GWP.L Regulatory News (GWP)

PROMISING PHASE II CLINICAL STUDY RESULTS OF SATIVEX® IN MS BLADDER DYSFUNCTION PUBLISHED IN PEER REVIEW JOURNAL

Porton Down, UK, 22 September 2010: GW Pharmaceuticals plc (GWP:AIM) announces that results of a Phase II clinical study of Sativex® (delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD)) in the treatment of bladder dysfunction in people with Multiple Sclerosis (MS) have been published in the peer-reviewed Journal, Multiple Sclerosis. The authors of the paper state that "this study does provide clinical evidence across a range of bladder-related endpoints that Sativex® has some beneficial effect when used for treatment of the bladder symptoms in patients with MS".

Preliminary headline results from this study have previously been announced by GW. The paper is published online and will appear in the print copy of the Journal in the coming months.i

The study was a double-blind, randomized, placebo-controlled, parallel-group trial of Sativex® in 135 people with MS and overactive bladder (OAB) that was not responding adequately to currently available treatment (e.g. oxybutinin). During the study, patients remained on their existing bladder medication. Treatment duration in the study was 8 weeks.

In the trial, Sativex achieved statistically significant improvements in a range of bladder symptoms, including nocturia (p=0.01), daytime frequency (p=0.044), frequency per 24 hours (p=0.001), and bladder symptom severity (p=0.001). A significant effect was also seen in the patient's global impression of change (p=0.005). There was also a strong trend in favour of Sativex in urgency (p=0.07).

There was no significant effect on incontinence, the pre-specified primary endpoint of the study. The paper's authors state a possible reason for this may be the relatively low baseline number of incontinence episodes resulting from patients remaining on their existing medication.

In the trial, the adverse event data showed the medicine to be generally well tolerated.

Professor Cris Constantinescu, Professor of Neurology, University of Nottingham, said, "Bladder dysfunction is a common feature of MS and many current treatments are less than ideal due to lack of efficacy or tolerability. These data provide promising evidence for the positive effects of Sativex® on bladder symptoms in patients with MS."

Dr Stephen Wright, GW's R&D Director, said: "This study demonstrates that in people with MS who have exhausted other treatments, Sativex® improved some of their most troublesome symptoms of bladder dysfunction. We believe that Sativex® has broad therapeutic potential and this area represents one of a number of options for future development of this important medicine."

In recent months, Sativex® has been approved in the UK, Spain and Canada as a treatment for spasticity in MS. Sativex is not licensed as a treatment for overactive bladder.

Sativex® is marketed in the UK and Canada by Bayer Schering Pharma and will be marketed in the rest of Europe by Almirall S.A.

Enquiries:

Notes to Editors

Sativex®

Sativex® contains two cannabinoids or active ingredients - THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol). It is the first cannabinoid medicine derived from whole plant extracts from the cannabis sativa plant.

Sativex® is indicated as add-on treatment for symptom improvement in patients with moderate to severe spasticity due to multiple sclerosis (MS) who have not responded adequately to other anti-spasticity medication and who demonstrate clinically significant improvement in spasticity related symptoms during an initial trial of therapy. ii

Overactive Bladder (OAB) in MS

It is estimated that 87% of people with MS experience bladder problemsiii. Bladder symptoms are among those problems which cause the most distress for people living with MS.iv Symptoms of OAB such as episodes of leakage, increased frequency and urgency disrupt patients' daily routine and reduce quality of lifei.

GW Pharmaceuticals

GW Pharmaceuticals plc (AIM:GWP) was founded in 1998 and is listed on the AiM, a market of the London Stock Exchange. Operating under licence 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 MS 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. For further information, please visit www.gwpharm.com

This news release may contain forward-looking statements that reflect GWs current expectations regarding future events, including development and regulatory clearance of the GW's products. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors, including (inter alia), the success of the GW's research strategies, the applicability of the discoveries made therein, the successful and timely completion of uncertainties related to the regulatory process, and the acceptance of Sativex® and other products by consumer and medical professionals.

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i http://msj.sagepub.com/content/early/2010/09/08/1352458510378020

ii Sativex® Summary of Product Characteristics, 2010

iii Hemmett et al, Q J Med 2004; 97: 671-676

iv MS Society, Health Technology Appraisal, Cannabinoids for Symptom Relief in MS, 2003: