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PURPOSE The combination of the Bruton tyrosine kinase inhibitor ibrutinib with bendamustine-rituximab for first-line treatment of mantle cell lymphoma (MCL) prolonged progression-free survival (PFS), but without improvement in overall survival (OS), likely because of toxicity. Acalabrutinib was shown to be efficacious and less toxic than ibrutinib in a head-to-head trial in chronic lymphocytic leukemia and therefore might lead to better outcomes in MCL. METHODS Patients 65 years and older with previously untreated MCL received acalabrutinib (100 mg twice daily) or placebo (until disease progression or unacceptable toxicity), plus six cycles of bendamustine (90 mg/m 2 once daily; days 1 and 2) and rituximab (375 mg/m 2 as a single dose; day 1) followed by rituximab maintenance in responding patients for 2 years. Crossover to acalabrutinib at disease progression was permitted. The primary end point was PFS per the independent review committee; overall response rate and OS were secondary end points. RESULTS In total, 598 patients were randomly assigned, with 299 in each arm. At a median follow-up of 49.8 months using the reverse Kaplan-Meier method, the median PFS was 66.4 months in the acalabrutinib arm and 49.6 months in the placebo arm (hazard ratio [HR], 0.73 [95% CI, 0.57 to 0.94]; P = .0160). Benefit was seen across all subgroups, including those with high-risk features. Overall response/complete response rates were 91.0%/66.6% and 88.0%/53.5% in the acalabrutinib and placebo arms, respectively. OS was not significantly different (HR, 0.86 [95% CI, 0.65 to 1.13]; P = .27). Grade 3 or greater adverse events were reported in 88.9% and 88.2% in the acalabrutinib and placebo arms, respectively. CONCLUSION The combination of acalabrutinib with bendamustine-rituximab significantly improved PFS. Clinical benefit of acalabrutinib with bendamustine-rituximab was achieved with manageable toxicity.

SummaryThe phase I/II AU‐003 study in patients with treatment‐naïve (TN) or relapsed/refractory (R/R) chronic lymphocytic leukaemia/small lymphocytic lymphoma demonstrated that zanubrutinib therapy results in clinically meaningful and durable responses with acceptable safety and tolerability. We report updated safety and efficacy data for 123 patients with a median follow‐up of 47·2 months. Patients received zanubrutinib 160 mg twice daily (81 patients), 320 mg once daily (40), or 160 mg once daily (two). Discontinuations due to adverse events or disease progression were uncommon. The overall response rate (ORR) was 95·9% (TN, 100%; R/R, 95%) with 18·7% achieving complete response (CR). Ongoing response at 3 years was reported in 85·7%. The ORR in patients with del(17p)/tumour protein p53 mutation was 87·5% (CR 16·7%). The 2‐ and 3‐year progression‐free survival estimates were 90% (TN, 90%; R/R, 91%) and 83% (TN, 81%; R/R, 83%) respectively. The most reported Grade ≥3 adverse events were neutropenia (15·4%), pneumonia (9·8%), hypertension (8·9%) and anaemia (6·5%). The annual incidence of atrial fibrillation, major haemorrhage, Grade ≥3 neutropenia and Grade ≥3 infection decreased over time. With a median follow‐up of ~4 years, responses remain clinically meaningful and durable and long‐term tolerability to zanubrutinib therapy continues.

AbstractBackgroundThe World Trade Center (WTC) general responder cohort (GRC) was exposed to environmental toxins possibly associated with increased risk of developing autoimmune conditions.ObjectivesTwo study designs were used to assess incidence and risks of autoimmune conditions in the GRC.MethodsThree clinically trained professionals established the status of possible GRC cases of autoimmune disorders adhering to diagnostic criteria, supplemented, as needed, by specialists’ review of consenting responders’ medical records. Nested case‐control analyses using conditional logistic regression estimated the risk associated with high WTC exposure (being in the 9/11/2001 dust cloud or ≥median days' response worked) compared with low WTC exposure (all other GRC members'). Four controls were matched to each case on age at case diagnosis (±2 years), sex, race/ethnicity, and year of program enrollment. Sex‐specific and sensitivity analyses were performed. GRC age‐ and sex‐adjusted standardized incidence ratios (SIRs) were compared with the Rochester Epidemiology Project (REP). Complete REP inpatient and outpatient medical records were reviewed by specialists. Conditions meeting standardized criteria on ≥2 visits were classified as REP confirmed cases.ResultsSix hundred and twenty‐eight responders were diagnosed with autoimmune conditions between 2002 and 2017. In the nested case‐control analyses, high WTC exposure was not associated with autoimmune domains and conditions (rheumatologic domain odds ratio [OR] = 1.03, 95% confidence interval [CI] = 0.77, 1.37; rheumatoid arthritis OR = 1.12, 95% CI = 0.70, 1.77). GRC members had lower SIR than REP. Women's risks were generally greater than men's.ConclusionsThe study found no statistically significant increased risk of autoimmune conditions with WTC exposures.

