ALBERT

Description: Ibrutinib is a promising targeted therapy for chronic lymphocytic leukemia (CLL). However, a small subset of patients progress on ibrutinib either through progressive CLL or Richter's transformation. Patients responding to ibrutinib and then progressing with Richter's transformation do so most commonly within the first 2 years of treatment and have an extremely poor prognosis. Identifying biomarkers associated with this transformation is of utmost importance. Near-tetraploidy (4 copies of most chromosomes within a cell) has been reported in various lymphomas; however, its incidence in CLL has not been described. We investigated the prevalence of near-tetraploidy in CLL patients prior to starting ibrutinib and identified it as a pre-treatment biomarker for Richter's transformation. We examined near-tetraploidy in a large series of CLL patients enrolled across four ibrutinib clinical trials at the Ohio State University, for which extensive correlative studies and follow up data are available (previously described by Maddocks et al., JAMA Oncol, 2015). We identified this abnormality in 9 of 300 patients (3.0%, 95% CI: 1.4-5.6) in blood or bone marrow samples taken prior to starting therapy. Near-tetraploidy was detected by the presence of four signals with four or more fluorescence in situ hybridization (FISH) probes and confirmed in the metaphase karyotype of each patient in at least one cell. Near-tetraploidy was associated with aggressive disease characteristics including: Rai stage 3/4 (p=0.03), deletion 17p (p=0.03), and complex karyotype (p=0.01), as well as trisomy 12 (p=0.05). With a median follow-up time of 40.5 months, in patients positive with near-tetraploidy, one patient (11%) progressed with CLL on ibrutinib, six patients (67%) progressed with Richter's transformation, and two patients (22%) were still on treatment. Cumulative incidence of Richter's transformation was significantly higher in patients with near-tetraploidy (Figure; p

Description: Background: Ibrutinib, an orally bioavailable small molecular inhibitor of Bruton's tyrosine kinase (BTK), is an approved therapy for chronic lymphocytic leukemia (CLL), relapsed mantle cell lymphoma (MCL) and Waldenstrӧm's macroglobulinemia (WM). Beyond B lymphocytes, BTK signaling is important for collagen-mediated platelet activation, and BTK inhibition has been associated with primary hemostatic bleeding events (Levade et al Blood 2014). Although serious bleeding events have been uncommon (1-5%) in clinical trial populations, there is limited data describing the potential for increased serious bleeding incidence when ibrutinib is co-administered with other agents affecting the clotting cascade or platelet function. Methods: We conducted a retrospective cohort study to evaluate the incidence of major bleeding in patients receiving ibrutinib concomitantly with antiplatelet agents (non-steroidal anti-inflammatory agents, ADP inhibitors), anticoagulants (heparins, warfarin, novel oral anticoagulants), or supplements with potential anticoagulant activity (vitamin E and fish oil). Major bleeding events were identified using criteria developed by the International Society on Thrombosis and Haemostasis (Schulman et al J Thromb Haemost 2005). Patients 18-89 years of age and treated with ibrutinib for CLL, MCL, or WM between March 1, 2010 and March 1, 2015 were included. The primary endpoint of this study was the incidence of major bleeding events, but we also sought to identify risk factors associated with the development of major bleeding, focusing on potential drug interactions. Based on the historic prevalence of major bleeding in ibrutinib clinical studies, we calculated that at least 20 major bleeding events would need to be identified in order to perform blinded multinomial regression on the collected data of an estimated 400 patients. Results: 437 eligible patients were included in the analysis. Patients were overwhelmingly male (71.4%) and white (94.8%), with a mean age of 67.1 years (range: 29-89). 