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

Inclusion Criteria:

* A signed informed consent document.
* Male and non-pregnant, non-lactating female subjects.
* Female subjects must be post menopausal, surgically sterile, or practicing an effective method of birth control and continue to do so throughout the trial.
* At least 18 years of age.
* Have chronic malignant tumor-related pain
* Are opioid-naïve or have been pretreated with an equianalgesic dose range equivalent of up to 160 mg oral morphine per day and are dissatisfied with prior treatment.
* Have a mean pain intensity of at least 5 points on an 11-point Numeric Rating Scale (where 0 indicates no pain and 10 indicates worst possible pain).
* Have an expected course of the disease such that the pain that will permit compliance with the trial protocol over the entire trial period.

Exclusion Criteria:

* Have a life-long history of seizure disorder or epilepsy.
* Have had any of the following within one year: mild/moderate traumatic brain injury, stroke, and transient ischemic attack.
* Have had severe traumatic brain injury within 15 years (consisting of ≥ 1 of the following: brain contusion, intracranial hematoma, and either unconsciousness or post-traumatic amnesia lasting for more than 24 hours) or residual sequelae suggesting transient changes in consciousness.
* Have a known history and/or presence of cerebral metastases.
* Have moderately or severely impaired hepatic function.
* Have laboratory values reflecting inadequate hepatic function.
* Have thrombopenia, leucopenia or hypercalcemia
* Have severely impaired renal function.
* Having uncontrolled hypertension
* Having clinically relevant history of hypersensitivity, allergy or contraindications to morphine or any of the excipients.
* Have chronic hepatitis B or hepatitis C, or Human Immunodeficiency Virus (HIV).
* Subjects currently undergoing the following concomitant therapy: radiotherapy, pain inducing chemotherapy, anti-parkinsonian drugs, neuroleptics, monoamine oxidase inhibitors, serotonin norepinephrine re-uptake inhibitors (SNRI) or any other analgesic therapy than investigational medication or rescue medication during the trial. Selective serotonin re-uptake inhibitor (SSRI) treatments are allowed if taken for at least 30 days before the screening period of the trial at an unchanged dose.