Abstract Background: The oral BTK inhibitor ibrutinib is the only approved therapy for patients with symptomatic Waldenström macroglobulinemia (WM). Bing-Neel syndrome (BNS) is a rare complication of WM that results from infiltration of malignant lymphoplasmacytic cells into the central nervous system (CNS) causing neurological deficits. Treatment options in patients with BNS are limited to agents with CNS penetration. Ibrutinib can penetrate into the CNS, but data on its efficacy in BNS is lacking outside case reports. Methods: We performed a multicenter retrospective study evaluating the efficacy of ibrutinib in patients with BNS. The diagnosis of BNS was established in patients with a clinicopathological diagnosis of WM by radiological and/or cytological evidence of CNS involvement by WM, and response was assessed based on recently published criteria. Ibrutinib was given orally at doses of 420-560 mg PO once daily until disease progression or intolerable toxicity. Response was assessed using criteria from the 8th International Workshop for WM (Minnema et al. Haematologica 2017). Events were defined as death from any cause, progression of disease and stopping ibrutinib from any reason. Time to events was estimated using the Kaplan-Meier method. Results: We present data on 24 patients with BNS treated with ibrutinib. The median age at diagnosis of WM was 60 years (range 38-76 years) and 14 patients (58%) were men. The median lines of therapy for WM prior to BNS diagnosis was 1 (range 0-7 lines), and 9 patients (38%) were untreated for WM at the time of BNS diagnosis. Previous WM therapies included anti-CD20 antibodies (n=15), alkylators (n=13), nucleoside analogues (n=8), proteasome inhibitors (n=3), immunomodulators (n=2), and autologous transplant (n=1). The median age at BNS diagnosis was 65 years (range 38-80). The median time from WM to BNS diagnosis was 4 years (range 0-27 years). In 2 patients, the diagnosis of BNS was made concurrently with WM diagnosis. The median number of BNS lines prior to ibrutinib was 1 (range 0-5 lines). Previous BNS therapies included intrathecal chemotherapy (n=9), high-dose methotrexate (n=6), bendamustine (n=3) and radiation therapy (n=3). In 7 patients (29%), ibrutinib was the first line of treatment for BNS. The most common symptoms at BNS presentation were cognitive deficits (n=10), sensory deficits (n=8), ataxia/falls (n=8), motor deficits (n=6), headache (n=5) and seizures (n=5). MRI findings included leptomeningeal enhancement (n=16) and brain masses (n=5). Cerebrospinal fluid (CSF) flow cytometry confirmed the presence of clonal CD19+ in 19 patients (79%). Biopsies were performed in 5 patients (21%) and confirmed presence of WM cells. 4 patients had normal MRI but had abnormal CSF cytology and/or flow cytometry. Tissue was not obtained in 1 patient in whom MRI showed leptomeningeal enhancement. Interestingly, 2 patients were diagnosed with lymphoplasmacytic lymphoma secreting IgG paraprotein. The median serum IgM (n=20) prior to ibrutinib initiation was 1,294 mg/dl (range 125-5,938 mg/dl), and the median hemoglobin level was 11.9 g/dl (7.7-15.2 g/dl). Ten patients (42%) received ibrutinib 560 mg PO once daily, and 14 (58%) received ibrutinib 420 mg PO once daily. At best response, median serum IgM and hemoglobin levels were 340 mg/dl (82-3,330 mg/dl) and 14.6 g/dl (range 9.2-16.0 g/dl). Based on consensus BNS response criteria, complete response was attained in 2 patients (8%), partial response in 14 (58%) and clinical improvement in 3 patients (13%). With a median follow-up time of 13 months (95% CI 8-21 months), 5 patients have stopped ibrutinib, 3 due to BNS progression, 1 due to grade 3 muscle cramps and 1 due to arrhythmia, and 3 patients have died, 2 from infection and 1 from BNS progression. The median event-free survival (EFS) from ibrutinib initiation was not yet reached. The 1-year and 