53.1% received ibrutinib as participants of a clinical trial, and the remainder received standard-of-care ibrutinib treatment. The table (upper panel) summarizes use of concomitant antihemostatic agents by presence or absence of major bleeding events. Characteristics of the major bleeding events are further detailed in the lower panel. The most commonly observed concomitant antihemostatic medication was aspirin, with 147 patients (33.6%) being exposed to aspirin within the study period. Fourteen instances of major bleeding were observed, corresponding to an overall incidence of 3.2%. These major bleeding events all occurred in CLL patients receiving ibrutinib at the standard dose of 420 mg daily. Two patients had platelet counts less than 50 k/µL at time of the bleeding event. One-half of the major bleeding events were observed in the absence of an antihemostatic medication, and 2 of the observed major bleeding events resulted in death (1 received concomitant warfarin). Fourteen patients (3.3%) in the group without major bleeding were on anticoagulation, 4 being warfarin. The most common sites of major bleeding were gastrointestinal (50%), intracranial (14.3%) and thoracic (14.3%). While most patients developing major bleeding permanently discontinued ibrutinib (57.1%), approximately one third of the patients who developed major bleeding subsequently resumed ibrutinib following resolution of the bleeding event. Subsequently, these patients did not experience a recurrent major bleeding event. The rate of major bleeding did not meet power to detect statistical differences in bleeding events when comparing concomitant therapy, Conclusions: Our observed incidence of major bleeding is consistent with previous controlled clinical trials, suggesting similar safety profile when ibrutinib is used outside of a controlled setting. Major bleeding events were uncommon despite the frequent co-administration of antiplatelet agents. However, because we modified practice early to avoid therapeutic anticoagulation during ibrutinib therapy whenever possible, the number of patients receiving such drugs in combination was small and precludes inferences regarding safety. Table Table. Disclosures Blum: Pharmacyclics: Research Funding. Awan:Innate Pharma: Research Funding; Pharmacyclics: Consultancy; Novartis Oncology: Consultancy. Woyach:Acerta: Research Funding; Karyopharm: Research Funding; Morphosys: Research Funding. Christian:Pharmacyclics: Research Funding; Janssen: Research Funding. Jones:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Description: BACKGROUND: Ibrutinib is an irreversible inhibitor of BTK in the B-cell receptor signaling cascade and is widely used to treat chronic lymphocytic leukemia (CLL) and other B-cell malignancies. Ibrutinib also inhibits the tyrosine kinase Tec in platelets, which may be one of the mechanisms of its bleeding toxicity. This makes concomitant use of anticoagulation (AC) or antiplatelet agents challenging, which is a common delimma as many patients taking ibrutinib are elderly and have increased risks of venous and arterial thromboses. The incidence of thrombosis in patients taking ibrutinib is unknown, and we hypothesized that the risk of thrombosis may be reduced during ibrutinib treatment. Therefore, we conducted a single-institution retrospective cohort study to determine the incidence and type of both arterial and venous thromboses during ibrutinib treatment and their management. METHODS: We reviewed medical records of all patients treated with ibrutinib for a hematological malignancy at the Ohio State University between 6/1/2010 and 3/31/2016. Baseline patient and disease characteristics were captured at time of starting ibrutinib. All thrombotic events occurring at any time during treatment with ibrutinib and within three days of its discontinuation were recorded. Time to thrombosis was calculated from the date of starting ibrutinib to the date of thrombosis or censored at the last assessment date, treating discontinuation of ibrutinib or death prior to thrombosis as competing risks. The cumulative incidence of thrombosis was estimated and the Fine and Gray regression models accounting for competing riskes were used to examine the association between patient characteristics and risk of thrombosis. RESULTS: The cohort included 565 patients. Median age was 