FDA May Halt Safety Study on GSK's Diabetes Drug Avandia

FDA May Halt Glaxo's Avandia Safety Study
FDA May Halt Glaxo's Avandia Safety Study

The U.S. Food and Drug Administration is considering halting a safety study on GlaxoSmithKline's (GSK) diabetes drug Avandia, The Wall Street Journal reported Sunday. Previous studies have linked Avandia to an increased risk of heart attacks. The implication is a serious threat to the continued sale of Avandia in the U.S.

Back in 2007, the New England Journal of Medicine published an article warning of Avandia's possible cardiovascular risk. The article triggered an investigation by Sens. Max Baucus (D-Mont.) and Chuck Grassley (R-Iowa), and the diabetes treatment has been in the spotlight ever since.

In February, the senators released a report on the drug which questioned its safety and challenged both regulators and the drugmaker's behavior in handling the matter. The senators suggested that GSK was aware of the heightened cardiac risk but chose not to disclose it. Their report also showed that the FDA itself estimated the drug caused approximately 83,000 excess heart attacks between 1999 and 2007.

The senators questioned the ethics of a study called TIDE the FDA had approved which compared Avandia to competing drug Actos from rival firm Takeda. In 2008, FDA officials called the clinical trial "unethical and exploitative" of patients. They were not alone: Many observers asked for the justification of giving a drug with a known cardiac risk when a safer alternative exists.

According to the The Wall Street Journal, FDA Commissioner Margaret Hamburg wrote a letter to Grassley in late March saying that the agency was reassessing the trial. Further, FDA Principal Deputy Commissioner Joshua Sharfstein told the Journal that the decision on the trial "cannot be de-linked from the agency's view of Avandia."

GSK: More Studies Are Needed

Dr. Hertzel Gerstein, the trial's principal investigator, however, sees no ethical issues with the trial, telling the Journal that medical societies including the American College of Cardiology have called for more data on both Actos and Avandia.

Mary Anne Rhyne, a media relations director at GSK, responded that "GSK welcomes additional scientific information that could help guide decisions around clinical trials and ultimately patient safety. ... The TIDE trial will provide the best evidence regarding the cardiovascular safety of Avandia and Actos." So far, Rhyne adds, two heart associations have found that "Insufficient data exist to support the choice of" one over the other.

"The TIDE trial design was directed by FDA and the study has been approved by Institutional Review Boards and Ethics Committees around the world. ... Patient safety in the TIDE trial is monitored by an independent data monitoring committee. ... To date, the TIDE IDMC has not expressed any concerns regarding the safety of participants in the study and has recommended that the study continue without modification." GSK will present data on Avandia at the FDA Advisory Committee meeting this summer.

Sales of Avandia topped $2.6 billion in 2006 but fell to $1.2 billion in 2009 after the FDA added a label warning regarding the elevated cardiac risk. If the FDA halts TIDE, it could also decide to halt U.S. Avandia sales. This would be devastating for GSK: Half of its Avandia sales are made in the U.S.