Experimental diabetes medication – dapagliflozin – was found to raise the risk of developing breast and bladder cancers, researchers reported at the American Diabetes Association meeting, San Diego, California.

Drug companies, Bristol-Myers Squibb and Astra Zeneca are studying dapagliflozin as a potential treatment for type 2 diabetes. Although the drug’s method of action can operate on either diabetes type, and even other conditions resulting in hyperglycemia (high blood sugar), the clinical trials excluded those with Type 1 diabetes.

The two-year study demonstrated that dapagliflozin was effective, however when comparing those on Dapagliflozin plus metformin with a control group (just on metformin), there were:

  • 9 breast cancer cases in the dapagliflozin group and one case in the control group
  • 9 bladder cancer cases in the dapagliflozin group and one case in the control group

Elisabeth Svanberg, the vice president of development for Bristol-Myers, believes the difference in cancer risk is most likely “a numerical imbalance. Those occur in clinical trials.”

Svanberg explained that in animal studies, dapagliflozin did not increase cancer risk – in such preclinical trials the animals are given up to 100 times the human dose.

The presenters also reported that a higher percentage of those on dapagliflozin developed urinary tract infection compared to those in the control group.

SGLT2 (sodium-glucose transport proteins) is responsible for at least 90% of the glucose reabsorption in the kidney. Dapagliflozin blocks this transporter, resulting in blood glucose being eliminated through the urine.
In a communiqué, the two companies said that breast and bladder don’t express SGLT-2.

These cancer findings will definitely catch the attention of regulators when they come to discuss the drug’s submission for approval, experts say.

Dapagliflozin was estimated to bring Bristol-Myers Squib over $610 million in sales by 2015, experts at Thomson Pharma said.

Earlier on this year, the two companies filed for European and American approval of dapagliflozin. An FDA Advisory Panel meets on July 19th to review the application.

Dapagliflozin had other side effects, including upper respiratory tract infection, renal impairment, renal failure, back pain, diarrhea, headache, influenza, and nasopharyngitis.

Written by Christian Nordqvist