Kipps, Thomas J.

Abstract Approximately 10–15% of patients with CLL report a family history (FH) of CLL or a related lymphoproliferative disorder. Whether the biologic features of CLL that occurs within families differ from those that occur sporadically is unknown. A recent study addressing this question has reported that mutated IgVH is significantly more common among familial than sporadic CLL, 68% vs 47%, although the distribution of VH genes used was similar (Blood111:5691, 2008). Therefore we compared IgVH mutational status and gene usage, as well as other biologic features, between familial and sporadic CLL derived from patients enrolled on the CLL Research Consortium (CRC) Tissue Core. Of 4533 patients enrolled in the CRC database and tissue bank, 3328 had adequate family history information, and these were subdivided into 4 groups: FH of CLL (n=468), FH of other heme cancer but not CLL (n=421), FH of non-heme cancer (n=1444), and sporadic cases (no FH of any cancer) (n=995). Of those patients reporting a FH of CLL, 63% had at least one affected 1st degree relative, 20% at least one affected 2nd or greater degree relative, and 17% unknown. 68% of those reporting a FH of CLL also had other cancers in their family. Patients reporting a FH of CLL or non-CLL heme cancers were more frequently white (91%), compared to 87% of those with FH non-heme cancer and 84% of sporadic CLL patients (p=0.005). The proportion of CLL cases that were female was similar among groups, at 37.6% of patients with FH CLL, as compared to 32.5% of sporadic patients (p=0.12). The age at diagnosis of CLL also did not differ among the four groups, although a trend toward a difference was observed between the FH CLL patients, whose mean age at diagnosis was 54.9 (range 30, 93), and the sporadic patients, whose mean age at diagnosis was 56.1 (range 30, 84) (p=0.08). No significant difference was observed among groups in the frequency of IgVH mutation (defined as <98% homology to the most similar germline VH gene), which was present in 50.3% (95% CI 44.5–56.2) of patients with FH CLL, 56.3% (95% CI 49.7–62.7) of patients with FH other heme cancer, 51.9% (95% CI 48.5–55.3) of patients with FH non-heme cancer, and 51.3% (95% CI 47.0–55.5) of sporadic patients (p=0.53). The pattern of IgVH family gene usage also did not differ among the groups; the VH3 subgroup was most commonly used, at 45%, 52%, 46% and 47% of patients with FH CLL, FH other heme cancer, FH non-heme cancer and sporadic, respectively. The VH1 subgroup was next most common in all 4 groups, at 28%, 24%, 26% and 25%, respectively, followed by the VH4 subgroup, at 19%, 17%, 21% and 21%. In addition, no significant difference was observed in the distribution of ZAP-70 expression amongst the four family history subgroups (mean %ZAP-70 expression, 22.8% for FH CLL patients and 24.4% for sporadic patients, p=0.31), or in the fraction considered ZAP-70 positive (>20% expression), which was 40% for FH CLL patients and 45% for sporadic patients (p=0.16). The relative expression of CD23 and CD38 did not differ among groups, nor did levels of beta-2-microglobulin or IgG determined at time of CRC enrollment. Time from diagnosis to initial treatment for each of the subgroups is currently being analyzed. These data on patterns of biologic risk factors in this large group of familial CLLs compared to sporadic CLLs suggest that familial and sporadic CLL are biologically similar and therefore likely to have similar pathogenetic mechanisms, including perhaps an underlying genetic susceptibility.

