GW Pharmaceuticals plc (AIM: GWP) today announces that the Journal of Clinical Therapeutics has published the results of a study which show that Sativex® provides effective long term treatment of central neuropathic pain in Multiple Sclerosis (MS) and that these benefits are obtained without any evidence of tolerance (increase in dose) to the medicinei.
The open label extension trial results published follow a previously reported short term randomised controlled trial of the effect of Sativex for the treatment of central neuropathic pain in MS. Improvements in the pain scores for those patients who completed the extension trial showed sustained improvement over two years. At the end of the two year treatment period, the mean pain score was 2.9 (out of 10), a severity which can be described as mild. The mean pain score for all patients at entry into the initial short term controlled trial was 6.5.
Side effects reported during the two year period were in general mild or moderate in severity. The mean number of sprays remained stable throughout the two year period, hence there was no evidence of tolerance (escalation in dose) with long term exposure and the study did not raise any additional safety concerns.
The authors of the paper conclude that “Sativex is efficacious as a treatment for central pain due to multiple sclerosis in the long-term with no evidence of tolerance”.
Dr David Rog, first author of the paper and Consultant Neurologist at Greater Manchester Neurosciences Centre, who completed the study while at The Walton Centre for Neurology and Neurosurgery, Liverpool, commented “This study demonstrates that long-term use of Sativex provides sustained benefit in around half of patients with MS and central neuropathic pain. The improvement in these patients is obtained without the need for them to increase their dose.”
Sativex is approved as a prescription medicine in Canada for the relief of central neuropathic pain in MS. This approval was based on a previously reported study, which was published in the peer-reviewed journal, Neurology, which showed that Sativex was significantly superior to placebo in reducing pain (p=0.005) and sleep disturbance (p=0.003)ii. This previous study showed Sativex to be effective in short-term use, whereas this newly-published study confirms that its effect in reducing pain and improving sleep is maintained over a prolonged period.
In addition to these completed trials, GW has recently completed patient recruitment in an additional pivotal Phase III trial in MS neuropathic pain. The study has recruited 339 patients and is GW’s largest clinical trial to date. The duration of treatment in the study is 14 weeks and headline results are expected in H1 2008.
Dr Stephen Wright, GW’s R&D Director, said “The results announced today confirm that Sativex is able to provide substantial relief from pain for a long period of time to patients who have previously failed to obtain benefit from other available treatments. We believe that this study shows, in a setting that reflects normal clinical practice, that Sativex is able to meet a real medical need. The results add to what we know from short-term clinical trials, and we look forward to seeing the results of our ongoing pivotal study in the same condition in the first half of next year.”