A mid-stage trial assessing an experimental cannabinoid being developed by GW Pharma for adults with focal seizures has failed to hit key targets.

The Phase IIa placebo-controlled study evaluated the efficacy and safety of GWP42006, which features cannabidivarin (CBDV) as the primary cannabinoid molecule, as add-on therapy in 162 adult patients with inadequately controlled focal seizures.

Preliminary top-line data show that both active and placebo arms demonstrated similar reductions in focal seizures of around 40 percent.

However, the extent of this placebo response is substantially greater than that seen in published studies of other treatments in similar patient populations, the firm noted, adding that it is now “working to understand the potential reasons for this result”.

In the trial, GWP42006 was generally well tolerated, but more patients in the active group (73 percent) experienced treatment emergent adverse events compared to the placebo group (48 percent).

GW said the drug has shown anti-epileptic properties across a range of in vitro and in vivo models of epilepsy, and will continue to explore its potential in the field, as well as in autism spectrum disorders.

“Whilst the results of this adult focal seizure study for GWP42006 are disappointing, we remain committed to advancing this pipeline compound to address unmet needs in the field of autism spectrum disorders, in which a promising body of preclinical data has already been generated, as well as continuing to explore the product’s potential within the field of epilepsy,” said Justin Gover, GW’s chief executive.

“The company’s top priority in 2018 remains Epidiolex, for which we have generated compelling positive data in three Phase III trials, and which is currently under regulatory review in the US and Europe.”