Shares of the French drugmaker are getting pummeled over at least three analyst reports identifying a leak about a study or studies that could go public soon. Their research suggests the data is related to a suspected or "theoretical" higher cancer risk associated with SNY's Lantus.

Sanofi-Aventis issued a statement defending the safety of Lantus, which it claims has been established in large clinical trials and in the monitoring of patients who've used it over the several years it's been on the market.

Lantus is the world's top-selling insulin with sales of around $3.5 billion last year and it's SNY's #2 product. So, that may explain why investors are in a panic. They're also selling shares of the two other insulin makers Novo Nordisk and Eli Lilly.

But they're buying shares of Amylin Pharmaceuticals, which along with Eli Lilly, makes the insulin-alternative drug Byetta. AMLN, LLY and Alkermes are also waiting for the FDA to decide on whether to approve a once-a-week version of Byetta. And NVO is expecting the agency to make a call soon on its similar one-a-day diabetes treatment, Victoza.

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David Kliff, a Type-2 diabetic who writes the "Diabetic Investor" newsletter, put out a strongly worded note to subscribers today. "Unfortunately for (Sanofi-Aventis)," he wrote, "they are about to be caught in a meat grinder as this premature release of the study's existence puts them on the defensive. Let's hope that before this story turns into another lynching as it did when the (GlaxoSmithKline) Avandia controversy came to light that cooler heads prevail." Avandia is the embattled diabetes pill whose sales got taken down by a controversial study identifying an increased heart risk with the drug.

Over the phone Kliff said a "really, really, really good source" told him there are multiple studies which will possibly be published in two medical journals. He doesn't know when. Kliff said his source claims the reports will show evidence of a link between Lantus and colon cancer, but he did not yet know the incidence rate. "Our sources have indicated that the data is compelling," Kliff later wrote in a follow-up email to subscribers.

Bernstein analyst Dr. Tim anderson put out a research note to clients today titled, "Lantus and the Possibility of Cancer-Real or NOT, Commercial Damage May Follow." And his colleague across the pond who covers European pharma, Jack Scannell, in a separate note says if the cancer risk (if, in fact, there is one) turns out to be specific to Lantus, that Novo Nordisk could be a beneficiary.A part of Bernstein owns at least one percent of SNY and NVO shares.

Kliff is calling on the medical journal(s) to release the study (studies) "immediately." I'd be shocked if the publication(s) would change the release date based on speculation circulating in the stock market. But if investors continue to punish shares of SNY and the analyst commentary reaches critical mass, you have to wonder if the company might, at least, try to influence the publishing schedule.

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