Abstract Fluorescence in situ hybridization (FISH) probes and analysis methods for B-cell Chronic Lymphocytic Leukemia (CLL) vary extensively among cytogenetic laboratories. This is not unexpected, as neither national nor international standards have been established for most FISH studies. Lack of standardization is problematic when data collected at multiple institutions are used for clinical correlative studies. To circumvent such problems, the five participating laboratories in the CLL Research Consortium (CRC) designed and executed a joint CLL FISH validation study. Methods: Initially a survey was sent to assess equipment, methods and experience with FISH for CLL. In a pilot study to compare laboratory performance in scoring patient samples, slides from ten patients were prepared and sent to each participating lab to be hybridized with five probe sets (= 50 hybridizations) and analyzed according to their local protocol. In a second pilot study, slides from two patient samples and identical probe sets were sent to the participating labs where hybridization and analysis were carried out according to their local protocol. Next, technologists and directors from all participating labs attended a workshop where technologists working in pairs scored nuclei together, techniques and scoring criteria were established, and consensus reached on other concerns. In a proficiency test nine months after the workshop, slides from two patient samples (10 hybridizations) were hybridized and scored according to each lab’s protocol and results shared using a common reporting form. Results: Survey results indicated that four labs used the same commercially available CLL FISH panel, and one used a combination of probes from the same vendor plus several home-brew probes. Each lab scored between 100 and 200 nuclei per hybridization site, and each independently set normal cutoff values. The FISH panel included probes to detect 11q, 13q, and 17p deletions, trisomy 12, and IGH gene rearrangement. One lab included probes to detect 6q deletion. In the first pilot study each lab used their hybridization methods, probe sets, and scoring criteria. Differences among labs were observed due to variations in probe strategy, reporting of anomalies, and perhaps most important, scoring criteria. Probe strategy differences resulted in variable reporting of 11q- vs monosomy 11 and 12q duplication vs trisomy 12. Some participants reported 13q-x1 and 13q-x2 as subclones and some reported only 13q-. One lab reported an IGH rearrangement whereas the others scored IGH as normal. In the second pilot study each lab used the same methods and probe sets to facilitate comparison of scoring by the technologists. All labs correctly identified the abnormalities, and there were no false positive results. Minor scoring differences were attributed to variation in scoring criteria or inexperience with an unfamiliar FISH probe strategy. The proficiency test that followed the workshop demonstrated 100% concordance in identification of abnormalities. Inter-lab scoring was much improved compared to the first pilot study. The only exceptions were a 13q- range of 72–90% in one case, and a 17p- range of 38–67% in another case. Conclusion: The pilot studies identified a need to develop common scoring criteria. The subsequent workshop and proficiency test demonstrated that the collaborative effort resulted in more standardized scoring among the CRC laboratories. Our collaborative study emphasizes the need to establish rigorous standards and guidelines for FISH procedures and scoring criteria. Standardization of FISH methods among participating laboratories will enhance the confidence in FISH studies for both clinical applications and cooperative intergroup clinical research.

Abstract We performed immunophenotypic and IgVH mutation analyses on the chronic lymphocytic leukemia (CLL) cells of 307 patients for expression of CD38, ZAP-70, and IgVH mutation status to determine the relative strength of each in predicting the need for early treatment. For this we assessed the time from diagnosis to initial therapy for progressive and/or symptomatic disease. Patients confirmed to have remained untreated were censored for this endpoint. Expression of CD38 was defined as the proportion of CD38-stained CLL cells that had fluorescence intensity above a defined threshold. Similarly, cases were defined as ZAP-70+ when 20% or more of the ZAP-70-stained CLL cells had fluorescence intensity above a defined threshold, as described (NEJM351:893, 2004). CLL cells were classified as expressing mutated IgVH genes if they expressed IgVH with <98% homology with a known germline IgVH gene. The median percentage of cells expressing CD38 in our cohort was 11.5% (range 0.1% to 99.5%). In patients with multiple samples, the CD38 expression level appeared constant over time, with a median S.D. of 0.8%. We defined patient samples that had CD38 expression levels at or below the median as having low expression. There was a significant association between low expression of CD38 and lack of ZAP-70 or expression of a mutated IgVH (p < 0.0001 for each assessment by the Fisher exact test). Median level of CD38 among cases expressing mutated IgVH was 4.0%, compared to 27.4% among cases expressing unmutated IgVH (p < 0.0001 by the Wilcoxon rank sum test). Median level of CD38 among ZAP-70 negative cases was 5.3%, compared to 27.2% among ZAP-70+ cases (p < 0.0001 by the Wilcoxon rank sum test). Patients with low-level expression of CD38 had a median time to initiation of therapy of 8.2 years; whereas, patients with high-level expression of CD38 had a median time to initiation of therapy of 4.0 years (p<0.0001). Although high-level expression of CD38 was associated with a shorter time from diagnosis to initiation of therapy (p < 0.0001 in a Cox proportional hazards regression), the inclusion of IgVH mutation status (p < 0.0001) or expression of ZAP-70 (p < 0.0001) in these models reduced the contribution of CD38 status to a p-value of 0.051 (ZAP-70 model) or 0.052 (mutation status model). Although ZAP-70 expression and mutation status each contributed significantly to the hazard of initiating therapy in a Cox proportional hazards model, high-level expression of CD38 did not add significantly to the model that already addresses ZAP-70 and mutational status, p=0.425. As such, although knowledge of the CD38 expression level can be used as a predictor of the time from diagnosis to the initiation of therapy it provides only marginal value if either the IgVH mutational status or expression of ZAP-70 is known and no value if knowledge of both ZAP-70 expression and IgVH mutational status is available.

