Abstract: Introduction: Ibrutinib is a first-in-class small molecule inhibitor that binds irreversibly to Bruton's Tyrosine Kinase (BTK) and has shown remarkable efficacy in the treatment of CLL. Current guidelines recommend life-long therapy with administration at a fixed daily dose of 420 mg. However, lower doses of ibrutinib have been demonstrated to adequately abrogate kinase function. Limited clinical data suggests that dose reductions are not associated with inferior outcomes. Hypothetically, judicious dose reductions to manage toxicities could result in improved tolerance and decreased discontinuation rates. Our objective was to study the impact of dose reductions on outcomes in CLL patients treated with ibrutinib in a real-world setting. Methods: We conducted a retrospective chart review of all CLL patients treated with ibrutinib at Roswell Park Comprehensive Cancer Center between January 2014 and June 2017. Patients who underwent ibrutinib dose reduction were identified. Baseline characteristics and outcomes were compared between patients who underwent dose reductions vs those who did not. Reason and timing of dose reduction was also elucidated. Mann-Whitney U and Fisher's Chi Square test were used to compare groups, Kaplan Meier methods were used for time to event analysis, and Cox regression was used to obtain hazard ratios (HR). Overall survival (OS) was calculated as time from start of ibrutinib until death or last follow-up, freedom from progression (PFS) was taken as time from start of ibrutinib until progression or last follow-up. All analyses were performed in SAS v9.4 (Cary, NC). Results: A total of 70 CLL patients treated with ibrutinib were followed for a median period of 21.9 months. Most patients had RR disease (n = 63) and 7 received ibrutinib as frontline therapy. All patients received a fixed dose regimen with the standard dose of 420 mg once daily. Twenty-three (31.3%) patients required dose reductions and received ibrutinib at a median dose of 140 mg . Eleven (47.8%) of these had dose reductions within 3 months of treatment initiation. There was no statistically significant difference in baseline characteristics including age, number of prior lines of treatment, WBC count, hemoglobin or LDH level in the dose reduced group (DRG) and standard dose group (SDG). Patients in the DRG had a lower median platelet count at initiation of ibrutinib than patients in the SDG (86 x 103/mm3 vs 145 x 103/mm3, p 〈 0.05). The most frequent reasons for dose reductions included cytopenia (n=8), fatigue (n=5), infections (n=4) and atrial fibrillation (n=3) with 2 patients requiring dose reduction due to simultaneous CYP inhibitor administration. There was no statistically significant difference in the overall response rate (ORR) (p=0.25) and clinical benefit rate (CBR) (p=1.00) between the DRG (ORR- 65.2%, CBR- 91.4%) and SDG (ORR 78.7%, CBR 91.5%). Median PFS and OS was not reached in both groups. PFS at 12 months was 86% (95% CI 63-95%) and 87% (95% CI 71- 94%) in the DRG and SDG respectively (p=0.92). OS at 12 months was 83% (95% CI 60-93%) and 84% (95% CI 69-92%) in the DRG and SDG respectively (p=0.53). We noticed no statistically significant difference in the median PFS and OS between the two groups (Figure 1). In a subgroup analysis, we compared outcomes in patients in the SDG with those who had dose modifications within 3 months of initiating therapy or later and found no statistically significant differences in OS and PFS between the groups (p=0.15 and p=0.46 respectively). Of the 23 patients requiring dose modifications, 11 (47.8%) had to eventually discontinue therapy as compared to 17 (36.2%) patients in the SDG and we noticed similar 1-year discontinuation rates in the DRG and SDG groups (22% vs 21% respectively, p=0.91). Conclusion: In CLL patients treated with ibrutinib, reductions in the dose of ibrutinib were not associated with worse outcomes. These results extended to all patients with dose modifications, irrespective of whether the modification was made within 3 months of treatment initiation, or later in the course of treatment. Disclosures No relevant conflicts of interest to declare.

