Approvals of type 2 diabetes drugs tested in cardiovascular outcome trials: A tripartite comparison

In 2008, the US Food and Drug Administration (FDA) issued a guidance requiring that cardiovascular outcome trials (CVOTs) be conducted for newer hypoglycaemic drugs for type 2 diabetes (T2D). We aimed to examine the decisions by 3 regulatory authorities in response to identical CVOT data.

We surveyed ClinicalTrials.gov to identify CVOTs and examined the revision histories of drug labels in databases from the FDA, the European Medicines Agency, and the Pharmaceuticals and Medical Devices Agency in Japan.

We selected 14 drugs and corresponding CVOTs, 12 of which were conducted as postmarketing trials. In the USA and the EU, the pre-CVOT indication on all 14 labels was "improvement in glycaemic control". Six drugs showed significant cardiovascular risk reduction, which led to an additional indication regarding reduction of cardiovascular adverse events in the USA, and a change to the EU indication to specify treatment of adults with T2D. The initial indication in Japan, T2D, remained unchanged. Regarding safety, significant increases in heart failure were observed only in the saxagliptin trial. A warning was added to the saxagliptin labels in the EU and Japan, whereas the FDA required a class effect warning to be added to the labels of all 4 dipeptidyl peptidase-4 inhibitors.

Regulatory authorities using identical trial data made substantially different decisions regarding both safety and efficacy of hypoglycaemic drugs. The differences in initial indication wording between Japan and the other authorities suggest that trial data and T2D are interpreted differently in these regions.