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Bruton tyrosine kinase (BTK) inhibition is an effective therapy for many B-cell malignancies. Acalabrutinib is a next-generation, potent, highly selective, covalent BTK inhibitor. To characterize acalabrutinib tolerability, we pooled safety data from 1040 patients with mature B-cell malignancies treated with acalabrutinib monotherapy in nine clinical studies (treatment-naïve: n = 366 [35%], relapsed/refractory: n = 674 [65%]; median [range] age: 67 [32-90] years; median [range] prior treatments: 1 [0-13]; median [range] duration of exposure: 24.6 [0.0-58.5] months). The most common adverse events (AEs) were headache (38%), diarrhea (37%), upper respiratory tract infection (22%), contusion (22%), nausea (22%), fatigue (21%), and cough (21%). Serious AEs (SAEs) occurred in 39% of patients; pneumonia (6%) was the only SAE that occurred in ≥2%. Deaths due to AEs occurred in 52 patients (5%); pneumonia (n = 8) was the only fatal AE to occur in ≥3 patients. AEs led to treatment discontinuation in 9%. Rates for the AEs of interest (all grades) included infections (67%), hemorrhages (46%), neutropenia (16%), anemia (14%), second primary malignancies (12%), thrombocytopenia (9%), hypertension (8%), and atrial fibrillation (4%). This pooled analysis confirmed acalabrutinib's tolerability and identified no newly emerging late toxicities, supporting acalabrutinib as a long-term treatment for patients with mature B-cell malignancies., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Acalabrutinib has demonstrated significant efficacy and safety in relapsed chronic lymphocytic leukemia (CLL). Efficacy and safety of acalabrutinib monotherapy were evaluated in a treatment-naive CLL cohort of a single-arm phase 1/2 trial (ACE-CL-001). Adults were eligible for enrollment if chemotherapy was declined or deemed inappropriate due to comorbidities (N = 99). Patients had a median age of 64 years and 47% had Rai stage III/IV disease. Acalabrutinib was administered orally 200 mg once daily, or 100 mg twice daily until progression or intolerance. A total of 99 patients were treated; 57 (62%) had unmutated immunoglobulin heavy-chain variable gene, and 12 (18%) had TP53 aberrations. After median follow-up of 53 months, 85 patients remain on treatment; 14 discontinued treatment, mostly because of adverse events (AEs) (n = 6) or disease progression (n = 3). Overall response rate was 97% (90% partial response; 7% complete response), with similar outcomes among all prognostic subgroups. Because of improved trough BTK occupancy with twice-daily dosing, all patients were transitioned to 100 mg twice daily. Median duration of response (DOR) was not reached; 48-month DOR rate was 97% (95% confidence interval, 90-99). Serious AEs were reported in 38 patients (38%). AEs required discontinuation in 6 patients (6%) because of second primary cancers (n = 4) and infection (n = 2). Grade ≥3 events of special interest included infection (15%), hypertension (11%), bleeding events (3%), and atrial fibrillation (2%). Durable efficacy and long-term safety of acalabrutinib in this trial support its use in clinical management of symptomatic, untreated patients with CLL., (© 2021 by The American Society of Hematology.)

Inhibition of the B-cell receptor pathway, and specifically of Bruton tyrosine kinase (BTK), is a leading therapeutic strategy in B-cell malignancies, including chronic lymphocytic leukemia (CLL). Target occupancy is a measure of covalent binding to BTK and has been applied as a pharmacodynamic parameter in clinical studies of BTK inhibitors. However, the kinetics of de novo BTK synthesis, which determines occupancy, and the relationship between occupancy, pathway inhibition and clinical outcomes remain undefined. This randomized phase 2 study investigated the safety, efficacy, and pharmacodynamics of a selective BTK inhibitor acalabrutinib at 100 mg twice daily (BID) or 200 mg once daily (QD) in 48 patients with relapsed/refractory or high-risk treatment-naïve CLL. Acalabrutinib was well tolerated and yielded an overall response rate (ORR) of partial response or better of 95.8% (95% confidence interval [CI], 78.9-99.9) and an estimated progression-free survival (PFS) rate at 24 months of 91.5% (95% CI, 70.0-97.8) with BID dosing and an ORR of 79.2% (95% CI, 57.9-92.9) and an estimated PFS rate at 24 months of 87.2% (95% CI, 57.2-96.7) with QD dosing. BTK resynthesis was faster in patients with CLL than in healthy volunteers. BID dosing maintained higher BTK occupancy and achieved more potent pathway inhibition compared with QD dosing. Small increments in occupancy attained by BID dosing relative to QD dosing compounded over time to augment downstream biological effects. The impact of BTK occupancy on long-term clinical outcomes remains to be determined. This trial was registered at www.clinicaltrials.gov as #NCT02337829.