Abstract: Thrombocytopenic thrombotic purpura (TTP) and hemolytic uremic syndrome (HUS) form a group of diseases distinguishable by the development of thrombotic microangiopathy. Both are life-threatening disorders classically described by a pentad of symptoms: microangiopathic hemolytic anemia, thrombocytopenia, fever, renal failure and altered mental status. Early initiation of plasma exchange (PEX) is vital when TTP/HUS is suspected. However, diagnostic criteria are imprecise and clinical judgment remains the primary impetus for initiation of treatment. ADAMTS13 levels have not proven to be highly specific or sensitive for diagnosis of outcomes in TTP/HUS, and the delay in laboratory reporting limits its use in the acute setting. There may be other data available that more closely correlates with prognosis. The goal of this single institution retrospective study is to assess (i) the association of easily available clinical and laboratory factors with early death in patients with clinically diagnosed TTP/HUS, and (ii) the association of these factors among survivors with the length of stay (LOS) during the initial hospitalization with TTP/HUS. Design and methods After IRB approval, medical record review of adult patients at a single tertiary medical center treated with plasma exchange (PEX) for presumed TTP/HUS between 1999 and May 2013 was performed. For the 62 discrete cases identified, demographic and clinical data was obtained from the medical center and pertinent information was collected. Descriptive analysis was used to evaluate clinical symptoms and laboratory biomarkers with respect to their associations with survival. Episodes of TTP/HUS in the same patient were considered discrete if they occurred greater than 3 months apart. Survival was defined by hospital discharge without readmission for TTP/HUS or their sequelae for 3 months following discharge. The association of demographic factors (age, gender), symptoms (fever, neurologic changes, abdominal pain), and laboratory factors (hemoglobin [Hb], white blood cell count [WBC] , platelet count, acute kidney injury [AKI] based on creatinine, AST, ALT, lactate dehydrogenase (LDH), indirect bilirubin, prothrombin time (PT), partial thromboplastin time (PTT), reticulocyte count) with survival during the first 3 months was studied using univariate analysis. ADAMTS13 levels were not included in analysis as the decision to treat with PEX was made in all cases prior to knowledge of any deficiency. All factors that attained a p value of, 〈 = 0.1 were analyzed collectively using logistic regression with backward model selection. For survivors (n=49), the association with length of stay was compared with each of the above factors and was similarly studied using univariate analysis and multiple linear regression. Results In our sample (n=62), median age was 48 years and 26 (42%) were male. Of these, 79% (n=49) survived to discharge and did not have relapse or known death until 3 months afterwards. Thirteen (21%) died during hospitalization or within 3 months after discharge. There were 55 TTP and 7 HUS patients included in this retrospective cohort. Acute kidney injury (AKI) was diagnosed in 44 (71%) patients. On univariate analysis, factors associated with death included: AST (p=0.009) and AKI (p=0.045) with trends noted for hemoglobin (p=0.080) and PT (p=0.078). On multiple logistic regression, association with death was observed with AKI (OR: 0.093, 95% CI 0.009 – 0.950, p= 0.04) and hemoglobin (OR: 0.65, 95% CI 0.434 – 0.975, p=0.037). Among the 49 survivors (median age 45.1, range 12-81 years; 28 (57%) were female), correlation of the LOS in hospital with all variables was assessed. On linear regression analysis, elevated white blood cell count (WBC) (p=0.027) and prolonged prothrombin time (PT) (p=0.035) were independently associated with prolonged hospitalization. Conclusion Clinical and laboratory markers found to have an independent association with death are AKI and low hemoglobin. It may be possible to risk stratify patients more accurately with clinical algorithms based on this evidence even before ADAMTS13 levels are available. Increased WBC count and prolonged PT are independently associated with increased length of stay. The application of our results could therefore be used for further risk stratification in prospective studies of outcomes in patients diagnosed with TTP/HUS. Disclosures: No relevant conflicts of interest to declare.

Abstract: Background: The spectrum of FL varies from an indolent disease course spanning decades to early transformation and death. Longitudinal studies have identified a subset of high risk patients (pts) who progress within 24 months of frontline therapy. It is still unclear how best to treat these patients and as yet, there is no standard 2nd line therapy for FL. Given the multitude of treatments available and the heterogenous disease course, it is challenging to compare outcomes of 2nd line therapy. It is unclear if the efficacy of second-line therapy in FL is influenced by the type of therapy, disease biology (early vs. late progression) or both. We conducted a single institute, retrospective study to determine the clinical benefit of 2nd line therapy in FL and to evaluate if any particular type of therapy was associated with improved outcomes in FL patients with early progression (EP). Methods: All patients with relapsed/refractory FL treated at our Institute between 1990 and 2014 were included. Patients were included if they received anti-CD20 monoclonal antibody (mAb)-based therapy in the first-line setting and completed both, first-line and second-line therapy at our Institution. Demographic, clinical, pathological and outcomes data was collected by retrospective chart review. Clinical endpoints included overall response rate (ORR), progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS). Treatments were divided in two groups for comparison: immunotherapy alone (anti-CD20 mAb) (IT) or chemo-immunotherapy (CIT). Differences in clinical outcomes were analyzed between FL patients