Inclusion criteria: <br>1. Presence of a solid neoplasm and between the ages of 18 and 65 years, inclusive <br>2. Able to understand written and verbal communication in the primary language of the country in which the study is being undertaken<br>3. Life expectancy a minimum of 3 months with Karnofsky score =50 at the Screening Visit (Day -7)<br>4. History of daily pain attributable to cancer and requiring treatment with strong opioids for at least 3 months duration<br>5. Pain with neuropathic characteristics that include one or more of the following: throbbing, shooting, stabbing, sharp, cramping, gnawing, hot-burning, aching, heavy, tender, splitting, tiring-exhausting, sickening, fearful, punishing-cruel, electric-shock, cold-freezing, piercing, caused by light touch, itching, tingling or ‘pins and needles’, or numbness.<br>6. Pain inadequately relieved despite active management including strong opioids<br>7. Currently taking morphine, oxycodone, hydromorphone, buprenorphine, or transdermal fentanyl for daily, non-breakthrough pain management (i.e., maintenance opioid treatment) with no changes in dose in the 2 weeks preceding the Screening Visit (Day -7)<br>8. Completion of a daily diary in which the 24-hour AP score has been entered for at least 5 of the last 7 days preceding Day 1<br>9. Average of non-missing 24-hour AP scores over the last 7 days before the day of randomization is 4 or greater<br>10. If on gabapentin, pregabalin or selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants, no changes in dose in the 2 weeks preceding the Screening Visit (Day -7)<br>11. Willing to maintain existing analgesic medications, including maintenance opioid treatment, at same dose(s) and schedule for a minimum of 6 weeks following the Screening Visit (Day -7)<br>12. Able to take oral medication<br>13. If female subject of childbearing potential, a negative serum beta human chorionic gonadotropin (hCG) pregnancy test, performed at the Screening Visit (Day -7). Must be willing to use effective methods of birth control and/or refrain from participating in a conception process during the study and for 30 days following study drug exposure.<br>14. Willing and able to comply with protocol requirements for the duration of study participation<br>15. Contractual capability and signed informed consent<br>Are the trial subjects under 18? no<br>Number of subjects for this age range: 0<br>F.1.2 Adults (18-64 years) yes<br>F.1.2.1 Number of subjects for this age range 280<br>F.1.3 Elderly (>=65 years) yes<br>F.1.3.1 Number of subjects for this age range 20<br>