Please use this link to access this publication. Abstract Background: Opioids are critical for managing cancer pain, but may provide inadequate relief and/or unacceptable side effects in some cases. Objective: To assess the analgesic efficacy of adjunctive Sativex (Δ9-tetrahydrocannabinol (27 mg/mL): cannabidiol (25 mg/mL)) in advanced cancer patients with chronic pain unalleviated by optimized opioid therapy. Methods: This report describes two phase 3, double-blind, randomized, placebo-controlled trials. Eligible patients had advanced cancer and average pain numerical rating scale (NRS) scores ≥4 and ≤8 at baseline, despite optimized opioid therapy. In Study-1, patients were randomized to Sativex or placebo, and then self-titrated study medications over a 2-week...