with early progression after 1st line therapy (EP, i.e. progression ≤ 2yrs) vs. FL with late relapse (LP, i.e. progression 〉 2yrs). Comparisons were made using the Mann-Whitney U and Person chi-square tests as appropriate. Survival outcomes were assessed using standard Kaplan-Meier methods. All analyses were conducted in SAS v9.4 (Cary, NC) at a significance level of 0.05. Results: A total of 537 newly diagnosed FL pts were identified of which 291 pts received 1st line therapy at our Institute. IT or CIT was given to 19.6% and 80.4% pts respectively. IT treated pts were older (median age: 61y vs 57y, p=0.033) and had lower FLIPI scores (1.5 vs 2.1, p 〈 0.001) than CIT treated pts. Disease progression requiring 2nd line therapy was observed in 108 of 291 pts (36.4%) , 64 (59.3%) of which had EP vs 44 (40.7%) had LP. Baseline characteristics including age, gender and FLIPI scores were similar between EP and LP groups. ORR to 2nd line therapy was similar between EP and LP pts (64.3 vs. 78%, P=0.53). After a median follow up of 89.5 months (mo), the PFS, TTNT and OS of pts requiring 2nd line therapy was 14.3 mo, 17.5 mo and 92.9 mo respectively. Pts with EP had a significantly lower PFS (6.6 vs 32.8 mo, p 〈 0.001) and TTNT (11.7 vs 36.2 mo, p 〈 0.001) compared to LP pts with no difference in OS (77 vs 132 mo, p=0.36) [Figure 1]. Among pts with EP receiving 2nd line therapy, there were no differences between IT and CIT in terms of PFS (9.3 vs 6.4 mo, P=0.50) or TTNT (15 vs 11.6 mo, P=0.59). The OS was better in IT vs CIT (NR vs 47.6 mo, p=0.036) but has to be interpreted in the context of most pts (except one) in each group going on to receive subsequent therapies [Figure 2] . Of interest, the ORR of 2nd line therapy among pts with LP was excellent regardless of the use of IT or CIT (90.4 vs 100%, P=0.07). Moreover, in pts with LP, there were no difference in PFS (29.4 vs 32.8 mo, p=0.83), TTNT (102 vs 36.2 mo, p=0.96) and OS (132 vs 93 mo, p=0.34) based on the choice of 2nd line therapy (IT or CIT) [Figure 3]. Conclusion: FL pts with LR have excellent outcomes to 2nd line therapy and treatment selection could be determined by the agent(s) toxicity profile. In contrast, EP predicts poor clinical outcomes with short duration of response to standard IT or CIT. Therapeutic approaches incorporating clinically available targeted agents (i.e. immunomodulatory agents of B-cell receptor signaling inhibitors) or novel agents in the context of clinical trials, may provide a more effective disease control in this subgroup. Disclosures No relevant conflicts of interest to declare.

Abstract: Introduction: T-cell lymphomas (TCL) are a heterogenous group of lymphoid malignancies that account for 10-15% of all lymphoproliferative disorders. Histological bone marrow involvement (BMI) ranges between 20-40% of all TCLs at time of diagnosis with bone marrow aspirate and biopsy (BMAB) considered the gold standard test to detect BMI. 18-Fluoro-deoxyglucose positron emission tomography combined with computed tomography (PET-CT) is a standard pretreatment imaging in the staging of TCL. In other lymphomas like DLBCL, PET-CT may obviate the need for BMAB as a component for staging, but this has not been studied in TCL. The aim of this retrospective study is to determine the accuracy of PET-CT in detecting BMI in newly diagnosed TCL. Methods: This is a single institution retrospective medical chart review study. All TCL patients(pts) diagnosed at Roswell Park Cancer Institute between January 2003 to December 2017 and underwent pre-treatment PET-CT and BMAB were included. PET-CT images were visually assessed for BMI. We excluded cases in which BMAB specimens were qualitatively and/or quantitatively insufficient to determine the presence or absence of BMI. Ann Arbor staging was determined using PET-CT and BMAB and the proportion of patients upstaged to Stage IV due to BMI detected by either modality was calculated. The BMAB and PET-CT results were summarized using a 2x2 contingency table. The performance of the PET-CT was evaluated using the sensitivity, specificity, positive predictive value, and negative predictive value. Confidence intervals for these measures were obtained using Jeffrey's prior method. Results: In total 89 pts were included in the analysis. Median age at time of diagnosis was 60 (range 20-92), 52 were male (58%), 20 had elevated LDH (22%), 7 had ECOG greater or equal to 2 (8%), 66 had an IPI score 0-2 (74%) and 23 had an IPI score 3-4 (26%), 7 had 〉 2 extra-nodal sites of involvement (8%). In total, 38 pts (42.6%) had BMI at time of diagnosis, established by either BMAB (n= 25; 28%), PET-CT (n=13; 15%) or by both modalities (n=10 pts; 11%). There were 15 pts (17%) that were negative for BMI on PET-CT but had positive involvement of TCL on BMAB. The sensitivity and specificity of PET-CT to detect BMI by TCL was 40% (95% CI 22.7, 59.4) and 95.3% (95% CI 88.0, 98.7), respectively. Seventy-one pts (79.7%) had concordant results between lymphomatous BMAB and PET-CT (10 pts were positive for both, 61 pts were negative for both) and 18 pts (20.2%) had discordant interpretation (15 pts were negative by PET-CT and positive by BMAB and 3 pts were negative by BMAB and positive on PET-CT). BMAB upstaged 4 out of the 32 (12.5%) stage I-II pts to stage IV; out of these only 1 patient had positive BMI detected by PET-CT. The positive predictive value of PET-CT for detecting BMI was found to be 76.9 % (50.3, 93.0) with a negative predictive value of 80.3 % (70.3, 88.0) (Figure 1). Conclusion:In our cohort of TCL pts, staging PET-CT does not identify all cases with BMI. BMAB upstaged more pts with Stage I/II to Stage IV than PET-CT. Although PET-CT has high negative predictive value for ruling out marrow involvement by TCL, BMAB remains a necessary component in the evaluation of pts with newly diagnosed TCL because of its ability to detect lymphomatous involvement of bone marrow missed by PET-CT which has implications in staging and treatment of TCL. Disclosures No relevant conflicts of interest to declare.

