This study was performed following regulatory guidance from the UK regulatory authority (MHRA) and provides evidence of long term efficacy to be included as part of the forthcoming European regulatory submission planned for Q2 09.

Separately, GW remains on track to report results of its Phase III MS Spasticity trial towards the end of Q1 09.

This randomized withdrawal study evaluated 36 MS patients with spasticity who had previously been taking Sativex on prescription. The mean duration of prior Sativex prescription use was 3.6 years. The patients were randomized to Sativex or placebo for 4 weeks in a double-blinded manner. During the randomized period, patients were not permitted to adjust their dose. The purpose of this blinded 4-week "randomized withdrawal" study was to assess the maintenance of spasticity relief in patients who remain on Sativex versus those who switch to placebo.

The prospectively defined primary efficacy endpoint of the study - the time to treatment failure - was statistically significantly in favour of Sativex (p=0.013). The difference between Sativex and placebo was also significant for the patient global impression of change (p=0.017) and the carer functional-ability global impression of change (p=0.001). This means that the carer recognised that the patient's spasticity became worse when they stopped taking Sativex - thus providing independent verification of the primary endpoint.

There was no evidence of a withdrawal syndrome in those patients who stopped Sativex, despite a very prolonged period on the medicine. Overall, there was a similar frequency and severity of adverse events in both the Sativex and placebo groups of patients, with more than 85% of such events being deemed mild or moderate in severity.

In September 2008, GW reported positive results from a placebo-controlled randomized withdrawal study of Sativex in patients with neuropathic pain due to MS. The results reported today are from a study with a similar design but in patients with a different MS symptom. Taken together, these studies show that the efficacy of Sativex in the treatment of both neuropathic pain and spasticity due to MS is maintained in long-term use.

Dr Stephen Wright, GW's R&D Director, said: "This placebo-controlled study shows that Sativex provides meaningful long term efficacy for people with spasticity due to MS. These results will be an important new feature of the efficacy and safety data to be submitted in our next regulatory application. Separately, I am able to confirm that the pivotal Phase III trial in MS spasticity is on track to report results towards the end of Q1 09 and a regulatory submission is targeted for Q2 09."

Notes

Time to Treatment Failure Analysis

The primary endpoint in the study was a time to treatment failure analysis. In the context of this study, a time to treatment failure means either (i) time to the patient experiencing a clinically meaningful worsening of their spasticity (as measured on a Numeric Rating Scale) or (ii) a decision to withdraw from the study (and to go back to their prescription Sativex).

Sativex Prescription Use

Sativex is approved and marketed in Canada for the treatment of cancer pain and MS neuropathic pain. In addition, Sativex is available on prescription in the UK on a "named patient" basis and has to date been exported to 22 countries around the world.

Sativex and MS Spasticity

Spasticity (spasms and stiffness) is one of the most common symptoms of MS occurring in as many as three-quarters of people with MS. Spasticity can affect many aspects of daily life, such as walking and sitting. Sativex aims to treat high need patients who have previously failed to gain adequate benefit from currently available anti-spasticity treatments

GW has a body of clinical data in approximately 700 patients with MS spasticity, including two pivotal Phase III trials as well as two supportive trials. A third Phase III trial, involving 575 patients, is due to report results in late Q1 2009.

Following these results, GW intends to submit a regulatory application in Q2 09 in selected European countries. Upon approval, Sativex will be exclusively marketed in the UK by Bayer HealthCare and in the rest of Europe by Laboratorios Almirall, S.A.

Sativex and Cancer Pain

Over one-third of patients with cancer, and more than three-quarters of those with advanced disease, have chronic pain. Currently available opioid therapies do not yield sufficient relief in a substantial proportion of these patients and there is a clear need for new treatments.

Cancer pain is the lead indication for the development of Sativex in the United States. GW has completed a positive Phase II cancer pain study in Europe in 177 patients and is now carrying out a 336 patient Phase IIb/III study in collaboration with its partner, Otsuka Pharmaceutical Co. Ltd. Upon approval, Sativex will be exclusively marketed in the US by Otsuka.

About GW

GW was founded in 1998 and listed on the AiM, a market of the London Stock Exchange, in June 2001. Operating under license from the UK Home Office, the company researches and develops cannabinoid pharmaceutical products for patients who suffer from a range of serious ailments, in particular multiple sclerosis and cancer pain. GW has assembled a large in-house scientific team with expertise in cannabinoid science as well as experience in the development of both plant-based prescription pharmaceutical products and medicines containing controlled substances. GW occupies a world leading position in cannabinoids and has developed an extensive international network of the most prominent scientists in the field.

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