The decision by pharmaceutical giant Roche to cancel all clinical trials of its diabetes drug aleglitazar may dent confidence in a new class of treatment targeted at people's genetic susceptibility to diabetes.

Roche has listened to safety concerns raised by an independent clinical board and made the decision to halt all clinical development of the drug, which many hoped would reduce cardiovascular risks in people with diabetes.

Aleglitazar had reached the final stages of development and was being tested in the larger, late-stage clinical trials (phase three).

The drug company points to "safety signals and lack of efficacy," adding: "We are disappointed by this outcome as we hoped that aleglitazar would provide significant benefit for patients with type 2 diabetes who are at risk of cardiovascular disease."

The canned drug is a PPAR agonist - designed to target a type of peroxisome proliferator activated receptor (PPAR).

Aleglitazar would have broken new ground in a novel class of diabetes drugs, and it was genetic research that led to the hopes for this. Mutations in the PPAR gamma receptor were found to put people at higher risk of diabetes - so blocking this with drugs has been a new avenue in the fight against type 2 diabetes.

Knock-on effect for other drugs

This news is not bad just for the new PPAR drug - it could have a knock-on effect for another diabetes drug already in widespread clinical use, rosiglitazone (Avandia).

As with aleglitazar, the mode of action for Avandia also involves PPAR gamma. While the drug has succeeded in reaching the market for diabetes patients, it too has had safety issues. The US Food and Drug Administration (FDA) eased restrictions on the drug in June, but there have been concerns some people taking it could suffer a heart attack.

The new findings from Roche's research on aleglitazar may, the New York Times suggests, play into the hands of Avandia critics, although the safety problems for Roche's drug may not be related. A spokesman for Roche told the Times the safety problems found in the aleglitazar research included a higher risk of bone fractures, kidney problems and heart failure.

Hal Barron, Roche's chief medical officer and head of its global product development, says people with diabetes involved in the clinical developments will not be left without treatment:

"The safety of patients is our first priority. Roche is working with investigators to support the management of patients and their transition from aleglitazar treatment to other blood sugar control therapies."

As well as GlaxoSmithKline's Avandia, another diabetes drug already on the market also targets PPAR gamma, Takeda's pioglitazone (Actos).

Written by Markus MacGill