Eisai says that it is terminating development of perampanel for Parkinson's disease, but will continue studies of the compound as a treatment for neuropathic pain and epilepsy.

Perampanel, also known as E2007, is a first-in-class, orally administered, highly selective non-competitive AMPA-type glutamate receptor antagonist, which Eisai was developing in several indications, including Parkinson's disease, neuropathic pain, epilepsy, multiple sclerosis and migraine prophylaxis.
The most advanced indication was Parkinson's disease and the Japanese drugmaker had been conducting three global Phase III studies with perampanel as add-on therapy to levodopa in patients with late-stage disease.

However, the second of those studies, a 20-week trial comparing two doses of 2mg and 4mg of perampanel to placebo, did not show a significant difference in the primary endpoint of reduction of ‘off’ time (time when signs and symptoms of Parkinson's disease return as the effect of levodopa wears off). Eisai’s drug was well-tolerated but after analysing the data, it has decided to discontinue the Parkinson's disease programme.

Eisai said that it will focus resources on two other ongoing indications, epilepsy and neuropathic pain, both of which have different pathophysiology from that of Parkinson's disease and robust scientific rationale. It is preparing to initiate global Phase III studies with perampanel as add-on therapy in patients with refractory partial seizures in the next few months, while a Phase II study of the compound in painful diabetic neuropathy completed enrollment in March and is expected to provide top-line results in September 2008.