Interferon-targeted therapy with anifrolumab in monogenic pediatric systemic lupus erythematosus due to C1q deficiency: a case report.

Monogenic Pediatric systemic lupus erythematosus (SLE) secondary to complement deficiencies, including C1Q deficiency caused by C1QA mutations, is a rare and severe type of SLE that can be characterized by early onset and refractory disease. Inhibiting the interferon pathway has proved to be an effective treatment option, although there is little evidence in monogenic pediatric SLE. We describe a 10-year-old female with genetically-verified C1Q deficiency who had persistent and severe mucocutaneous disease, with recurrent skin rash, ulcerations, and oral sores, despite long-term immunosuppressive and biologic treatment. After a disease flare, the patient was started on anifrolumab, a monoclonal antibody against type I interferon receptor. She showed significant clinical improvement and full recovery of mucocutaneous lesions, restoration of laboratory parameters and successful discontinuation of corticosteroids after the seventh monthly infusion. It was well tolerated with no serious side effects. The case demonstrates the possible effectiveness and safety of anifrolumab in the treatment of refractory cutaneous manifestations in children with monogenic pediatric SLE, which is linked to interferon pathway dysregulation. Further studies are needed to establish its role in this population.