The study was stopped early due to recruitment challenges

The purpose of this study is to compare the effect of NKTR-118 with placebo in the treatment of opioid-induced constipation (OIC) in patients with cancer-related pain, including those patients that have inadequate response to laxative therapy (LIR).

The study consists of 2 parts; A initial 4-week treatment period (part A) and then a 12 week extension with active treatment (part B).

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.