Abstract: Background: Oral targeted therapies (OTT) have transformed the care of patients with non-Hodgkin lymphoma (NHL) with significantly improved survival outcomes compared to chemo-immunotherapy. While data from clinical trials suggest improvement in global health and some symptom scores, there is limited data on health-related outcomes in older adults who are more vulnerable to treatment-related adverse effects. Geriatric assessments can predict chemotherapy-related toxicity in older adults and the presence of geriatric impairments is associated with inferior quality of life. The role of geriatric assessment (GA) in predicting health-related quality of life (HRQoL) and treatment toxicity in patients with NHL on OTT is unknown. In this prospective study, we describe the association between OTT and HRQoL in older adults with NHL. We further describe the relationship between baseline geriatric assessment and longitudinal HRQoL parameters. Methods: We included patients (pts) ≥70 years (yrs) of age with NHL, initiating or already receiving OTT. A GA, including assessment of function, depression, cognition, physical performance and comorbidities, was performed at baseline. Pts were followed monthly for the first 3 months (mos), then every 3 mos for 1 year. Quality of life (QoL) was measured at each visit using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaires Core 30 (EORTC QLQ-C30) and EORTC QLQ - chronic lymphocytic leukemia 16 (EORTC QLQ-CLL16). The log QoL scores were modeled as a function of visit and mean scores at 6 months were compared to baseline using a linear mixed model. A change in score of & gt;10 was considered clinically significant based on previous work. Results: We enrolled 25 pts with a median age of 77 yrs (71-93 yrs). Median follow up was 6.3 mos (range, 2.7-8.8 mos). The most common diagnosis was chronic lymphocytic leukemia (n=21) followed by mantle cell lymphoma (n=3) and marginal zone lymphoma (n=1). Most pts (72%) were on OTT at study entry and the most frequently used OTTs were ibrutinib (n=17) and venetoclax (n=5). GA revealed the presence of a geriatric syndrome (GS) in more than 90% of pts, including cognitive impairment (28%), depression (24%), polypharmacy (92%) and recent falls (12%); 48% of pts had ≥2 GS. Nine pts (36%) had impaired 4-meter gait speed and/or timed-up-and-go (TUG); 20 pts (80%) had an adjusted CIRS-G score of ≥6. At baseline, dependence in independent activities of daily living (IADL) was associated with inferior global health status scores (69.1 vs 86.1, p=0.023) and physical functioning scores (66.7 vs 88.1, p=0.008). Similarly, an abnormal TUG ( & gt;10 seconds) was associated with a lower global health score (71.3 vs 86.1, p=0.037). Dependence in 2 or more activities of daily living (ADL) was also associated with lower baseline physical functioning scores (57.8 vs 88.0, p=0.003) and role functioning scores (61.1 vs 90.8, p=0.030). During the 6-month follow up, there was significant worsening of global health status (mean difference -5.4, p=0.024) and cognitive functioning scores (mean difference -9.6, p & lt;0.001) in the entire cohort. There were no changes in other functional scales (physical, role, emotional and social functioning, fatigue scale, infection scale, social problems and future health) over time (Figure 1). Trends in symptom scores were mixed with improvement in some scores (pain, fatigue) and worsening of others (dyspnea, diarrhea, constipation), none of which met the predefined criteria for clinical relevance (absolute difference of & gt;10). Presence of various geriatric impairments at baseline did not impact changes noted in global health, physical, emotional, social and role functioning over time. Interestingly, we found a greater improvement in symptom scores in patients with baseline impairments in IADL (fatigue, pain), ADL (pain) and a CIRS-G score of ≥6 (insomnia). Conclusion: The presence of geriatric syndromes is common in older adults with NHL with almost half of the patients in our cohort with ≥2 GS. Older adults with GS had lower baseline global health status and physical functioning scores but experienced greater improvement in symptoms scores and maintenance of longitudinal HRQoL than those without GS at baseline. Chronological age had no impact on baseline or longitudinal HRQoL, underscoring the need to incorporate GA into clinical practice rather than relying on age alone. Figure 1 Figure 1. Disclosures Wildes: Janssen: Consultancy; Carevive: Consultancy; Seattle Genetics: Consultancy; Sanofi: Consultancy. Torka: TG Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Abstract: Introduction The treatment of aggressive B-cell NHL has evolved rapidly over the last 5 years, owing to the FDA approval of 3 CD19 CAR T-cell constructs (CARTs) along with other novel targeted therapies. Real world practice data suggest that CARTs have been successfully administered in populations typically excluded from clinical trials. However, data on how to best utilize novel targeted agents as a pathway to CARTs and feasibility of CARTs in rare histologies remains limited. This retrospective multicenter study describes patient (pt) selection and practice patterns in pts treated