Blindsided by a big placebo effect, GW Pharma says its lead therapy SativexÂ for pain narrowly missed hitting the goal of statistically significant improvement for patients with multiple sclerosis. The news ripped right into the company's stock price, with shares plunging more than 20 percent after the numbers were released. Half of the patients in the trial reported a 30 percent reduction in pain, but so did about 45 percent of the placebo group.
The trial design may be the primary culprit, points out The Times. Volunteers were allowed unlimited access to under-the-tongue spray, allowing the placebo group easy access to an alternative therapy. Sativex, a therapy derived from cannabis, will now be studied for MS spasticity and cancer pain.