Wendtner, Clemens‐Martin

7015 Background: Besides clinical staging, a number of biomarkers predicting OS in CLL have been identified. The multiplicity of markers, limited information on their independent value, and a lack of understanding of how to interpret discordant markers are major barriers to use in routine clinical practice. We developed an integrated prognostic index using the database of the German CLL Study Group (GCLLSG), which was subsequently validated in a cohort of untreated CLL patients (pts) from the Mayo Clinic. Methods: The analysis was based on a dataset collected between 1997 and 2006 in 3 GCLLSG phase III trials. The external validation was performed on a series of newly diagnosed CLL pts managed at Mayo Clinic. Results: The GCLLSG dataset (1,948 physically fit pts at early and advanced stage; median age: 60 yr (range 30-81); median observation time 63.4 mo) was used as a training dataset. 7 parameters were identified as independent predictors for OS: sex, age, ECOG status, del 17p, del 11q, IGHV mutation status, thymidine kinase and β2-microglobulin. By using a weighted grading a prognostic index was derived separating four different pts groups: low risk (score 0 - 2), intermediate risk (score 3-5), high risk (score 6-10) and very high risk (score 11-14) with significant different OS rates (95.2%, 86.9%, 67.7% and 18.7% OS after 5 yr for the low, intermediate, high and very high risk group respectively (p<0.001). This prognostic index was validated in a cohort of 676 newly diagnosed, untreated pts from the Mayo Clinic (median age 61.5 yr (range 32 - 89); median observation time 47.0 mo). The 4 risk groups were reproduced with 98.3%, 95.4%, 75.4% and 10.8% OS after 5 yr. The prognostic index predicts OS independent of Rai/Binet stage and provides accurate estimations regarding time to first treatment (TTF). C-statistic is 0.75. Conclusions: Using a multi-step process including external validation, we developed a comprehensive prognostic index combining clinical, serum, and molecular information into a single risk score for pts with untreated CLL. The prognostic index provides more accurate prediction of both TTF and OS. To our knowledge it is the first prognostic model in CLL to reach the C-statistic threshold (c > 0.70) necessary to have utility at the level of the individual.

Introduction: Patients (pts) with relapsed or refractory (R/R) chronic lymphocytic leukemia (CLL) who failed treatment with the Bruton's tyrosine kinase inhibitor (BTKi) ibrutinib have a poor outcome and are difficult to treat. This ongoing, two-cohort, Phase II trial evaluates the safety and preliminary efficacy of tafasitamab (MOR208), an Fc-enhanced anti-CD19 monoclonal antibody in combination with idelalisib (IDE) (Cohort A) or venetoclax (VEN) (Cohort B) in R/R CLL pts previously treated with a BTKi. Preliminary results were published at EHA 2018 for Cohort A and at ASH 2018 for Cohort B. Here, we report the results of the primary analysis for both cohorts. Methods and Patients: Pts who either progressed or were intolerant to BTKi were enrolled at 12 sites in six countries in Europe and the US from Nov 2016 to Apr 2018. The primary endpoint is the incidence and severity of adverse events (AEs); secondary endpoints include overall response rate (ORR) as per investigator assessment according to International Workshop on CLL (IWCLL) 2008 guidelines. Complete response (CR) was confirmed by computed tomography assessment and by bone marrow (BM) biopsy. The exploratory endpoint minimal residual disease (MRD) was assessed centrally by quantitative allele-specific oligonucleotide-polymerase chain reaction (ASO-PCR) in peripheral blood (PB) and BM. Each treatment cycle (C) lasts 28 days (D). Dose and administration: tafasitamab intravenous infusion, 12 mg/kg weekly in C1-C3, every other week in C4-C6 and monthly from C7D1; IDE orally, 150 mg twice daily; VEN orally, weekly ramp up starting on C1D8 at 20 mg to full daily dose of 400 mg. Patients: mean time since first CLL diagnosis was 135 months (mos) for pts in Cohort A and 105 mos in Cohort B. Median number of prior therapy lines was five (2-9) and three (1-5), respectively. All pts had received ibrutinib; one pt had subsequent acalabrutinib treatment as last prior therapy line. Mutations of BTK and PLCγ2 were assessed in nine pts in Cohort A and 13 pts in Cohort B. BTK/PLCγ2 mutations were centrally detected in 4/3 pts in Cohort A and in 2/3 pts in Cohort B, respectively. Complex karyotype was observed in six (54.5%) pts in Cohort A and 12 (92.3%) pts in Cohort B. Results with a data cut-off date of 9 Nov 2018 are presented. Results: Cohort A: Median time on study was 9.9 mos (95% confidence interval [CI]: 5.7-not reached). Eleven pts were enrolled and received tafasitamab and IDE. Two pts discontinued treatment due to AEs (aspartate-aminotransferase increased; acute pancreatitis), two due to progressive disease (PD) and one pt by physician's decision. One pt died due to PD and one pt due to cardiac failure. At the cut-off date, treatment was ongoing in four pts. Table 1 summarizes treatment-emergent adverse events (TEAEs) with