BioWorld International Correspondent

LONDON - Shares in GW Pharma plc fell by 25 percent after it indicated it might miss the promised June deadline for a European filing of its Sativex cannabis-based medicine, following equivocal results in a Phase III trial in the relief of spasticity in multiple sclerosis (MS).

The company now will consult with regulators and marketing partners to decide if it should await data from two Phase III trials in neuropathic pain.

The latest Phase III data in MS, "does give us enough to file," Stephen Wright, R&D director said in a conference call. "But we have got data coming through on neuropathic pain, which is a larger market. Even if the MS [data] were clear-cut, we would have to consider waiting," he said.

Shares in Salisbury, UK-based GW Pharma fell by 32 pence to 94.5 pence (US$1.65) when the trial results were released March 17.

The rules in Europe mean that if it files for approval now, GW Pharma will have to sit on the neuropathic pain data until the MS spasticity review is completed.

But what the company is most anxious to avoid is another rebuff like that from UK regulators who turned down Sativex on appeal in June saying there was no "compelling" evidence of efficacy in treating spasticity caused by MS.

Julian Gover, managing director, said it was important to ensure, "the next regulatory process is one that is robust and is going to end up with the right result, not only for the UK [but] across Europe.

"We might, if we file straight away, be sitting on good neuropathic pain data, while awaiting the outcome of the spasticity filing."

The Phase III study of Sativex was confounded by a higher placebo effect than GW has seen in any previous study, and because 45 of 335 subjects did not comply with the protocol. If the placebo effect had been at the same level as other studies, the trial would have been positive.

As it were, the intention to treat population was in favor of Sativex but not statistically significant, while the per-protocol population showed a positive and statistically significant result for the primary, and two secondary, endpoints.

A meta-analysis of three Sativex MS spasticity trials, covering 652 patients, shows it to be significantly superior to placebo.

All patients entering the latest study had suffered MS for more than 14 years and were severely affected, with more than half using wheelchairs.

All of them were taking the best available anti-spasticity medication and remained on it throughout the trial.

There would be no immediate cash impact from a decision to hold off filing, as GW Pharma’s European marketing deal with Almirall Prodesfama for Sativex does not include filing milestones.