Cyberonics (CYBX) recently reported results from a dosing study (D-21) that was conducted as a condition for gaining US Food and Drug Administration (FDA) approval, for Vagus Nerve Stimulation (VNS) Therapy. This therapy was approved in July 2005 for patients suffering from chronic and recurrent treatment-resistant depression. It is also approved for the treatment of refractory epilepsy.
Results from the dosing study showed a sustained, consistent and clinically meaningful reduction in depression symptoms across all treatment groups. Adjunctive VNS Therapy was found to provide improving efficacy over time at all dosage levels. The study found that long-term (50 weeks) VNS Therapy improved symptoms of depression from 32.4% to 42.0%. Meanwhile, response rates ranged from 26.7% to 53.3%; and remission rates ranged from 14.6% and 22.5%.
About 47.8% of patients achieved response, which was defined as 50% or greater decline in depression symptoms. About 21.1% achieved remission, which was the absence of depression symptoms. The sustainability of response was high, as 80.6% of those who achieved response after 22 weeks were able to maintain that status even after 50 weeks.
The dosing study evaluated the safety and effectiveness of adjunctive VNS therapy, offered at three different stimulation levels (low, medium and high), and administered to 331 adult patients at 29 centers. Patients were randomized to receive a certain stimulation level during the acute phase of 22 weeks. The study permitted patients to receive higher levels of stimulation after 22 weeks. Patients were followed for 54 weeks.
The study was conducted with patients suffering from very serious levels of chronic and recurrent treatment-resistant depression who had been unresponsive, thus far, to several antidepressant treatments. The results of this study will enable Cyberonics to further explore its reimbursement options. In fiscal 2009, total revenues of Cyberonics increased about 19% year over year to $143.6 million.
Cyberonics faces strong competition from players like Medtronic (MDT) and St. Jude Medical (STJ). We currently have a Neutral rating on Cyberonics.
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