Sanofi-Aventis to finally probe link between cancer and insulin use

Sanofi-Aventis (SNY), the maker of diabetes drug Lantus, said Tuesday it will launch a massive research program to probe a possible link between cancer and insulin. Such a link has been the subject of extensive debate in the scientific and medical communities.

The most recent uproar was in June when European studies published in Diabetologica suggested just that -- an association between cancer and Sanofi-Aventis' diabetes treatment Lantus. But the results were inconclusive and Sanofi said it "stands behind the safety of Lantus."

For Sanofi, at the time, this was quite a blow. Though the company has been in the news lately, mostly for its H1N1 swine flu vaccine and the HIV vaccine study, Lantus sales, which rose 28 percent last year, reaching 2.45 billion euros, represent 9.9 percent of its net pharmaceutical revenue. That's no small order. Lantus is the world's biggest-selling insulin.

The European study covered registries with 301,136 insulin-treated patients in Germany, Sweden and Britain, and suggested Lantus might increase the risk of cancer, though the data was not conclusive. The smallest study found no signs of a link. Breast cancer was particularly of note, but the absolute risk was small.

Scientists explain that there is a theoretical link between some insulin to cancer because in addition to lowering glucose, the drug causes cell proliferation. But studies and research, including the recent one from June, found little evidence and cautioned about limitations as patients taking Lantus were generally older, more overweight and had higher blood pressure than the general population -- all possible contributing factors to cancer risk.

The company in June promised to investigate further and finally Tuesday announced plans for a "research that will contribute to the scientific resolution of the debate over insulin safety, including insulin analogs and Lantus."

Sanofi's research program "is designed to generate more information on whether there is any association between cancer and insulin use and to assess if there is any difference in risk between insulin glargine (Lantus) and other insulins." Sanofi added that it is "committed to exploring this matter in depth."

Attempts to reach the company were not immediately answered, but in the statement, Sanofi said its "scientific plan will encompass state-of-the-art pre-clinical and clinical programs involving human insulin and insulin glargine [...] designed and implemented with the support of international experts and institutions, that will be conducted across Europe and North America."

Reuters reports that since the recent brouhaha in June, prescription data showed demand for the long-acting insulin was holding up. It helped that diabetes associations in the U.S. and Europe, as well as regulators, have backed the product.

The problem, everybody agrees, is to properly weigh risks and benefits. Even the researchers who found the possible link between cancer and insulin in June were worried about "causing unnecessary alarm." Meanwhile, diabetes experts recommend patients should not stop treatment.

Diabetes is a chronic, widespread condition in which the body does not produce or properly use insulin, the hormone needed to transport glucose (sugar) from the blood into the cells of the body for energy. According to Sanofi, more than 230 million people worldwide have diabetes and this number is expected to rise to a staggering 350 million within 20 years. It is estimated that nearly 24 million Americans have diabetes, including an estimated 5.7 million who remain undiagnosed.

On Wednesday, Sanofi also published two more studies to further prove the safety of Lantus compared to peers -- one compared Lantus and detemir, the other compared Lantus and NPH insulin. Both studies showed Lantus having the better results.

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