7086 Background: The HRQOL of patients (pts) with chronic lymphocytic leukemia (CLL) has not been adequately delineated across patient, disease and treatment characteristics. We evaluated HRQOL of CLL pts undergoing treatment in the United States (US) by age, gender and line of therapy. Methods: Data were collected in Connect CLL, a prospective observational US registry. Physicians provided data on demographics, clinical characteristics and line of therapy at enrollment. HRQOL was self-reported by pts at enrollment using the Functional Assessment of Cancer Therapy-Leukemia, an instrument that yields a leukemia-specific total HRQOL score (FACT-Leu) and a cancer-specific total HRQOL score (FACT-G). Mean total scores were analyzed by line of therapy, age and gender. Statistical significance was ascertained by ANOVA using SAS 9.2. Multivariate analyses were conducted to assess the relative association of line of therapy, age and gender with HRQOL. Results: Among 1,252 pts enrolled from 161 geographically diverse centers (90% community, 8% academic, 2% veterans/military), pts were predominantly male (63%), white (89%) with mean age 69 yrs. Pts were categorized by line of therapy at enrollment: First 61%, Second 18%, Third 11%, Higher 9%; and by age group: <65 33%, 65-74 35%, 75+ 32%. Univariate analyses suggested that the total FACT-Leu score was significantly better in men than women (P=0.004); in pts aged 65-74 vs younger or older pts (P=0.033); and in pts initiating first-line treatment vs pts receiving subsequent treatments (P=0.0002). Similar results were found with the FACT-G score except that gender differences were not statistically significant. Multivariate analysis confirmed that line of therapy (P=0.007), gender (P<0.0001), and age group (P=0.039) were each associated with significant differences in the FACT-Leu total score. Conclusions: Results from the Connect CLL Registry indicate that HRQOL is better among pts initiating first-line therapy compared to pts initiating subsequent treatments, and that this remains true when age and gender are considered. Future analyses should determine how HRQOL may change over time relative to treatment and treatment response.

TPS8619 Background: Chemoimmunotherapy (CIT) treatment approaches such as FCR have markedly improved outcomes for CLL pts when administered as initial or second-line therapy. Despite this progress, virtually all pts relapse and effective salvage regimens that induce durable remissions or can be administered safely to elderly pts or those with comorbidities are lacking. BTK, an essential mediator of B-cell receptor signaling, is a novel target in CLL. Ibrutinib, a first-in class inhibitor of BTK, promotes apoptosis and inhibits proliferation, migration and adhesion in CLL cells. Phase II data of ibrutinib monotherapy in RR CLL demonstrated an estimated PFS and OS of 75% and 83% respectively at 26 months (Byrd Abst #189 ASH 2012). These findings confirmed BTK as an important target in CLL and supported initiation of a pivotal phase III study in pts with RR CLL/SLL. Methods: PCYC-1112-CA is an ongoing international Phase 3 randomized controlled study of ibrutinib versus ofatumumab for treatment of pts with RR CLL/SLL. The study is enrolling 350 planned pts in 9 countries. Pts are randomized 1:1 to receive ibrutinib 420 mg orally once daily or ofatumumab per the package insert at 300 mg for the first dose, then 2000 mg for a total of 12 doses over 24 weeks. Pts are stratified based on del 17p and disease refractory to purine analogs. Key inclusion criteria include RR CLL/SLL with >= 1 prior line of therapy including pts who experienced a short remission duration to purine analog based CIT, pts who are older or have comorbidities, and pts with del 17p. Pts must have active disease meeting criterion for requiring therapy and measurable nodal disease by CT. Key exclusion criteria include Richter’s transformation, stem cell transplantation within 6 months, GVHD or immunosuppression, platelet count <30,000 cells/ul or use of warfarin The primary objective of the study is PFS evaluated by an IRC. Other outcomes include ORR, OS, hematologic improvement, and safety. An independent DMC is monitoring the study. Clinical trial information: NCT01744691.

