Assessment of Efficacy and Safety in Relieving Opioid-induced Constipation in Patients With Cancer-related Pain

Inclusion Criteria: * Provision of written informed consent prior to any study-specific procedures. * Men and women aged 18 or older. * Histologically or cytologically confirmed neoplasm causing pain and requiring management with opioids. * Self-reported active symptoms of OIC at screening (\<3 RFBMs/week and experiencing \>1 reported symptom of hard/lumpy stools, straining, or sensation of incomplete evacuation/anorectal obstruction in at least 25% of BMs over the previous 4 weeks); and Documented confirmed OIC (\<3 RFBMs/week on average aver the 2-week OIC confirmation period. * Receiving a stable maintenance opioid regimen consisting of a total daily dose of \>30 mg of oral morphine, or equianalgesic amount(s) of 1 or more opioid therapies for a minimum of 4 weeks prior to screening for cancer-related pain with no anticipated change in opioid dose requirement over the proposed study period as a result of disease progression. Exclusion Criteria: * Patients receiving Opioid regimen for treatment of pain other than related to cancer. * Any condition that may have affected the permeability of the blood-brain barrier, eg, known brain metastases, meningeal metastases, brain injury, multiple sclerosis, recent brain injury, uncontrolled epilepsy. * Patients with cancer-related pain due to ovarian cancer, leukaemia, or lymphoma are excluded. Patients with multiple myeloma will be allowed. * Patients requiring radiation therapy between the diaphragm and pelvis 4 weeks prior to Visit 1 (screening) and/or during Part A of the study are excluded. Any patients with suspected clinically relevant radiation-induced injury of small or large intestine are excluded. * Pregnancy or lactation.