Search

In ELEVATE-RR (NCT02477696) at a median follow-up of 41 mo, Acala demonstrated noninferior progression-free survival with fewer cardiovascular adverse events versus ibrutinib (Ibr) in patients (pts) with relapsed/refractory (R/R) CLL. Characterization of Mechanisms of Resistance in Previously Treated Chronic Lymphocytic Leukemia (CLL) From a Head-to-Head Trial of Acalabrutinib Versus Ibrutinib B Introduction: b Acalabrutinib (Acala) is a highly selective, next-generation covalent Bruton tyrosine kinase inhibitor (BTKi) approved for CLL. [Extracted from the article]

Abstract: Chronic lymphocytic leukemia (CLL) progression during Bruton tyrosine kinase (BTK) inhibitor treatment is typically characterized by emergent B-cell receptor pathway mutations. Using peripheral blood samples from patients with relapsed/refractory CLL in ELEVATE-RR (NCT02477696; median 2 prior therapies), we report clonal evolution data for patients progressing on acalabrutinib or ibrutinib (median follow-up, 41 months). Paired (baseline and progression) samples were available for 47 (excluding 1 Richter) acalabrutinib-treated and 30 (excluding 6 Richter) ibrutinib-treated patients. At progression, emergent BTK mutations were observed in 31 acalabrutinib-treated (66%) and 11 ibrutinib-treated patients (37%; median variant allele fraction [VAF], 16.1% vs 15.6%, respectively). BTK C481S mutations were most common in both groups; T474I (n = 9; 8 co-occurring with C481) and the novel E41V mutation within the pleckstrin homology domain of BTK (n = 1) occurred with acalabrutinib, whereas neither mutation occurred with ibrutinib. L528W and A428D comutations presented in 1 ibrutinib-treated patient. Preexisting TP53 mutations were present in 25 acalabrutinib-treated (53.2%) and 16 ibrutinib-treated patients (53.3%) at screening. Emergent TP53 mutations occurred with acalabrutinib and ibrutinib (13% vs 7%; median VAF, 6.0% vs 37.3%, respectively). Six acalabrutinib-treated patients and 1 ibrutinib-treated patient had emergent TP53/BTK comutations. Emergent PLCG2 mutations occurred in 3 acalabrutinib-treated (6%) and 6 ibrutinib-treated patients (20%). One acalabrutinib-treated patient and 4 ibrutinib-treated patients had emergent BTK/PLCG2 comutations. Although common BTK C481 mutations were observed with both treatments, patterns of mutation and comutation frequency, mutation VAF, and uncommon BTK variants varied with acalabrutinib (T474I and E41V) and ibrutinib (L528W and A428D) in this patient population. The trial was registered at www.clinicaltrials.gov as #NCT02477696., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: Atherosclerosis is the major underlying pathology of cardiovascular disease and is driven by dyslipidemia and inflammation. Inhibition of the immunoproteasome, a proteasome variant that is predominantly expressed by immune cells and plays an important role in antigen presentation, has been shown to have immunosuppressive effects., Methods: We assessed the effect of ONX-0914, an inhibitor of the immunoproteasomal catalytic subunits LMP7 (proteasome subunit β5i/large multifunctional peptidase 7) and LMP2 (proteasome subunit β1i/large multifunctional peptidase 2), on atherosclerosis and metabolism in LDLr -/- and APOE*3-Leiden.CETP mice., Results: ONX-0914 treatment significantly reduced atherosclerosis, reduced dendritic cell and macrophage levels and their activation, as well as the levels of antigen-experienced T cells during early plaque formation, and Th1 cells in advanced atherosclerosis in young and aged mice in various immune compartments. Additionally, ONX-0914 treatment led to a strong reduction in white adipose tissue mass and adipocyte progenitors, which coincided with neutrophil and macrophage accumulation in white adipose tissue. ONX-0914 reduced intestinal triglyceride uptake and gastric emptying, likely contributing to the reduction in white adipose tissue mass, as ONX-0914 did not increase energy expenditure or reduce total food intake. Concomitant with the reduction in white adipose tissue mass upon ONX-0914 treatment, we observed improvements in markers of metabolic syndrome, including lowered plasma triglyceride levels, insulin levels, and fasting blood glucose., Conclusions: We propose that immunoproteasomal inhibition reduces 3 major causes underlying cardiovascular disease, dyslipidemia, metabolic syndrome, and inflammation and is a new target in drug development for atherosclerosis treatment., Competing Interests: Disclosures None.

Acalabrutinib is a covalent Bruton tyrosine kinase (BTK) inhibitor approved for relapsed/refractory mantle cell lymphoma and chronic lymphocytic leukemia/small lymphocytic lymphoma. A major metabolite of acalabrutinib (M27, ACP-5862) was observed in human plasma circulation. Subsequently, the metabolite was purified from an in vitro biosynthetic reaction and shown by nuclear magnetic resonance spectroscopy to be a pyrrolidine ring-opened ketone/amide. Synthesis confirmed its structure, and covalent inhibition of wild-type BTK was observed in a biochemical kinase assay. A twofold lower potency than acalabrutinib was observed but with similar high kinase selectivity. Like acalabrutinib, ACP-5862 was the most selective toward BTK relative to ibrutinib and zanubrutinib. Because of the potency, ACP-5862 covalent binding properties, and potential contribution to clinical efficacy of acalabrutinib, factors influencing acalabrutinib clearance and ACP-5862 formation and clearance were assessed. rCYP (recombinant cytochrome P450) reaction phenotyping indicated that CYP3A4 was responsible for ACP-5862 formation and metabolism. ACP-5862 formation K m (Michaelis constant) and V max were 2.78 μM and 4.13 pmol/pmol CYP3A/min, respectively. ACP-5862 intrinsic clearance was 23.6 μL/min per mg. Acalabrutinib weakly inhibited CYP2C8, CYP2C9, and CYP3A4, and ACP-5862 weakly inhibited CYP2C9 and CYP2C19; other cytochrome P450s, UGTs (uridine 5'-diphospho-glucuronosyltransferases), and aldehyde oxidase were not inhibited. Neither parent nor ACP-5862 strongly induced CYP1A2, CYP2B6, or CYP3A4 mRNA. Acalabrutinib and ACP-5862 were substrates of multidrug resistance protein 1 and breast cancer resistance protein but not OATP1B1 or OATP1B3. Our work indicates that ACP-5862 may contribute to clinical efficacy in acalabrutinib-treated patients and illustrates how proactive metabolite characterization allows timely assessment of drug-drug interactions and potential contributions of metabolites to pharmacological activity. SIGNIFICANCE STATEMENT: This work characterized the major metabolite of acalabrutinib, ACP-5862. Its contribution to the pharmacological activity of acalabrutinib was assessed based on covalent Bruton tyrosine kinase binding kinetics, kinase selectivity, and potency in cellular assays. The metabolic clearance and in vitro drug-drug interaction potential were also evaluated for both acalabrutinib and ACP-5862. The current data suggest that ACP-5862 may contribute to the clinical efficacy observed in acalabrutinib-treated patients and demonstrates the value of proactive metabolite identification and pharmacological characterization., (Copyright © 2022 by The Author(s).)