Symptomatic Thrombocytopenia After One Dose of Alemtuzumab With Successful Rechallenge (P5.400)

Objective: We report a case of a patient with relapsing-remitting multiple sclerosis who developed symptomatic thrombocytopenia immediately after receiving one dose of alemtuzumab. Background: Alemtuzumab is a monoclonal antibody which has been shown to be an effective agent for relapsing-remitting multiple sclerosis. Alemtuzumab’s mechanism of action occurs through its binding to CD52 which is a cell surface antigen on T and B lymphocytes. Antibody-dependent cellular cytolysis and complement-mediated lysis then occur after alemtuzumab binding. Delayed onset immune thrombocytopenia purpura has been reported in relapsing-remitting multiple sclerosis patients treated with alemtuzumab as well as immediate-post infusion asymptomatic thrombocytopenia. Design/Methods: Case report and review of the literature. Results: Patient is a thirty-five year old Caucasian woman with a past medical history of relapsing-remitting multiple sclerosis, migraine, seizures and bipolar disorder and a family history of idiopathic thrombocytopenic purpura who subsequent to the first infusion of alemtuzumab 12 mg and prior to the second infusion on the following day developed a 1.5 by 1.0 cm purpuric lesion on her right upper lateral thigh and multiple abdominal ecchymoses with purpura with a peripheral blood platelet count of 111 K/mm3, decreased from a baseline level of 145 K/mm3 from a week prior. Alemtuzumab was discontinued. The skin rash improved over one day with the patient reaching a nadir platelet count of 75 K/mm3 on day three. The platelet count then recovered to 155 K/mm3 on day eight. She received the additional four alemtuzumab daily infusions one month later without any further clinical adverse events. Conclusions: This is the first reported case of a relapsing-remitting multiple sclerosis patient with acute symptomatic thrombocytopenia after one infusion of alemtuzumab 12mg. This case shows that despite experiencing symptomatic thrombocytopenia after one dose of alemtuzumab, a patient may be successfully rechallenged. Disclosure: Dr. Derlet has nothing to disclose. Dr. Agius has received personal compensation for activities with Teva Neuroscience, Biogen Idec, Berlex Labs and Serono as a speaker and consultant. Dr. Agius has received research support from Novartis, Teva, Biogen, Genzyme, Roche, Immune Tolerance Network, Actelion, and Acorda Therapeutics. Dr. Apperson has nothing to disclose.