Cancer patients in severe pain were today offered hope that their suffering could be relieved by a new drug derived from cannabis.

British company GW Pharmaceuticals said clinical trials of its Sativex oral spray had shown that it was statistically superior to placebo in relieving pain.

The drug was tested on 177 cancer patients in final trials and was found to improve their pain by a third in approximately 40% of cases.

Shares rose 2% after the preliminary findings of the trials were announced alongside GW’s annual results, which showed losses widening to £15.7m (€22.6m) during the year to September 30 from £9.6m (€13.8m) a year ago.

Sativex is a whole plant medicinal cannabis extract containing tetrahydrocannabinol and cannabidiol.

It has received preliminary approval in Canada for easing the pain of patients with multiple sclerosis, while trials have also shown the drug to be effective in treating arthritis sufferers.

But efforts to get Sativex approved in the UK suffered a setback at the start of December when regulators demanded further tests, causing the company to lose almost a quarter of its value.

GW, which grows cannabis plants at a secret location, said it was determined to prove the efficacy of Sativex and should know in the summer whether it has secured UK approval.

Executive chairman Dr Geoffrey Guy said the raft of positive clinical data and the imminent approval of Sativex in Canada meant there was “good reason to be excited about the year ahead”.

“We expect 2005 to be the year of our first product launch, a time of restored momentum, as well as a financial turning point as we start to generate commercial revenues from product sales,” he said.

German drugs group Bayer Healthcare will exclusively market the medicine once it gains final approval.