UPDATE 4-Amylin reports four additional deaths with Byetta

(Adds Amylin CEO, analyst comment, updates shares)

By Toni Clarke

BOSTON, Aug 26 (Reuters) - Amylin Pharmaceuticals Inc (AMLN.O) said there have been four deaths among patients with pancreatitis who took its diabetes drug, Byetta, in addition to two deaths reported last week by U.S. regulators.

The company said the four cases had not been captured in the report last week by the Food and Drug Administration, which said it had received six reports of patients who developed hemorrhagic or necrotizing pancreatitis that required hospitalization. Two of those patients died.

Amylin shares, after closing 2 percent lower at $27.24 on Nasdaq, fell 13 percent in extended trading after the four additional deaths were announced, but they later pared those losses to about 8 percent down.

The additional four cases did not involve patients with the necrotizing form of the disease, which affects 15 percent to 20 percent of patients with inflammation of the pancreas, said Amylin, which makes Byetta with partner Eli Lilly & Co (LLY.N).

Orville Kolterman, Amylin's senior vice president of research and development, said in an interview the four deaths were not considered related to the pancreatitis.

"It appears the FDA focused on necrotizing and hemorrhagic pancreatitis, whereas these other four cases only had pancreatitis in their history," Kolterman said.

In the necrotizing form of pancreatitis, enzymes digest the pancreas, which can lead to a hemorrhage.

Even so, he said the company was reporting them "in the interests of transparency."

Canaccord Adams analyst Adam Cutler said the company was trying to make a case for why pancreatitis is unlikely to be caused by Byetta, "yet the FDA is concerned."

Byetta, known chemically as exenatide, was launched in mid-2005. Amylin and Lilly hope to file for U.S. approval of a longer-acting version of the drug that needs to be taken just once a week by mid-2009.

Given the FDA's concerns, Cutler said: "I'm wondering whether they will have to do longer, larger, safety trials" of the version that is designed to stay in the body for a full week. Such a decision could significantly delay the drug reaching the market.

The prescribing information for Byetta was updated to include the risk of pancreatitis last October. The FDA cited 30 reports of pancreatitis in Byetta patients and said the drug was suspected in some cases. Amylin alerted doctors.

One of the four deaths reported on Tuesday was known at that time, Kolterman said.

Amylin CEO Daniel Bradbury told analysts on a conference call that the company has since received positive feedback from doctors.