SAFETY CONCERNS have forced Elan and its partner Wyeth to pull one of the three dosages in a phase III trial of its most advanced Alzheimer’s drug.

Elan and Wyeth were testing efficacy of bapineuzimab – one of the first designed to attack the plaque that forms clumps in the brains of people with Alzheimer’s disease – in patients with doses ranging from 0.5 mg/kg to 2mg/kg.

However, a safety monitoring committee raised concerns about brain swelling in a number of patients due to vasogenic oedema.

Elan president Carlos Paya said: “Our review of the safety data and the feedback from the Safety Monitoring Committee made it clear that continued development of the highest dose was not advisable. The decision to remove the highest dose from development reduces risk to patients and it also helps to reduce risk to the overall development effort.”

A statement from Elan said the safety monitoring committee had also reviewed data for patients on the 0.5mg/kg and 1mg/kg doses and “does not have concerns about these cohorts at this time”.

Vasogenic oedema is an accumulation of water in brain tissue.Twelve cases were reported in an earlier trial, all of which were successfully treated.

The majority of those cases occurred in patients carrying the ApoE4 gene – who carry a higher risk of developing Alzheimer’s – and it was more prevalent at higher dosages.

As a result, the phase III trials were designed to dose only patients not carrying that gene at the 2mg/kg level.

In a note to clients yesterday, Goodbody analyst Ian Hunter said: “We are reducing our probability that the drug will get to market to 30 per cent from 70 per cent.”

Shares in Elan fell by around 5 per cent in both Dublin and new York but volumes were reported to be normal. – Additional reporting Bloomberg