2-year EFS rates were 71% (95% CI 46-86%) and 52% (23-75%), respectively. Conclusion: Ibrutinib is a safe and effective treatment option for patients with BNS. Disclosures Palomba: Pharmacyclics: Consultancy; Celgene: Consultancy. Talaulikar:Amgen: Consultancy, Honoraria; Takeda: Research Funding; Janssen: Honoraria, Speakers Bureau; Roche: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Buske:Janssen: Honoraria, Research Funding; Bayer: Research Funding; Roche: Honoraria, Research Funding. Tedeschi:Gilead: Consultancy; AbbVie: Consultancy; Janssen: Consultancy, Speakers Bureau. Simpson:Pharmacyclics LLC, an AbbVie Company: Research Funding; Acerta: Research Funding; Merck: Honoraria, Research Funding; BeiGene: Research Funding; Sanofi: Research Funding; Bristol-Myers Squibb: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Celgene: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Novartis: Other: TRAVEL, ACCOMMODATIONS, EXPENSES; MSD: Honoraria; Roche: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Amgen: Research Funding, TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen: Honoraria, Research Funding. Tam:Janssen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BeiGene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Ansell:Affimed: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Pfizer: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Celldex: Research Funding; LAM Therapeutics: Research Funding. Treon:Johnson & Johnson: Consultancy; BMS: Research Funding; Pharmacyclics: Consultancy, Other: Travel, Accommodations, Expenses, Research Funding; Janssen: Consultancy, Other: Travel, Accommodations, Expenses. Castillo:Millennium: Research Funding; Genentech: Consultancy; Abbvie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Beigene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.

Background Ixazomib is the first orally administered PI studied in the clinic. The feasibility of combining ixazomib weekly and lenalidomide-dexamethasone (Rd) in the first all-oral PI- and immunomodulatory drug-containing triplet regimen was evaluated in a phase 1/2 trial of 65 pts with newly diagnosed MM. Results indicated a 90% ORR (62% ≥VGPR) using ixazomib 4 mg (recommended phase 2/3 dose), with a manageable safety profile, including 14% gr ≥3 skin/subcutaneous tissue disorders and limited (4% gr 3) peripheral neuropathy (PN) (Kumar et al, Lancet Oncol 2014). These data provided the rationale for phase 3 investigation of IRd vs placebo-Rd in pts with RRMM in this randomized, double-blind, placebo-controlled, international, multicenter study. Methods Adults with RRMM after 1-3 prior lines of therapy who were not refractory to prior lenalidomide or PI-based therapy were randomized 1:1 to receive ixazomib 4 mg or matching placebo weekly on d 1, 8, and 15, plus lenalidomide 25 mg PO on d 1-21 (dose reduced for renal impairment per local label/practice) and dexamethasone 40 mg PO on d 1, 8, 15, and 22, in 28-d cycles. Randomization was stratified by number of prior therapies (1 vs 2/3), PI exposure (naïve vs exposed), and ISS disease stage (I/II vs III). Cycles were repeated until disease progression or unacceptable toxicity. Primary endpoint was PFS as assessed by an independent review committee blinded to treatment, per IMWG criteria. Key secondary endpoints were OS and OS in high-risk pts with del(17). Sample size was determined to provide 80% power for the OS endpoint and adequate power to test PFS. Three interim analyses (IAs) and a final analysis were planned to test PFS and OS; here, we report data from the first IA, the final analysis for PFS. Results 722 pts were randomized (360 IRd; 362 Rd). Baseline characteristics were balanced between groups; overall median age was 66 yrs (30-91), 70% were PI-exposed, 88% were ISS stage I/II, 59% had received 1 prior therapy, and 77%/11%/11% were relapsed/refractory/relapsed and