65 (range 23-〉89) years and 70.3% (397/565) were men. The majority of patients had CLL (73.6%, 416/565). Other diagnoses included mantle cell lymphoma (9.9%, 56/565), indolent B-cell malignancies (8.1%, 46/565), and aggressive lymphomas (8.3%, 47/565). Median number of prior treatments was 3 (range 0-18) and 6.5% (37/565) of patients were treatment naïve. Prior to ibrutinib, 144 of 565 patients (25.5%) had a history of thrombosis. Sixty-four (11.3%, 64/565) patients had only venous thromboses, 66 (11.7% 66/565) had only arterial thromboses, and 14 patients had both. Concurrently with ibrutinib, 193 (34.2%) patients received antiplatelet agents, 16 (2.8%) patients received AC, and 31 (5.5%) patients received both. Total ibrutinib exposure for the cohort was 1,429 person-years with a median exposure of 2.39 (range 0-7.36) years per patient. A second antineoplastic agent was given with ibrutinib in 30.8% (174/565) of cases, including an immunomodulatory drug in 24 (4.2%, 24/565) patients. During ibrutinib treatment, 22 of 565 (3.9%) patients experienced 24 acute thrombotic events, mostly arterial (Table 1). The incidence of thrombosis was 1.7 (95% CI 1.1-2.5) per 100 person-years of ibrutinib exposure. Of the venous thromboses, 87.5% (7/8) were deep vein thromboses and developed at a median of 7.5 (range 0.5-75.3) months after starting ibrutinib. Of the arterial thromboses, the majority were acute cerebrovascular accidents (37.5%, 6/16) and developed at a median of 27.4 (range 0.4 - 56.6) months after starting ibrutinib. Thrombosis treatment is summarized in Table 1. After thrombosis, ibrutinib was discontinued or held in the majority of cases (75%, 18/24). One patient developed a recurrent thrombosis while on ibrutinib and AC. There were six bleeding events, 3 major (based on ISTH criteria) and 3 minor: all were taking ibrutinib and most were on AC (2 patients on antiplatelet, 1 on AC, 2 on both, 1 on neither). On univariable analysis, the only factors associated with significant (p2) increased risk of venous thrombosis were prior venous (HR 4.73, CI: 1.06-21.11) and arterial (HR 15.66, CI: 3.07-79.87) thromboses. Antiplatelet use was not significantly associated with either thrombus type. CONCLUSIONS: The cumulative incidence of thrombosis during ibrutinib treatment was low (1.7 per 100 person-years), with the majority being arterial. Prior thrombosis was associated with increased venous thrombosis risk. There are more bleeding than thrombotic complications after patients develop thromboses on ibrutinib, and optimal treatment strategies for this population requires further investigation. Disclosures Kander: AstraZeneca: Consultancy. Wang:Daiichi Sankyo: Consultancy, Other: Travel.

Description: Introduction: Idelalisib (IDELA, Zydelig®) is the first-in-class PI3Kδ inhibitor and is approved in the U.S. as an oral monotherapy for relapsed / refractory follicular lymphoma (R/R FL) after at least two prior lines of systemic therapy. IDELA's regulatory approval was based on a phase 2, open-label clinical trial in 125 patients with R/R indolent non-Hodgkin's lymphoma (Gopal et al., NEJM, 2014) and outcomes in the FL subgroup were published by Salles et al. (Haematologica, 2017). The current study evaluates the characteristics and treatment patterns of patients treated with IDELA for R/R FL in a real-world setting. Methods: Adult patients diagnosed with R/R FL (grades 1, 2, and 3a) and treated with IDELA within the US Oncology Network (USON) between 7/1/2014 to 6/30/2018 were analyzed retrospectively. Patient data were obtained from USON's structured electronic health records' system, iKnowMed (iKM)TM. Manual chart review (ChR) was used to determine physician response and to confirm IDELA treatment patterns. Overall survival (OS) and progression-free survival (PFS) were estimated using Kaplan-Meier methods. Descriptive statistics were generated for outcomes of interest, including duration of therapy (DoT), median follow-up, and adverse event (AE) frequency. Results: A total of 124 patients with FL and prescribed IDELA were identified in iKM TM. After Chr confirming the diagnosis of follicular lymphoma diagnosis and initiation of IDELA, 88 