The majority of advisers on a federal health panel say a first-of-a-kind diabetes drug that uses a new method to reduce blood sugar shouldn't be approved for U.S. patients after higher rates of bladder and breast cancer were reported among patients in company trials.
A Food and Drug Administration panel voted 9-6 against the experimental diabetes pill from Bristol-Myers Squibb and AstraZeneca, while expressing hope that the drug might ultimately be approved if safety questions are resolved. The vote is only a recommendation for FDA, which will make a final decision on the drug before the end of October.
Dapagliflozin is a once-a-day pill designed to help diabetics eliminate excess sugar in their urine. That differs from older drugs that decrease the amount of sugar absorbed from food and stored in the liver. The companies have touted it as the first in a new class of drugs to address the nation's growing diabetes epidemic, which affects more than 25 million people.
Nearly all the panelists praised the drug's innovative approach to lowering blood glucose, but a majority said they wanted more information on a host of safety concerns, including cancer, infections and possible liver toxicity.
"It was the closest of calls, I changed my mind about four times in the last 10 seconds," said Dr. Erica Brittain, a biostatistician with the National Institutes of Health, who voted against the drug. "The level of evidence about the cancer is fairly weak, but it's just that the uncertainty is still there."
The companies reported nine bladder cancers among over 5,000 people taking the drug in company studies, compared with none among those taking a dummy pill. There were nine cases of breast cancer among 2,100 women taking the drug, compared with one in the control group. While the company studies were not designed to measure cancer risk, panelists noted that the incidence of cancers was four to five times higher than expected in the population.
Panelists said they would like more data on cancer rates in patients, but acknowledged that a definitive study of the risk probably would not be feasible, since it would mean enrolling more than 30,000 patients for several years.
"There are some things we can't learn from clinical trials," said Dr. Ed Hendricks of the Center for Weight Management in Sacramento, Calif., who voted to approve the drug. "Sometimes to introduce new, innovative medical therapies we have to make decisions with a certain amount of uncertainty."
The drug was also associated with bladder and urinary tract infections, due to increased sugar eliminated in patients' urine, and the companies suggested this factor may have led to higher detection of bladder cancers. That rationale did not explain why bladder cancers reported were limited to men, since urinary tract infections are more common in women. Panelists also complained about the small number of elderly and African-American patients enrolled in company studies. People in those groups are more predisposed to have diabetes.
People with type 2 diabetes are unable to properly break down carbohydrates, either because their bodies do not produce enough insulin or have become resistant to the hormone, which controls blood sugar levels. These patients are at higher risk for heart attacks, kidney problems, blindness and other serious complications. Diabetics often require multiple drugs with different mechanisms of action to control their blood sugar levels.
New York-based Bristol-Myers Squibb Co. and London-based AstraZeneca PLC already co-market the diabetes drug Onglyza, which increases insulin production while reducing glucose production.
Shares of Bristol-Myers Squibb fell 21 cents to $28.60 in afterhours trading Tuesday.