FDA adviser casts doubts over diabetes drug approvals

The chairman of the FDA advisory panel which reviewed the safety of Avandia (rosiglitazone) has said that surrogate endpoints for approval of type 2 diabetes drugs should be abandoned.

Endocrinologist Dr Clifford J Rosen wrote in an online article in the New England Journal of Medicine (NEJM) that the percentage decrease in glycated haemoglobin should no longer be used as the regulatory standard for approval.

Dr Rosen wrote: "We urgently need to change the regulatory pathway for drugs for the treatment of type 2 diabetes to make clinical outcomes, not surrogates, the primary end points. The problem is that a change in glycosylated haemoglobin level is a relatively poor surrogate for cardiovascular outcomes in type 2 diabetes, accounting for only five to 15 per cent of the variation in ischemic risk."

GlaxoSmithKline (GSK), which manufactures Avandia, said that the original meta-analyses, which all confirmed an increased myocardial ischemic risk, were not scientifically rigorous, compared with the longitudinal study data they later showed the FDA in defence of the product.

Rosen counters that the meta-analyses, while far from perfect, would likely remain the best available evidence for the foreseeable future, adding: "none of the proposed analyses of the ongoing clinical trials of rosiglitazone is likely to define an absolute risk for myocardial ischemic events in patients with diabetes who are taking this drug."

Rosen said that data from two large observational studies conducted by Tricare, which used US Department of Defense data, and Wellpoint, which noted no appreciable signal of increased cardiovascular risk with either of the available thiazolidinediones (rosiglitazone and Takeda's pioglitazone), failed to demonstrate rosiglitazone safety.

Rosen warned that if the FDA failed to change from surrogate to clinical end points with regard to diabetes drugs, the agency and pharmaceutical industry would ìagain find ourselves in possession of a new wonder drug that is designed to treat a devastating chronic disease but that may do more harm than good."

Rosen disclosed that he received lecture fees from GSK and grant support from Eli Lilly, Merck & Co and Novartis.