Alemtuzumab is a powerful medication used to treat multiple sclerosis (MS), particularly in patients with active relapsing forms of the disease. Its effect on MS relapses is significant because it works by targeting and depleting specific immune cells that contribute to the disease process, thereby reducing the frequency and severity of relapses.
To understand how alemtuzumab affects MS relapses, it’s important to first grasp what causes these relapses. MS is an autoimmune disorder where the immune system mistakenly attacks the protective covering of nerve fibers in the central nervous system. This attack leads to inflammation and damage, causing symptoms to flare up or worsen temporarily—these episodes are called relapses or flare-ups.
Alemtuzumab is a monoclonal antibody that specifically binds to a protein called CD52 found on the surface of certain immune cells, mainly T and B lymphocytes. These lymphocytes play a crucial role in the autoimmune attack in MS. By binding to CD52, alemtuzumab triggers the destruction of these cells through immune-mediated mechanisms, effectively depleting them from the bloodstream. This depletion is followed by a gradual repopulation of the immune system, but importantly, the new immune cells tend to be less aggressive or less likely to attack the nervous system.
This process of immune cell depletion and reconstitution essentially “resets” the immune system. Because the harmful immune cells are reduced, the inflammation that causes MS relapses is also diminished. Clinical studies and patient experiences have shown that after treatment with alemtuzumab, the number of relapses decreases substantially, often more than with many other disease-modifying therapies. This reduction in relapse rate can translate into fewer new symptoms, less disability progression, and improved quality of life for patients.
Alemtuzumab is typically given in two annual courses of intravenous infusions. The first course involves daily infusions over five days, and the second course is given a year later over three days. After these treatments, many patients experience long-lasting effects, with relapse rates remaining low for years without continuous medication. This is different from many other MS treatments that require ongoing regular dosing.
However, because alemtuzumab profoundly affects the immune system, it can also increase the risk of infections and other immune-related side effects. Patients receiving alemtuzumab are closely monitored for these risks, but the benefit of reducing relapses often outweighs these concerns in people with highly active MS.
In summary, alemtuzumab reduces MS relapses by targeting and depleting immune cells responsible for the autoimmune attack, leading to a reset of the immune system. This results in a significant and sustained decrease in relapse frequency, helping to control disease activity and improve patient outcomes over the long term.
