Very high effectiveness and negligible side effects: When natalizumab, trade name Tysabri, was approved against relapsing-remitting multiple sclerosis and especially against aggressive courses, the enthusiasm was great at first. The side effects were manageable – initially:
- Headache,
- Fatigue,
- joint pain and
- Fatigue did not occur in everyone, and if it did then all of them only occurred and disappeared again as part of the infusion.
Rarely came
- allergic reactions.
The most cumbersome were actually those
- Antibodies that some patients made against natalizumab, which neutralized the effect. These patients then had to be switched to another drug.
If it weren’t for the word “if”: PML on natalizumab
However, in the period after the approval studies were completed, some patients experienced a very serious, sometimes fatal side effect:
- PML, the progressive multifocal leukocyte encephalopathy.
This is a brain infection caused by the JC virus. Because most people carry this virus, it’s usually harmless, but certain drugs like natalizumab can attack the brain, a strong argument against natalizumab.
Studies have shown that in JC-positive patients who have been taking natalizumab for more than two years, the risk is many times greater than in negative patients or those who are still under the two-year limit, even an extension of the dosing interval The risk is reduced to 5-6 weeks instead of four, but this sometimes very severe side effect has led to the fact that natalizumab is hardly ever prescribed anymore. Above all, this is also due to the fact that some other highly effective active ingredients are now available.
So natalizumab, which is given as a blue infusion solution, often called smurf-colored, almost only plays the role of an alternative drug if all comparatively effective MS drugs cannot be taken for other reasons.