SUCCESSFUL DESENSITIZATION FOR DELAYED URTICARIA TO ADALIMUMAB

Abstract

Introduction Adalimumab is an anti-tumor necrosis factor monoclonal antibody effective in treating autoimmune and inflammatory diseases. Although adalimumab is fully human and considered of low immunogenicity, there have been rare reports of local and systemic reactions. Case Description A 17-year-old male with Crohn's disease failed infliximab therapy and was switched to adalimumab. He tolerated the first 3 weekly loading doses, but developed delayed generalized urticaria 6 hours and 24 hours after his subsequent two maintenance doses (q2 weeks), respectively, despite antihistamine premedication. Although urticaria resolved within days, he had persistent pruritus. On examination in the allergy/immunology clinic, he had localized urticaria and profound dermatographia, a new finding since initiation of adalimumab. Desensitization to adalimumab was recommended due to severe Crohn's disease and failure of multiple prior therapies. This was done at the hospital infusion center over 4 weekly visits, with the first dose in 7 steps and subsequent doses in 2 steps, before spacing back to q2 week injections. He developed faint rash after the first desensitization visit, with no subsequent symptoms. He now self-administers the injections at home and the Crohn's disease is in a quiescent state. Discussion Cutaneous manifestations of adalimumab sensitivity have been reported as immediate-type injection site reactions or psoriasis-like rash. Desensitization to adalimumab has previously been reported for immediate-type reactions, but we present successful desensitization in a patient with a more delayed and prolonged manifestation of hypersensitivity. The two-week half-life of the medication allows for maintenance of the desensitized state in between injections.