Effective desensitization in an IgE-mediated hypersensitivity reaction to tocilizumab in neuromyelitis optica

Neuromyelitis optica is a rare, inflammatory autoimmune disease of the central nervous system. Tocilizumab is a humanized monoclonal antibody, which targets the inhibition of the interleukin-6 receptor, a mediator with an important role in the pathophysiological mechanism of neuromyelitis optica. Hypersensitivity reactions to tocilizumab are rare, but similar to other biological drugs can elicit a hypersensitivity reaction. The authors present a case of a 50-year-old female patient, with a neuromyelitis optica, with a severe reaction at the 6th cycle of treatment. The patient was referred to Drug Allergy Consultation, where she underwent tocilizumab skin tests: intradermal test 1/1,000 with a positive result. The patient was then proposed for drug desensitization, and, to date, the patient has undergone 22 desensitization cycles, all of which were uneventful. This case emphasizes the importance of trying to phenotype the hypersensitivity reactions to monoclonal antibodies, and therefore invest in an allergy workup to make the best decision for our patients.