Teva Pharmaceutical Industries Ltd., a leading global pharmaceutical company, and Xenon Pharmaceuticals Inc.,a clinical-stage biopharmaceutical company, reported top line results from the double-blind, placebo-controlled phase 2b study designed to evaluate the safety and efficacy of topically applied TV-45070 (4 per cent and 8 per cent w/w ointment) in patients with chronic pain due to osteoarthritis (OA) of the knee.

TV-45070 is a small molecule inhibitor of the sodium channel Nav1.7 and other sodium channels, including those that are expressed in the pain-sensing peripheral nervous system. Results from this trial showed that TV-45070 4 per cent and 8 per cent did not demonstrate statistically significant difference from placebo in efficacy endpoints of reductions in pain due to OA.

TV-45070 did demonstrate a favourable safety and tolerability profile, with no drug-related serious adverse events. This is important given the ongoing phase 2b study of TV-45070 in post-herpetic neuralgia (PHN). The most common adverse events were application site dermal skin reactions which were mostly mild and less frequent than seen with other topical analgesics. There were no cardiac or CNS safety issues.

"The rationale for development of TV-45070 in OA has unfortunately not been confirmed with these results. However, neuropathic pain represents a distinct mechanism of chronic pain to OA and, as such, the potential for positive study results in PHN is not impacted by these data," said Richard Malamut M.D. Teva's vice president and head of pain therapeutic development.

"Given the favourable safety and tolerability profile demonstrated, we remain hopeful that TV-45070 can offer a new and valuable option to patients with neuropathic pain."

"While we are disappointed that the phase 2b trial top-line results did not indicate efficacy in OA, Teva and Xenon have always been committed to a broad development plan for TV-45070 in both nociceptive and neuropathic pain," said Dr. Simon Pimstone, Xenon's president and chief executive officer.

"The phase 2b trial in PHN being conducted by Teva is progressing as planned, and we look forward to seeing top-line results from that trial in the second half of 2016. In addition, Xenon will continue to focus on advancing our partnered and proprietary pipeline programmes, and leveraging the potential of our Extreme Genetics platform and expertise in ion channel target discovery. We look forward to other near-term milestone opportunities across our diverse product candidate pipeline."

Applied topically, TV-45070 acts locally to inhibit Nav1.7 in the skin and underlying tissue, mitigating systemic absorption and the potential risks of side-effects that accompany systemic drug metabolism. The pain target Nav1.7 was identified by Xenon using its Extreme Genetics discovery platform. Xenon developed TV-45070 through early clinical development and partnered with Teva through a collaborative development and license agreement established in 2012, providing Teva with an exclusive worldwide license to develop and commercialize TV-45070. A Phase 2b trial in PHN is currently underway, with results expected in the second half of 2016.

The phase 2b osteoarthritis trial of TV-45070 was a randomized, double-blind, placebo-controlled study conducted at approximately 40 clinical sites across the US. There were three arms in the study and a total of 389 patients were randomized on a 1:1:1 basis: experimental TV-45070 4 per cent administered twice per day; experimental TV-45070 8 per cent administered twice per day; and placebo comparator (matched ointment without TV-45070) administered twice per day. Patients were eligible to participate in the trial if they were 40-85 years of age, had primary OA in a single knee (target knee), and met pre-specified visual analog scale (VAS) pain scores and were otherwise medically healthy. The primary endpoint of the phase 2b trial was to evaluate the efficacy of four weeks of topical administration of TV-45070 (4 per cent and 8 per cent ointment) compared with placebo for the relief of symptoms of primary OA of the target knee as assessed by the change from baseline to the last five days of treatment in average evening pain score upon walking on a flat surface using question 1 of the Western Ontario and McMasters Universities Arthritis Index (WOMAC) on a 0-100 mm visual analog scale. The efficacy endpoints were analysed on a full analysis set defined as all patients having received at least one dose of study drug and having at least one post baseline efficacy assessment. Key secondary objectives of the trial included changes in WOMAC pain subscale scores, responder rates, and patient-reported outcome assessments.