with CD19 CARTs and provides insight on feasibility of CARTs in special populations. Methods Adult pts with R/R aggressive B-cell NHL treated with CD19 CARTs between 2015- 2020 across 12 US academic centers were identified. Data on demographic and clinical characteristics, disease and toxicity outcomes were collected. Univariate analyses (UVA) were performed to determine impact of demographic/clinical variables on survival. Survival curves were calculated using Kaplan-Meier method. Subgroup analysis was performed for pts with secondary central nervous system lymphoma (sCNSL). Results Clinical and demographic features were recorded from 400 pts (Table 1). Median age was 59 years (range 18-84). Of 271 pts with immunohistochemistry data, 79 (29%) had double-expressor lymphoma. Of 178 pts with FISH data captured, 62 (35%) had double/triple-hit lymphoma. Most common histological subtypes included 271 (68%) pts with de novo DLBCL, 81 (20%) with transformed FL, 13 (3%) with Richter's syndrome, and 8 (2%) with PMBCL. Rare histologies included 7 (2%) with transformed MZL, 5 (1%) with PTLD and 2 (0.5%) with grey zone lymphoma. 24 (6%) pts had sCNSL at time of CART apheresis. Two (0.5%) pts were HIV-positive. Median number of lines of therapy prior to CART was 2 (range 1-8); 182 (46%) pts received ≥ 3 lines. 114 (28%) pts previously had an autologous stem cell transplant. Targeted therapies used as salvage regimens at any point prior to CART are listed in Table 2: commonly used salvage targeted therapies included lenalidomide based therapy (imids, n=37, 9%), BTK inhibitors (BTKis, n=30, 8%), checkpoint inhibitors (CBIs, n=17, 4%) and polatuzumab-containing regimens (n=10, 3%). 2 (1%) pts received loncastuximab, and no pts received tafasitamab. Six (1.5%) pts proceeded to CART despite complete response to most recent pre-CART therapy. 191 (48%) pts received bridging between apheresis and CART infusion, choice of bridging noted in Table 2: the majority received chemotherapy (n=103, 54%); 28 (15%) received radiation (XRT); 25 (13%), 24 (13%) and 18 (9%) pts received imids, polatuzumab-containing regimens, or BTKis, respectively. With median follow-up of 22.4 months (mo) for the overall group, median (m) PFS was 11 mo (n=363); mOS, was 27 mo (n=397; Fig 1). Pts with sCNSL had a mPFS and mOS of 2 and 4 mo, respectively (Fig 1). On UVA, factors predicting poorer PFS and OS in the overall group included ≥3 pre-CART lines (p & lt;/= 0.004), use of bridging (p & lt;/=0.001), IPI 4-5 at apheresis (p=0.014), LDH elevation at apheresis (p=/ & lt;0.001), and sCNSL (p & lt;/= 0.013). For outcomes according to bridging regimens: mPFS after CART for most commonly used systemic bridging therapies was 86 days (d) for platinum-based chemotherapy, 77 d for imids, 90 d for BTKis, 98 d for polatuzumab-bendamustine/rituximab, and 274 d for XRT. Median PFS for XRT bridging (274 d) was statistically better when compared to mPFS for listed systemic therapies combined (p & lt;0.05) (Fig 2). Conclusion Survival outcomes with CARTs in our data set are consistent with those reported in clinical trial settings. CARTs are utilized in real world practice in rare subsets of aggressive R/R B-cell NHL not routinely included in clinical trials. Despite early data suggesting pts with sCNSL benefit from CART, our data suggest outcomes with CART are dismal in this group. Targeted therapies including imids, polatuzumab, BTKis and CBIs are feasible choices for salvage and/or bridging as a pathway to CARTs. Bridging with XRT resulted in improved mPFS post CART as compared to bridging with systemic therapies and suggests differences in pt selection for each with systemic therapies likely favored in those with more widespread disease burden. Minimal use of CD19-targeted agents pre-CART is attributed to later approval of these agents and concern for potential loss of CD19 antigen leading to CART resistance. Figure 1 Figure 1. Disclosures Cohen: Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo, BeiGene, Adaptive: Consultancy; Genentech, BMS/Celgene, LAM, BioINvent, LOXO, Astra Zeneca, Novartis, M2Gen, Takeda: Research Funding. Shouse: Kite Pharma: Speakers Bureau; Beigene: Honoraria. Hess: ADC Therapeutics: Consultancy; BMS: Speakers Bureau. Stephens: Beigene: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Epizyme: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Arqule: Research Funding; Mingsight: Research Funding; JUNO: Research Funding; Celgene: Consultancy; CSL Behring: Consultancy; AstraZeneca: Consultancy; Abbvie: Consultancy; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ma: Loxo: Research Funding; AstraZeneca: Honoraria, Research Funding, Speakers Bureau; Juno: Research Funding; Beigene: Research Funding, Speakers Bureau; Abbvie: Honoraria, Research Funding; Janssen: Research Funding, Speakers Bureau; TG Therapeutics: Research Funding; Pharmacyclics: Research Funding, Speakers Bureau. Winter: BMS: Other: Husband: Data and Safety Monitoring Board; Actinium Pharma: Consultancy; Janssen: Other: Husband: Consultancy; Gilead: Other: Husband: Consultancy; Agios: Other: Husband: Consultancy; Epizyme: Other: Husband: Data and Safety Monitoring Board; Merck: Consultancy, Honoraria, Research