Purpose: To determine the pharmacodynamic relationship between target occupancy of Bruton tyrosine kinase (BTK) and inhibition of downstream signaling., Patients and Methods: Patients with chronic lymphocytic leukemia (CLL) enrolled in a phase II clinical trial (NCT02337829) with the covalent, selective BTK inhibitor acalabrutinib donated blood samples for pharmacodynamic analyses. Study design included randomization to acalabrutinib 100 mg twice daily or 200 mg once daily and dose interruptions on day 4 and 5 of the first week. BTK occupancy and readouts of intracellular signaling were assessed sequentially between 4 and 48 hours from last dose., Results: Four hours from last dose, BTK occupancy exceeded 96% and at trough, was higher with twice daily, median 95.3%, than with once daily dosing, median 87.6% ( P < 0.0001). By 48 hours from last dose, median free BTK increased to 25.6%. Due to covalent binding of acalabrutinib, free BTK is generated by de novo synthesis. The estimated rate of BTK synthesis varied widely between patients ranging from 3.6% to 31.4% per day. Acalabrutinib reduced phosphorylation of BTK and inhibited downstream B-cell receptor (BCR) and NFκB signaling. During dosing interruptions up to 48 hours, expression of BCR target genes rebounded, while phosphorylation of signaling molecules remained repressed. In vitro cross-linking of IgM on CLL cells obtained 36 to 48 hours from last dose upregulated CD69, with high correlation between cellular free BTK and response ( R = 0.7, P ≤ 0.0001)., Conclusions: Higher BTK occupancy was achieved with twice daily over once daily dosing, resulting in deeper and more sustained inhibition of BCR signaling., (©2020 American Association for Cancer Research.)

Patients with severe COVID-19 have a hyperinflammatory immune response suggestive of macrophage activation. Bruton tyrosine kinase (BTK) regulates macrophage signaling and activation. Acalabrutinib, a selective BTK inhibitor, was administered off-label to 19 patients hospitalized with severe COVID-19 (11 on supplemental oxygen; 8 on mechanical ventilation), 18 of whom had increasing oxygen requirements at baseline. Over a 10-14 day treatment course, acalabrutinib improved oxygenation in a majority of patients, often within 1-3 days, and had no discernable toxicity. Measures of inflammation - C-reactive protein and IL-6 - normalized quickly in most patients, as did lymphopenia, in correlation with improved oxygenation. At the end of acalabrutinib treatment, 8/11 (72.7%) patients in the supplemental oxygen cohort had been discharged on room air, and 4/8 (50%) patients in the mechanical ventilation cohort had been successfully extubated, with 2/8 (25%) discharged on room air. Ex vivo analysis revealed significantly elevated BTK activity, as evidenced by autophosphorylation, and increased IL-6 production in blood monocytes from patients with severe COVID-19 compared with blood monocytes from healthy volunteers. These results suggest that targeting excessive host inflammation with a BTK inhibitor is a therapeutic strategy in severe COVID-19 and has led to a confirmatory international prospective randomized controlled clinical trial., (Copyright © 2020, American Association for the Advancement of Science.)

Therapeutic targeting of Bruton tyrosine kinase (BTK) has dramatically improved survival outcomes for patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Acalabrutinib is an oral, highly selective BTK inhibitor that allows for twice-daily dosing due to its selectivity. In this phase 1b/2 study, 134 patients with relapsed/refractory CLL or SLL (median age, 66 years [range, 42-85 years]; median prior therapies, 2 [range, 1-13]) received acalabrutinib 100 mg twice daily for a median of 41 months (range, 0.2-58 months). Median trough BTK occupancy at steady state was 97%. Most adverse events (AEs) were mild or moderate, and were most commonly diarrhea (52%) and headache (51%). Grade ≥3 AEs (occurring in ≥5% of patients) were neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%), and diarrhea (5%). Atrial fibrillation and major bleeding AEs (all grades) occurred in 7% and 5% of patients, respectively. Most patients (56%) remain on treatment; the primary reasons for discontinuation were progressive disease (21%) and AEs (11%). The overall response rate, including partial response with lymphocytosis, with acalabrutinib was 94%; responses were similar regardless of genomic features (presence of del(11)(q22.3), del(17)(p13.1), complex karyotype, or immunoglobulin variable region heavy chain mutation status). Median duration of response and progression-free survival (PFS) have not been reached; the estimated 45-month PFS was 62% (95% confidence interval, 51% to 71%). BTK mutation was detected in 6 of 9 patients (67%) at relapse. This updated and expanded study confirms the efficacy, durability of response, and long-term safety of acalabrutinib, justifying its further investigation in previously untreated and treated patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443., (© 2020 by The American Society of Hematology.)

