Cubist Pharmaceuticals, Inc. has initiated phase III CB-5945 opioid-induced constipation (OIC) Ascent programme with the enrollment of the first patient in the long-term safety study, which is one of four registrational studies in patients with chronic non-cancer pain.

The trial is a multicentre, randomized (1:1), double-blind, placebo-controlled study that compares CB-5945 (0.25 mg twice a day) with placebo and is expected to enroll 1,400 eligible patients in the US and Canada. The primary objective of the study is to evaluate the safety of CB-5945 (0.25 mg twice a day) compared with placebo over a one year treatment period. Importantly, this study also examines the effects of CB-5945 on quality of life as a secondary objective.

The long-term safety study complements the three planned efficacy studies scheduled to begin in the first half of 2013. Overall enrollment for the phase III CB-5945 programme is expected to be approximately 3,200 patients.

Cubist’s chief scientific officer Steve Gilman, PhD, said, “Opioid-induced constipation is a debilitating side effect for millions of people who have chronic non-cancer pain. We are excited to begin the robust phase III development programme for CB-5945 and hope one day to make this important therapy available for patients.”

The American Pain Foundation estimates that nine per cent of the US adult population suffers from moderate to severe non-cancer related chronic pain, which is commonly defined as pain that lasts longer than the usual course of an injury or illness. Long-term management of chronic pain often includes treatment with opioid analgesics. Many people receiving this treatment will develop constipation, as well as other associated gastrointestinal complications. This is believed to be the result of the stimulation of mu opioid receptors within the gastrointestinal tract by opioid analgesics. The stimulation of these peripheral mu opioid receptors disrupts regulation of motility, secretion, and absorption. CB-5945 is a potent, peripherally acting mu opioid receptor antagonist that is designed to block the adverse effects of opioid analgesics on the gastrointestinal tract without compromising centrally mediated pain relief. Currently, there are no FDA-approved therapies to treat OIC in patients with chronic non-cancer pain.

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the research, development, and commercialization of pharmaceutical products that address significant unmet medical needs in the acute care environment.