refractory, with 6% primary refractory. Based primarily (97%) on central laboratory evaluation, 19% had high-risk cytogenetics by FISH (del(17), t(4;14), or t(14;16)), including 10% del(17). Prior therapies included 69% bortezomib, 45% thalidomide, and 12% lenalidomide. The study met the primary endpoint at the first IA (median follow-up 14.8 vs 14.6 mos with IRd vs Rd), demonstrating a 35% improvement in PFS with IRd vs Rd (HR 0.742; p=0.012; Table). In pts with high-risk cytogenetics, the PFS HR was 0.543 with IRd vs Rd (HR 0.596 in pts with del(17)), with a median PFS similar to the overall IRd group, indicating ixazomib may overcome the negative impact of cytogenetic alterations. OS data were not yet mature. Key response data are shown in the Table. Pts received a median of 13 (1-26) vs 12 (1-25) cycles of IRd vs Rd; 55% and 52% of pts remained on treatment. With IRd vs Rd, 68% vs 61% of pts had gr ≥3 AEs (driven by thrombocytopenia), 40% vs 44% had serious AEs, 13% vs 11% discontinued all study drugs due to AEs, and 3% vs 5% died on treatment. AEs observed with IRd were consistent with reported safety profiles for the individual agents. Common gr ≥3 AEs were neutropenia (19% vs 16%), anemia (9% vs 13%), thrombocytopenia (13% vs 5%), and pneumonia (6% vs 8%). Gastrointestinal events included 42% vs 36% diarrhea (6% vs 2% gr 3), 26% vs 21% nausea (2% vs 0% gr 3), and 22% vs 11% vomiting (1% vs <1% gr 3). PN rates were 28% vs 21% (2% vs 2% gr 3), 35% vs 21% had rash events (4% vs 1% gr 3), 4% vs 6% had renal failure (2% vs 3% gr ≥3), and 4% vs 3% had heart failure (2% vs 2% gr ≥3). Conclusion At this first prespecified IA, addition of ixazomib to Rd in pts with RRMM increased median PFS to 20.6 from 14.7 mos without a substantial increase in overall toxicity, including cardiac and PN toxicity. Benefit with IRd was also noted in pts with high-risk cytogenetics, including those with del(17), in whom median PFS was similar to all IRd-treated pts indicating that ixazomib may have a favorable impact on the adverse prognosis associated with genetic mutations. If approved, this all-oral combination of IRd may become a new standard of care in this setting. Table. Key efficacy data IRd Rd HR / OR Median PFS, mos 20.6 14.7 HR 0.742; 95% CI: 0.587-0.939; p=0.012 Confirmed ORR, % 78.3 71.5 OR 1.44; p=0.035 CR 11.7 6.6 OR 1.87; p=0.019 ≥VGPR 48.1 39.0 OR 1.45; p=0.014 Median time to first response (ITT analysis), mos 1.1 1.9 Median duration of response (≥PR), mos 20.5 15.0 Disclosures Moreau: Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Off Label Use: Investigational proteasome inhibitor ixazomib in combination with lenalidomide and dexamethasone for patients with relapsed/refractory multiple myeloma. Masszi:Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Bahlis:Johnson & Johnson: Speakers Bureau; Johnson & Johnson: Consultancy; Amgen: Consultancy; Johnson & Johnson: Research Funding; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau. Sandhu:Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Ganly:Novartis: Honoraria; Roche: Honoraria; Medipics: Equity Ownership. Baker:Janssen-Cilag New Zealand: Membership on an entity's Board of Directors or advisory committees. Stoppa:Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Simpson:Celgene: Honoraria; Janssen-Cilag: Honoraria; Onyx Pharmaceuticals: Research Funding; Roche: Honoraria. Gimsing:Amgen: Honoraria. Palumbo:Celgene, Millennium Pharmaceuticals, Amgen, Bristol-Myers Squibb, Genmab, Janssen-Cilag, Onyx Pharmaceuticals: Consultancy, Honoraria; Novartis, Sanofi Aventis: Honoraria. Garderet:Bristol-Myers Squibb: Consultancy. Cavo:Janssen-Cilag, Celgene, Amgen, BMS: Honoraria. Kumar:AbbVie: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Onyx: Research Funding; Celgene, Millenium, Sanofi, Skyline, BMS, Onyx, Noxxon,: Other: Consultant, no compensation,; Skyline, Noxxon: