Cladribine (Merck Serono), which has been approved for cancer treatment, is a small molecule which may influence behaviour and cell division of white blood cells which may be involved in the pathological processes of MS. Fingolimod (Novartis) prevents potentially damaging immune cells from the lymph nodes from reaching the bloodstream and prevented from contributing to the development of inflammations in the central nervous system.
It reacts directly with central nervous system cells, where it can promote the regeneration of tissue. Although the active mechanisms of cladribine and fingolimod are different, they deliver similar therapeutic results. The test phases taking place over the past two years have delivered satisfactory results with respect to reducing attacks of MS.
The results of the phase III cladribine (CLARITY) study involving over a thousand relapsing remitting MS patients showed that after 96 weeks the annual rate of attacks compared to placebo was reduced by over 50% and almost 80% of those treated with cladribine remained free of attacks until the end of the study.
The worsening of MS related disabilities among those receiving treatment was a third less pronounced than among the placebo group. The positive effects also appeared in MRT examinations.
In the two-year clinical fingolimod (FREEDOMS) study with over a thousand relapsing remitting MS patients, it was demonstrated that fingolimod also reduced the frequency of attacks by over 50% in comparison to placebo. There was also a reduction of MS related disabilities of around 30%.
MRT showed that the number of inflammation sites to decline and depletion of brain tissue delayed.
A further one-year study demonstrated the superiority of fingolimod over interferon. However, doctors have diagnosed an increasing incidence of Herpes zoster infections among cladribine patients as well as with fingolimod, and a temporary decline in the heart rate with initial doses of fingolimod.
In both studies, the development of a small number of rare tumours was also noted. “Though the results of the studies are very promising, we can assess rare and serious side effects only after approval and general use. Thus follow-up studies after they are introduced to the market are extremely important,” said Toyka. Fampridine (Acorda) has been shown in a small study to have an effect on around 40% of participants by improving their ability to walk. The active substance works as a potassium channel blocker to improve signal transmission in demyelinised nerve tracts and been licensed in the US under the name Ampyra.