8032 Background: Btk supports activation, survival, and proliferation of malignant B cells in CLL and B-NHL. AVL-292 is an oral, potent (IC50 < 0.5nM), selective small molecule covalent inhibitor of Btk. Methods: Patients (pts) with previously treated CLL or B-NHL were administered AVL-292 in escalating cohorts of 125, 250, or 400 mg po QD using a 3+3 design in continuous 28 day cycles until progressive disease (PD) or toxicity. Key objectives were safety, DLT, MTD, PK, and Btk occupancy. Plasma AVL-292 levels were assessed by LC-MS-MS. Btk occupancy by AVL-292 was assessed by covalent probe assay in peripheral blood mononuclear cells. Results: 12 pts have enrolled (3 each at 125 and 250 mg and 6 at 400 mg: 5M/7F; median age 68 years, range 45-79; median 2.5 prior therapies, range 1-10) including 8 CLL (2 with 17p-, 2 with 11q22-, 2 with both 17p-/11q22-; 2 mutated IGHV, 5 unmutated IGHV, 1 missing) and 4 B-NHL (1 diffuse large B cell lymphoma (DLBCL); 1 follicular (FL); 2 marginal zone (MZL)). Median time on treatment is 65 days, range 28-158. Ten of 12 pts continue on treatment: 1 pt (DLBCL) discontinued for PD after 1 cycle and 1 pt (FL) for DLT (Gr 4 plts; 400 mg QD). No other DLTs or grade 4 adverse events (AEs) have occurred and MTD has not been reached. Most frequent AEs reported include transient diarrhea, rash/skin infection, URI, nausea, and fatigue. Gr 3 AEs include 1 atrial fibrillation (not drug related) and 1 ANC low (probably drug related). To date, 8 of 8 CLL patients have stable disease (SD) with median 28% decrease from baseline lymph node measurement (range 3-40% decrease). Six of 8 pts with CLL experienced increased ALC in cycle 1: median increase 89.5% (range 50-212%). Two of 4 NHL pts have SD (both MZL), 1 PD (DLBCL), and 1 not evaluable due to DLT (FL). Full Btk occupancy was achieved with dose levels ≥ 250 mg. Multiple dose PK exposure (AUClast) was linear with no accumulation from Day 1 to 15. Conclusions: AVL-292 was well tolerated from 125-400 mg po QD and early efficacy analysis in CLL and B-NHL shows 10/11 efficacy evaluable pts with SD. Full Btk occupancy was achieved with ≥ 250 mg QD and PK was predictable with no accumulation. Dose escalation is ongoing and MTD cohort expansion is planned.