patients were retained for analysis. Median age of patients was 68.9 years, with 52.3% female and the majority white and non-Hispanic (90.9% and 93.2%, respectively, Table 1). The most common regimens immediately prior to IDELA initiation were bendamustine + rituximab (22.7%), rituximab (17%), and rituximab maintenance (11.4%). Eighty-six (97.7%) patients had co-morbidities categorized as vascular (50%), endocrine (33%), respiratory (13.6%), or cardiac (12.5%). Thirteen (14.8%), 21 (23.9%), and 54 (61.4%) patients initiated IDELA in second line (2L), 3L, and 〉4L, respectively. Baseline lab values at IDELA initiation were similar regardless of line of therapy (LOT). mDOT was 5.5 mos. for the entire population and was similar across all LOTs (4.1 mos., 6.1 mos., and 5.5 mos. in 2L, 3L, and 〉4L, respectively). AEs were noted in 45.5% with the most common being gastrointestinal (31.8%) and dermatologic (10.2%). Respiratory and infectious AEs were noted in 2.3% and 1.1%, respectively, although Pneumocystis jirovecii pneumonia (PJP) prophylaxis was rarely prescribed (2.3%). Toxicity as a reason for IDELA discontinuation varied in frequency across LOT and was more common in 2L compared to 3L and 〉4L (91.7% compared to 43.8% and 46.9%, respectively). With a median follow-up of 18.6 months for the population, the mPFS was 11.4 mos. [95%CI: 8.5,17.0] and mOS was 32.5 mos. [95% CI: 25.3,NR]. Stratified by LOT, median follow-up time, mOS, and mPFS were greater in 2L (30.8 mos., NR [95% CI: 27.37,NR], and 29.0 mos. [95% CI: 8.6,NR], respectively) than in 3L or 〉4L (3L: 17.9 mos., 29.4 mos. [95%CI: 18.6,NR], and 17.5 mos. [95% CI: 6.1,NR]; 〉4L: 16.5 mos., 25.3 mos. [95%CI: 13.5.,NR], and 8.6 mos. [95% CI: 6.1,12.6], respectively, Figures 1 and 2). Conclusion: Findings from this analysis suggest that R/R FL patients treated with IDELA in a real-world setting experience a similar mDOT and mPFS as those treated in the clinical trial setting (Salles et al., Haematologica, 2017). Patients treated in 2L demonstrated longer PFS and OS compared to later lines, but also experienced increased IDELA discontinuation due to toxicity, perhaps reflecting a lower incidence of progressive disease in earlier treatment lines, or a more immunocompetent population leading to higher rates of autoimmune AEs. Use of PJP prophylaxis in IDELA-treated patients was uncommon, an observation suggesting an opportunity for provider education. Our findings enhance available data on relapsed FL patient outcomes in real-world clinical practice and support the use of IDELA in patients with R/R FL after at least 2 systemic therapies. Disclosures Andorsky: Gilead: Research Funding; Genetech: Research Funding; CTI: Research Funding; AstraZeneca: Consultancy; Celgene: Research Funding. Chan:Gilead Sciences, Inc.: Employment, Equity Ownership. Clark:McKesson: Consultancy, Employment, Equity Ownership. Ruzicka:Gilead Sciences, Inc.: Employment. Robert:McKesson: Employment. Awan:Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Janssen: Consultancy; Genentech: Consultancy; Sunesis: Consultancy; Gilead: Consultancy. OffLabel Disclosure: Idelalisib is a PI3 kinase inhibitor indicated for the treatment of patients with relapsed follicular B-cell lymphoma who have received at least two prior systemic therapies. Some patients in this observational study used Idelalisib after one prior systemic treatment.

Description: Key Points Cytoreduction with obinutuzumab and ibrutinib followed by the addition of venetoclax has acceptable safety with no tumor lysis syndrome. This combination has preliminary activity including complete remissions with undetectable residual disease in relapsed or refractory CLL.