Honoraria; Millenium/Takeda: Research Funding. Touzeau:AbbVie: Research Funding. Laubach:Novartis: Research Funding; Onyx: Research Funding; Celgene: Research Funding; Millennium: Research Funding. Lin:Millennium Pharmaceuticals, Inc.: Employment. Berg:Millennium Pharmaceuticals, Inc.: Employment. DiBacco:Millennium Pharmaceuticals, Inc.: Employment. Hui:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Richardson:Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Millennium Takeda: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Introduction: Despite recent advances in available treatments, chronic lymphocytic leukemia (CLL) remains an incurable disease, and the vast majority of patients (pts) will relapse and require additional lines of therapy. Thus, prolonging remission is a key treatment goal in CLL. This multicenter, randomized, double-blinded phase 3 trial (NCT00774345) was designed to evaluate the efficacy and safety of lenalidomide (LEN) vs placebo (PBO) as maintenance therapy in previously treated CLL pts. Methods: Eligible CLL pts must have had at least a partial response (PR) to second-line therapy. Pts were randomized 1:1 to receive either LEN 2.5 mg once daily on days 1-28 of the first 28-day cycle, or matching PBO. If LEN was well tolerated, escalation to 5 mg/day was permitted from cycle 2, and further escalation to 10 mg/day at cycle 7 and thereafter. Pts were stratified by their response at the end of second-line therapy (PR, nodular PR, complete response [CR], or CR with incomplete bone marrow recovery; vs minimal residual disease [MRD]-negative CR by flow cytometry); age (≤ 70 vs > 70 years); and presence of at least one of the following poor prognostic factors: del(11q), del(17p), unmutated IGHV, or b2M > 0.4 mg/L (Yes vs No vs Unknown). Co-primary endpoints were progression-free survival (PFS; IRAC assessed) and overall survival (OS). Secondary endpoints included: safety, tumor response, duration of response, second PFS (PFS2, time from randomization to second disease progression or death), and health-related quality of life (HRQoL). Results: Overall, 314 pts were enrolled (LEN, n = 160; PBO, n = 154). Baseline characteristics were balanced between the treatment arms: median age was 63 years (range 37-82) and 63 years (range 37-84), 71.9% and 72.1% were male, 9.4% and 11.7% had MRD-negative CR to second-line treatment, and 47.5% and 47.4% had at least one poor prognostic factor, in the LEN and PBO arms, respectively. On review of the primary analysis, 30 Sept 2015 data cutoff, the required number of progression events to complete the co-primary analysis had occurred, and the data monitoring committee recommended that the study be unblinded. Median follow-up time was 31.5 months, and the median PFS was significantly longer for LEN vs PBO: 33.9 vs 9.2 months, respectively (HR 0.40 [95% CI 0.29, 0.55]; P < 0.001). At the time of the analysis there were 86 deaths and there was no significant difference in the OS (HR 0.96 [95% CI 0.63, 1.48]; P = 0.856). Subsequent CLL therapy was received by 35.7% of pts in the LEN arm and 58.4% of pts in the PBO arm, of these pts 16% in the LEN arm and 20% in the PBO arm were treated with a BTK or PI3K inhibitor. Median PFS2 was significantly longer for LEN vs PBO: 57.5 vs 32.7 months, respectively (HR 0.46 [95% CI 0.29, 0.70]; P <0.001). Median number of treatment cycles received was 18 vs 9 cycles, for LEN vs PBO, respectively; a higher proportion of pts in the LEN arm started ≥25 cycles vs the PBO arm (38.9% vs 24.0%, respectively). Median dose intensity in the LEN arm was 4.2 mg/day. The most common adverse events (AEs) of all grades were neutropenia (66.2% vs 30.5%) and diarrhea (40.8% vs 16.2%) in the LEN vs PBO arm, respectively. Febrile neutropenia occurred in 1.9% vs 0%, deep vein thrombosis in 1.9% vs 0%, and pulmonary embolism in 2.5% vs 0.6% of pts in the LEN vs PBO arm, respectively. Most