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Introduction: Bruton's tyrosine kinase (BTK) inhibition is an emerging standard of care for WM. The ASPEN trial (NCT03053440) is a randomized phase 3 study comparing zanubrutinib, a potent and selective BTK inhibitor, versus ibrutinib, a first generation BTK inhibitor, in patients with WM. Method(s): Patients with MYD88 mutation-positive (MYD88mut+) WM were randomly assigned 1:1 to receive zanubrutinib (160 mg twice daily) or ibrutinib (420 mg once daily). Patients without MYD88 mutations were assigned to a separate cohort, received zanubrutinib, and are reported separately. Randomization was stratified by CXCR4 mutational status and the number of lines of prior therapy (0 vs 1-3 vs >3). The primary end point was the proportion of patients achieving a complete response or very good partial response (CR+VGPR). Sample size was calculated to provide 81% power to detect a difference in CR+VGPR rate of 35% vs 15% in the subset of patients with relapsed or refractory WM. Primary analysis was planned to occur at ~12 months after the last patient enrolled. Result(s): In total, 201 patients were randomized from Jan 2017 to Jul 2018. The treatment groups were well balanced for important baseline factors, with the exception of more elderly patients (aged >75 years, 33.3% vs 22.2%) and more anemia (hemoglobin <=110 g/L, 65.7% vs 53.5%) in the zanubrutinib arm. At a median follow-up of 19.4 months, the rate of VGPR (no CRs were observed) was 28.4% vs 19.2% with zanubrutinib vs ibrutinib, respectively (2-sided P=0.09). Rates of atrial fibrillation, contusion, diarrhea, edema peripheral, hemorrhage, muscle spasms, pneumonia, and adverse events leading to discontinuation or death were lower with zanubrutinib. The rate of neutropenia was higher with zanubrutinib (Table), but grade >=3 infection rates were similar (17.8% vs 19.4%). Conclusion(s): ASPEN is the largest phase 3 trial of BTK inhibitors in WM and the first head-to-head comparison of BTK inhibitors in any disease. Although

Introduction: Inhibitors of Bruton's tyrosine kinase (BTK) have shown significant activity in patients with MYD88 mutation-positive (MYD-88mut+) WM. However, lower response rates and shorter progression-free survival have been reported in patients with WM who lack such mutations (N Engl J Med. 2015;372:1430). The ASPEN trial (NCT03053440) evaluated zanubrutinib, a potent and selective BTK inhibitor, in patients with MYD88WT WM. Here, we present the safety and efficacy of zanubrutinib in these patients. Method(s): At study entry, bone marrow MYD88 mutations were assessed by a central laboratory (NeoGenomics). Based on these results, patients were assigned to cohort 1 (MYD88mut+) or cohort 2 (MYD88WT or unknown mutation status). Patients received zanubrutinib 160 mg twice daily until disease progression. Result(s): In total, 28 patients were enrolled in cohort 2, of which 26 were centrally confirmed as MYD88WT. Median age of patients was 72 years; five patients were treatment-naive and 23 patients had relapsed/refractory (>=1 prior therapy) WM. Most patients had intermediate-risk (39.3%) or high-risk (42.9%) disease, as defined by the International Prognostic Scoring System for WM. At median follow-up of 17.9 months, two patients discontinued zanubrutinib due to adverse events (AEs), and six experienced disease progression; there were no cases of disease transformation. In patients with confirmed MYD88WT, the overall response rate by independent review was 80.8%, with a major response rate of 50.0%, including a very good partial response rate of 26.9%. The progression-free survival event-free rate at 12 months was 72.4%. The most frequently reported AEs were diarrhea, anemia, contusion, pyrexia, and upper respiratory tract infection. Major hemorrhage was reported in two patients, and atrial fibrillation was reported in one patient. There were no fatal AEs. Conclusion(s): Zanubrutinib showed clinically meaningful antitumor activity, including achieving major responses

