GW Pharmaceuticals plc and Otsuka Pharmaceutical Development & Commercialization, Inc. reported the top-line results from the first of three Phase 3 trials for the investigational product Sativex in the treatment of pain in patients with advanced cancer who experience inadequate analgesia during optimized chronic opioid therapy. In this first trial, Sativex (as adjunctive treatment to optimized chronic opioid therapy) did not meet the primary endpoint of demonstrating a statistically significant difference from placebo. The primary efficacy measure of the study was a patient assessment of pain using a 0-to-10 Numeric Rating Scale (NRS) which was analysed using percent improvement from baseline as the primary analysis.

In addition, improvement was also analysed using a cumulative proportion of responders analysis (CPRA), which analyses the full range of responses achieved across the entire patient population within a trial. In this trial, these analyses did not show a statistically significant difference between Sativex and placebo. The secondary endpoints followed the pattern of the primary endpoint.

In this study, the United States was the single recruiting country. Although not statistically significant, the efficacy data from U.S. sites showed more positive trends than those in non-U.S. sites. This is consistent with data from the Phase 2b trial.

The safety profile of Sativex in this Phase 3 trial was consistent with previous studies in this patient population. Overall, Sativex was well tolerated. The only adverse events reported at greater than 10% for the Sativex population were neoplasm progression (16% on Sativex vs 18% on placebo) and somnolence (12% on Sativex vs 4% on placebo).

The other most frequently reported adverse event on Sativex was dizziness (8% on Sativex vs 5% on placebo). Otherwise, there was little difference in the adverse event pattern between Sativex and placebo. There were 38 (19%) withdrawals due to adverse events on Sativex compared with 29 (15%) on placebo.