Cypress Bioscience Inc. announced data from its Phase II Fibromyalgia Syndrome (FMS) study demonstrating that treatment with milnacipran was equally effective in reducing pain for both depressed and non-depressed patients. However, the response rate in patients treated with placebo was considerably lower in non-depressed patients than in those patients who met criteria for major depression at the time of entry into the trial. The therapeutic benefits of milnacipran observed are a result of its analgesic (pain elimination) properties, rather than secondary to its ability to improve mood. Milnacipran is being evaluated in a Phase III programme for the treatment of FMS, a complex widespread pain syndrome that affects an estimated 5-11 million Americans.
Milnacipran is a novel dual-acting agent that acts on two key neurotransmitters in the human body, norepinephrine and serotonin, which are involved with the central modulation and processing of chronic pain. Data from the Phase II study provides evidence that milnacipran may be an effective treatment for the pain and other symptoms associated with FMS such as fatigue, sleep disturbances, and depression. Milnacipran is approved for non-pain indications in 22 countries, and has a well-established safety profile from its use by over 2,000,000 patients during more than six years of commercial availability in Europe, South America, and Asia.
"The patients in the Phase II study who were treated with milnacipran exhibited superior pain relief compared to the placebo-treated patients," noted Jay D Kranzler, MD, PhD, chairman of the board and CEO of Cypress. "The fact that milnacipran worked equally well for non-depressed and depressed patients, whereas the non-depressed patients had a lower placebo response rate than the depressed group, is important to our understanding of FMS. It suggests that the pain experienced is not directly related to their mood. The effective treatment of FMS-related pain is therefore distinct from the treatment of the patients' depression."
The Phase II study was a 12-week, randomized, double-blind, placebo-controlled trial that enrolled 125 patients at several medical centres in the US. Participants used an electronic diary to record pain, fatigue, sleep, and quality of life information frequently, on an out-patient basis. The patients' self-reporting of pain via the electronic diary was supplemented with traditional pain and quality of life inventories during monthly clinic visits. The analgesic effect of milnacipran appeared to be independent of the patients' depression status at baseline, as indicated by the similarity of pain scores between depressed and non-depressed patients.
There is no US FDA approved product for treating FMS, which affects 2-4 per cent of the US population, and is the second most commonly diagnosed condition in rheumatology clinics in the US after osteoarthritis. Cypress' current clinical program constitutes the first Phase III studies ever conducted in the US to assess a potential treatment for these patients.