乌鸦传媒

Despite FDA and EMA warnings to the contrary, a European study has found no link between pioglitazone (Actos) and bladder cancer.

In a large observational study, there was no increased risk of bladder cancer per 100 days of cumulative exposure, , of the University of Dundee in Scotland, and colleagues .

"To fully resolve this controversy, future analyses are needed, involving longer follow-up of exposed persons and using methods to minimize allocation bias," they wrote.

In August, Actos drugmaker Takeda released initial data from its 10-year analysis of the potential link between its drug and bladder cancer, finding no increased risk, either with any exposure or with a long duration of use.

That result was in contrast to an earlier 5-year interim analysis that showed a significantly higher incidence of bladder cancer in long-term pioglitazone users.

Both the FDA and the EMA have warned against the use of pioglitazone in patients with bladder cancer, and urge cautious use in patients who've previously had bladder cancer. The drug was also pulled from the market in France and Germany.

Calhoun and colleagues wrote that several studies have also shown no link between pioglitazone and bladder cancer. But a potential mechanistic link exists. Pioglitazone and a sister drug rosiglitazone (Avandia) are peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonists -- and this nuclear transcription factor is overexpressed in bladder tumors.

The researchers looked at data from about 1 million patients from British Columbia, Finland, Manchester, Rotterdam, Scotland, and the U.K. Clinical Practice Research Datalink, finding a total of 3,248 cases of bladder cancer.

They found no evidence of an association between bladder cancer and 100 days of cumulative exposure to pioglitazone in either men or women:

• Men: RR 1.01, 95% CI 0.97 to 1.06
• Women: RR 1.04, 95% CI 0.97 to 1.11

Nor was there any association between rosiglitazone and bladder cancer in either gender, they reported.

In a statement, the researchers said their analysis "is the only one to use identical methodology across international centers involving a large number of diabetic patients," but they still called for further research to "fully resolve this controversy."

Comment