Funding; Novartis: Other: Husband: Consultancy, Data and Safety Monitoring Board; Ariad/Takeda: Other: Husband: Data and Safety Monitoring Board; Karyopharm (Curio Science): Honoraria. Gordon: Zylem Biosciences: Patents & Royalties: Patents, No royalties; Bristol Myers Squibb: Honoraria, Research Funding. Danilov: Astra Zeneca: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding; Takeda Oncology: Research Funding; TG Therapeutics: Consultancy, Research Funding; Abbvie: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria; Gilead Sciences: Research Funding; Bristol-Meyers-Squibb: Honoraria, Research Funding; Rigel Pharm: Honoraria; Bayer Oncology: Consultancy, Honoraria, Research Funding; SecuraBio: Research Funding. Shah: Umoja: Consultancy; Legend: Consultancy; Kite: Consultancy; Miltenyi Biotec: Consultancy, Honoraria, Research Funding; Lily: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy; Incyte: Consultancy. Barta: Seagen: Honoraria; Daiichi Sankyo: Honoraria; Acrotech: Honoraria; Kyowa Kirin: Honoraria. Epperla: Genzyme: Honoraria; Karyopharm: Other: Ad Board; Beigene: Speakers Bureau; Verastem: Speakers Bureau. Torka: TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Karmali: Epizyme: Consultancy; BeiGene: Consultancy, Speakers Bureau; EUSA: Consultancy; Roche: Consultancy; AstraZeneca: Speakers Bureau; Morphosys: Consultancy, Speakers Bureau; Karyopharm: Consultancy; Takeda: Research Funding; BMS/Celgene/Juno: Consultancy, Research Funding; Janssen/Pharmacyclics: Consultancy; Genentech: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau.

Abstract: Background: Pre-clinical studies have shown that host immune system activation by G-CSF/GM-CSF enhances the biologic activity of rituximab through up-regulation of CD11b/18 expression on neutrophils, increase in the number of circulating granulocytes and higher CD20 epitope density on tumor cells. To further explore the role of augmenting neutrophil function in B-cell lymphoma, we conducted an open-label, single-arm, phase II study evaluating the safety and clinical efficacy of peg-filgrastim and rituximab in patients with low-grade CD20 positive B-cell Non-Hodgkin lymphomas (B-NHL) [chronic lymphocytic leukemia (CLL), follicular lymphoma (FL) and marginal zone lymphoma (MZL)]. (NCT01682044) Materials and methods: Twenty patients with untreated or relapsed/refractory indolent lymphoma were treated with rituximab (375 mg/m2) every other week for 4 doses, and after 8 weeks every 2 months for 4 additional doses (total 8 doses). Peg-filgrastim (6mg) was administered subcutaneously 3 days before each dose of rituximab. Clinical responses and tolerability were examined according to standard international criteria. Biologic monitoring included evaluation of phenotype characteristics of host neutrophils, changes in oxidative burst, and in vitro functional assays including CMC and ADCC at baseline and before each dose of rituximab. Results: Baseline patient characteristics were as follows: Median age: 64 (28-86) yrs; 70% male; FL: 70%, CLL: 20%, MZL: 10%; Ann-Arbor stage- II- 10%, III- 30% and IV- 60%; disease status- newly diagnosed: 1, rituximab refractory: 2, relapsed ≥1 line of therapies: 17. Median number of prior therapies was 2 (1-5); 75% had previously received rituximab and 90% had received prior anti-CD20 monoclonal antibody therapy. The addition of peg-filgrastim to rituximab was well tolerated, and did not increase the frequency or severity of rituximab-related toxicities. Most of the adverse events were grade 1-2 infusion-related toxicities. One patient developed grade 4 hyperuricemia. One patient with MZL died while on treatment due to disease progression. The overall response rate (ORR) was 60% (12/20) with a complete response (CR) rate of 35% (7/20). Median progression-free survival (PFS) was 17.9 months (95% CI- 9.9-27.6 months); median overall survival (OS) was not reached. A shorter time-to-peak oxidative burst after first dose of peg-filgrastim was associated with higher rates of CR (p= 0.04) and longer PFS (p=0.03, figure 1). Though intensity of peak oxidative burst did not correlate statistically with outcomes, patients who achieved CR (and OR) had consistently higher free radical levels compared to those who did not, especially during the first 2 months of treatment. This trend waned during the latter part of therapy suggesting neutrophil exhaustion. Further analyses are ongoing to evaluate the association between rituximab ex vivo immunological assays and clinical endpoints outcomes. Conclusion: The combination of peg-filgrastim and rituximab was well tolerated with favorable response rates and PFS compared to historical controls treated with single-agent rituximab. Augmented neutrophil function was associated with higher CR rates and OS. Our results support further evaluation of strategies that enhance the innate immune system to improve rituximab activity in B-cell lymphoma. Disclosures Off Label Use: Pegfilgrastim has been combined with rituximab in this phase 2 study for treatment of indolent B-cell Non-Hodgkin lymphoma.. Czuczman:Celgene: Employment; Immunogen: Other: Advisory board; MorphoSys: Consultancy; Boehringer-Ingelheim: Other: Advisory Board.

