Eisai Co., Ltd. announced that an oral presentation highlighting results from a phase III clinical study (Study 335) of its in-house developed antiepileptic drug (AED) perampanel hydrate (global product name: Fycompa) in patients with refractory partial-onset seizures conducted in Asia, including Japan, was given at the 49th Congress of the Japan Epilepsy Society held from October 30 to 31 in Nagasaki, Japan.

In the study, perampanel demonstrated a significantly higher reduction in seizure frequency compared to placebo. In Japan, new drug applications were submitted in July 2015 seeking the approval of perampanel as an adjunctive therapy for partial-onset and generalized tonic-clonic seizures based on the results of Study 335 and other studies.

Study 335 was a phase III clinical study conducted in Asia, including Japan, to evaluate the efficacy and safety of adjunctive perampanel therapy in 710 patients aged 12 years and older with refractory partial-onset seizures. In this study, eligible patients receiving one to a maximum of three AEDs were randomized to receive perampanel (4 mg, 8 mg or 12 mg) or placebo.

In the study’s primary endpoint of percent change in seizure frequency (per 28 days in the randomization phase relative to the pre-randomization phase), the percent change in the placebo group was -10.8 per cent while in the perampanel (4 mg, 8 mg, 12 mg) groups it was -17.3 per cent, -29.0 per cent and -38.0 per cent, respectively. The difference between perampanel and placebo was statistically significant for the perampanel 8 and 12 mg groups (p=0.0003 for 8 mg, p<0.0001 for 12 mg).

Furthermore, in the study’s secondary endpoint of percent change in seizure frequency of secondarily generalized seizures, the percent change in the placebo group was -12.1 per cent while in the perampanel (4 mg, 8 mg, 12 mg) groups it was -17.9 per cent, -45.0 per cent and -52.5 per cent, respectively, demonstrating that perampanel, depending on dosage, reduces seizure frequency in secondarily generalized seizures as well, especially the 12 mg group which showed over a 50 per cent reduction in seizure frequency. The most common adverse events (>10 per cent in the perampanel groups) observed in the study were dizziness, somnolence and nasopharyngitis.

Meanwhile, the results of an Asia-Pacific (Japan, China, South Korea, India, Australia) regional sub-group analysis of Study 332, a global study of primary generalized tonic-clonic (PGTC) seizures in patients with generalized epilepsy, were also presented at this same congress meeting. Study 332 was a phase III clinical study to evaluate the efficacy and safety of adjunctive perampanel as treatment for with PGTC seizures in 164 patients aged 12 years or older. A statistically significant improvement in the primary endpoint of change in PGTC seizure frequency, as well as the secondary endpoint of responder rate (percentage of patients who experience a 50 per cent or greater reduction in PGTC seizure frequency per 28 days in the Maintenance period relative to baseline) was observed for perampanel compared to placebo.

The results of the analysis showed that both change in PGTC seizure frequency and responder rate for Asia-Pacific region patients (42 patients) were similar to the total patient population results already presented, and there were no large regional differences in the incidence of adverse events.

Perampanel is a first-in-class AED discovered and developed by Eisai. With epileptic seizures being primarily mediated by the neurotransmitter glutamate, the agent is a highly selective, noncompetitive AMPA receptor antagonist that reduces neuronal hyperexcitation associated with seizures by targeting glutamate activity at postsynaptic AMPA receptors. Perampanel is approved in more than 45 countries including in Europe and North America, as well as countries in Asia such as Malaysia, Thailand, the Philippines and South Korea, as an adjunctive treatment for partial-onset seizures (with or without secondary generalized seizures) in patients with epilepsy aged 12 years and older, and has been launched in 25 countries around the world under the Fycompa brand name. Furthermore, perampanel was approved for an indication expansion regarding the adjunctive therapy of PGTC seizures in patients from 12 years of age with generalized epilepsy in the US and Europe in June 2015.

Eisai considers epilepsy a therapeutic area of focus and by providing multiple treatment options in addition to perampanel as part of an extensive epilepsy product portfolio, Eisai seeks to make continued contributions to address the diverse needs of, as well as increasing the benefits provided to, patients with epilepsy and their families.