New Diabetes Drug May Increase Risk of Breast, Bladder Cancer: FDA

A new diabetes drug being developed by Bristol-Myers Squibb and AstraZeneca could be derailed by increased risks of bladder cancer and breast cancer. 

An FDA advisory committee will meet this week to review data from clinical trials of the experimental diabetes drug dapagliflozin, which have revealed an unusually high number of users who developed bladder cancer or breast cancer.

The panel of outside experts will likely issue a recommendation on the new drug application for dapagliflozin by October, which could be endangered by the high rate of cancer. Although the FDA is not required to follow the recommendations of it’s advisory committees, the agency usually does.

Bristol-Myers Squibb and AstraZeneca have maintained that there is no evidence linking the diabetes drug to cancer, and suggest that the numbers could be a statistical hiccup.

Out of 5,478 patients taking part in dapagliflozin clinical trials, nine were diagnosed with breast cancer and nine were diagnosed with bladder cancer, according to FDA briefing material (pdf) submitted to the advisory committee. That compares to one case of bladder and breast cancer each among the 3,156 control subjects taking part in the two year study.

Because of the brief duration of the study, Bristol-Myers Squib and AstraZeneca officials said it is very likely that the subjects had cancer before they took part in the clinical trials. However, they said there is a possibility that the experimental drug sped up the cancer’s development. Company officials noted that there were no increases in bladder or breast cancer during clinical trials on mice.

The potential bladder and breast cancer side effects with the diabetes drug is just one of several problems the FDA has found. The agency also reports that the drug is not as effective on diabetes patients with moderate or severely impaired kidney functions, and the drug also appears to increase the risk of urinary infections and genital infections. There was also at least one case of severe liver injury reported.

The cancer concerns are particularly noteworthy because of increasing concern in recent months over the potential risk of bladder cancer with Actos, the leading type 2 diabetes treatment in the world. Last month, an Actos recall was issued in France and Germany after studies showed that the medication may increase the risk of bladder cancer. However, the drug remains widely used in the United States, where the FDA has issued an Actos bladder cancer warning and is continuing to review the safety of the drug.

Actos (pioglitazone) was approved by the FDA to treat Type 2 Diabetes in July, 1999. It is Takeda Pharmaceuticals’ best-selling drug, with sales of $3.4 billion last year. A number of former users of the diabetes drug are now considering potential Actos bladder cancer lawsuits, alleging that the drug makers failed to adequately research the medication or warn about the cancer risk before it was released to the public.