfizer: Research Funding; Amgen: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Agios: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AROG Pharmaceuticals: Research Funding; AbbVie: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding. Stilgenbauer:AbbVie: Consultancy, Honoraria, Other: travel support, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding; Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding; Celgene: Consultancy, Honoraria, Other: travel support, Research Funding; Amgen: Consultancy, Honoraria, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Other: travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: travel support, Research Funding. Wendtner:Mundipharma: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding; Abbvie: Consultancy, Honoraria, Other: travel support, Research Funding; Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding; MorphoSys: Consultancy, Honoraria, Other: travel support, Research Funding. Goede:Roche: Consultancy, Honoraria, Other: Travel grants; Janssen: Consultancy, Honoraria, Other: Travel grants; Gilead: Consultancy, Honoraria; AbbVie: Consultancy. Fischer:Roche: Other: Travel support. Böttcher:Genentech: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Research Funding; Janssen: Honoraria; Celgene: Research Funding. Hallek:Janssen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding. Eichhorst:AbbVie, Celgene, Gilead, Janssen, Mundipharma, Novartis, Roche: Honoraria, Other: Travel support, Research Funding.

Introduction Chronic lymphocytic leukemia (CLL) is a disease of the elderly patient with a median age of 72 years at diagnosis. In addition to a generally increased obesity prevalence, higher age is also associated with increased body fat contents, and currently 22.5% of men and 31.8% of women above 65 years in Germany qualify as obese (body mass index [BMI] ≥30 kg/m²). While high BMI values are regarded as a risk factor for certain cancers, the impact of obesity on treatment outcomes is controversial and differs between genders. In aggressive B-cell lymphoma the prognosis of obese elderly women was worse following R-CHOP chemoimmunotherapy (CIT). With this meta-analysis the question whether obesity has an impact in CLL was addressed. Methods We analyzed pooled data from three prospective phase III trials (CLL4, CLL8, CLL10) of the German CLL study group (GCLLSG). With the aim to assess the effect of rituximab, patients treated with fludarabine monotherapy (F) or bendamustine and rituximab (BR) were excluded from this analysis. Underweighted patients (BMI Results In this combined cohort 560 (45.3%) patients received FC and 677 (54.7%) received FCR. 319 (25.8%) patients were female, 918 (74.2%) were male, median age was 60 years (range 30-81). The cohort comprised 497 (40.2%) NW patients, 521 (42.1%) OW patients and 219 (17.7%) OB patients. Median BMI was 25.1 kg/m² (range 18.6-45.0) in the female and 26.0 kg/m² (range 18.7-45.2) in the male study population. Clinical characteristics, in particular CLL-IPI risk groups and other prognostic factors, were equally distributed between BMI subgroups. Median observation time was 68.4 (range 0.4-151.3) months. OB patients received lower CIT doses compared to NW patients with regard to planned doses based on body surface area (Table 1). Medians of given dose intensities were for fludarabine: NW 95.1% (range 10.8-124.7) vs. OB 84.0% (range 9.2-121.0), for cyclophosphamide: NW 93.5% (range 11.1-105.7) vs. OB 84.0% (range 9.2-102.3), and for rituximab: NW 98.2% (range 0.1-108.7) vs. OB 88.9% (range 26.8-101.3). This difference was observed in male and female patients. We found significantly increased creatinine clearance rates in OB patients of both genders calculated by three different methods including the Salazar/Corcoran method that adjusts for obesity. PFS and OS according to the three BMI groups were not different in the entire cohort comprising both genders or males only. However, obese females had significantly worse outcomes following FCR treatment compared to NW females: median PFS was 44.6 in OB vs. 73.0 months in NW females (HR 1.743 [1.022-2.973]; p=0.041) and the median OS was 83.7 months compared to not reached in the female NW group (HR 3.013 [1.345-6.752]; p=0.007) (Figure 1). These survival differences could not be detected in FC treated females (Figure 2). Conclusions Our data suggest that obesity is associated with significantly shorter PFS and OS in female CLL patients undergoing FCR chemoimmunotherapy but not conventional FC chemotherapy without rituximab. Therefore we assume that lower relative chemotherapy dose exposition that OB females received was not the major contributing factor to this survival difference. In contrast, we assume lower rituximab exposure in OB females treated with FCR due to obesity-associated increased clearance rates as described before. The significantly increased creatinine clearance rates in OB female patients might have additionally contributed to this effect, however the detailed mechanisms remain to be characterized. Our results are in line with recently published data on obesity as a survival risk factor in female patients with aggressive B-cell lymphoma undergoing R-CHOP CIT. Taken together, this warrants closer metabolic and anthropometric status evaluation in future immunotherapeutic studies. Disclosures Hopfinger: Roche: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; GlaxoSmithKline: Honoraria; Celgene: Honoraria; Novartis: Consultancy, Honoraria; Janssen: Honoraria; Gilead: Honoraria, Research Funding. Fink:Celgene: Consultancy, Research Funding; AbbVie: Consultancy, Other: travel geants; Roche: Other: travel grants; Mundipharma: Other: travel grants. Al-Sawaf:Roche: Honoraria; Gilead: Honoraria; Abbvie: Honoraria. Langerbeins:Sunesis: Consultancy; AbbVie: Research Funding; Janssen: Consultancy, Honoraria, Other: Travel support, Research Funding; Mundipharma: Consultancy, Other: Travel grants; Roche: Consultancy, Other: Travel grants, Research Funding. Cramer:Mundipharma: Other: Travel grants; Roche: Honoraria, Other: Travel grants, Research Funding; Acerta: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; GlaxoSmithKline: Research Funding; Gilead: Other: Travel grants, Research Funding; Abbvie: Consultancy, Honoraria, Other: Travel grants, Research Funding; AstraZeneca: Consultancy; Janssen: Consultancy, Honoraria, Other: Travel grants, Research Funding. Von Tresckow:Celgene: Consultancy, Other: Travel grants; Roche: Consultancy, Honoraria, Other: Travel grants, Research Funding; Janssen-Cliag: Consultancy, Honoraria, Other: Travel grants, Research Funding; AbbVie: Consultancy, Honoraria. Kutsch:Janssen: Other: Travel support; AbbVie: Other: Travel support; Mundipharma: Other: Travel support; Gilead: Research Funding. Hoechstetter:Hexal: Other: Travel Grants; Abbvie: Other: Travel Grants; Gilead Sciences: Consultancy, Other: Travel Grants. Dreyling:Gilead: Consultancy, Honoraria; Mundipharma: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Acerta: Consultancy; Sandoz: Consultancy. Kneba:AbbVie: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Stilgenbauer:Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: travel support, Research Funding; Celgene: Consultancy, Honoraria, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Amgen: Consultancy, Honoraria, Other: travel support, Research Funding; AbbVie: Consultancy, Honoraria, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Other: travel support, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding. Döhner:AbbVie: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Amgen: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Amgen: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Agios: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding. Hensel:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jaeger:Amgen: Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Takeda-Millenium: Membership on an entity's Board of Directors or advisory committees; MSD: Research Funding; Takeda-Millenium: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Infinity: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria. Wendtner:Gilead: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; MorphoSys: Consultancy, Honoraria, Other: travel support, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding; Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding. Goede:Janssen: Honoraria, Other: Travel grants; Abbvie: Consultancy; Gilead: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Other: Travel grants. Fischer:Roche: Other: Travel support. Hallek:Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; Mundipharma: Honoraria, Research Funding. Eichhorst:AbbVie, Celgene, Gilead, Janssen, Mundipharma, Novartis, Roche: Honoraria, Other: Travel support, Research Funding.