A Randomized, Double-blind, Parallel-group, Placebo-controlled Study to Assess the Clinical Benefit of SSR411298 as Adjunctive Treatment for Persistent Cancer Pain

Change from baseline in average Numeric Rating Scale (NRS) pain intensity score

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The NRS is an 11-category descriptive anchor scale that is one of the most frequently employed and accepted scales for pain evaluation. Score ranges from 0 \[no pain\] to 10 \[worst possible pain\]. Average NRS score is defined as the average of pain intensity scores measured daily by NRS during a week.

Change from baseline in Brief Pain Inventory Short-Form (BPI-SF) scores

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The BPI-SF is a 9-point questionnaire that measures the intensity of pain, interference of pain, pain relief, pain quality, and patient perception of the cause of pain.

Responder rates

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Responders are defined as: * reduction from baseline ≥30% of pain intensity as measured by NRS; * reduction from baseline ≥50% of pain intensity as measured by NRS; * composite of decrease in pain intensity or decrease in background therapy utilization.

Breakthrough pain frequency

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Opioid consumption expressed as the morphine-equivalent dose per day

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Rescue medication consumption expressed as the number of rescue medication doses per day

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Mood disorders as measured by the Hospital, Anxiety & Depression Scale (HADS)

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The HADS is a self-reported scale that contains 14 items rated on 4-point Likert scales. Two subscales assess depression (7 items) and anxiety (7 items). Each 7-item subscale yields a score of 0 to 21 that is interpreted with the following cut points: 0-7, normal; 8-10, mild mood disturbance; 11-14, moderate mood disturbance; and 12-21, severe mood disturbance.

Change in nausea as measured by Visual Analog Scale (VAS)

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The nausea VAS is a patient-centered instrument to measure nausea on a continuous 100-mm scale.

Constipation as measured by the Bowel Function Index (BFI)

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The BFI is a 3-item questionnaire to measure constipation from the patient's perspective. The time frame for the questions is "during the last 7 days". The answer for each of the 3 items is rated on a scale from 0 (easy or no difficulty) to 100 (severe difficulty).

Healthcare utilization

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Healthcare utilization is measured as the number unscheduled hospitalizations, emergency department visits, healthcare provider office visits, and sick leave days.

Patient satisfaction of pain relief

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

Patient satisfaction of pain relief is a 5-point Likert scale that measures patient satisfaction with treatment. The five categorical responses are: extremely unsatisfied, unsatisfied, neutral, satisfied, extremely satisfied.

Quality of life as measured by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30) version 3

Time frame: 5 weeks (from D-7 (seven days before randomization) up to D28)

The EORTC QLQ-C30 questionnaire contains a total of 30 items, of which 28 items are rated on 4-point Likert-type scale and 2 items are rated on 7-point Likert scale. These include 5 functional scales, 3 symptom scales, a global health status/QoL scale, and 6 single items. A high scale score represents a higher response level. Thus a high score for a functional scale represents a high/healthy level of functioning, a high score for the global health status/QoL represents a high QoL, but a high score for a symptom scale/item represents a high level of symptomatology/problems.

Overview of adverse events (AE)

Time frame: up to 5 weeks (from 1st study drug intake up to 7 days after last study drug intake)

SSR411298 plasma concentration

Time frame: predose and 3-5 hours after study drug intake on Day D14 and Day 28

Plasma concentrations of SSR411298 will be determined by a validated liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) with a lower limit of quantification (LLOQ) of 10 ng/mL.