Immune complications of alemtuzumab

Epub ahead of printCuker et al. A distinctive form of immune thrombocytopenia in a phase 2 study of alemtuzumab for the treatment of relapsing-remitting multiple sclerosis. Blood. 2011 Sep 29.

In a phase 2 clinical trial of annual alemtuzumab for the treatment of relapsing-remitting MS, 6/216 (2.8%) patients developed immune thrombocytopenia (ITP). 

"Thrombocytes or platelets are the cells in the blood responsible for clotting; ITP occurs when your immune system makes antibodies (proteins) that attack and destroy the platelets. This is potentially a very serious condition and if the platelet counts drops very low you can die from excessive bleeding."

Over a mean follow-up of 4.5 years, the incidence rate of ITP was 6.2 (95% CI 2.3-13.3) per 1000 person-years. The average times from initial and last alemtuzumab exposure to ITP diagnosis were 24.5 and 10.5 months, respectively. Five patients developed severe thrombocytopenia. Four were symptomatic, including fatal intracranial hemorrhage in the index case. Four patients received standard first-line therapy for ITP, all of whom responded to treatment within 1 week. All 5 surviving patients achieved complete remission and remained in remission without the need for ongoing ITP therapy for a median duration of 34 months at last follow-up. A monitoring plan for the early detection of ITP, implemented after presentation of the index case, identified all 5 subsequent cases before serious haemorrhage or death occurred. 

Conclusion: The researchers describe a distinctive form of ITP associated with alemtuzumab treatment characterized by delayed presentation after drug exposure, responsiveness to conventional ITP therapies, and prolonged remission. Clinicians should maintain a high level of vigilance and consider routine monitoring for ITP in patients treated with this agent. 

"How do you know if you have ITP? You need to look out for early signs of bleeding; for example easy bruising, bleeding from the gums, petechiae or petechial rash (see below), blood in the urine (coca cola urine)."

"The treatment of ITP usually involved steroids and if that fails the intravenous infusion of high-dose immunoglobulins, called IVIG. Other more aggressive therapies are also available."

"The ITP and other autoimmune complications of alemtuzumab therapy are in my opinion the biggest hurdle for this drug been adopted early in the course of MS when it is likely to have its greatest impact. The other hurdle already discussed on this blog is the price of the drug."

Purpura of the type associated with ITP

Additional reading: ITP, alemtuzumab

CoI: Multiple

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