Alemtuzumab infusion-associated reactions and laboratory changes in patients with relapsing-remitting multiple sclerosis at baseline and first-year follow-up.

Background: Alemtuzumab (ATZ) is an anti-CD52 humanized monoclonal antibody indicated for treating highly active relapsing-remitting MS (RRMS). It alters the regulation of the immune system by depleting circulating lymphocytes. Changes in blood cell count, infusion-related reactions, and changes in vital parameters can be seen in the early period with ATZ. Aim: Changes in blood tests, serum tests, vital parameters, and characteristics of infusion-associated reactions (IARs) observed during the first course of ATZ treatment and thereafter were evaluated. Materials and methods: The systolic blood pressure (SBP), diastolic blood pressure (DBP), fever, heart rate (HR), changes in blood and serum tests, and IARs developed after the first course of 23 patients with RRMS who received ATZ treatment were evaluated by comparing the results of 26 patients with RRMS who received only intravenous methylprednisolone. Results: Mean age was 36.60 ± 8.98, 73.9% female (n = 17), diagnosis time was 8.52 ± 3.64 years, pre-EDSS: 3.93 ± 1.80. No significant difference was found in vital parameters except for sub-febrile fever that developed on the first day. The number of white blood cells increased significantly after the first day. The hemoglobin level did not change. Lymphocyte (very high) and platelet (mild) counts decreased starting from the first days, and eosinophil (very high) and monocyte (moderate) counts decreased from the third day. There were no significant changes in liver enzymes, thyroid function tests, serum urea, creatinine, and lipid profile during 1-year follow-up. The IAR rate was 95.6% and occurred most frequently on the second and third days. The most common are dermatological findings (52%), headache (20%), pain (10%) and fatigue (8%). Conclusion: Alemtuzumab has no appreciable effect on vital parameters during infusion. However, these changes are not clinically correlated, even if there is. Headache in the first days, dermatological (most common) findings, pain, and fatigue are seen in the following days. Most IARs can be resolved with symptomatic treatment and close follow-up. Lymphocytes, eosinophils, and monocytes are significantly reduced and return to baseline levels towards the end of the first year. The first year does not cause significant pathologies in other serum parameters. However, after the first year, watch out for associated autoimmune pathologies, especially thyroid involvement.