By Susan Heavey
WASHINGTON (Reuters) - An major trial of Avandia puts patients at risk and should be stopped, a U.S. advocacy group said on Tuesday, calling on regulators to immediately halt the global study of the controversial GlaxoSmithKline Plc diabetes drug.
The U.S. Food and Drug Administration asked the company in 2007 to conduct the trial to compare the drug's long-term heart effects with those of rival Actos by Takeda Pharmaceutical Co Ltd after other evidence suggested Avandia increased the risk of heart attack and chest pain.
Since then, even more data have linked Glaxo's drug to greater heart risks, the science-based consumer advocacy group Public Citizen said. Continuing to enroll patients in the trial -- which aims to study 16,000 worldwide through 2015 -- unnecessarily puts people with diabetes at risk, it added.
The trial, known as TIDE, is "exposing thousands of high-risk patients with diabetes to a drug with an unfavorable safety profile and no clinical advantage over its comparator," Public Citizen's Health Research Group Director Sidney Wolfe and Canadian researcher David Juurlink wrote in a letter to FDA Commissioner Margaret Hamburg.
"A wealth of data now suggests" that Avandia carries greater risks than Actos, the researchers said. Patients are also not adequately informed about the safety differences between the two medicines when deciding whether to participate in the trial, they added.
But FDA officials, who have said they are already taking a closer look at Avandia, are not likely to act so quickly.
"The TIDE trial will be discussed at a joint advisory committee in July," FDA spokeswoman Karen Riley said in an emailed statement. "Based on expert input and our own analysis, FDA will reassess the rationale for the TIDE trial, review the trial's enrollment and respond accordingly."
The agency has said it is reviewing all available data, but has yet to draw any new conclusions about Avandia, also known as rosiglitazone.
Glaxo spokeswoman Mary Anne Rhyne backed Avandia in an e-mailed statement, calling it an "important treatment option for physicians, who often need to prescribe two or three medicines to help their patients maintain their blood sugar levels." She added it has been shown to control blood sugar for up to five years.
The FDA's outside advisory panel noted the drug's heart risks at a 2007 meeting, but overwhelmingly recommended keeping it on the U.S. market, even though an agency staff scientist urged its removal.
The FDA later called for a "black box" warning on Avandia's label after a review of 42 studies associated the drug with an increased risk of heart problems compared with a placebo, although it called the overall data "inconclusive."
Another FDA advisory panel is scheduled to meet publicly in July to review Avandia's safety.
In its letter to the FDA, Public Citizen urged the agency to act before the summer meeting, adding U.S. and European diabetes associations have already advised against using the drug.
According to the group's letter, Glaxo's TIDE trial involves 137 sites in 14 countries, including recently added locations in developing countries such as Latvia and Pakistan.
Glaxo's Rhyne said many of the trial sites are just getting started and an independent data committee continues to monitor the trial's safety.
Both Glaxo and the FDA noted other groups, including the American Heart Association, have said more study about the drug's risk are needed.
In July, the Institute of Medicine is also expected to release its report on clinical trial ethics and informed consent issues as part of its ongoing study of drug safety issues, prompted in part over Avandia.
The diabetes medicine is no longer a top product for the British drugmaker as sales have fallen and lawsuits emerge.
The drug's sales have dropped by more than half since concerns over its heart risks emerged, from roughly $3 billion in 2006 to $1.2 billion in 2009. Sources have also said Glaxo agreed to pay out claims in roughly 700 lawsuits brought by people who allege the drug caused heart attacks.
Some U.S. lawmakers have also called for the FDA to pull Avandia from the market until the drug's safety and effectiveness can be firmly established.
Glaxo shares were at $36.67, up 38 cents or just over 1 percent, in afternoon trading.
(Reporting by Susan Heavey; editing by Lisa Von Ahn and Andre Grenon)