6122 Background: Clinicians and investigators commonly use ECOG PS and clinician-reported patient (pt) fatigue as surrogates for HRQOL, a multi-faceted construct that comprehensively looks at the pt perspective on disease and well-being. Because limited data exist on the relationships between PS, fatigue, and HRQOL for CLL pts, we examined the associations between these measures, and 3 validated HRQOL instruments: the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu), EQ-5D, and Brief Fatigue Inventory (BFI). Methods: Data were collected in CONNECT CLL, a prospective US observational registry initiated in 2010. Patient demographics and clinical characteristics were provided by clinicians. Patient HRQOL was self-reported at enrollment using the FACT-Leu, EQ-5D, and BFI. Scores were analyzed by ECOG PS (0, 1, 2-4) and clinician-reported fatigue (yes, no). Differences in HRQOL scores were assessed by ANOVA. Results: HRQOL data were reported by 899 pts from 148 community, 10 academic, and 3 government centers. ECOG PS was available on 711 pts. Overall HRQOL, measured by mean FACT-Leu, FACT-G and EQ-5D Visual Analogue Scale (VAS), worsened with ECOG PS severity and was worse in pts with fatigue (all p<0.0001). All FACT-Leu domains except social/family were worse in pts with fatigue and those with higher ECOG PS. Mean EQ-5D pain/discomfort, mobility, self care and usual activities domain scores worsened in severity as ECOG worsened and for pts with fatigue (all p<0.011). BFI data indicated that global fatigue, fatigue severity and fatigue-related interference worsened by ECOG severity and were associated with clinician-reported fatigue (all p<0.0001). Conclusions: Initial CONNECT CLL results confirm that HRQOL worsens with worsening ECOG PS and was worse among pts with fatigue, especially in physical/functioning domains, pain/discomfort, and mobility. These results indicate that baseline ECOG PS and physician-rated fatigue are rapid assessments that predict robust measures of HRQOL. Future analyses are planned to examine how HRQOL, ECOG PS and fatigue change over time with changes in treatment and CLL disease status.

Abstract Introduction: CLL pts who qualify for participation in clinical trials are often thought of as a highly selected population. Therefore whether safety and efficacy data from these trials can be generalized to all CLL pts treated in the community setting is unknown. Prospective, observational studies can provide significant insight into pt and disease characteristics as well as practice patterns in different clinical settings. Here we report on baseline demographics and clinical characteristics for 1495 pts who participated in the Connect CLL observational study and were followed prospectively. Methods: Connect®CLL is a non study-specific intervention treatment registry which collects data on the management and outcomes of CLL pts in clinical, academic and community practices in the US. Clinical information was prospectively collected for pts treated in community (n=1312), academic (n=155), or government (n=28) centers in the US between March 2010 – Jan 2014. Pts eligible for treatment or on treatment not more than 2 months were eligible for enrollment. Here we report on the baseline demographics and clinical characteristics of a large CLL cohort stratified by AG, LOT and type of treatment center. Results: In total,1,495 pts were accrued with a median age at enrollment of 69 (range 22–99). Pts were Caucasian (92.2%), African American (6.9%), and male (63.7%). Median duration from diagnosis until initial therapy was 3.7 years (range 0-32). Age of enrolled pts was as follows; 527 pts age <65 years (AG1; 35%); 511 age 65–75 (AG2; 34%); and 457 age ≥75 (AG3; 31%) at the time of enrollment. Eight hundred and ninety-four pts (60%) were treated with front-line therapy (LOT1); 259 pts (17%) treated with second-line therapy (LOT2); and 342 pts (23%) treated beyond second-line therapy (LOT≥3). Patient age: Pt age was associated with significant