Nature Medicine | Spoonful of Medicine

Cancer concerns emerge about experimental diabetes drug ahead of FDA evaluation

Ahead of a US Food and Drug Administration advisory committee meeting next month to evaluate the experimental diabetes drug dapagliflozin, its developers, Bristol-Myers Squibb and AstraZeneca, released positive two-year trial data over the weekend showing that the medication lowered blood sugar levels more than other diabetes drugs. But people on dapagliflozin also had higher rates of certain cancers and infections, which could factor into regulatory decisions at the 19 July panel meeting.

Dapagliflozin is one of a new class of diabetes drugs called SGLT-2 inhibitors. Unlike most approved agents, which work to modulate the insulin pathway, SGLT-2 inhibitors work independently of insulin to simply increase the amount of glucose excreted in urine.

As discussed in a news story this month in Nature Medicine, dapagliflozin is the first such drug to go before the FDA. Analysts have forecast annual sales for the drug in excess of $600 million within a few years. But the new safety data, presented at the American Diabetes Association meeting in San Diego, could give investors pause.

The companies reported that genital and urinary-tract infections occurred in around 14% of people treated with dapagliflozin, compared with only around 5% of those taking the insulin-modulating drug metformin. Among the 5,500 or so individuals who took the new drug, 18 also developed breast or bladder cancer, compared to only two cases in the 3,000-plus people in the control arm.

The cancer figures might look alarming. But statistically, the overall numbers are so low as to possibly make little difference in the eyes of the FDA. Smoothing the numbers over the dozens of studies to date, 1.4% of people taking dapagliflozin and 1.3% of controls developed some type of cancer with no signs of tumors in animal studies, Reuters reports. “Importantly, overall cancers are not imbalanced,” Elisabeth Bjork, vice president of development for dapagliflozin at AstraZeneca, told the wire service.


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