No added benefit from retigabine therapy in adults with epileptic seizures

Drug manufacturer deviates from appropriate comparator therapy specified by the G-BA

The drug retigabine (trade name: Trobalt-) was approved in March 2011 as add-on therapy for adults with epileptic seizures. In an early benefit assessment pursuant to the "Act on the Reform of the Market for Medicinal Products" (AMNOG), the German Institute for Quality and Efficiency in Health Care (IQWiG) examined whether retigabine offers an added benefit compared with the present standard therapy. However, no such added benefit can be inferred from the dossier, as the drug manufacturer deviated from the specifications of the Federal Joint Committee (G-BA) and chose a different comparator therapy.

Epileptic seizures are referred to as partial (or focal) seizures if they only affect a small part of the brain, and muscle twitching and cramps are restricted to single regions of the body. However, such seizures may spread across the whole body and are then referred to as "secondary generalization". Retigabine is approved as add-on therapy for the treatment of partial seizures with or without secondary generalization in persons aged 18 years and over.

The G-BA has specified lamotrigine as the appropriate comparator therapy if this drug is used as an add-on. In cases where lamotrigine is used as basic therapy, add-on topiramate is specified as the appropriate comparator therapy. The drug manufacturer did not make use of the option of seeking advice from the G-BA.

However, in its dossier the pharmaceutical company compared retigabine with lacosamide and thus deviated from the G-BA's specifications. From IQWiG's point of view the company did not sufficiently justify this deviation. Neither did it submit studies that would have been relevant to an assessment of retigabine versus the appropriate comparator therapy specified by the G-BA. Therefore no proof of an added benefit can be inferred from the assessment presented in the manufacturer dossier.

The procedure for inferring the overall conclusion on the extent of added benefit is a proposal from IQWiG. The G-BA, which has opened a formal commenting procedure, decides on the extent of added benefit.