US FDA warns of bladder and breast cancer risk for Bristol-Myers/AstraZeneca diabetes drug dapagliflozin ahead of advisory

Ahead of an advisory panel meeting scheduled for tomorrow (July 19) to discuss US drug major Bristol-Myers Squibb (NYSE; BMY) and Anglo-Swedish AstraZeneca’s (LSE: AZN) New Drug Application for their diabetes drug candidate dapagliflozin, the US Food and Drug Administration issued briefing papers suggesting that, while it is seen to be effective, the drug may increase the risk of bladder and breast cancer.

“Several unexpected safety issues identified in this clinical development program were of sufficient concern to FDA to merit discussion of their impact on the overall benefit-risk consideration of dapagliflozin,” said FDA reviewers. The FDA also said that the effectiveness of dapagliflozin declines in patients with kidney impairment, which the agency said "can impact a sizable portion of patients" with diabetes.

Although some analysts think an outside panel of experts will still recommend dapagliflozin’s approval, the agency would probably call for a strong warning about the drug's risks, reports Reuters. That may cause physicians to use caution until long-term safety data is available - and could cut into AstraZeneca and Bristol-Myers Squibb's bottom line. Dapagliflozin is not viewed as a “blockbuster,” with analysts predicting that, if the drug gains approval, it will reach peak sales of just around $630 million by 2015.