Ireland’s Elan Corp and the USA’s Wyeth have announced what they call encouraging preliminary findings from a mid-stage trial of their new Alzheimer’s disease drug bapineuzumab.

The two companies noted that AAB-001 (bapineuzumab) did not achieve statistical significance in its primary endpoints, which was expected somewhat due to imbalances in patient numbers (240 took part) and “characteristics at baseline between subgroups studied that may or may not have affected these results”. However, post-hoc analyses did show “clinically meaningful benefits in important subgroups”.

Specifically, in non-carriers of the Apolipoprotein E4 (ApoE4) allele, estimated to make up 40%-70% of the Alzheimer’s disease population, the data revealed statistically significant benefits associated with bapineuzumab treatment “on several key efficacy endpoints”. These included the Alzheimer’s Disease Assessment Scale, the Neuropsychological Test Battery and the Mini Mental State Examination.

Additionally in non-carriers, preliminary evaluation of MRI results showed less loss of brain volume among treated patients versus the placebo group. Elan added that a more detailed analysis of the study will be presented at the International Conference on Alzheimer's Disease in Chicago at the end of July.

Kelly Martin, chief executive of the Dublin-headquartered group, said that the preliminary analyses “are a continued validation of the amyloid approach to Alzheimer's disease” and the results “clinically support our decision to move into Phase III last year”. His counterpart at Wyeth, Bernard Poussot, said “we are encouraged by these findings” but “we recognise there is a great deal of hard work left as we move from this phase of learning towards confirming the potential of bapineuzumab”.

The excitement surrounding AAB-101, a humanised monoclonal antibody, and if the Phase III programme proves successful, Elan and Wyeth may have on their hands the first drug to modify the course of Alzheimer's rather than just relieving its symptoms. Investors are certainly excited and Elan’s shares were up 5.6% to 18.21 euros at 9.30 this morning.