On December 6, members of the Peripheral and Central Nervous System Drug Advisory Committee unanimously voted to recommend FDA approval for tetrabenazine. This is a huge step forward because the FDA almost always follows the recommendations from it's advisory committees.
The First Meeting: Following the first meeting with the FDA in March of 2006, Prestwick Pharmaceuticals received a Letter of Approval. This meant that the company was required to address specific FDA concerns about the drug. In addition to safety concerns, there were questions about why chorea benefit in the HSG clinical trial did not translate into improvement in levels of function (as measured by the UHDRS, the standard research scale).
The Second Meeting: Prestwick presented safety data that convinced the committee that benefits outweighed the risks. The question about why improved chorea scores, with clear benefits in functionality reported by patients, did not result in improved UHDRS function scores remains unanswered. I believe the most likely explanation for this problem is that UHDRS is not a good measure of many important aspects of function in Huntington's.
Most Important: The room was packed with HD patients and their families, some of whom had traveled long distances. There is no question that patient and family letters and testimony were immensely important for this favorable decision. One after another, they gave poignant and convincing testimony about the hardships caused by their chorea, and how tetrabenazine made a difference in their lives. Nancy Wexler from Hereditary Disease Foundation and Barbara Boyle from National HDSA added strong and eloquent support.
At HDDW we are so thankful to all who supported approval of tetrabenazine. We thank Prestwick for working diligently to get this drug to HD people, and for a planned patient assistance program to cover the costs for those without insurance. And we thank all clinical investigators, and HD patients and families for the hard work of clinical trials.
We hope that the FDA will now make timely decisions about mechanisms for physician education and long term safey evaluations, so this drug can be made available to the patients who need it.