Examining the Incidence of Immune Thrombocytopenia in Alemtuzumab Treatment for MS

Activated platelets. Coloured scanning electron micrograph (SEM) of activated platelets attached to surgical gauze. Platelets are tiny blood cells that help the body form clots to stop bleeding. If a blood vessels gets damaged, it sends out signals that are picked up by platelets. The platelets then rush to the site of damage and form a plug, or clot, to repair the damage. The process of spreading across the surface of a damaged blood vessel to stop bleeding is called adhesion. This is because when platelets get to the site of the injury, they grow sticky tentacles that help them adhere. They also send out chemical signals to attract more platelets to pile onto the clot in a process called aggregation. Magnification: x7000 at 10cm wide.
The majority of treatment-related cases of immune thrombocytopenia can be remedied with the use of corticosteroids, platelets, or intravenous immunoglobulin.

The occurrence of immune thrombocytopenia (ITP) associated with alemtuzumab treatment in patients with multiple sclerosis (MS) is low and the majority of treatment-related ITP cases can be remedied with corticosteroids, platelets, and/or intravenous immunoglobulin, according to study results published in Multiple Sclerosis.

Researchers pooled data from phase 2 and 3 studies (3-year CAMMS223 [ClinicalTrials.gov identifier NCT00050778] and 2-year CARE-MS I and CARE-MS II [ClinicalTrials.gov identifiers NCT00530348 and NCT00548405]), both of which randomly assigned patients with MS to either 2 annual courses of alemtuzumab or thrice-weekly subcutaneous injections of 44 μg IFNB-1a. Treatment with alemtuzumab was administered intravenously (12 mg/day or 24 mg/day) on 5 consecutive days at baseline and then 3 consecutive days at 12 months. An extension phase was performed in patients who completed the core studies. Researchers evaluated monthly ITP monitoring data that were recorded until 48 months following the last treatment.

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Approximately 2% (n=33) of the 1485 patients who were treated with alemtuzumab developed ITP (12 mg [2.0%] vs 24 mg [3.3%]). The incidence of ITP occurred over a median 6.1-year follow-up period following the first alemtuzumab infusion. Treatment of ITP with corticosteroids, platelets, and/or intravenous immunoglobulin was associated with a fairly high sustained response.

The occurrence of ITP did not appear to adversely affect the clinical outcomes of patients with MS. For example, the annualized relapse rate was low during the 12-month period prior to (0.06; 95% CI, 0.017-0.241]) and following (0.03; 95% CI, 0.005-0.216) the onset of ITP. The mean score on the Expanded Disability Status Scale was also stable 1 year before (2.64; 95% CI, 2.03- 3.26]) and 1 year after (2.83; 95% CI, 2.20-3.45) ITP onset.

“Patients selected for alemtuzumab treatment in the real-world setting must understand the importance of, and agree to, adherence to the [Risk Management Plan or Risk Evaluation and Mitigation Strategy],” the researchers wrote. “Furthermore, patient education and involvement are essential for the effectiveness of the monitoring program, as mucocutaneous manifestations may provide the first warning of severe thrombocytopenia.”


Cuker A, Bass AD, Nadj C, et al. Immune thrombocytopenia in alemtuzumab-treated MS patients: Incidence, detection, and management [published online February 20, 2019]. Mult Scler. doi:10.1177/1352458518816612