Genentech and partner Roche are to add information about a rare brain condition called reversible posterior leukoencephalopathy to the label of their blockbuster cancer drug Avastin (bevacizumab), after a report in the New England Journal of Medicine (March 2) threw up two cases of the disease.

According to correspondence published in the prestigious journal, two women developed RPLS whilst receiving intravenous infusions of the drug, but both recovered after being taken off Avastin. Although most patients do recover if they receive prompt treatment, RPLS is associated with a rapid rise in blood pressure that overwhelms normal regulatory mechanisms in the body, causing leakage of the blood vessels in the brain and haemorrhage.

A spokeswoman from Roche told PharmaTimes News Online that of 63,000 people who have been treated with Avastin globally, there have now been four recorded cases of RPLS, all of whom are “improving or who have completely recovered.” She added that whilst the condition is “exceptionally rare,” it will be updating its warnings and precautions section of the data sheet, alerting physicians to discontinue Avastin treatment in such cases and has updated regulatory authorities about this latest turn of events.

The move is likely to have little impact on sales, according to analyst reports, which will certainly please the drug giants as Avastin reeled in 1.7 billion Swiss francs ($1.3 billion) for Roche in 2005 - its first full year on the market. However, this latest scare follows news that Roche has halted enrollment into a Phase III colon cancer trial of Avastin after more patients in the active treatment arm died versus those in the control group, although the spokeswoman stressed that this decision was not linked to any cases of RPLS.