A Study to Evaluate the Effectiveness and Safety of CG5503 (Tapentadol) in the Treatment of Chronic Tumor Related Pain Compared With Placebo and Morphine

Normally chronic tumor related pain is controlled when subjects receive repeated doses of opioid analgesics. However, opioid therapy is commonly associated with side effects such as nausea, vomiting, sedation, constipation, addiction, tolerance, and respiratory depression. Tapentadol, a newly synthesized drug with an Prolonged Release (ER) formulation, also acts as a centrally acting pain reliever but has a dual mode of action. The aim of this trial is to investigate the effectiveness (level of pain control) and safety (side effects) of Tapentadol Prolonged Release (ER) compared to a tablet with no active ingredient drug (placebo) and a corresponding dose of Morphine (an opioid commonly used to treat tumor related pain). This trial is a randomized, double-blind (neither investigator nor patient will know which treatment was received), active- and placebo-controlled, parallel-group, randomized-withdrawal, multicenter trial. To maintain the blind all subjects were re-randomized at the start of the maintenance period. To maintain the blind all tapentadol subjects were re-randomized at the start of the maintenance period. Subjects that received morphine in the titration period continued in the maintenance period on morphine. The trial includes a 2 week titration phase starting with either 45 mg Morphine Sulfate Controlled Release (CR) twice daily or 100 mg tapentadol ER taken twice daily (bid). Based on effectiveness and side effects participants can up-titrate in steps of 50 mg Tapentadol ER or 15 mg Morphine Sulfate CR to a maximal dose of 250 mg Tapentadol ER bid or 90 mg Morphine Sulfate CR twice daily respectively. If subjects meet the stabilization criteria at the end of the titration phase they will be re-randomized to either placebo or active treatment and will continue 4 weeks at the last dose level in the maintenance phase. Assessments of pain relief, defined as a responder include the pain intensity numeric rating scale (NRS). The Patient Global Impression of Change scale (PGIC) will also be used as a secondary efficacy endpoint. Safety evaluations include monitoring of adverse events, physical examinations, and clinical laboratory tests. Venous blood samples will be collected for the determination of serum concentrations of tapentadol.