Abstract: Based on molecular studies, DLBCL is now further divided in three subtypes with distinct pathogenesis and clinical outcomes. Fluorescence in situ hybridization (FISH) studies identified a subgroup of DLBCL with a poor clinical outcome harboring concurrent gene rearrangements of the MYC, BCL2 and/or BCL6 proto-oncogenes leading to the over-expression of c-Myc, Bcl-2 and Bcl-6, inferior response rates to rituximab-based chemotherapy, and a shorter progression-free survival (PFS)/overall survival (OS). This group of patients is now categorized as double-hit (DHL) or triple-hit (THL) DLBCL. Immunohistochemistry (IHC) studies suggested that DLBCL patients with over-expression of Bcl-2 and c-Myc proteins exhibit a similar clinical course than those patients with DHL/THL. Alternative transcriptional (i.e. gene amplification or chromosomal gain) or post-translational regulatory mechanisms (yet to be defined) may be responsible for the over-expression of c-Myc, Bcl-2, or Bcl-6 in some patients with DHL/THL phenotype. The appropriate therapy for DHL/THL remains to be defined, but retrospective studies had demonstrated that at standard doses of R+CHOP are suboptimal. In order to study the impact of more aggressive therapeutic approaches in the management of DHL/THL, we retrospectively evaluated our single institution outcome experience over the last 14 years. Using the lymphoma translational database that includes 611 DLBCL patients, we identified 24 patients (M=13/F=11) (4%) with FISH-confirmed DHL/THL DLBCL. Demographic characteristics, clinical data, treatment history in the front line (including the use of CNS prophylaxis, high-dose chemotherapy and autologous stem cell support [HDC-ASCS] or allogeneic bone marrow transplant [allo-BMT] ) were collected. In addition, response rate, PFS and OS were calculated. Since the first case-reports were published, we observed a steady increase in the number of DHL/THL patients at our Institution (7 vs. 18 cases before or after 2011) which represents an increasing medical awareness of this new clinical entity. The mean age at diagnosis was 62 years (25 to 85 years), most of them Caucasians (N=22). The median Ki67 proliferation index was 90%. Using the Han’s algorithm, 11 of the DHL/THL were categorized as germinal center B-cell like (GCB), 6 patients as non-GCB, and 7 patients could not be classified. By FISH studies, 58% were DHL (involvement of MYC and BCL2 [N=22] or BCL6 [N=10] ) and 42% THL (involvement of MYC, BCL2 and BCL6, N=10). Gene rearrangements involving MYC, BCL2, or BCL6 were observed in 18 patients and MYC, BCL2 or BCL6 gain in 6. Clinically, 95% of the patients presented with stage III/IV, 67% with High-intermediate/High IPI score, and 79% of the patients had extranodal disease. Front-line chemo-immunotherapy included 1) standard doxorubicin-containing regimens: R+CHOP (N=10) or R-EPOCH (N=7), or 2) intensified regimens: R-DHAC (N=2) and R+HyperCVAD/R+HDMTXCytarabine (N=4). Prophylaxis IT chemotherapy was administered to 16 (67%) patients. The complete remission (CR) rate was 62.5% and 29% of the patients underwent HDC-ASCS (N=4)/allo-BMT (N=2) in first (N=2) or second-remission (N=4). In this group of patients, the use of intensified regimens was associated with a non-statistically significant improvement is OS when compared to R+CHOP/R+DA-EPOCH (OS at 3 years of 85.7% vs. 58%). Similarly, an improvement in OS was observed among patients receiving HDC-ASCT/allo-BMT as consolidation (71% vs. 60%, P=0.27). Of interest, CNS prophylaxis was associated with an improvement in OS at 3 years (81% vs. 37%, P=0.032). No differences in clinical outcomes were observed between DHL/THL harboring gene-rearrangements vs. gene gain. In summary, our single institution experience suggests that DHL/THL are increasingly being recognized as more aggressive sub-types of DLBCL with a dismal outcome with conventional therapeutic approaches. A high-index of suspicion should be raised and testing for DHL/THL in those DLBCL presenting with advance stage, multiple extra-nodal site of disease, and an elevated Ki67 index should be done. The accurate identification of DHL/THL patients is necessary, as they appear to benefit from rituximab-based intensified cytarabine-containing regimens, CNS prophylaxis and HDC-ASCT/allo-BMT consolidation. Disclosures No relevant conflicts of interest to declare.