neutropenia Grade ≥3 being most common (5 [46%]). Fourteen treatment-emergent serious AEs (SAEs) were reported in eight (72.7%) pts. ORR was 90.9% (CR=9.1%, partial response [PR]=81.8%), disease control was achieved in all 11 pts. One of eight pts (12.5%) assessed for MRD status reached MRD-negativity in PB at C14. Cohort B: Median time on study was 12 mos (95% CI: 2.8-not reached). Eleven of 13 enrolled pts received tafasitamab and VEN while two pts received tafasitamab only. Three pts discontinued treatment due to AEs (infusion-related reactions [two pts], diarrhea [one pt], one due to PD and one withdrew consent. At the cut-off date, treatment was ongoing in eight patients. Table 2 summarizes TEAEs, neutropenia Grade ≥3 was most commonly observed (six [46%] pts). Fourteen SAEs were reported in nine (69.2%) pts. The ORR in all 13 pts was 76.9% (CR=23.1%, PR=53.8%, not evaluable=23.1%). Six of seven pts assessed for MRD in PB (46.2% of 13 [100%] pts) reached negative status in PB by C7 at the latest. One of three pts assessed for MRD in BM (7.7% of 13 [100%] pts) reached MRD negative status in BM at C15. Conclusions: This trial demonstrates that in heavily pretreated pts with R/R CLL who failed prior BTKi, tafasitamab in combination with IDE or VEN is a potential therapeutic option. The safety profiles of the combinations are influenced by the combination partner, but both combinations are manageable. The response rates and MRD-negativity rates indicate that combinations of targeted agents with anti-CD19 tafasitamab have valuable antitumor activity and warrant further investigation of tafasitamab-based combinations in CLL. Disclosures Staber: AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Honoraria, Speakers Bureau; Celgene: 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, Research Funding, Speakers Bureau; Takeda-Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Jurczak:Celtrion: Research Funding; Sandoz: Membership on an entity's Board of Directors or advisory committees, Research Funding; Morphosys: Research Funding; Celgene Corporation: Research Funding; Incyte: Research Funding; Servier: Research Funding; Roche: Research Funding; Novo Nordisk: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Gilead: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Loxo: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; TG Therapeutics: Research Funding. Brugger:AstraZeneca: Equity Ownership; MorphoSys: Employment. Chanan-Khan:Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; Xencor: Research Funding; AbbVie: Research Funding. Greil:Mundipharma: Honoraria, Research Funding; Bristol-Myers-Squibb: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Sanofi Aventis: Honoraria; Sandoz: Honoraria; AstraZeneca: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Celgene: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Eisai: Honoraria; Janssen-Cilag: Honoraria; Cephalon: Consultancy, Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Merck: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Boehringer Ingelheim: Honoraria; Amgen: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Ratiopharm: Research Funding; Takeda: Consultancy, Honoraria, Research Funding; MSD: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Pfizer: Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; Roche: Consultancy, Honoraria, Other: Travel/accomodation expenses, Research Funding; GSK: Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Dirnberger-Hertweck:MorphoSys: Employment. Kelemen:MorphoSys: Employment. Middeke:Janssen: Consultancy, Speakers Bureau; MSD: Consultancy; AbbVie: Consultancy, Speakers Bureau; Gilead: Consultancy; Roche: Speakers Bureau; Sanofi: Research Funding, Speakers Bureau. Montillo:Roche: Consultancy, Honoraria, Research Funding; Acerta: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; AstraZeneca: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau; Versatem: Membership on an entity's Board of Directors or advisory committees. Munir:Acerta: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Other: TBC; AbbVie: Honoraria; Alexion: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Roche: Honoraria; Morphosys: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sunesis: Consultancy. Parikh:Pharmacyclics: Honoraria, Research Funding; Ascentage Pharma: Research Funding; Genentech: Honoraria; MorphoSys: Research Funding; Acerta Pharma: Research Funding; AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Janssen: Research Funding. Stilgenbauer:Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding, Speakers Bureau; AstraZeneca: Consultancy, Honoraria, Research Funding, Speakers Bureau; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Hoffmann La-Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Weirather:MorphoSys: Employment. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding. Wendtner:AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Hoffman-La Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen-Cilag: Consultancy, Honoraria, Research Funding, Speakers Bureau; 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.

