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

The purpose of this study will be to determine whether tapentadol (CG5503) is effective and safe in the treatment of chronic tumor related pain compared to placebo. In addition tapentadol (CG5503) will also be compared to morphine controlled release, also referred to as slow release (SR).

\*Tapentadol prolonged-release (PR) is the term used in the European Union and is referred to as extended release (ER) in the United States.

Normally chronic tumor related pain is controlled when participants 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 (CG5503), a newly synthesized drug with an prolonged release (PR) formulation, also acts as a centrally acting pain reliever but has 2 mechanisms of action. The aim of this trial is to investigate the effectiveness (level of pain control) and safety (side effects) of tapentadol (CG5503) PR compared with no drug (placebo) and 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 design, multicenter trial.

The trial includes a 2 week titration phase starting with either 40 mg morphine (PR) bid (bid = twice daily dosing, one dose in the morning and one dose in the evening) or 100 mg tapentadol (CG5503) PR bid. Based on effectiveness and side effects subjects can up-titrate in steps of 50 mg tapentadol (CG5503 PR) to a maximal dose of 250 mg tapentadol (CG5503) PR bid or 100 mg morphine PR bid. If participants meet the stabilisation 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. Only participants on tapentadol in the titration phase will be re-randomized to either matching placebo or to tapentadol. To maintain the blinding nature of the trial participants in the morphine arm during the titration phase will also be re-randomized however they will all remain on morphine controlled release in the maintenance phase. Placebo to match tapentadol tablets, as well as placebo to match morphine capsules, will be used to mask the treatment allocation.

Participants will be issued with an electronic diary (eDiary) to capture Numeric Rating Scale (NRS) pain intensities.

Assessments of pain relief include the pain intensity numeric rating scale (NRS) and patient global impression of change (PGIC). Safety evaluations include monitoring of adverse events, physical examinations, clinical laboratory tests and electrocardiograms. Venous blood samples will be collected for the determination of serum concentrations of tapentadol (CG5503).

Eligibility Criteria:
Inclusion Criteria

* Male and non-pregnant, non-lactating female subjects.
* Of at least 18 years of age with chronic malignant tumor-related pain with a mean pain intensity (NRS) of 5 points or higher.
* Subjects who are opioid-naïve or pretreated with an equianalgesic dose range equivalent of up to 160 mg oral morphine per day and are dissatisfied with prior treatment.
* Women must be postmenopausal, surgically sterile, or practicing or agree to practice an effective method of birth control throughout the trial.
* Expected course of the disease and the pain that would permit compliance with the trial protocol over the entire trial period.

Exclusion Criteria

Key Exclusion Criteria:

* Subjects will be excluded from the study if they have a history of seizure disorder or epilepsy;
* known history and/or presence of cerebral tumor or cerebral metastases.
* history of alcohol or drug abuse;
* uncontrolled hypertension,
* clinical laboratory values reflecting severe renal insufficiency,
* moderate or severe hepatic impairment,
* hepatitis B or C, HIV,
* inadequate bone marrow reserve
* currently treated with radiotherapy,
* pain-inducing chemotherapy,
* anti-parkinsonian drugs, neuroleptics, monoamine oxidase inhibitors, serotonin norepinephrine reuptake inhibitor (SNRI) or any other analgesic therapy than investigational medication or rescue medication during the trial.
* selective serotonin reuptake inhibitor (SSRI) treatments are allowed if taken for at least 30 days before the screening period of the study at an unchanged dose.