common grade 3/4 AEs were neutropenia (59.9% vs 22.7%), thrombocytopenia (16.6% vs 6.5%), and diarrhea (8.3% vs 0.6%) in the LEN vs PBO arm, respectively; all other grade 3/4 AEs occurred in <5% of pts in either arm. While there was a significant difference in the incidence of neutropenia, the rate of grade 3/4 infections was 16.6% for LEN vs 10.4% for PBO-treated pts. There were 13 (8.3%) vs 14 (9.1%) pts with at least one invasive second primary malignancy (SPM) in the LEN vs PBO arm, respectively. Hematologic invasive SPMs occurred in 7 vs 2 pts, and solid tumor invasive SPMs occurred in 7 vs 12 pts, in the LEN vs PBO arm, respectively. Overall, 44 pts in the LEN arm and 41 pts in the PBO arm died; 1 pt died on treatment in the LEN arm, and 2 pts in the PBO arm. There was no clinically meaningful difference in HRQoL for LEN vs PBO, as measured by FACT-Leu and EQ-5D, during maintenance treatment. Conclusions: LEN maintenance therapy significantly improved PFS from 9.2 to 33.9 months following second-line treatment in pts with CLL. The incidence of invasive SPMs was similar in both arms, and LEN maintenance treatment had an expected and acceptable safety profile. Disclosures Foà: Roche: Consultancy, Speakers Bureau; Janssen: Speakers Bureau; Gilead,: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Celgene Corporation: Consultancy, Speakers Bureau; Pfizer, Ariad: Speakers Bureau; Genentech, Janssen, BMS: Consultancy. Schuh:Gilead: Consultancy, Honoraria, Research Funding; Roche, Janssen, Novartis, Celgene, Abbvie: Consultancy, Honoraria. Zaritskey:Novartis: Consultancy; Janssen: Consultancy. Semochkin:Celgene, Sandoz, Novartis, Astellas, Janssen Pharmaceuticals, Bristol-Myers Squibb: Speakers Bureau; Celgene, Bayer Healthcare, Astellas Pharma Inc.: Research Funding; City Clinical Hospital 52, Moscow, Russia: Consultancy. Simpson:Amgen Pharmaceuticals: Research Funding; Celgene, Roche, Janssen: Honoraria. Vokurka:Roche: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Zhang:Celgene Corporation: Employment, Equity Ownership. Purse:Celgene Corporation: Employment, Equity Ownership.

Abstract Zanubrutinib is a potent and highly selective inhibitor of Bruton tyrosine kinase (BTK). In this first-in-human, open-label, multicenter, phase 1 study, patients in part 1 (3 + 3 dose escalation) had relapsed/refractory B-cell malignancies and received zanubrutinib 40, 80, 160, or 320 mg once daily or 160 mg twice daily. Part 2 (expansion) consisted of disease-specific cohorts, including treatment-naive or relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). The primary end points were safety and tolerability, and definition of the maximum tolerated dose (part 1). Additional end points included pharmacokinetics/pharmacodynamics and preliminary efficacy. Reported herein are results from 144 patients enrolled in the dose-finding and CLL/SLL cohorts. No dose-limiting toxicities occurred in dose escalation. Median BTK occupancy in peripheral blood mononuclear cells was &gt;95% at all doses. Sustained complete (&gt;95%) BTK occupancy in lymph node biopsy specimens was more frequent with 160 mg twice daily than 320 mg once daily (89% vs 50%; P = .0342). Consequently, 160 mg twice daily was selected for further investigation. With median follow-up of 13.7 months (range, 0.4-30.5 months), 89 CLL/SLL patients (94.7%) remain on study. Most toxicities were grade 1/2; neutropenia was the only grade 3/4 toxicity observed in &gt;2 patients. One patient experienced a grade 3 subcutaneous hemorrhage. Among 78 efficacy-evaluable CLL/SLL patients, the overall response rate was 96.2% (95% confidence interval, 89.2-99.2). Estimated progression-free survival at 12 months was 100%. Zanubrutinib demonstrated encouraging activity in CLL/SLL patients, with a low incidence of major toxicities. This trial was registered at www.clinicaltrials.gov as #NCT02343120.