alemtuzumab
Meaning of alemtuzumab: An antibody that strips lymphocytes out of the blood, used to reset an immune system attacking the nervous system.
Definition of alemtuzumab
Alemtuzumab is a laboratory-made antibody that locks onto CD52, a marker carried on the surface of lymphocytes, and marks those cells for destruction. It clears them from the blood for months. It is used chiefly in relapsing multiple sclerosis, where the immune system attacks nerve coverings, and it has also been used against chronic lymphocytic leukemia.
How does it work?
CD52 is a protein sitting on the surface of mature lymphocytes, both the B and T varieties, and on a few other white cells. It is absent from the stem cells in the marrow that produce them. As a monoclonal antibody, alemtuzumab binds that one target and nothing else, and the immune system then destroys whatever it has labeled. Circulating lymphocytes disappear within days. Because the marrow stem cells are untouched, the population rebuilds over the following months, and the cells that return differ in their mix from those that were removed. That reconstitution is thought to be why a short course produces years of effect.
What is it used for?
| Condition | Role |
|---|---|
| Relapsing multiple sclerosis | Its principal use, given as short courses a year apart |
| Chronic lymphocytic leukemia | An earlier use, now largely displaced by newer drugs |
| Transplant conditioning | Used in some protocols to deplete lymphocytes |
What are the risks of removing lymphocytes?
Two categories dominate. The first is infection, since the cells removed are the ones that fight it, and dormant viruses such as herpes and cytomegalovirus can reactivate while numbers are low. Preventive antiviral cover during that window is standard practice. The second is stranger. As the immune system rebuilds, a substantial proportion of people develop a new autoimmune condition aimed at a different target, most often the thyroid, and sometimes the platelets or the kidney. These can appear years after the last dose, which is why blood and urine monitoring continues long after treatment finishes. Infusion reactions with rash, fever and headache are common during administration itself.
Why does it appear under two brand names?
The same antibody is marketed separately for cancer and for multiple sclerosis, at different doses and under different names. The multiple sclerosis dose is much lower than the one used in leukemia.
Also known as
Used in a sentence
Thyroid function and urine testing continued on a scheduled basis after the second course of alemtuzumab.
Good to know
Alemtuzumab is now used mainly in relapsing multiple sclerosis rather than in leukemia, and new autoimmune disease, most often of the thyroid, can appear years after the final dose.