Alemtuzumab‐induced immune‐mediated thrombotic thrombocytopenic purpura: A newly described drug‐related autoimmune disease

Summary

Immune‐mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and life‐threatening disease that may result from drug exposure. We report a case of iTTP occurring in a 39‐year‐old patient, 45 months following introduction of the anti‐CD52 lymphoid cell depleting monoclonal antibody alemtuzumab, to treat a relapsing‐remitting multiple sclerosis. Treatment consisted in plasma exchange, corticosteroids and caplacizumab, allowing clinical remission 3 months after the diagnosis, attested by the absence of thrombocytopenia and recovery of ADAMTS‐13 activity. As other autoimmune disorders, iTTP may occur following alemtuzumab. This diagnosis should be suspected in patients with features of thrombotic microangiopathy following this treatment.