Class: Purine antimetabolites
Name: Cladribine (Mavenclad®)
General Dosage: Oral chemotherapy medication with two treatment cycles over a little more than one year.
Mechanism of Action: Inhibits pro-inflammatory lymphocytes. Temporarily reduces the number of both T and B lymphocytes.
Effectiveness: Compared to placebo, decreases relapse rate by 58%; modest positive effect on disability progression and rate of brain volume loss.
Possible Side Effects: Boxed warnings* for risk of cancers and birth defects if used in pregnant woman. Approved by FDA for rescue use only.
Cladribine, an FDA approved chemotherapy treatment, is a small molecule that can both kill and alter the function of certain white blood cells. This is significant in the treatment of MS in that two types of white blood cells, T and B lymphocytes, are thought to play key roles in disease progression. To date, cladribine is most often used to treat leukemia and lymphoma.
A study on cladribine which involved 1,326 patients, looked at the rate of relapse between patients on cladribine compared to placebo. Study participants either received cladribine in a 3.5 mg or 5.25 mg dose, or placebo. Of the three groups, patients on cladribine demonstrated significantly lower annualized rates of relapse (0.14 and 0.15) than those on placebo (0.33). As in previous studies, adverse events among the cladribine groups included lymphocytopenia (type of cancer) and herpes zoster.
The safety profile of cladribine has been reported as acceptable and a great deal is known about the agent as a treatment for other diseases, particularly certain types of cancer. Cladribine, a chemotherapy and immunosuppressive therapy, does pose significant risk of complications including toxic effects on organs such as the liver. The therapy reduces the number of white bloods cells in patients’ blood and bone marrow, which can make them more susceptible to infection.
In addition, the drug causes long term, if not permanent, changes in the white blood cells in the blood, the consequences of which are not fully understood. The drug may also cause a certain kind of cancer, most likely one of the blood such as leukemia or lymphoma. Further research is needed in order to evaluate the effects of long-term use and expand what is known about the safety profile.
* Boxed Warning: A black boxed warning is the FDA’s most stringent warning for drugs and medical devices on the market. Black box warnings, or boxed warnings, alert the public and health care providers to serious side effects, such as injury or death.