Acalabrutinib is a selective irreversible Bruton tyrosine kinase (BTK) inhibitor that does not affect IL2-associated tyrosine kinase or antibody-dependent cellular cytotoxicity, making it an attractive candidate for combination therapy with anti-CD20 antibodies. We investigated acalabrutinib plus obinutuzumab in a phase Ib/II study (NCT02296918) of patients with treatment-naïve or relapsed/refractory chronic lymphocytic leukemia (CLL). Nineteen treatment-naïve and 26 relapsed/refractory patients were treated with acalabrutinib (100 mg twice daily) until progression and obinutuzumab (cycle 1: 100 mg day 1, 900 mg day 2, 1000 mg days 8 and 15; cycles 2-6: 1,000 mg day 1). Grade 3/4 adverse events occurred in 71% of patients. Overall response rates were 95% (treatment-naïve) and 92% (relapsed/refractory). Thirty-two percent of treatment-naïve and 8% of relapsed/refractory patients achieved complete remission. At 36 months, 94% (treatment-naïve) and 88% (relapsed/refractory) were progression free. Acalabrutinib plus obinutuzumab was well tolerated, producing high and durable responses in treatment-naïve and relapsed/refractory CLL. SIGNIFICANCE: Rituximab plus the less selective BTK inhibitor ibrutinib has not shown benefit in CLL; however, the selective BTK inhibitor acalabrutinib plus the antibody-dependent cellular cytotoxicity-enhanced antibody obinutuzumab yielded durable responses that deepened over time in treatment-naïve and relapsed/refractory CLL, supporting the evaluation of this approach in larger, comparative studies in CLL. This article is highlighted in the In This Issue feature, p. 327 ., (©2020 American Association for Cancer Research.)

Background: Chemoimmunotherapy is typically the standard of care for patients with Waldenström macroglobulinemia; however, infectious and hematologic toxic effects are problematic. Acalabrutinib is a selective, potent Bruton tyrosine-kinase inhibitor. The aim of this trial was to evaluate the activity and safety of acalabrutinib in patients with Waldenström macroglobulinemia., Methods: This single-arm, multicentre, phase 2 trial was done in 19 European academic centres in France, Italy, Greece, the Netherlands, and the UK, and eight academic centres in the USA. Eligible patients were 18 years or older and had treatment naive (declined or not eligible for chemoimmunotherapy) or relapsed or refractory (at least one previous therapy) Waldenström macroglobulinemia that required treatment, an Eastern Cooperative Oncology Group performance status of 2 or less, and received no previous Bruton tyrosine-kinase inhibitor therapy. Patients received 100 mg oral acalabrutinib twice per day in 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed overall response (at least a minor response) according to the 6th International Workshop for Waldenström Macroglobulinemia (IWWM) and the modified 3rd IWWM workshop criteria. The primary outcome and safety were assessed in all patients who received at least one dose of treatment. This study is registered with ClinicalTrials.gov, number NCT02180724, and is ongoing, but no longer enrolling., Findings: Between Sept 8, 2014, and Dec 24, 2015, 122 patients were assessed for eligibility, of which 106 (87%) patients were given acalabrutinib (14 were treatment naive and 92 had relapsed or refractory disease). With a median follow-up of 27·4 months (IQR 26·0-29·7), 13 (93% [95% CI 66-100]) of 14 treatment naive patients achieved an overall response and 86 (93% [86-98]) of 92 relapsed or refractory patients per both the modified 3rd and 6th IWWM criteria. Seven (50%) of 14 treatment naive patients and 23 (25%) of 92 relapsed or refractory patients discontinued treatment on study. Grade 3-4 adverse events occurring in more than 5% of patients were neutropenia (17 [16%] of 106 patients) and pneumonia (7 [7%]). Grade 3-4 atrial fibrillation occurred in one (1%) patient and grade 3-4 bleeding occurred in three (3%) patients. The most common serious adverse events were lower respiratory tract infection (n=7 [7%]), pneumonia (n=7 [7%]), pyrexia (n=4 [4%]), cellulitis (n=3 [3%]), fall (n=3 [3%]), and sepsis (n=3 [3%]). Pneumonia (n=5 [5%]) and lower respiratory tract infection (n=4 [4%]) were considered treatment related. One treatment-related death was reported (intracranial hematoma)., Interpretation: This study provides evidence that acalabrutinib is active as single-agent therapy with a manageable safety profile in patients with treatment-naive, or relapse or refractory Waldenström macroglobulinemia. Further studies are needed to establish its efficacy against current standard treatments and to investigate whether outcomes can be improved with combination therapies., Funding: Acerta Pharma., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The Bruton tyrosine kinase (BTK) inhibitor ibrutinib improves patient outcomes in chronic lymphocytic leukemia (CLL); however, some patients experience adverse events (AEs) leading to discontinuation. Acalabrutinib is a potent, covalent BTK inhibitor with greater selectivity than ibrutinib. We evaluated the safety and efficacy of 100 mg of acalabrutinib twice daily or 200 mg once daily in patients with CLL who discontinued ibrutinib because of intolerance as determined by the investigators. Among 33 treated patients (61% men; median age, 64 years; range, 50-82 years), median duration of prior ibrutinib treatment was 11.6 months (range, 1-62 months); median time from ibrutinib discontinuation to acalabrutinib start was 47 days (range, 3-331 days). After a median of 19.0 months (range, 0.2-30.6 months), 23 patients remained on acalabrutinib; 10 had discontinued (progressive disease, n = 4; AEs, n = 3). No acalabrutinib dose reductions occurred. During acalabrutinib treatment, the most frequent AEs included diarrhea (58%), headache (39%), and cough (33%). Grade 3/4 AEs occurred in 58%, most commonly neutropenia (12%) and thrombocytopenia (9%). Of 61 ibrutinib-related AEs associated with intolerance, 72% did not recur and 13% recurred at a lower grade with acalabrutinib. Overall response rate was 76%, including 1 complete and 19 partial responses and 5 partial responses with lymphocytosis. Among 25 responders, median duration of response was not reached. Median progression-free survival (PFS) was not reached; 1-year PFS was 83.4% (95% confidence interval, 64.5%-92.7%). Acalabrutinib was well tolerated with a high response rate in patients who were previously intolerant to ibrutinib. This trial was registered at www.clinicaltrials.gov as #NCT02029443., (© 2019 by The American Society of Hematology.)

