Who can take cladribine?
You can take cladribine if:
- you have ‘highly active’ relapsing MS. This means you’ve had two or more disabling relapses in the past year and MRI scans show you have more, or bigger, lesions. Guidelines call this ‘rapidly evolving severe relapsing remitting MS’
- despite taking a DMT, you’ve had a relapse in the past year and new or bigger lesions can be seen on your MRI scans
How does cladribine work?
Cladribine kills certain types of blood cells made by your immune system. These white blood cells (or lymphocytes) are called T and B cells.
These cells normally attack viruses and bacteria that get into your body. But in MS they attack the covering (called myelin) around the nerves in your brain and spinal cord. Cladribine stops these cells, especially the B cells, from getting into your brain and spinal cord, so they can’t damage the nerves there.
You take this drug as a tablet in two courses. Each treatment course consists of two treatment weeks, one at the beginning of the first month and one at the beginning of the second month. This is then repeated a year later. Hopefully the two courses will control your MS and you won’t need any more treatment.
How well does cladribine work?
Other MS drugs are classed as having a ‘moderate’, ‘good’ or ‘high’ impact on MS. This is based on how much a drug reduces your relapses and how much it slows your disability getting worse.
It’s too early to say where cladribine ranks with the other MS drugs. That’s because no trial has yet judged it against another DMT. Also, cladribine is only now becoming available to many people. Looking at the impact cladribine has on relapses and on stopping disability getting worse, it should be classed as either ‘good’ or ‘high’.
In a large trial:
Relapses dropped by 58% compared to a placebo (a dummy pill with no drug in it)
This means that during the two years of the trial, on average, people saw a drop of 58% in the number of relapses they had. This was compared to people who took the placebo. During the two years after the trial ended this drop was kept up.
Disability getting worse was slowed by 33% compared to the placebo
This means that in the trial, on average, people saw a drop of 33% in the risk of their disability getting worse (compared to people who took the dummy pill).
Over the two years the trial lasted, nearly half of people (46%) had no signs their MS was still active.
What are the side effects of cladribine?
Cladribine doesn’t weaken your immune system as much as some other MS drugs. So the risk of getting infections isn’t as high as with some DMTs.
The most common side effect is a drop in the number of your white blood cells that fight infections (lymphopenia). This is seen in about one in four to one in three people. Cladribine is meant to make this happen but this drop can last a long time and be severe.
Other side effects can include a slightly higher risk of getting headaches, colds, and infections caused by the herpes viruses. This includes the skin rash shingles, which one in 50 people on the drug get. You’ll be vaccinated against some infections like chicken pox before you take cladribine.
An earlier study seemed to show a higher risk of cancer but we now know this isn't the case.