• G M Gauvreau, L-P Boulet, D W Cockcroft, J M FitzGerald, I Mayers, C Carlsten, M Laviolette, K J Killian, B E Davis, M Larché, C Kipling, B Dua, S Mosesova, W Putnam, Y Zheng, H Scheerens, D McClintock, J G Matthews, and P M O'Byrne.
• Department of Medicine, McMaster University, Hamilton, ON, Canada.
• Clin. Exp. Allergy. 2014 Jan 1;44(1):29-37.

BackgroundThe OX40/OX40L interaction contributes to an optimal T cell response following allergic stimuli and plays an important role in the maintenance and reactivation of memory T effector cells.ObjectiveWe tested whether treatment with an anti-OX40L monoclonal antibody (MAb) would inhibit allergen-induced responses in subjects with asthma.MethodsTwenty-eight mild, atopic asthmatic subjects were recruited for a double-blind, randomized, placebo-controlled, parallel-group trial (ClinicalTrials.gov identifier NCT00983658) to compare blockade of OX40L using a humanized anti-OX40L MAb to placebo-administered intravenously in 4 doses over 3 months. Allergen inhalation challenges were carried out 56 and 113 days after the first dose of study drug. The primary outcome variable was the late-phase asthmatic response. Other outcomes included the early-phase asthmatic response, airway hyperresponsiveness, serum IgE levels, blood and sputum eosinophils, safety and tolerability.ResultsTreatment with anti-OX40L MAb did not attenuate the early- or late-phase asthmatic responses at days 56 or 113 compared with placebo. In the anti-OX40L MAb treatment group, total IgE was reduced 17% from pre-dosing levels, and sputum eosinophils decreased 75% by day 113 (both P = 0.04). There was no effect of anti-OX40L MAb on airway hyperresponsiveness or blood eosinophils. The frequency of AEs was similar in both groups.Conclusion And Clinical RelevancePharmacological activity of anti-OX40L MAb was observed by decreases in serum total IgE and airway eosinophils at 16 weeks post-dosing, but there was no effect on allergen-induced airway responses. It is possible that the treatment duration or dose of antibody was insufficient to impact the airway responses.© 2013 The Authors Clinical & Experimental Allergy Published by John Wiley & Sons Ltd.

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