FDA Requires Additional Byetta Safety Data Before Considering Long-Acting Version

The FDA has rejected data submitted by Amylin Pharmaceuticals for a longer-acting Byetta, which will likely delay the new version of their diabetes drug. This is another blow to Amylin, which has seen their stock price plummet this year after Byetta was linked to fatal pancreatitis cases in August.

Byetta (exenatide) is a synthetic hormone sold in a pre-filled pen by Amylin Pharmaceuticals Inc. and Eli Lilly & Co.

The type 2 diabetes drug, which is currently administered twice a day as a subcutaneous injection, lowers blood glucose levels by stimulating insulin secretion from pancreatitis cells.

Byetta has been used by over 700,000 people in the United States since it was first approved by the FDA in 2005. Last year, the drug generated sales of about $636 million.

Amylin Pharmaceutical’s stock price began falling sharply in August, when concerns emerged about potentially fatal Byetta pen pancreatitis side effects.

On August 18, 2008, the FDA informed doctors that they have received reports of at least six cases of severe forms of pancreatitis, known as necrotizing pancreatitis and hemorrhagic pancreatitis, associated with Byetta, including two death. Eli Lilly and Amylin later disclosed that they were aware of at least 4 additional Byetta pancreatitis deaths, though they denied that there was any causal connection between Byetta and pancreatitis.

Investors have been concerned that the potential Byetta pancreatitis risks may delay the FDA approval of a new longer-acting once-weekly version of Byetta, which Amylin had been planning to apply for by June 2009.

This week, Amylin disclosed in a filing with the Securities and Exchange Commission that the FDA was not satisfied with data they provided prior to seeking approval for the once-weekly version of the drug, known as Byetta LAR.

The FDA has indicated that additional Byetta safety data must be presented to show that Amylin’s new Ohio facility can make a product that adequately matches a Byetta LAR prototype made by the drug makers’ partner, Alkermes, Inc. in Cambridge, Massachusetts. Data from studies at the two manufacturing plants have not met the FDA requirements of comparability.

It is possible that a new clinical study and submission of a new drug application may now be required. As a result, some analysts are now suggesting that the Byetta LAR filing with the FDA could be delayed until late 2010 or early 2011, with approval and sales potentially not occurring until 2012.