According to a recent study, published in the journal Neurology, sirolimus* add-on treatment does not significantly reduce seizure frequency in children with tuberous sclerosis complex (TSC) and drug-resistant epilepsy.
The authors state, however, that due the small size of the study, larger ones are needed to verify this finding.
TSC is a genetic condition that causes tumours to form in different organs, and very often the brain. Here they can cause difficult-to-treat (drug-resistant) seizures, developmental delay, intellectual disability and autism. Previous research has suggested that sirolimus might be effective in reducing seizure frequency in children with TSC and many doctors prescribe it off-label.
During the present study, a team at Erasmus MC, in Rotterdam, recruited 23 children with TSC and drug-resistant epilepsy, aged between one and 11 years. The children were then randomly assigned to one of two groups: 1) in which sirolimus was added to their existing (‘standard’) epilepsy treatment regime immediately, and 2) in which sirolimus was added after six months. The team examined seizure frequency in both groups during the sixth month of sirolimus treatment.
The scientists found that, although sirolimus add-on treatment decreased seizure frequency by an average of 40% compared with standard therapy, this reduction was not ‘statistically significant’ (meaning that the chance that the result could have occurred by chance was too high for it to be conclusive). No change was seen in the children’s cognitive performance (which was also tested) when sirolimus was added to standard therapy.
Adverse side effects associated with sirolimus were also a problem, with five children leaving the trial before it had ended because of these.
However, the number of participants in the study may have been too small for the ‘true’ effects of sirolimus to be detected, particularly as recruitment targets weren’t met. Larger studies are warranted, to properly assess the effects of sirolimus add-on treatment in this population.
*Sirolimus is an inhibitor of a signalling complex called ‘mammalian target of rapamycin complex 1’ (mTORC1). This signalling pathway plays a role in acquired forms of epilepsy and may also be involved in TSC.
Author: Dr Özge Özkaya
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