Description: BACKGROUND Development of targeted therapies for CLL including the anti-CD20 monoclonal antibody obinutuzumab (OBIN), Bruton's tyrosine kinase inhibitor ibrutinib (IBR), and Bcl-2 inhibitor venetoclax (VEN) have demonstrated significant clinical activity in CLL. As they have high response rates as single agents, largely non-overlapping toxicities, and distinct and potentially synergistic mechanisms of action, we designed and initiated a triplet regimen with OBIN, IBR, and VEN for a fixed duration of treatment. The goal of the regimen is to achieve deep remissions and facilitate treatment discontinuation. The previously reported phase 1b cohort on this study established VEN 400 mg daily as the recommended dose for use with the label doses of OBIN and IRB in this combination. To determine response rates, eradication of minimal residual disease (MRD), and progression-free survival (PFS) in relapsed/refractory (RR) and treatment-naïve (TN) CLL with this regimen, two separate cohorts were accrued to a phase 2 trial. METHODS Patients with RR or TN CLL requiring therapy were eligible. Patients were required to have ECOG PS ≤1 and preserved end-organ function, including normal serum creatinine or creatinine clearance ≥50 mL/min/m2. RR patients had to have ≥1 prior CLL therapy. Treatment was given at the doses and schedule established in the preceding phase 1b study (Jones ASH 2016) for 14 cycles (C) of 28 days with OBIN, IBR, and VEN started sequentially over the first 3 cycles. Risk for tumor lysis syndrome (TLS) with VEN was assessed according to US prescribing information with monitoring instituted according to risk. Adverse events (AEs) were assessed and graded using the NCI CTCAE v4.03 except hematologic AEs which were graded according to the IWCLL 2008 guidelines. Response was determined according to IWCLL 2008 criteria after C8 (mid-therapy) and 2 months after completing C14 (EOT). MRD was measured in the bone marrow and peripheral blood by standard 10-color flow cytometry at these time points. The primary endpoint was MRD negative complete response at EOT. For each cohort, 25 patients provided at least 90% power to detect an increase in MRD negative complete response rate from 10% to 30% using a single stage design and constraining type I error rate to 10%. Herein, toxicity and mid-therapy responses are presented. RESULTS The study enrolled a total of 50 patients with 25 RR and 25 TN in separate cohorts. Baseline characteristics are in Table 1. The adverse event (AE) profile was similar to the phase 1b study and consistent with the known toxicities of the included individual agents. Frequent treatment-related AEs are found in Table 2. Hematologic toxicity was most frequent with the majority of patients experiencing thrombocytopenia (80%) and/or neutropenia (76%). The most frequent non-hematologic toxicities were hypertension (70%), infusion related reactions (66%), bruising (52%), myalgia (50%), and nausea (50%). Grade 3-4 toxicities were largely hematologic with 56% experiencing grade 3-4 neutropenia and 34% grade 3-4 thrombocytopenia. The only frequently occurring non-hematologic grade 3-4 toxicity was hypertension (32%). The median follow-up for the study was 18.0 months (range 0-24.8) for the RR cohort and 20.6 months (range 7.4-23.9) for the TN cohort. At mid-therapy assessment 23/25 of the RR patients remained on study and all had achieved a response. Three patients achieved CR, 3 a CR with incomplete marrow recovery, and 17 a partial remission. The ORR in RR patients at mid-therapy was 92% (95% CI: 74-99%). Twenty-three (92%) RR patients tested for mid-therapy MRD, with 16 (70%) MRD negative in both the blood and marrow. Two patients had MRD in the blood only, 2 in the marrow only, and 3 in both the blood and the marrow. Mid-therapy responses for the TN cohort have previously been reported (Rogers ASH 2017). To date in 21 (84%) TN patients completed treatment through C14 and 23 (92%) RR remain on study with 21 completing treatment. No patients in either cohort had progressive disease. There was one death from neutropenia and colitis in a TN patient. CONCLUSIONS OBIN, IBR, and VEN in combination have a tolerable safety profile in both RR and TN CLL patients with the majority of toxicities being hematologic. This regimen has a high mid-therapy response rate (92%) in RR patients with early MRD negative responses. EOT responses in TN and RR patients will be presented at the meeting. Disclosures Maddocks: Teva: Honoraria; AstraZeneca: Honoraria; Pharmacyclics/Janssen: Honoraria; Novartis: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; BMS: Research Funding. Jones:Celgene: Employment, Equity Ownership.