Abstract Introduction: The CD19 antigen is an attractive therapeutic target as it is highly expressed in chronic lymphocytic leukemia (CLL). CD19 is not down-regulated in patients (pts) pretreated with CD20-targeting agents and has a signaling function that promotes the malignant phenotype. In preclinical studies, the Fc-enhanced, humanized, CD19 antibody MOR208 showed synergistic potential in combination with venetoclax (VEN, a small molecule selective inhibitor of the apoptosis regulator BCL-2). Pts with relapsed or refractory (R/R) CLL who failed treatment with the Bruton's tyrosine kinase inhibitor (BTKi) ibrutinib have poor prognosis. A previous phase I study showed that MOR208 was well tolerated, with encouraging single-agent activity in pts with R/R CLL. This ongoing phase II study was designed to assess the safety and preliminary efficacy of MOR208 in combination with idelalisib (Cohort A) or VEN (Cohort B) in pts with R/R CLL previously treated with a BTKi. Results of Cohort A were previously published at EHA 2018 (Poster PF350). Here we report the initial safety and efficacy results for Cohort B. Methods: Adult pts with R/R CLL without transformation or Richter's syndrome, who progressed on BTKi therapy or were intolerant to a BTKi during their last prior therapy, were eligible if they had ECOG performance status 0-2 and adequate organ function. In Cohort B, pts were treated until progression or for up to 24 cycles (C; 28 days (D)/C). MOR208 was administered intravenously at 12 mg/kg body weight, starting from C1D1, weekly during C1-3 (with an equivalent loading dose on D4 of C1), every other week in C4-6, and monthly in C7-24. Oral VEN was administered daily starting from C1D8 on a weekly ramp up dosing schedule, starting at 20 mg on C1D8, increasing to 50 mg on C1D15, 100 mg C1D22, 200 mg C2D1 and reaching the full daily dose of 400 mg from C2D8 onwards. Primary endpoint is the incidence and severity of adverse events (AEs); secondary endpoints include overall response rate (ORR) as per investigator assessment according to IWCLL 2008 guidelines. Results: We report preliminary results of Cohort B with a data cutoff date of June 18, 2018 and a median observation time of 4.6 months. Recruitment in Cohort B was completed with 13 pts who received at least one dose of MOR208. Eleven pts started combination treatment with VEN; 10 pts completed at least 5 weeks of combination treatment, reaching the full daily dose of VEN. Baseline characteristics are shown in Table 1. All pts had received ibrutinib therapy and 1 pt had subsequent acalabrutinib treatment. The median number of prior treatment lines, including BTKi therapy in all 13 pts, was 3 (range 1-4). Table 2 summarizes treatment-emergent (TE)AEs. The most common hematological TEAE was neutropenia (38%). Eleven TE serious (S)AEs were reported in 9 pts (69%); all resolved. One grade 3 SAE, tumor lysis syndrome, occurred at ramp up to 50 mg VEN. The pt recovered after treatment and continued VEN 50 mg the day after event onset. Three serious adverse reactions (2 pts with infusion-related reactions, 1 pt with bone pain with pyrexia) were reported in total. Two pts (15%) permanently discontinued study treatment due to an infusion-related reaction arising during MOR208 monotherapy (i.e. before C1D8). One pt (8%) discontinued study participation due to withdrawal of informed consent, when on a dose of 50 mg VEN. The 3 discontinued pts did not undergo a response assessment. Treatment of 10 pts is ongoing and seven pts had at least 1 post-baseline assessment of tumor response on C4D1; all (7/7) had a partial response (PR) based on local investigator