Background: ASPEN is a randomized, open-label, phase 3 study comparing ZANU, a potent and selective Bruton tyrosine kinase inhibitor (BTKi), with the first-generation BTKi IBR in patients with WM. We present data with a median follow-up of 43 months. Method(s): Patients with MYD88 mutations were assigned to cohort 1 and randomized 1:1 to receive ZANU 160 mg twice daily or IBR 420 mg once daily. Randomization was stratified by CXCR4 mutational status and lines of prior therapy (0 vs 1-3 vs > 3). Patients without MYD88 mutations were assigned to cohort 2 and received ZANU 160 mg twice daily. The primary endpoint was proportion of patients achieving complete response or very good partial response (CR+VGPR). Result(s): A total of 201 patients (ZANU arm, n = 102; IBR arm, n = 99) were enrolled in cohort 1 and 28 patients were enrolled in cohort 2. A larger proportion of patients in the ZANU arm of cohort 1 vs IBR had CXCR4 mutations by next-generation sequencing (32% vs 20%, or 33 of 98 vs 20 of 92 with data available) and were aged > 75 years (33% vs 22%). Median duration of treatment was 42 months (ZANU) and 41 months (IBR), with 67% and 58% remaining on treatment, respectively. The CR+VGPR rate by investigator was 36% with ZANU vs 22% with IBR (p= 0.02) in cohort 1, and 31% in cohort 2. One patient achieved CR (cohort 2). In patients with wild type or mutant CXCR4 from cohort 1, CR+VGPR rates with ZANU vs IBR were 45% vs 28% (p= 0.04) and 21% vs 5% (p= 0.15), respectively. Median progression-free survival and overall survival were not yet reached. Rates of atrial fibrillation, diarrhea, hypertension, localized infection, hemorrhage, muscle spasms, pneumonia, and adverse events leading to discontinuation or death were lower with ZANU vs IBR (Table). Exposure-adjusted incidence rates of atrial fibrillation/flutter and hypertension were lower with ZANU vs IBR (0.2 vs 0.8 and 0.5 vs 1.0 persons per 100 person-months, respectively; p< 0.05). Rate of neutropenia was higher

Background: ZANU is a potent and selective next-generation Bruton tyrosine kinase inhibitor (BTKi) designed to have greater affinity to BTK while minimizing off-target inhibition of TEC-and EGFR-family kinases. ASPEN (NCT03053440) is a randomized, open-label, phase 3 study comparing ZANU with the first-generation BTKi IBR in pts with WM. We present data with a median follow-up of 43 months. Aim(s): To compare the efficacy and safety of ZANU vs IBR in pts with MYD88 mutant (MYD88mut) WM and ZANU in pts with wild-type MYD88 (MYD88wt) WM. Method(s): Pts with MYD88mut WM were assigned to cohort 1 and randomized 1:1 to receive ZANU 160 mg twice daily or IBR 420 mg once daily. Pts with MYD88wt were assigned to cohort 2 and received ZANU 160 mg twice daily until disease progression. Randomization was stratified by CXCR4 mutational status by Sanger sequencing and lines of prior therapy (0, 1-3, or >3). All pts gave informed consent. The primary endpoint was proportion of pts achieving very good partial response or better (VGPR + complete response [CR]). Primary analysis occurred at 19 months median follow-up, and final analysis is planned to occur ~4 years after the first pt enrolled. Result(s): A total of 201 pts (102 ZANU; 99 IBR) were enrolled in cohort 1 and 28 pts in cohort 2. Baseline characteristics in cohort 1 differed between pts treated with ZANU vs IBR in CXCR4 mutations by next-generation sequencing (32% vs 20%, or 33 of 98 vs 20 of 92 available samples, respectively) and pts aged >75 years (33% vs 22%, respectively). Median duration of treatment was 42 months (ZANU) and 41 months (IBR), with 67% and 58% remaining on treatment, respectively. The VGPR+CR rate by investigator was 36% with ZANU vs 22% with IBR (descriptive p = 0.02) in cohort 1, and 31% in cohort 2. One pt in cohort 2 obtained a CR. In pts with wild-type (65 ZANU; 72 IBR) or mutant CXCR4 (33 ZANU; 20 IBR) from cohort 1, VGPR+CR rates with ZANU vs IBR were 45% vs 28% (p = 0.04) and 21% vs 5% (p = 0.