Abstract: Background: The development of drugs targeting BTK and BCL2 has dramatically improved the therapeutic landscape in chronic lymphocytic leukemia (CLL). However, resistance to these agents has been reported due to non-recurrent changes in oncogenic pathways and gene expression signatures. The bromodomain and extra terminal (BET) family proteins (BRD2, BRD3, BRD4 and BRDT) are epigenetic reader proteins that recognize acetylated lysine residues in histones. They play a critical role in mediating gene transcription and have been considered as highly promising targets in several diseases including cancer. Of these, the BRD4 protein is highly enriched in super enhancers and regulates transcription of relevant oncogenes such as MYC, CDK genes, cyclin-D1, BCL2 and MCL-1. BRD4 inhibitors (BRD4i) block the transcription of these key oncogenes through the displacement of BRDs and other epigenetic modifiers from chromatin. In this study, we investigated the preclinical activity of two BRD4i, AZD5153 and PLX51107, and their cooperative role with the BCL2 inhibitor venetoclax and BTK inhibitor ibrutinib in CLL. Methods: Primary tumor cells were isolated from 36 CLL patients. Peripheral blood mononuclear cells were isolated via histopaque-1077 (Sigma-Aldrich, St Louis MO) from peripheral blood apheresis samples from consenting adults under RPCCC protocol CIC-01-16. B-cells were then isolated from enriched lymphocytes by MACS separation using a human B-cell Isolation Kit II. CLL cells were seeded at 3 x106/mL in a 384 well tissue culture plates and exposed to different doses of AZD5153 (1-20uM) or PLX51107 (1-20uM) as a single agent or in combination with venetoclax (1-100nM) or ibrutinib (50-1000nM) for 48 and 72hrs (Selleck Chemicals, Houston TX). Cell viability was assessed using Cell Titer-glo (Promega, Madison WI) with all data being normalized to untreated controls. Synergy was calculated using Calcusyn (Cambridge, UK) software to determine Coefficient of Synergy (CI) values. In addition, CLL cells were plated in 6 well plates and exposed to AZD5153 or PLX51107 alone or in combination with either venetoclax or ibrutinib for 24 hrs. Induction of apoptosis and changes in B-cell receptor signaling, BCL2 and NF-kB pathway related proteins were evaluated by flow cytometry or Western blotting respectively. Results: The study included 33 treatment naïve and 3 relapsed/refractory CLL patients. Deletion 11q was detected in 6 patients and del 17p was seen in 1 patient. Both AZD5153 and PLX51107 displayed time and dose dependent induction of apoptosis of CLL cells. Activity was observed in both treatment naïve and relapsed/refractory samples. Moreover, activity was observed in del 17p or ATM deletion samples. Synergistic activity was observed between BRD4is and venetoclax. PLX51107 exhibited synergy with venetoclax in 83% of the samples tested. Similarly, AZD5153 exhibited synergistic effects when combined with venetoclax in 61% of the samples. To a lesser degree, BRD4is exhibited synergistic activity when combined with ibrutinib, (44% with PLX51107 and 39% with AZD5153). Induction of apoptosis was observed in CLL cells exposed to either BRD4i. Morevoer, an increase in the percentage of apoptosis was observed when BRD4i was combined with venetoclax. Western blotting showed a accumulation of p21, reduced levels of C-MYC, as well as modulation of BCL-2 family member proteins such as BCL2, MCL-1 following BRD4i ex vivo exposure. Conclusions: Our data indicate that BRD4 inhibition results in apoptosis of primary tumor cells isolated from patients with various subtypes of CLL. PLX51107 and AZD5153 exhibit synergistic effects when combined with venetoclax and to a lesser degree with ibrutinib. Modulation of BCL-2 family members following BRD4 inibition could play a role in the synergistic activity observed in our studies. A better understanding of the key signaling pathways involved in proliferation and survival of CLL cells impacted by BRD4i in combination with venetoclax and ibrutinib would provide a proof-of-concept rationale for studies validating BRD4i as epigenetic approach to target BCR signaling in CLL. Disclosures Hernandez-Ilizaliturri: Karyopharm: Consultancy; Celgene: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Gilead: Consultancy; Pharmacyclics: Consultancy; Seattle Genetics: Consultancy; Astra Zeneca: Consultancy; Epyzome: Consultancy.