variation in several clinical variables: Charlson comorbidity index (CCI) score ≥3 (AG 1-3 35/46/52%; p<0.0001), ECOG PS = 0 (AG1-3 60, 48, 33%, p<0.0001) and mean creatinine clearance (CrCl) decreased (AG 1-3 101/74/53 mL/min; p<0.0001). Line of therapy: Differences in baseline characteristics were observed between pts enrolled at LOT1 (previously untreated) and LOT2/≥3 (relapsed). Median age of pts accrued at LOT1 was 68 vs. 70 years for pts enrolled at LOT2/≥3 (p=0.007). ECOG PS = 0 was more frequent at LOT1 (50%) vs. LOT2/≥3 (42%) (p=0.0057). CCI ≥3 at LOT1 was 41% vs 48% at LOT2/≥3 (p=0.0072). When adjusted for differences in age, logistic regression also demonstrated significant differences in performance status (PS=0; p=0.02) and CCI (p=0.03) stratified by LOT. Treating institution: Baseline characteristics also differed by type of treating institution. Median age was 63 vs 70 at academic vs non-academic (p<0.0001). Pts treated at academic sites also had lower CCI (CCI≤2; 72.9% vs 54.2%, academic vs non-academic) and higher median CrCl (86.4 vs 71.4) (p=0.0017). In this registry, only 16% of patients under age 75 had CCI <= 2, CrCl >= 70 mL/min, ECOG 0-1; 18% of patients on LOT1 and 12% of pts on LOT=2 would satisfy these criteria. They represent 36% of eligible pts from academic treating institutions and 13% from community/government centers. Only 20% of patients on LOT1 would satisfy enrollment criteria for CLL8 (FCR vs. FC; Hallek; Lancet 2010) CLL 10 (BR vs FCR; NCT00769522). which did not have enrollment restrictions for age. Conclusions:Baseline characteristics of pts with CLL vary by age, LOT, and type of treatment center. In this large prospective observational study, our data confirms that older pts typically have a worse ECOG PS, more medical comorbidities, more advanced disease when initiating therapy and a lower probability of being treated at an academic medical center. Based on inclusion criteria used for entry in either CLL10 or CLL8, fewer than 20% of pts satisfy age, renal clearance, and fitness profile to be considered suitable for aggressive chemoimmunotherapy in the front line setting. This observation supports the notion that current clinical trial data might not always be applicable to the general CLL population seen in the community and argues for designing clinical trials that are more generalizable to the broader pt population. Disclosures Sharman: Gilead: Research Funding; Calistoga: Honoraria; Phamacyclics: Honoraria, Research Funding; Celgene: Consultancy, Research Funding; TG therapeutics: Research Funding; Roche: Research Funding. Mato:Millennium: Speakers Bureau; Celgene: Speakers Bureau; Genentech: Speakers Bureau. Kay:Celgene: Research Funding. Kipps:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Lamanna:Genentech-Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Infinity: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Weiss:Celgene: Consultancy; Phamacyclics: Consultancy; Gilead: Consultancy. Nabhan:Celgene: Honoraria, Research Funding. Flinn:Celgene: Research Funding. Grinblatt:Celgene: Honoraria, Speakers Bureau. Kozloff:Celgene: Consultancy. Farber:Alexion: Equity Ownership, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Speakers Bureau; Janssen/Pharmacyclics: Speakers Bureau; Seattle Genetics: Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees. Sullivan:Celgene: Employment, Equity Ownership. Street:Celgene: Employment, Equity Ownership. Swern:Celgene: Employment, Equity Ownership. Flowers:TG Therapeutics: Research Funding; Phamacyclics: Research Funding; Acerta: Research Funding; Abbvie: Research Funding; Infinity: Research Funding; Lymphoma Research Foundation: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Spectrum: Research Funding; Gilead: Research Funding; Genentech: Unpaid consultancy Other; Millennium: Research Funding, Unpaid consultancy, Unpaid consultancy Other; Seattle Genetics: Consultancy; Prescription Solutions: Consultancy; Celgene: Unpaid consultancy Other.