PURPOSE The double-blind, randomized, placebo-controlled phase III iNNOVATE study showed sustained efficacy of ibrutinib-rituximab in Waldenström’s macroglobulinemia (WM). Here, we present the final analysis from iNNOVATE. METHODS Patients had confirmed symptomatic WM, either previously untreated or previously treated; patients with prior rituximab had at least a minor response to their last rituximab-based regimen. Patients were randomly assigned to once-daily ibrutinib 420 mg plus rituximab or placebo plus rituximab (n = 75 per arm). The primary end point was progression-free survival (PFS). Secondary end points included response rate, time to next treatment, hemoglobin improvement, overall survival, and safety. RESULTS With a median follow-up of 50 (range, 0.5-63) months, median (95% CI) PFS was not reached (57.7 months to not evaluable) with ibrutinib-rituximab versus 20.3 months (13.0 to 27.6) with placebo-rituximab (hazard ratio, 0.250; P < .0001). PFS benefit was regardless of prior treatment status, MYD88 and CXCR4 mutation status, or key patient characteristics. Higher response rates (partial response or better) were observed with ibrutinib-rituximab (76% v 31% with placebo-rituximab; P < .0001) and were sustained over time. Median time to next treatment was not reached with ibrutinib-rituximab versus 18 months with placebo-rituximab. More patients receiving ibrutinib-rituximab versus placebo-rituximab had sustained hemoglobin improvement (77% v 43%; P < .0001). Median overall survival was not reached in either arm. Ibrutinib-rituximab maintained a manageable safety profile; the prevalence of grade $ 3 adverse events of clinical interest generally decreased over time. CONCLUSION In the final analysis of iNNOVATE with a median follow-up of 50 months, ibrutinib-rituximab showed ongoing superiority across clinical outcomes in patients with WM regardless of MYD88 or CXCR4 mutation status, prior treatment, and key patient characteristics.

Patients with Waldenstrom macroglobulinemia (WM) lacking activating mutations in the MYD88 gene (MYD88WT) have demonstrated relatively poor outcomes to ibrutinib monotherapy, with no major responses reported in a phase 2 pivotal study. Zanubrutinib is a novel, selective Bruton tyrosine kinase (BTK) inhibitor designed to maximize BTK occupancy and minimize off-target activity. The ASPEN study consisted of a randomized comparison of zanubrutinib and ibrutinib efficacy and safety in patients with WM who have the MYD88 mutation, as well as a separate cohort of patients without MYD88 mutation (MYD88WT) or with unknown mutational status who received zanubrutinib. Results from the latter single-arm cohort are reported herein. Efficacy endpoints included overall, major and complete (CR) or very good partial response (VGPR) rates, progression-free survival (PFS), duration of response (DOR), and overall survival (OS). Twenty-eight patients (23 relapsed/ refractory; 5 treatment-naive) were enrolled, including 26 with centrally confirmed MYD88WT disease and 2 with unknown MYD88 mutational status. At a median follow-up of 17.9 months, 7 of 26 MYD88WT patients (27%) had achieved a VGPR and 50% a major response (partial response or better); there were no CRs. At 18 months, the estimated PFS and OS rates were 68% and 88%, respectively, while the median DOR had not been reached. Two patients discontinued zanubrutinib due to adverse events. Treatment-emergent hypertension, atrial fibrillation, and major hemorrhages were reported in 3, 1 and 2 patients (including 1 concurrent with enoxaparin therapy), respectively. Results of this substudy demonstrate that zanubrutinib monotherapy can induce high quality responses in patients with MYD88WT WM. This trial is registered on www.clinicaltrials.gov as NCT #03053440.Copyright © 2020 by The American Society of Hematology

