Amylin shares plunge 26% on possible Byetta LAR US approval delay

Shares in Amylin Pharmaceuticals plunged 25.8%, to close at $7.94 on November 4, after the US drugmaker announced that the approval of its lead product candidate, the once-weekly diabetes injection exenatide LAR, could be delayed. The US Food and Drug Administration rejected data from a study aiming to demonstrate bioequivalence between batches of the long-acting GLP1 drug made by development partner Alkermes and those from Amylin, raising the possibility that further trials might be necessary. On the day of the news, shares in Alkermes also suffered, dropping 9.8% to $9.11. Eli Lilly is also partnered with Amylin on the drug and currently helps to market the twice-daily formulation, Byetta (exenatide). Shares in the US drug major rose 3.4% to $35.15. BMO Capital Markets analyst Robert Hazlett expects a filing in either late 2010 or early 2011 and noted that a delay narrows the advantage that the drug has on competitors like Novo Nordisk's once-daily GLP1 drug liraglutide.