Description: Chronic lymphocytic leukemia (CLL), characterized by the progressive and uncontrolled accumulation of CD19+ B cells, currently remains as an incurable malignancy. The difficulties of eliciting curative measures in CLL are partly driven by the adaptability of the transcriptional response mediated by epigenetic mechanisms. In this study, we sought to better characterize the complexities of the CLL transcriptional profile by conducting an integrative analysis between the B cell enhancer and super enhancer signatures defined from 3 B cell H3K27Ac ChIPseq samples (CD19+ B cell, GM12878, and MEC1), the DNA methylation signatures defined from reduced-representation bisulfite sequencing (RRBS) of 42 CLL patient and 8 healthy donor samples, and the mRNA expression signatures defined from RNA sequencing of 47 CLL patient and 5 healthy donor samples. From our analysis, we identified super enhancers (SEs) in each of the ChIPseq profiles (approximately 4% of called enhancers) and discovered 741 SEs in GM12878, 374 SEs in MEC1, and 523 SEs in the CD19+ B cell profiles, respectively. Based on MSigDB gene ontology analysis, many of the genes corresponding with SEs were involved in pathways regulating immune signaling activation (e.g. TNFA_SIGNALING_VIA_NFKB, INFLAMMATORY RESPONSE) or metabolic homeostasis (e.g. MTORC1_SIGNALING, FATTY_ACID_METABOLISM). By further analyzing the corresponding expression level of SE-associated genes in CLL patients, we identified 190 transcripts associated with SEs that were significantly overexpressed in CLL patient B cells (Student's t-test p

Description: Introduction: The Bruton's Tyrosine Kinase (BTK) inhibitor ibrutinib (IB) is a standard therapy for previously untreated CLL patients. While therapy is currently indicated only for patients with progressive, symptomatic disease, the introduction of targeted therapies in CLL has re-opened the question of whether asymptomatic high risk patients would benefit from early intervention. As well, even in early stages CLL is associated with profound cellular, humoral and innate immune suppression and patients with CLL respond poorly to routine vaccinations. IB has been shown to reverse disease mediated immune dysfunction partly through Th1 skewing. We undertook a phase 2 study of IB in asymptomatic high risk CLL patients who did not otherwise require therapy to evaluate: 1) the safety and efficacy of 2 years of IB in this clinical setting and 2) ability of IB to improve the efficacy of routine vaccines. Methods: This is a single-stage phase II study of IB in previously untreated asymptomatic, genetically high-risk patients with CLL, who did not meet IWCLL treatment criteria. High risk genomics were defined as del(11)(q22.3), del(17)(p13.1), unmutated IGHV, and/or complex karyotype (≥3 cytogenetic abnormalities). Patients were randomized to receive IB 420mg PO daily either concurrent with the pneumococcal (PCV13), influenza and TdaP vaccines (Arm A) or following vaccination (Arm B) for a total of 27 cycles (2 years). The primary objective of the study was to determine the safety and 2-year progression-free survival (PFS) of asymptomatic, high-risk CLL patients treated with IB. Secondary objectives include determination of safety and immune responses to vaccines in relation to IB administration, development of resistance, and quality-of-life (QOL). QOL measures assessed general QOL (SF-12, EORTC), anxiety (GAD-7) and depression (PHQ-9). Results: Forty-four patients (pts; 21 in Arm A, 23 in Arm B) were enrolled from 1/2016 to 6/2017, with a median age of 58 (range 35-82). Sixty-six percent of pts were male and all were high-risk: 91% with unmutated IGHV, 14% with del(17)(p13.1), 34% with del(11)(q22.3), and 24% with complex karyotype (≥ 3 abnormalities). Median follow-up is 2.6 years (range: 0.2-3.2). Excluding 2 patients in Arm B who progressed prior to receipt of IB, 2-year PFS was 92%. From a landmark of 2-years and including 33 patients who reached this point and discontinued IB, 6-month PFS was 87% (95% CI: 69-95%; Figure 1). Of 9 pts who progressed after IB discontinuation, 3 have not required further treatment, 5 restarted IB or acalabrutinib, and 1 started venetoclax/rituximab, and all responded. For PCV13, in Arm A, 15/16 patients showed a significant increase in antibody titer 2 cycles following vaccination, but response disappeared by cycle 12. In Arm B, 3/13 patients had an increase in antibody titer, with no increase following second vaccination. For influenza, patients in Arm B showed a significant response to influenza A vaccination, while patients in both arms responded to influenza B vaccination. IB was generally well tolerated, and only one pt discontinued treatment due to toxicity (atrial fibrillation). Grade 3+ toxicities that occurred in 〉2% of patients included anemia (7%), atrial fibrillation (11%), dental caries (7%), hyperglycemia (7%), hypertension (43%), and neutropenia (7%). At baseline, patients' reports of physical health-related (M=48.52, SD=7.96) and mental health-related quality of life (M=52.20, SD=8.57) similar to U.S population norms, along with moderately high global health (M=78.49 of 100, SD = 20.51). Additionally, patients' anxiety (M=3.56, SD=4.71) and depressive symptom reports (M=3.65, SD=4.46) were in the "none/mild" range. There was no significant change in the latter measure from baseline to 12 months (p〉0.25), excepting anxiety which slightly decreased (M=1.31, SD=2.33; F(3,44)=5.94, p

Description: Key PointsAEB071 demonstrates preclinical in vitro and in vivo activity against CLL independent of survival signaling and stromal cell protection. AEB071 can either inhibit or activate the WNT pathway emphasizing the importance of pharmacodynamic monitoring in its development.

