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GW's 11-year Sativex Effort Culminates with UK Approval

BioWorld International Correspondent

LONDON – GW Pharmaceuticals plc is celebrating the first full regulatory approval and the UK launch of the cannabis-based drug Sativex for the treatment of spasticity due to multiple sclerosis, events that triggered a 10 million (US$14.8 million) payment from UK marketing partner Bayer Schering Pharma.

The orally administered spray contains two cannabinoids, delta-9-tetrahydrocannabinol and cannabidiol, extracted from Cannabis sativa plants grown at a secret and secure location in the UK.

The 11-year long haul through development to reach the point where the UK Medicines and Healthcare products Agency (MHRA) granted approval at the end of last week was marked by several setbacks and probing questions on whether GW Pharma had truly demonstrated efficacy. The product was initially turned down on appeal almost exactly five years ago, when the company was required to conduct another Phase III trial. More recently, GW Pharma was told to conduct a further trial in which patients stopped using Sativex, in order to demonstrate the product remains effective in the long term.

The label on the product, launched by Bayer on Monday, allows Sativex to be prescribed for treating spasms and cramps associated with spasticity in multiple sclerosis patients who have failed on existing treatments. Bayer will build on its position as supplier of the multiple sclerosis treatment Betaferon to 85 specialist centers, in developing the UK market. There are around 100,000 multiple sclerosis sufferers in the UK, of whom 84 percent are reported to suffer from spasticity at some point. In its market projections Bayer said 11,500 of these would be eligible for treatment with Sativex.

GW Pharma's manufacturing facility currently can produce enough Sativex to treat 25,000 patients per year. It has also built up stocks to cope with an increase in demand following approvals in the UK and elsewhere in Europe, and holds material at various intermediate stages. In the past year the company has taken over responsibility for extracting active ingredients from a subcontractor and now runs the complete supply chain.

Justin Gover, managing director, said the process is operating at a commercial scale and the company has space within its glass houses to grow three times as many cannabis plants as currently are grown. "We will be manufacturing solely in the UK. The control of the starting material and the very tight manufacturing controls are critical," he told BioWorld International.

Details of Monday's launch leaked out at the end of last week after the MHRA gave its final nod. Shares in Salisbury, UK-based GW Pharma closed up 12 pence at 1.41 on Friday in response to the news.

GW Pharma was licensed to develop a cannabis-based prescription medicine for multiple sclerosis by the UK government, in response to the knowledge that some multiple sclerosis sufferers were smoking the illegal drug to soothe their symptoms.

The 11 years it has taken to get the approval has seen huge leaps in understanding of the cannabinoid system. That means the launch of Sativex is not only important in terms of its financial impact on GW Pharma, but also because it demonstrates the company's prowess in cannabinoid biology. Geoffrey Guy, chairman, said, "[This] validates our cannabinoid technology platform and enables us to progress the development of our pipeline across a range of therapeutic areas with increasing confidence."

Following on from the UK, Sativex is expected to be approved in Spain under the European Medicines Agency's mutual recognition procedure. That opens the way for approvals elsewhere in Europe, where it will be marketed by Almirall SA. "This marks the beginning of the transition from late-stage development company to a commercial pharmaceutical business," Guy said,

Sativex was previously given a conditional approval in Canada for treating pain associated with multiple sclerosis in 2005, and subsequently in treating cancer pain. GW has now applied for full approval of Sativex in spasticity in Canada. It is also working on getting approval in cancer pain in the U.S., where it reported positive data in a Phase IIb 360 patient study in March.

There was a statistically significant difference from placebo in pain scores in the dose-ranging study carried out in patients with advanced cancer who did not get adequate relief from opioids. Given the side effect profile of opioids, it would also be helpful to have an alternative therapy, even where those painkillers remain effective.

Preparations are now in hand for U.S. Phase III development. Gover said he expects GW Pharma and its Japanese partner Otsuka Pharmaceutical Co. Ltd. to hold a Phase III meeting with the FDA early in the next quarter. As things stand, the company expects to be asked to do two Phase III studies, which it will carry out simultaneously, and Gover said the aim is to get approval in two years. Otsuka is bearing the full cost of the U.S. development, but the data will be available for GW to extend the European label on Sativex to cancer pain.

GW Pharma also has a research collaboration with Otsuka, under which the two are working on further applications of cannabinoids in cancer and central nervous system diseases, including schizophrenia. Gover said the partners now have "Preclinical data of a scope and type and strength that would allow programs to progress into Phase I." Decisions on when, and if to advance programs will be made by Otsuka.

Published: June 23, 2010