Alemtuzumab, a humanized monoclonal antibody that targets CD52, is a potent treatment for relapsing-remitting multiple sclerosis (RRMS). Despite its efficacy, alemtuzumab can trigger secondary autoimmune disorders, which most commonly involve the thyroid and hematologic systems. Herein, we have presented the case of a 36-year-old woman with highly active RRMS who developed a rare presentation of systemic lupus erythematosus (SLE) and secondary Sjgren’s syndrome (sSS) 42 months after her last alemtuzumab infusion. While cases of SLE following alemtuzumab administration are extremely rare, the development of Sjgren’s syndrome (SS) in this context is previously unreported. The patient exhibited pancytopenia, proteinuria, autoimmune marker positivity (anti-nuclear, anti-double stranded DNA, anti-Sjgren’s syndrome type A), and low complement levels. leading to the SLE and sSS diagnoses and treated with corticosteroids, hydroxychloroquine, mycophenolate mofetil, and tacrolimus. This case underscores the importance of monitoring alemtuzumab-treated patients for delayed autoimmune complications and highlights the potential role of B and T cell dysregulation in secondary autoimmunity. Further research is necessary to elucidate the mechanisms underlying these rare adverse events.
