A new study conducted by Canadian researchers has found that users of the type 2 diabetes drug, Actos (pioglitazone), may face a higher risk of developing bladder cancer than first thought. The study, published in the British Medical Journal, found that taking Actos for two years doubles the likelihood that a patient will get bladder cancer.
The new study, conducted by researchers from McGill University and Montreal’s Jewish General Hospital, examined data on nearly 116,000 people treated for diabetes from 1988 to 2009 who were listed in the U.K.’s General Practice Research Database. The 376 people in the study who developed bladder cancer were compared to nearly 6,700 people who didn’t get the disease. The patients with bladder cancer were divided into those who took Actos, those who took Avandia, those who had taken both, and those who had taken neither.
The study found that patients who had taken Actos had an 83 percent increase in the relative risk for bladder cancer. The risk increased for patients who took Actos longer, and who were exposed to the highest cumulative dose. For example, among patients who had taken Actos for two years or longer, who would have consumed 28,000 milligrams or more over that time, the relative risk of bladder cancer grew to 88 percent.
Avandia was not associated with an increased risk of bladder cancer. However, it s been linked to increased heart risks, and Avandia sales have been severely restricted in the U.S.
Reaction to Actos Bladder Cancer Study
Dr. David Juurlink, head of the division of clinical pharmacology at the University of Toronto, told the Vancouver Sun that the study’s findings suggest the link between Actos and bladder cancer is real
“I think this is probably the single best study of this issue, and I think (it) leaves little doubt that pioglitazone is a potential risk factor for bladder cancer,” said Juurlink, who was not involved in the study.
“But from a clinical perspective, when you have a drug that has cardiovascular toxicities and appears to increase the risk of a fairly serious cancer, one would have to argue that the drug’s benefits are compelling to justify use in the face of those risks. And that’s just not the case here,” he added.
Actos Bladder Cancer Background
The Canadian study is just the latest to link Actos to an increased risk of bladder cancer. On June 15, 2011, the U.S. Food & Drug Administration (FDA) issued a safety communication stating that use of Actos for more than one year may be associated with an increased risk of bladder cancer. The June safety communication was a follow-up to one the agency issued in September 2010 after preliminary data from a study conducted by Kaiser Permanente demonstrated that the risk of bladder cancer rises with increasing dose and duration of Actos use, reaching statistical significance after 24 months. That same month, the French and German governments decided to suspend sales of Actos in those countries after a separate study commissioned by French regulators demonstrated an increased risk of bladder cancer associated with Actos in people who took it the longest and at the highest cumulative dose. On July 12, 2011, Takeda Pharmaceuticals officially recalled Actos from the market in France.
Since the FDA issued its Actos bladder cancer warning, Takeda Pharmaceuticals has been named in a number of U.S. lawsuits that accuse it of concealing knowledge of Actos’ bladder cancer risks and failing to adequately warn consumer and health care providers about its association with bladder cancer. Late last year, all federally filed Actos bladder cancer lawsuits were ordered transferred to the U.S. District Court, Western District of Louisiana, by the U.S. Judicial Panel on Multidistrict Litigation in December. As we’ve reported previously, some legal experts estimate that Takeda could face as many as 10,000 Actos bladder cancer lawsuits in the U.S.