[Successful subcutaneous desensitization in a patient with systemic reaction due to ixekizumab].

Background: Ixekizumab is a high-affinity IgG4 monoclonal humanized antibody useful for the treatment of ankylosing spondylitis. Benign skin reactions are a common adverse event with ixekizumab but systemic hypersensitivity reactions are much more unusual.

Case report: We describe the case of a 54-female patient with HLAB27+ spondyloarthritis. Treatment with ixekizumab 80 mg subcutaneous (containing polysorbate) was prescribed. The patient experienced immediate severe dyspnea, skin erythema and flushing. Intradermal test (0.8 mg/ml) was clearly positive in the immediate reading. The patient was planned to undergo ixekizumab desensitization according to an 8-step protocol with good tolerance.

Conclusion: We report a patient with HLAB27+ spondyloarthritis treated with ixekizumab who developed a systemic IgE-mediated reaction. A successful and easy to perform subcutaneous desensitization protocol is described.