US FDA exec questions safety of Lilly and Amylin's Byetta, saying it may pose cancer risk

Clinical data on intravenous dosing and a once-weekly version of drug major Eli Lilly and Amylin's type 2 diabetes therapy Byetta (exenatide) - which already generates turnover of nearly $700 million a year in its current indications - 'seem to give a similar signal' as cancers seen in rodent studies of Danish drugmaker Novo Nordisk competitor drug Victoza (liraglutide), according to Curtis Rosebraugh, head of the US Food and Drug Administration's Office of Drug Evaluation II, in a January 25 memo that was posted on the agency's web site last Friday and reported by the Bloomberg news service.

The FDA recently delayed approval of extended-release exenatide, which is planned to be marketed under the trade name Bydureon, primarily raising questions related to the finalization of the product labeling with accompanying Risk Evaluation and Mitigation Strategy (REMS) and clarification of existing manufacturing processes (The Pharma Letter March 16).

Victoza was approved earlier this year after 10 months of delay because of safety concerns. In animal studies, Victoza caused tumors of the thyroid gland in rats and mice. Some of these tumors were cancers, which were significantly increased in rats who received excessive doses that were 8-times higher than what humans would receive. It is not known if Victoza could cause thyroid tumors or a very rare type of thyroid cancer called medullary thyroid cancer in people (TPL January 26).