assessment. Conclusions: The novel combination treatment of MOR208 with VEN showed generally acceptable safety and tolerability as well as encouraging antitumor activity in pts with R/R CLL who discontinued prior treatment with a BTK inhibitor. Disclosures Staber: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda-Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees; CTI: 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. Munir:Alexion: Honoraria; Novartis: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Abbvie: Honoraria; MorphoSys: Membership on an entity's Board of Directors or advisory committees. Schetelig:Roche: Honoraria; Sanofi: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Abbvie: Honoraria; Janssen: Consultancy, Honoraria. Middeke:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Dirnberger-Hertweck:MorphoSys: Employment. Kelemen:MorphoSys: Employment. Weirather:MorphoSys: Employment. Parikh:MorphoSys: Research Funding; Gilead: Honoraria; Janssen: Research Funding; Pharmacyclics: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding. Stilgenbauer:Celgene: Consultancy, Honoraria, Other: travel support, Research Funding; AbbVie: Consultancy, Honoraria, Other: travel support, Research Funding; Amgen: Consultancy, Honoraria, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding; Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; Novartis: Consultancy, Honoraria, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding. Wendtner:Abbvie: Consultancy, Honoraria, Other: travel support, Research Funding; Genetech: Consultancy, Honoraria, Other: travel support, Research Funding; GlaxoSmithKline: Consultancy, Honoraria, Other: travel support, Research Funding; Pharmacyclics: Consultancy, Honoraria, Other: travel support, Research Funding; Janssen: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Other: travel support, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding; MorphoSys: Consultancy, Honoraria, Other: travel support, Research Funding; Gilead: Consultancy, Honoraria, Other: travel support, Research Funding.

Abstract Abstract 2859 Introduction: Patients with chronic lymphocytic leukemia who relapse following purine-analog or bendamustine-based treatments have a poor prognosis. These patients have limited therapeutic options and novel agents with alternative mechanisms of action are needed. In phase 1 and 2 trials, escalating dose regimens of the immunomodulatory agent lenalidomide demonstrated promising activity with relapsed/refractory CLL. Of interest, the data indicate that superior efficacy might be achieved by a starting dose above 2.5 mg daily lenalidomide. A phase 2 trial (CLL-009 study) was developed to investigate the safety of different starting doses of lenalidomide followed by a step-wise dose escalation as tolerated in relapsed/refractory CLL. Methods: In this ongoing trial, eligible subjects with relapsed/refractory CLL who have received at least 1 prior treatment regimen are being enrolled. Subjects are randomized 1 :1 :1 to receive a double-blinded starting dose of 5 mg, 10 mg, or 15 mg oral lenalidomide on days 1–28 of each 28-day cycle. The primary objectives are to determine the safety and efficacy of the different lenalidomide starting doses of 5 mg, 10 mg or 15 mg daily, followed by an intra-patient escalation up to a maximum of 25 mg daily using a Bayesian approach. Based on individual patient tolerability, the daily lenalidomide dose can be escalated every 28 days by 5 mg increments. Dose reductions also occur in 5 mg increments; however, dose levels below 5 mg sequentially include 2.5 mg and 1.25 mg daily. Tumor lysis syndrome (TLS) prophylaxis, comprised of oral hydration and allopurinol 300 mg/day is initiated at least 3 days prior to starting study drug and for a minimum of the first 3 treatment cycles. This adaptive design trial is considering joint efficacy and toxicity outcomes to stop randomization of less promising arms. Accrual to a starting dose arm will be stopped if unacceptable toxicities and/or high progression rate are observed in that arm. A total of 90 subjects will be enrolled in the study. Results: To date, 51 subjects with a median age of 63 years (range 39–78) have been enrolled. Subjects to date are primarily male (65%) and Caucasian (84%), and slightly more than half (53%) are ≥ 65 years old. Cytogenetic data is available for 42 subjects; 10 have del(11q), 8 have del(17p), and 24 have del(13q). Overall, 31 subjects had at least one cytogenetic deletion. Based on the Binet and Rai staging systems: 3 (6%), 10 (20%) and 15 (29%) of subjects are stage A, B and C, respectively; and, 6 (12%), 7 (14%) and 7 (14%) subjects are low, intermediate or high-risk disease, respectively. For 3 (6%) subjects the Binet/Rai staging is currently unknown. The most common hematological grade 3/4 adverse events (AEs) thus far include neutropenia (41% of patients) and thrombocytopenia (24%). The most common non-hematological grade 3/4 AEs include fatigue (12%) and tumor flare (12%). Only 1 subject (2%) experienced tumor lysis syndrome of grade 1. Over half of the subjects (53%) remain on therapy; 24 (47%) subjects have discontinued treatment. The longest subject has completed 17 cycles, and remains on study medication. The most common reasons for study discontinuation include disease progression (n = 8) and AEs (n = 10). To date, 20 subjects (54% of eligible patients) have successfully dose escalated above their respective starting double blinded dose level, including 3, 3, 2 and 12 subjects undergoing 4, 3, 2, and 1 dose escalations, respectively. As 14 patients are still in the first cycle of the study, a total of 20 subjects have had no dose level reduction or escalations. The average duration of treatment is 4.34 cycles, and the median number of cycles is 3. Efficacy evaluations are completed monthly after 3 months of study drug treatment. By investigator assessment, 34 subjects have been evaluated to date, including 1 (3%) complete response, 12 (35%) partial response, 7 (21%) stable disease, 10 (29%) progressive disease and 4 (12%) not evaluable. Conclusion: The independent Data Monitoring Committee, as of March 24, 2011 (N=41), recommended that accrual into all three treatment arms should continue as planned, suggesting all three starting doses were tolerated. To date, the ORR is 38% (13/34 evaluable subjects), and 54% of subjects (20/37) have dose escalated at least once. In this relapsed/refractory CLL population lenalidomide appears active, and completion of accrual will hopefully demonstrate the appropriate starting dose. Disclosures: Wendtner: Celgene: Consultancy, Honoraria, Research Funding. Off Label Use: lenalidomide in cll. Goldberg:Celgene: Honoraria, Research Funding, Speakers Bureau. Bloor:Celgene: Honoraria, Research Funding. Stilgenbauer:Celgene: Consultancy, Honoraria, Research Funding. Cymbalista:Roche: Research Funding; Mundipharma: Honoraria; Genzyme: Honoraria. Kipps:Celgene: Consultancy, Research Funding; Abbott Industries: Research Funding; Genentech: Research Funding; Gilead Sciences: Consultancy, Research Funding; Igenica: Membership on an entity's Board of Directors or advisory committees. Purse:Celgene: Employment, Equity Ownership. Zhang:Celgene: Employment, Equity Ownership. Mei:Celgene: Employment.