Background: Bruton tyrosine kinase is a clinically validated target in mantle cell lymphoma. Acalabrutinib (ACP-196) is a highly selective, potent Bruton tyrosine kinase inhibitor developed to minimise off-target activity., Methods: In this open-label, phase 2 study, oral acalabrutinib (100 mg twice per day) was given to patients with relapsed or refractory mantle cell lymphoma, until disease progression or unacceptable toxicity. The primary endpoint was overall response assessed according to the Lugano classification, and safety analyses were done in all participants. This trial is registered with ClinicalTrials.gov, number NCT02213926., Findings: From March 12, 2015, to Jan 5, 2016, 124 patients with relapsed or refractory mantle cell lymphoma were enrolled and all patients received treatment; median age 68 years. Patients received a median of two (IQR 1-2) previous therapies. At a median follow-up of 15·2 months, 100 (81%) patients achieved an overall response and 49 (40%) patients achieved a complete response. The Kaplan-Meier estimated medians for duration of response, progression-free survival, and overall survival were not reached; the 12-month rates were 72% (95% CI 62-80), 67% (58-75), and 87% (79-92%), respectively. The most common adverse events were primarily grade 1 or 2 and were headache (47 [38%]), diarrhoea (38 [31%]), fatigue (34 [27%]), and myalgia (26 [21%]). The most common grade 3 or worse adverse events were neutropenia (13 [10%]), anaemia (11 [9%]), and pneumonia (six [5%]). There were no cases of atrial fibrillation and one case of grade 3 or worse haemorrhage. The median duration of treatment was 13·8 months. Treatment was discontinued in 54 (44%) patients, primarily due to progressive disease (39 [31%]) and adverse events (seven [6%])., Interpretation: Acalabrutinib treatment provided a high rate of durable responses and a favourable safety profile in patients with relapsed or refractory mantle cell lymphoma. These findings suggest an important role for acalabrutinib in the treatment of this disease population., Funding: Acerta Pharma, a member of the AstraZeneca Group., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Acalabrutinib (ACP-196) is a second-generation inhibitor of Bruton agammaglobulinemia tyrosine kinase (BTK) with increased target selectivity and potency compared to ibrutinib. In this study, we evaluated acalabrutinib in spontaneously occurring canine lymphoma, a model of B-cell malignancy similar to human diffuse large B-cell lymphoma (DLBCL). First, we demonstrated that acalabrutinib potently inhibited BTK activity and downstream effectors in CLBL1, a canine B-cell lymphoma cell line, and primary canine lymphoma cells. Acalabrutinib also inhibited proliferation in CLBL1 cells. Twenty dogs were enrolled in the clinical trial and treated with acalabrutinib at dosages of 2.5 to 20mg/kg every 12 or 24 hours. Acalabrutinib was generally well tolerated, with adverse events consisting primarily of grade 1 or 2 anorexia, weight loss, vomiting, diarrhea and lethargy. Overall response rate (ORR) was 25% (5/20) with a median progression free survival (PFS) of 22.5 days. Clinical benefit was observed in 30% (6/20) of dogs. These findings suggest that acalabrutinib is safe and exhibits activity in canine B-cell lymphoma patients and support the use of canine lymphoma as a relevant model for human non-Hodgkin lymphoma (NHL).