Description: Background: Aberrant activation of B-cell receptor (BCR) signaling is considered to be a major oncogenic mechanism that leads to the development and progression of multiple B-cell malignancies. ARQ 531 is a reversible ATP competitive inhibitor of BTK that inhibits ibrutinib-resistant BTK-C481S mutant CLL cells and has demonstrated antitumor activity in CLL, Richter's transformation, and DLBCL mouse models. Objectives: The primary objectives of the clinical study are to assess the safety and tolerability, and to determine the recommended Phase 2 dose and schedule of ARQ 531. The secondary objectives are to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of anti-tumor activity of ARQ 531. Methods: This is a first in human, Phase 1 dose escalation study in patients with relapsed or refractory CLL/SLL, Waldenstrom's macroglobulinemia, or B-cell NHL who received at least 2 prior lines of systemic therapy. Prior therapy must have included a BTK inhibitor, if FDA approved for their disease. Dose escalation was performed according to a 3+3 study design. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v.4.03. Tumor responses were evaluated per disease specific guidelines. Results: A total of 16 patients enrolled (median age 65.5 years, male 93.8%, 2 DLBCL, 2 follicular lymphoma, 12 CLL/SLL, 5 median prior systemic regimens) and were treated at dose levels of 5, 10, 15, 20 and 30mg QD. No dose limiting toxicities have been reported with ARQ 531. Drug related TEAEs included diarrhea, nausea, vomiting, fatigue, pneumonia, amylase increased, lipase increased, neutrophil count decreased, platelet count decreased, decreased appetite, hypernatraemia, arthralgia, groin pain, dizziness, facial paralysis, headache, tremor and restlessness in one patient (6.3%) each. Drug related grade 3 or worse TEAEs included lipase increased and platelet count decreased in one patient (6.3%) each. No drug related serious TEAEs were reported. Among the 12 patients who have received at least 1 dose of study drug and have at least 1 post-treatment tumor measurement data, 5 achieved stable disease (SD) (1 follicular lymphoma, 1 DLBCL, 3 CLL) and 7 had progressive disease (6 CLL, 1 follicular lymphoma). Three of 5 SD patients (1 follicular lymphoma, 1 DLBCL, 1 CLL) had 35%, 34% and 29% tumor reduction and 2 of them are ongoing on study treatment at 53 and 18 weeks. The CLL patient with 29% tumor reduction had BTK C481S mutation. Preliminary PK data showed ARQ 531 exposure was close to dose proportional and the estimated plasma half-life generally ranged from 20-24 hours. Consistent with increases in exposure, pBTK knockdown was observed. In Cohort 4 (20mg QD), all three patients showed 100% pBTK knockdown at a mean plasma Cmax exposure of 300nM (~4h post dose). Levels of CCL3 protein, a plasma biomarker for BCR pathway activation, was significantly suppressed in CLL patients. Conclusions: ARQ 531 has demonstrated a manageable safety profile to date. Diminished pBTK signaling and CCL3 protein levels have been observed in CLL patients. Additionally, preliminary anti-tumor activity has been observed at doses of ARQ 531 that were not predicted to completely inhibit BTK. Updated safety, PK, biomarker and anti-tumor activity data will be presented at the meeting. Disclosures Flinn: Gilead: Research Funding; Infinity: Research Funding; Incyte: Research Funding; Celgene: Research Funding; Pfizer: Research Funding; Kite: Research Funding; Verastem: Consultancy, Research Funding; Pharmacyclics: Research Funding; Novartis: Research Funding; Curis: Research Funding; Seattle Genetics: Research Funding; Merck: Research Funding; Janssen: Research Funding; ArQule: Research Funding; Calithera: Research Funding; Genentech: Research Funding; Forma: Research Funding; Agios: Research Funding; Constellation: Research Funding; Trillium: Research Funding; Verastem: Research Funding; Portola: Research Funding; Takeda: Research Funding; TG Therapeutics: Research Funding; Forty Seven: Research Funding; BeiGene: Research Funding. Savage:ArQule, Inc.: Employment. Eathiraj:ArQule, Inc.: Employment. Tith:ArQule, Inc.: Employment.