UK company Alizyme presented Phase IIb trial data on its obesity drug cetilistat which supported its efficacy in achieving weight loss and its tolerability.

Cetilistat is a lipase inhibitor, working in a similar way to Roche’s already-marketed obesity drug Xenical (orlistat). The Phase IIb study found that in obese diabetics, cetilistat was as effective as Xenical in achieving weight loss and controlling glycated haemoglobin levels - a marker for glucose control used to measure the efficacy of antidiabetic drugs - but appeared to be better tolerated.

Xenical was launched onto the market shortly after the fen/phen group of centrally-acting weight loss drugs were taken off the market on safety grounds, and had been expected to be a big earner for Roche. But the product has some unpleasant gastrointestinal side effects that have limited its appeal and held it back from achieving blockbuster status – though it has still managed to garner revenues of around 600 million Swiss francs a year.

Fewer patients discontinued treatment with cetilistat than with Xenical or placebo, and Alizyme’s drug was associated with significantly fewer gastrointestinal side effects.

Dr Richard Palmer, Alizyme’s chief executive, said the results would allow the company to start planning Phase III trials of cetilistat and would help its search for a marketing partner for the product.

Xenical has seen a slight decline in sales over the last couple of years, but this is expected to be mitigated by having its label expanded to include a benefit on glucose intolerance, as well as approval for adolescent obesity.

It is also in the frame for a switch to over-the-counter status in the USA, where a non-prescription version would be sold by GlaxoSmithKline. A US Food and Drug Administration (FDA) advisory panel is due to consider the switch next month.