Positive Phase IIb trial of epilepsy drug XEN1101 sees Xenon shares double

Xenon Pharmaceuticals (Nasdaq: XENE) saw its shares rise more than a 100% in regular trading and a further 5% to $33.01 after-hours yesterday, as it released encouraging clinical results with its epilepsy candidate.

The Canadian biotech firm’s Phase IIb X-TOLE clinical trial, which evaluated the clinical efficacy, safety, and tolerability of XEN1101 – a differentiated Kv7 potassium channel modulator – administered as adjunctive treatment in adult patients with focal epilepsy met its primary efficacy endpoint with XEN1101 demonstrating a statistically-significant and dose-dependent reduction from baseline in monthly (defined as 28 days) focal seizure frequency when compared to placebo (monotonic dose response; p<0.001). Additional primary and secondary measures included a pairwise comparison of each active dose to placebo and a responder analysis with the proportion of patients who achieved a 50% or greater reduction in monthly focal seizure frequency from baseline.

Dr Christopher Kenney, Xenon’s chief medical officer, commented: “We have generated strong evidence that supports the efficacy, safety and tolerability of XEN1101 and depicts a highly favorable product profile for XEN1101. Importantly, we saw statistically significant reductions of focal onset seizures compared to placebo across all dose groups, which suggests it is highly active in the central nervous system. With these compelling top-line results, we are eager to work with the FDA to plan for an expedited development path moving forward.”