Abstract Abstract 3925 Introduction: CLL patients (pts) who relapse following purine-analog or bendamustine-based treatments have a poor prognosis. These pts have limited therapeutic options and novel agents with alternative mechanisms of action are needed. Several phase 1 and 2 trials in rel/ref CLL showed promising activity with escalating dose regimens of lenalidomide (LEN). In other phase II studies improved clinical responses to lenalidomide appeared to correlate with dose levels > 5mg/day. This phase 2 trial investigates the safety of LEN initiated at 3 different starting doses followed by a step-wise dose escalation as tolerated in rel/ref CLL. Methods: In this ongoing trial, eligible pts with rel/ref CLL who have received ≥ 1 prior treatment regimen containing purine-analog or bendamustine are being enrolled. The objectives of this study are to evaluate primarily the safety and secondarily the efficacy of different LEN dose regimens. Pts are randomized 1:1:1 to receive a double-blinded starting dose of 5 mg, 10 mg, or 15 mg oral LEN on days 1–28 of each 28-day cycle. In all 3 treatment arms, the dose is escalated by 5 mg increments every 28 days to reach a maximum dose of 25 mg/d, depending on tolerability. In instances of poor tolerability, dose reductions also occur in 5 mg steps. Pts are stratified by relapsed versus refractory status to their last purine-analog or bendamustine-based treatment regimen and according to age (< 65 vs ≥ 65 years). Tumor lysis syndrome (TLS) prophylaxis comprises of oral hydration and allopurinol 300 mg/day and is initiated ≥ 3 days prior to starting study drug and for a minimum of the first 3 treatment cycles. A total of 105 pts are planned for enrollment to the study. Per protocol, unblinded interim analyses were conducted by the independent Data Monitoring Committee (DMC) after 18 subjects completed 1 cycle and continue at 13-week intervals. Results: To date, 95 pts are enrolled at a median age of 64 years (range 32–81). Enrolled pts are primarily male (67%) and Caucasian (92%). Cytogenetic data are available for 73 pts; 21% have del(17p), 55% have del(13q), 25% have del(11q), and of 72 patients evaluable for trisomy 12, 11 patients (15%) tested positive. IGVH is unmutated in 77% of 77 evaluable pts and 44% of 84 evaluable pts are ZAP70-positive. Based on the Binet and Rai staging systems 9 (10%), 25 (26%) and 24 (25%) of subjects are stage A, B and C, respectively; 7 (7%), 12 (13%) and 16 (17%) subjects are low, intermediate or high-risk disease, respectively. For 2 (2%) subjects the Binet/Rai staging is currently unknown. Overall, 19 pts (20%) received prior bendamustine-containing treatment and 71 pts (75%) received prior fludarabine-based treatment. The median number of prior therapies was 3 (range 1–10). Most common hematological grade ≥ 3 AEs include neutropenia (62%) and thrombocytopenia (34%). At baseline, 19% of pts presented with grade 1–2 neutropenia. The most common non-hematological ≥ grade 3 AEs include pneumonia (13%), tumor flare (13%), and fatigue (11%). TLS was reported in 3 pts (3%): grade 1, 3, and 4. In total, 8 grade 5 events were reported, 3 of which were suspected to be related to LEN: 2 cases of pneumonia and 1 death for unknown cause. At the time of the cut-off, 59 pts (62%) have discontinued treatment. Most common reasons for treatment discontinuation include disease progression (n = 20) and AEs (n = 20). To date, 47 pts (49%) have dose escalated above their starting dose levels of which 12 patients escalated to the highest dose level (25 mg daily). 18 subjects have had no dose level reduction or escalations and 1 patient is still in the first cycle of the study. Average duration of treatment is 6.5 cycles, and median number of cycles is 4. Efficacy evaluations are completed monthly after 3 months of study drug treatment. At time of the data reporting, 5 pts were on study drug but did not reach the first assessment at cycle. For the 90 pts evaluable for response, the investigator's assessment indicates 2 pts (2%) reached CR, 36 (40%) achieved PR, 33 (37%) patients had SD, and 19 (21%) pts progressed. Conclusion: The independent DMC, as of 14 June, 2012 (N=95), recommended that accrual into all three treatment arms should continue as planned, suggesting all three starting doses were well tolerated. To date, the ORR is 42% and 49% of pts were dose escalated at least once. In this rel/ref CLL population LEN appears active, and completion of accrual will clarify the appropriate dose at which to initiate therapy. Disclosures: Wendtner: Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: use of lenalidomie in relapsed/refractory CLL. Hallek:Celgene Corporation: Consultancy, Honoraria, Research Funding. Hillmen:Celgene Corporation: Honoraria. Gregory:Celgene Corporation: Honoraria, Research Funding. Stilgenbauer:Celgene Corporation: Honoraria, Research Funding, Speakers Bureau. Kipps:Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Purse:Celgene Corporation: Employment, Equity Ownership. Zhang:Celgene Corporation: Employment, Equity Ownership. Mei:Celgene Corporation: Employment.

Key PointsPrognostic tool for CLL patients with high discriminatory power compared with conventional clinical staging systems. Prognostication on the individual patient level independent of clinical stage.