Abstract Obinutuzumab-Gazyva (G) is an anti-CD20 monoclonal antibody that has shown better outcomes in patients (pts) with chronic lymphocytic leukemia and low-grade lymphoma (Goede 2014, Marcus 2017). However, one limitation for its use when compared to Rituximab is the presence of significantly more frequent and more severe infusion related reactions (IRR). Strategies to mitigate this significant adverse event are needed particularly to allow a safer administration of this antibody to elderly pts or those with existing comorbidities. We have observed a reduction of G-induced IRR in previously untreated CLL pts that are enrolled on a phase Ib/II clinical trial (NCT02315768) that combines G with the Bruton's tyrosine kinase inhibitor, ibrutinib (Ibr). Only 5 out of 23 pts treated have developed IRR (Grade 1-2, 17% and Grade 3, 4%). This rate of IRR is much lower as compared with rates previously reported (all grades: 65%, grade 3-4: 20% - Goede 2014), (all grades: 92%, grade 3-4: 26.3% - Freeman,2015). Moreover, there were no pts that require permanent discontinuation of G due to IRR. To understand the biology of this beneficial effect of Ibr, we performed serial cytokine measurements on plasma samples from 23 pts enrolled in this study at different time points during the first week of combined treatment (Cycle 1 prior to the first infusion of G and post G infusion on Day 1, Day 2 and Day 8) - Figure 1. We developed a multiplex assay (Luminex) to measure 7 different cytokines previously reported to be involved in IRR (IFN-g, IL-10, IL6, IL8, CCL3/MIP1-a, CCL4/MIP1-band TNF-a). Standards were set up in duplicate yielding curves from 3.2 pg/ml to 10.000 pg/ml. Assays were performed according to manufacturer's instructions, with undiluted samples and overnight agitated incubation at 4 °C. We identified the maximum peak of cytokine levels post G infusion and compared those values with the baseline cytokine profile obtained prior to the first G infusion on Cycle 1 Day 1. The majority of pts (22 out of 23) showed cytokines maximum peaks in the middle of G-infusion during Cycle 1 Day 1 and this correlated with the onset of IRR associated symptoms in those pts that reacted to G. With the exception of IL-6, we observed statistically higher post vs. pre G infusion levels of TNF-a(p=0.0012), IFN-g(p=<0.0001), CCL3 (p=0.0458), CCL4 (p=<0.0001), IL-8 (p=<0.0001), and IL-10 (p=<0.0001) even in pts that did not develop IRR. However, the post infusion peak levels of TNF-a(p=0.0043), IFN-g(p=0.0457) and CCL3 (p=0.0460) were significantly higher in pts with IRR compared to those that had no IRR. Baseline levels prior to G infusion of TNF-a(p=0.0495) and IFN-g(p=0.0301) were higher in IRR pts, suggesting a possible predictive role in the development of IRR. Figure 1. Our study shows that concurrent administration of Ibr (Initiated on Cycle 1 Day 1 with pre-medications) and G shows a beneficial effect decreasing the rates of IRR (Amaya-Chanaga, 2016). All pts showed a significant increase of cytokine levels post G infusion with IL-6 levels being the exception. When we compared post G infusion cytokine levels, we observed that IRR-pts had a significant increase in TNF-a, IFN-g, and CCL3 suggesting a role of these cytokines in the clinical manifestations associated with IRR. In addition, higher levels of TNF-a and IFN-g, at baseline prior to G infusion appear to be predictive of the development of IRR. Even though our sample size is small, our observations provide additional insights into the biology of G associated IRR and how to decrease effectively those adverse events using Ibr while preserving the immune function needed for the activity of this monoclonal antibody. In addition, Ibr induced modulation of signaling through the B cell receptor and patterns of cytokine release might be efficacious in preventing other monoclonal antibody IRR as well as those reactions observed in pts that receive adoptive cellular therapy (i.e. CART cell treatment). Disclosures Choi: AbbVie, Inc: Consultancy, Speakers Bureau; Gilead: Speakers Bureau; Genentech: Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Rigel: Consultancy. Amaya-Chanaga:AbbVie: Equity Ownership, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.; Pharmacyclics, an AbbVie Company: Employment, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.. Kipps:Celgene: Consultancy; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech Inc: Consultancy, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees. Castro:F. Hoffmann-La Roche: Consultancy; Genentech, Inc: Consultancy; Pharmacyclics, LLC, an AbbVie Company:: Consultancy.

