Topic / Other MS News

Cladribine: its attraction as a pill for MS needs to be balanced against side effects

Cladribine, a new oral agent for MS, appears quite effective in reducing disease activity in MS, and may be quite attractive in comparison to regular self-injection. But side effects are a significant concern

With a rush of new pills that appear to be effective in modifying disease activity in MS about to come onto the market, it is useful for those in the MS community to get a better understanding of these drugs and their possible place in treatment. There is no doubt that these drugs will soon be offered to people with MS and it is worth being armed with information about them.

A new review of the drug cladribine, approved in July for use in MS (as Movectro) in Russia as the first oral pill for MS to be approved anywhere, and in September in Australia, makes interesting reading.

How does it work?

The drug is given in short courses of only 4-5 days at the start of every month. It appears to make a big difference to the number of new MRI lesions, increases time to relapse, and increases the number of relapse-free patients, but as a chemotherapy agent that inactivates some of the immune cells thought to play a big part in MS disease activity, it is relatively toxic.

Side effects 

In the clinical trials, shingles was quite common, and in some cases quite severe. Of more concern, in the pivotal CLARITY trial, there were 10 cases of cancer developing in people in the cladribine groups, and none in the placebo groups.

It is not certain whether this was just chance, or cladribine caused the cancers, but given that the development of cancers is not unusual as a result of chemotherapy, it is important to be very cautious about this possible side effect. Half of the cancers were benign, but the others were melanoma, pancreatic cancer, ovarian cancer, cervical cancer in situ, and choriocarcinoma.

Many people who are offered this drug in the future, and potentially other oral drugs for MS, will find them a much more attractive option than regular self-injection. But it is important to be wary of the possible side effects, some of them quite serious.

The full paper is attached below.