Results of a Double-Blind, Randomized, Placebo-Controlled Study of Nabiximols Oromucosal Spray as an Adjunctive Therapy in Advanced Cancer Patients with Chronic Uncontrolled Pain

Abstract

Context: Prior Phase 2/3 studies found that cannabinoids might provide adjunctive analgesia in advanced cancer patients with uncontrolled pain.

Objectives: To assess adjunctive nabiximols (Sativex^®), an extract of Cannabis sativa containing two potentially therapeutic cannabinoids (Δ9-tetrahydrocannabinol [27 mg/mL] and cannabidiol [25 mg/mL]), in advanced cancer patients with chronic pain unalleviated by optimized opioid therapy.

Methods: Phase 3, double-blind, randomized, placebo-controlled trial in patients with advanced cancer and average pain Numerical Rating Scale scores ≥4 and ≤8 despite optimized opioid therapy. Patients randomized to nabiximols (n = 199) or placebo (n = 198) self-titrated study medications over a two-week period, followed by a three-week treatment period at the titrated dose.

Results: Median percent improvements in average pain Numerical Rating Scale score from baseline to end of treatment in the nabiximols and placebo groups were 10.7% vs. 4.5% (P = 0.0854) in the intention-to-treat population (primary variable) and 15.5% vs. 6.3% (P = 0.0378) in the per-protocol population. Nabiximols was statistically superior to placebo on two of three quality-of-life instruments at Week 3 and on all three at Week 5. In exploratory post hoc analyses, U.S. patients, but not patients from the rest of the world, experienced significant benefits from nabiximols on multiple secondary endpoints. Possible contributing factors to differences in nabiximols efficacy include: 1) the U.S. participants received lower doses of opioids at baseline than the rest of the world and 2) the subgroups had different distribution of cancer pain types, which may have been related to differences in pathophysiology of pain. The safety profile of nabiximols was consistent with earlier studies.

Conclusions: Although not superior to placebo on the primary efficacy endpoint, nabiximols had benefits on multiple secondary endpoints, particularly in the U.S.

Patients: Nabiximols might have utility in patients with advanced cancer who receive a lower opioid dose, such as individuals with early intolerance to opioid therapy.

Keywords: Pain; advanced cancer pain; cannabinoids; nabiximols; numerical rating scale; opioids; randomized control trial.