Spinifex Pharmaceuticals, an Australian pain drug development company, has treated its first patient in its phase II study of EMA401 in Chemotherapy-Induced Peripheral Neuropathy (CIPN), a painful and debilitating condition that develops in some patients receiving cancer chemotherapy.

The study is an open label biomarker study being conducted at Hammersmith Hospital, London, UK. The trial is designed to provide proof of concept of the use of EMA401, an angiotensin II type 2 (AT2) receptor antagonist, in CIPN. Approximately 50 patients are expected to be enrolled into the trial. Patients will have received either taxane or platinum chemotherapy for any cancer type.

The primary endpoint is the change in mean spontaneous pain intensity score between baseline and the last week of 28 days of dosing using the Numeric Pain Rating Scale (NPRS). A number of secondary endpoints will also be evaluated including changes in nerve characteristics in skin biopsies taken from the calf pre-treatment and after EMA401 treatment at day 29.

Spinifex recently announced positive results from its phase II study of EMA401 in post-herpetic neuralgia (PHN), a neuropathic pain which follows herpes zoster (shingles) in some patients. The primary endpoint of reduction in mean daily pain score over the last week of 28 days of treatment was met, with EMA401 showing a clinically meaningful and statistically significant improvement versus placebo. In addition, a significantly greater proportion of patients on EMA401 reported a more than 30 per cent reduction in mean pain intensity score compared to baseline, meeting a key secondary endpoint. EMA401 was also shown to be generally safe and well tolerated with no serious treatment related adverse events reported.

Despite being a large and growing market, current therapy for chronic and neuropathic pain needs to be improved as a significant proportion of patients don't respond to current therapy and these treatments have dose-limiting side effects. As a result, EMA401 is being developed as a potential first-in-class oral treatment for chronic pain, including neuropathic pain, without central nervous system side effects.

Tom McCarthy, Spinifex Pharmaceuticals CEO said, "Today's announcement marks another significant step in the development of EMA401 and for Spinifex. Our recent results for EMA401 in PHN served to highlight its potential as an entirely novel approach for the treatment of neuropathic pain. We look forward to completing this study in a second key indication and to moving EMA401 further towards being an important treatment for broader chronic and neuropathic pain indications."

Professor Praveen Anand, Lead Investigator, said, "The pain associated with CIPN can be extremely debilitating and may affect the quality of life of patients for years, even when the cancer is in remission. Further, CIPN symptoms are a major reason for cancer treatments to be reduced or stopped early. The use of an AT2 receptor antagonist as a treatment for neuropathic pain is a highly innovative approach and, in addition to the strong Phase 2 results already seen by the company, my own group has undertaken non-clinical work which is highly compelling. EMA401 could represent a valuable new option for patients in an area where there is a clear need for new medicines."

As described above EMA401 is an AT2 receptor antagonist. The discovery that AT2 receptor antagonists offer an innovative approach to the treatment of neuropathic and inflammatory pain was originally made by Professor Maree Smith at The University of Queensland. Having acquired the technology, Spinifex has conducted a comprehensive pre-clinical and early clinical development program on EMA401. Spinifex continues to conduct research into the role of the AT2 receptor in nociceptive, inflammatory and neuropathic pain states and these fundamental studies support not only the EMA401 clinical program but also Spinifex's ongoing AT2 receptor antagonist drug discovery program.