Background: Irreversible inhibition of Bruton's tyrosine kinase (BTK) by ibrutinib represents an important therapeutic advance for the treatment of chronic lymphocytic leukemia (CLL). However, ibrutinib also irreversibly inhibits alternative kinase targets, which potentially compromises its therapeutic index. Acalabrutinib (ACP-196) is a more selective, irreversible BTK inhibitor that is specifically designed to improve on the safety and efficacy of first-generation BTK inhibitors., Methods: In this uncontrolled, phase 1-2, multicenter study, we administered oral acalabrutinib to 61 patients who had relapsed CLL to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of acalabrutinib. Patients were treated with acalabrutinib at a dose of 100 to 400 mg once daily in the dose-escalation (phase 1) portion of the study and 100 mg twice daily in the expansion (phase 2) portion., Results: The median age of the patients was 62 years, and patients had received a median of three previous therapies for CLL; 31% had chromosome 17p13.1 deletion, and 75% had unmutated immunoglobulin heavy-chain variable genes. No dose-limiting toxic effects occurred during the dose-escalation portion of the study. The most common adverse events observed were headache (in 43% of the patients), diarrhea (in 39%), and increased weight (in 26%). Most adverse events were of grade 1 or 2. At a median follow-up of 14.3 months, the overall response rate was 95%, including 85% with a partial response and 10% with a partial response with lymphocytosis; the remaining 5% of patients had stable disease. Among patients with chromosome 17p13.1 deletion, the overall response rate was 100%. No cases of Richter's transformation (CLL that has evolved into large-cell lymphoma) and only one case of CLL progression have occurred., Conclusions: In this study, the selective BTK inhibitor acalabrutinib had promising safety and efficacy profiles in patients with relapsed CLL, including those with chromosome 17p13.1 deletion. (Funded by the Acerta Pharma and others; ClinicalTrials.gov number, NCT02029443.).

PurposeAmong Bruton's tyrosine kinase inhibitors, acalabrutinib has greater selectivity than ibrutinib, which we hypothesized would improve continuous therapy tolerability. We conducted an open-label, randomized, noninferiority, phase III trial comparing acalabrutinib and ibrutinib in patients with chronic lymphocytic leukemia (CLL).MethodsPatients with previously treated CLL with centrally confirmed del(17)(p13.1) or del(11)(q22.3) were randomly assigned to oral acalabrutinib 100 mg twice daily or ibrutinib 420 mg once daily until progression or unacceptable toxicity. The primary end point was independent review committee-assessed noninferiority of progression-free survival (PFS).ResultsOverall, 533 patients (acalabrutinib, n = 268; ibrutinib, n = 265) were randomly assigned. At the data cutoff, 124 (46.3%) acalabrutinib patients and 109 (41.1%) ibrutinib patients remained on treatment. After a median follow-up of 40.9 months, acalabrutinib was determined to be noninferior to ibrutinib with a median PFS of 38.4 months in both arms (95% CI acalabrutinib, 33.0 to 38.6 and ibrutinib, 33.0 to 41.6; hazard ratio: 1.00; 95% CI, 0.79 to 1.27). All-grade atrial fibrillation/atrial flutter incidence was significantly lower with acalabrutinib versus ibrutinib (9.4% v 16.0%; P = .02); among other selected secondary end points, grade 3 or higher infections (30.8% v 30.0%) and Richter transformations (3.8% v 4.9%) were comparable between groups and median overall survival was not reached in either arm (hazard ratio, 0.82; 95% CI, 0.59 to 1.15), with 63 (23.5%) deaths with acalabrutinib and 73 (27.5%) with ibrutinib. Treatment discontinuations because of adverse events occurred in 14.7% of acalabrutinib-treated patients and 21.3% of ibrutinib-treated patients.ConclusionIn this first direct comparison of less versus more selective Bruton's tyrosine kinase inhibitors in CLL, acalabrutinib demonstrated noninferior PFS with fewer cardiovascular adverse events.