Vertex stock was on the rise over the weekend after the firm reported encouraging results from a mid-stage trial of its experimental epilepsy medicine.

The Phase II study of VX-765 - which involved 60 patients with treatment-resistant epilepsy - met its primary endpoint in showing that the drug was comparable to a placebo in terms of safety and tolerability.

The most common side effects recorded in both treatment groups were headache, dizziness, fatigue and gastrointestinal disorders, and the majority were classed as mild to moderate. The only one found to be 10% or greater in frequency in patients VX-765 was dizziness, and only one person dropped out of the study due to adverse events linked with the drug, the firm said.

Secondary targets and analyses looked at the clinical activity of VX-765 - i.e. the reduction in seizure rate - and indeed support a larger and longer Phase 2b study in patients with the condition, which the company said it expects to kick off sometime during the fourth quarter.

Although reductions in seizures between the two groups weren't statistically different, less episodes were recorded in the last two weeks of the trial and in the follow-up phase, indicating that a longer-duration study is needed to determine "any additional or more robust clinical activity" of the drug, Vertex said.

VX-765 is an oral anti-inflammatory that could offer a completely new approach for treating epilepsy, particularly for those patients who are unresponsive to standard therapies and "who are often severely debilitated by frequent seizures that limit daily activities and independence", said Peter Mueller, Vertex' executive vice president, global research and development.

Also last week, the drugmaker reportedly said plans to file its cystic fibrosis pill VX-770 during the second half of the year are on track, following positive results from a Phase III trial showing that the drug induced a 10.6% mean improvement in lung function versus placebo.