Bruton tyrosine kinase (BTK) inhibition is an effective treatment approach for patients with Waldenstrom macroglobulinemia (WM). The phase 3 ASPEN study compared the efficacy and safety of ibrutinib, a first-generation BTK inhibitor, with zanubrutinib, a novel highly selective BTK inhibitor, in patients with WM. Patients with MYD88L265P disease were randomly assigned 1:1 to treatment with ibrutinib or zanubrutinib. The primary end point was the proportion of patients achieving a complete response (CR) or a very good partial response (VGPR) by independent review. Key secondary end points included major response rate (MRR), progression-free survival (PFS), duration of response (DOR), disease burden, and safety. A total of 201 patients were randomized, and 199 received ++1 dose of study treatment. No patient achieved a CR. Twenty-nine (28%) zanubrutinib patients and 19 (19%) ibrutinib patients achieved a VGPR, a nonstatistically significant difference (P 5 .09). MRRs were 77% and 78%, respectively. Median DOR and PFS were not reached 84% and 85% of ibrutinib and zanubrutinib patients were progression free at 18 months. Atrial fibrillation, contusion, diarrhea, peripheral edema, hemorrhage, muscle spasms, and pneumonia, as well as adverse events leading to treatment discontinuation, were less common among zanubrutinib recipients. Incidence of neutropenia was higher with zanubrutinib, although grade ++3 infection rates were similar in both arms (1.2 and 1.1 events per 100 person-months). These results demonstrate that zanubrutinib and ibrutinib are highly effective in the treatment of WM, but zanubrutinib treatment was associated with a trend toward better response quality and less toxicity, particularly cardiovascular toxicity.Copyright © 2020 American Society of Hematology. All rights reserved.

Background: Bruton tyrosine kinase (BTK) inhibition is an emerging standard of care for WM. ASPEN is a randomized phase 3 study comparing zanubrutinib (ZANU), a potent and selective BTK inhibitor, versus ibrutinib (IBR), a first generation BTK inhibitor, in WM patients. Method(s): Patients with WM and MYD88 mutation were randomly assigned 1:1 to receive ZANU (160 mg twice daily) or IBR (420 mg once daily). Patients without MYD88 mutations were assigned to a separate cohort, received ZANU, and are reported separately. Randomization was stratified by CXCR4 mutational status and the number of lines of prior therapy (0 vs 1-3 vs >3). The primary end point was the proportion of patients achieving a complete response or very good partial response (CR+VGPR). Sample size was calculated to provide 81% power to detect a difference in CR+VGPR rate of 35% vs 15% in the subset of patients with relapsed or refractory (R/R) WM. Primary analysis was planned to occur at ~12 months after last patient enrolled. Result(s):In total, 201 patients were randomized from Jan 2017 to Jul 2018. The treatment groups were well balanced for important baseline factors, except in the ZANU arm there were more elderly patients (aged >75 years, 33.3% vs 22.2%) and more anemia (hemoglobin <=110 g/L, 65.7% vs 53.5%). At a median follow-up of 19.4 months, the rate of CR+VGPR was 28.4% vs 19.2% with ZANU vs IBR, respectively (2-sided P=0.09). Rates of atrial fibrillation, contusion, diarrhea, edema peripheral, hemorrhage, muscle spasms, pneumonia, and adverse events (AEs) leading to discontinuation or death were lower with ZANU. The rate of neutropenia was higher with ZANU (Table); however, grade >= 3 infection rates were similar (17.8% vs 19.4%). Conclusion(s): ASPEN is the largest phase 3 trial of BTK inhibitors in WM and the first head-to-head comparison of BTK inhibitors in any disease. Although not statistically significant, ZANU was associated with a higher CR+VGPR response rate, and demonstrated cl