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Vertex Pharmaceuticals.

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Integrins are a family of transmembrane glycoprotein signaling receptors that can transmit bioinformation bidirectionally across the plasma membrane. Integrin αIIbβ3 is expressed at a high level in platelets and their progenitors, where it plays a central role in platelet functions, hemostasis, and arterial thrombosis. Integrin αIIbβ3 also participates in cancer progression, such as tumor cell proliferation and metastasis. In resting platelets, integrin αIIbβ3 adopts an inactive conformation. Upon agonist stimulation, the transduction of inside-out signals leads integrin αIIbβ3 to switch from a low-to high-affinity state for fibrinogen and other ligands. Ligand binding causes integrin clustering and subsequently promotes outside-in signaling, which initiates and amplifies a range of cellular events to drive essential platelet functions such as spreading, aggregation, clot retraction, and thrombus consolidation. Regulation of the bidirectional signaling of integrin αIIbβ3 requires the involvement of numerous interacting proteins, which associate with the cytoplasmic tails of αIIbβ3 in particular. Integrin αIIbβ3 and its signaling pathways are considered promising targets for antithrombotic therapy. This review describes the bidirectional signal transduction of integrin αIIbβ3 in platelets, as well as the proteins responsible for its regulation and therapeutic agents that target integrin αIIbβ3 and its signaling pathways.

ObjectivesTo evaluate safety and efficacy of weekly (qw) and every other week (q2w) dosing of sarilumab, a fully human anti-interleukin 6 receptor α (anti-IL-6Rα) monoclonal antibody, for moderate-to-severe rheumatoid arthritis (RA).MethodsIn this dose-ranging study, patients (n=306) with active RA, despite methotrexate, were randomly assigned to placebo or one of five subcutaneous doses/regimens of sarilumab: 100 mg q2w, 150 mg q2w, 100 mg qw, 200 mg q2w, 150 mg qw for 12 weeks, plus methotrexate. The primary end point was ACR20 at Week 12. Secondary endpoints included ACR50, ACR70, Disease Activity Score in 28 joints (C reactive protein). Safety, pharmacokinetics, pharmacodynamics and efficacy in population subgroups were assessed.ResultsThe proportion of patients achieving an ACR20 response compared with placebo was significantly higher for sarilumab 150 mg qw (72.0% vs 46.2%, multiplicity adjusted p=0.0203). Higher ACR20 responses were also attained with 150 mg q2w (67%; unadjusted (nominal) p=0.0363) and 200 mg q2w (65%; unadjusted p=0.0426) versus placebo. Sarilumab ≥150 mg q2w reduced C reactive protein, which did not return to baseline between dosing intervals. Infections were the most common adverse event; none were serious. Changes in laboratory values (neutropenia, transaminases and lipids) were consistent with reports with other IL-6Rα inhibitors.ConclusionsSarilumab improved signs and symptoms of RA over 12 weeks in patients with moderate-to-severe RA with a safety profile similar to reports with other IL-6 inhibitors. Sarilumab 150 mg and sarilumab 200 mg q2w had the most favourable efficacy, safety and dosing convenience and are being further evaluated in Phase III.

Vertex Pharmaceuticals.

No abstract