Abstract Standard treatment for patients with chronic lymphocytic leukemia (CLL) is rapidly evolving and gradually has incorporated the combined use of monoclonal antibodies (mAbs) and targeted therapy with small molecules. Single agent Ibrutinib (Ibr), a first-in-class BTK inhibitor, is effective in previously untreated patients including those that are older than 65 or considered unfit to receive chemotherapy-based combinations. The complete response rate in patients receiving single agent Ibr is relatively low (overall response rate of 86% and complete response of 4% based on 2008 iwCLL criteria), though most patients have durable remissions. The combination of Ibr with mAbs like Obinutuzumab-Gazyva (G), a third-generation anti-CD20 mAb, can ameliorate the Ibr-induced lymphocytosis and increase the overall and complete response rates. Accordingly, we initiated an open-label phase Ib/II clinical study of Ibr in combination with G for first-line therapy of previous untreated pts with CLL. The study completed enrollment of 32 previously untreated patients with CLL. Patients received G administered based on FDA dosing recommendations for 6 cycles (28 days/cycle) and Ibr 420mg po (1-3 hours before starting G infusion), and daily for up to 3 years. All patients received prophylactic medications. Patients were assessed for response by 2008 iwCLL criteria two months after completion of G, as the primary efficacy endpoint. The median age of the patients was 65 (range: 46-78) years. 84% of the patients had a CIRS >6, 45% had a Rai stage III-IV and 19% had an ECOG performance ≤2. The median baseline absolute lymphocyte count (ALC) was 79x103/mm3(range: 1.4-412.4). Patients showed the following FISH/cytogenetic abnormalities: del(13q) in 55%, trisomy 12 in 23% and del(11q) in 19%. Only 2 (6%) of these patients showed del(17p). From the patients with IGVH mutational status available (n=17), 11 (65%) were unmutated (>98% homology). Most adverse events (AEs) were grade 1-2 (74%). Six patients (19%) had grade 1-2 G-infusion-related reaction (IRR) and only one patient (3%) showed grade 3 IRR (without the need for G discontinuation). We observed neutropenia (all grades: 52%, grade 3-4: 23%), thrombocytopenia (all grades: 71%, grade 3-4: 19%) and anemia (all grades: 26%). There were no cases of febrile neutropenia. Two patients (6%) had grade 1 bleeding (one patient with asymptomatic lower gastrointestinal bleeding and the second patient with epistaxis) that resolved spontaneously without requirement of blood transfusion or study treatment discontinuation. Two patients (6%) developed pneumonia, one was community-acquired pneumonia requiring inpatient treatment with IV antibiotics; the study treatment was held until resolution of symptoms and re-initiated at full dose. The most frequent non-hematological AEs were diarrhea, transaminitis, hyperbilirubinemia, hyperglycemia, and electrolyte alterations (grade 1-2). Three patients (9%) discontinued Ibr due to atrial fibrillation grade 1 (n=1), rash and headaches grade 2 (n=1), and persistent grade 4 thrombocytopenia (n=1). Twenty-three patients were evaluable for response assessment by 2008 iwCLL criteria (median follow-up of 11 months). 84% of the patients showed a rapid decrease in ALC from baseline during the first cycle of treatment and only four patients (13%) required more than 3 cycles of treatment to achieve an ALC response. The overall response rate was 100%. The majority of pts had a partial response and six of 23 evaluable patients (26%) achieved a complete remission with detectable Minimal Residual Disease in the bone marrow by multiparametric flow cytometry. In summary, Ibr-G combination has been generally well tolerated. AEs have been consistent with the known safety profiles of Ibr and G individually. The patients that discontinued Ibr remain in follow-up without disease progression. 100% of evaluable patients achieved response after 6 months of combination therapy, and 26% of patients met CR criteria. One important finding thus far has been a very low rate of IRR, (19% grade 1-2 and 3% grade 3-4), suggesting that Ibr can strongly mitigate the incidence and severity of G associated IRR. Disclosures Choi: AbbVie, Inc: Consultancy, Speakers Bureau; Rigel: Consultancy; Gilead: Speakers Bureau; Pharmacyclics: Consultancy, Research Funding, Speakers Bureau; Genentech: Speakers Bureau. Amaya-Chanaga:AbbVie: Equity Ownership, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.; Pharmacyclics, an AbbVie Company: Employment, Other: Research performed while employed as an investigator of this study at UCSD. Review and approval of abstract performed while employed at Pharmacyclics, LLC, an AbbVie Company.. Kipps:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Celgene: Consultancy; Verastem: Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Research Funding; Genentech Inc: Consultancy, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Membership on an entity's Board of Directors or advisory committees. Castro:F. Hoffmann-La Roche: Consultancy; Genentech, Inc: Consultancy; Pharmacyclics, LLC, an AbbVie Company:: Consultancy.