Another set of late stage data for GlaxoSmithKline's experimental diabetes drug albiglutide has failed to excite analysts.

While the drug was shown to be effective at lowering blood sugar, the data have cast more doubt over whether it will be able to make much of a mark in the ever-more-crowded marketplace of GLP-1 receptor agonists, which is currently dominated by Novo Nordisk's once-a-day Victoza (liraglutide), twice-daily Byetta (exenatide), which will be marketed by AstraZeneca and Bristol-Myers Squibb and an extended-release formulation of the latter, Bydureon. 

GSK's latest batch of data, from five Phase III studies called Harmony, all showed albiglutide to be effective in reducing levels of HbA1c.  

However, in the Harmony 5 study, the drug failed to show non-inferiority against Takeda's Actos (pioglitazone) in lowering blood glucose.

Also, a higher number of gastrointestinal side effects was observed in patients taking GSK's drug than in those on Actos, with 9.6% versus 4.3% experiencing nausea, 8.9% vs 5.4% diarrhoea, and 2.6% vs 1.8% vomiting, respectively. 

Injection site reaction were also more common in the albiglutide group (12.9%) than in the Actos arm (3.2%).

A higher proportion of GI events were observed in another trial - Harmony 3 - for albiglutide compared with Merck & Co's Januvia or Sanofi’s Amaryl, although GSK's drug fared better on the goal of reducing HbA1c.

However, all-in-all, "the data suggest that albiglutide is unlikely to be sufficient for it to be a serious competitor in the market,” Sam Fazeli, Bloomberg Industries analyst, told Bloomberg, and he cautioned of "a small risk that the regulators would say that the the risk-benefit profile isn’t supportive of approval".

Regulators of both sides of the Atlantic are currently reviewing the drug, and GSK will be hoping that its efficacy data and convenient once-weekly dosing regimen will be enough to convince of its potential benefit to patients.