ENhANCE trial protocol: A multi-centre, randomised, phase IV trial comparing the efficacy of oxycodone/naloxone prolonged release (OXN PR) versus oxycodone prolonged release (Oxy PR) tablets in patients with advanced cancer

BACKGROUND: Oxycodone is a frequently used opioid in cancer. Opioid-induced constipation (OIC) is common. Oxycodone/Naloxone Prolonged Release (OXN PR) contains naloxone, which mitigates OIC. Trials have either focused on non-cancer pain, or conducted before significant experience of using OXN PR. This trial aims to: demonstrate (1) analgesic equivalence between OXN PR and Oxycodone Prolonged Release (Oxy PR), and (2) superiority of constipation outcomes in OXN PR compared to Oxy PR in cancer pain. Unlike other trials, it will only include patients with at least moderate pain scores (≥4/10), allow usual laxatives, and exclude potential liver dysfunction. METHODS: This is a multi-centre, open-label, randomised, phase IV study of OXN PR vs Oxy PR in patients with cancer-related pain. The primary outcome is pain difference on Brief Pain Inventory-Short Form (BPI-SF) at 5 weeks. Secondary outcomes are comparison of other pain outcomes (BPI-SF) and neuropathic pain measures (Leeds Assessment of Neuropathic Symptoms & Signs (S-LANNS)), constipation (Bowel Function Index (BFI)), quality of life (EORTC-QLQ-C30), rescue analgesia use, total opioid dose, and total laxative dose over 5 weeks. CONCLUSION: The comparison of analgesic efficacy between both arms, and superiority of constipation in the OXN PR arm will add new knowledge on the comparisons of both agents, and oxycodone independently. This trial will extend knowledge of the effectiveness, safety, and adverse effect profiles of both drugs in terms of pain, constipation, quality of life outcomes for patients with cancer pain, and provide clinicians with high quality data to guide decision making. TRIAL REGISTRATION: Name of the registry: ANZCTR TRIAL REGISTRATION NUMBER: ACTRN12619001282178 DATE OF REGISTRATION: 17/09/2019 URL OF TRIAL REGISTRY RECORD: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377673&isReview=true Protocol version 2.1_28 August 2020