Background:: Eculizumab is a long-acting humanized monoclonal antibody targeted against complement C5. By preventing the cleavage of C5 into C5a and C5b, the deployment of the terminal complement system, including the formation of MAC, is inhibited. The FDA approved Eculizumab in 2019 for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in adult patients who are anti-aquaporin-4 (AQP4) antibody positive.
Results: Here we present a case of a 37 year old female patient diagnosed with NMOSD in 2018 with an AQP4 level of 3260.5 U/mL. She had been diagnosed with Cutaneous Lupus Erythematosus (CLE) seven years prior. CLE was controlled with hydroxychloroquine sulfate and prednisone. Patient received her first dose of eculizumab in September of 2019 with repeat infusions every two weeks. She developed multiple painful cold sores in October, which was not an expected side effect. Despite treatment with an anti-viral agent, valcyclovir, cold sores persisted throughout her treatment. MRI of the brain and cervical spine indicated stability of NMOSD without recurrent episodes of optic neuritis. She complained of dry eyes in February 2020 and a painful rash around her face, neck and chest in April. She was evaluated by Dermatology and Rheumatology. Skin biopsy in June confirmed CLE flare. She was started on high dose steroids and Eculizumab was discontinued.
Conclusions: SLE and CLE are triggered by a deficiency of complement, specifically, a deficiency in the classical complement pathway leading to an inability to clear antigen-antibody complexes, chromatin, or other immune aggregates. The mechanism of action of eculizumab likely caused the flare of CLE by blocking complement and triggering an inflammatory response