Elan and Wyeth Announce Results from Phase 2 Clinical Trial of Bapineuzumab for Alzheimer's Disease
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Elan Corporation, plc and Wyeth have announced encouraging preliminary findings from a Phase 2 study of bapineuzumab (AAB-001) in patients with mild to moderate Alzheimer's disease. In the 18-month trial, bapineuzumab appeared to have clinical activity in treating Alzheimer’s disease.
Efficacy Findings:
The study did not attain statistical significance on the primary efficacy endpoints in the overall study population. Post-hoc analyses did show statistically significant and clinically meaningful benefits in important subgroups.
In non-carriers of the Apolipoprotein E4 (ApoE4) allele, estimated in the literature to be from 40 to 70 percent of the Alzheimer’s disease population, post-hoc analyses showed statistically significant and clinically meaningful benefits associated with bapineuzumab treatment on several key efficacy endpoints, including the Alzheimer’s Disease Assessment Scale (ADAS-cog), the Neuropsychological Test Battery (NTB), the Mini Mental State Examination (MMSE) and the Clinical Dementia Rating – Sum of Boxes (CDR-SB). A favorable directional change was seen on the Disability Assessment Scale for Dementia (DAD), although this was not statistically significant.
Additionally in non-carriers, preliminary evaluation of MRI results showed less loss of brain volume among treated patients versus placebo patients, a finding that was statistically significant. Smaller increases in ventricular volume were seen in treated patients compared to placebo patients, although this finding was not statistically significant.
Progression of Alzheimer’s disease is generally associated with loss in brain volume and increases in ventricular volume. Further, treatment-related benefits seen on MRI were correlated to the favorable clinical changes observed in non-carriers.
In similar post-hoc analyses of carriers of the ApoE4 allele, no clinical benefits or statistically significant effects were observed on efficacy endpoints or the brain volume endpoint. However, favorable directional changes were observed on a number of endpoints. Preliminary analyses suggest possible increase of ventricular volume in treated patients versus placebo patients. The clinical significance of this finding is currently unclear and analyses are ongoing.
Safety Findings:
As expected given the nature of the population studied, adverse events were very common in both placebo and bapineuzumab-treated patients. In non-carriers, the number of patients experiencing serious adverse events was similar between placebo and bapineuzumab-treated patients. In carriers, serious adverse events were more frequently observed in bapineuzumab-treated patients than in placebo patients.
In addition, vasogenic edema was reported in the treated population with an increased frequency in carriers and at higher doses. No cases were reported in placebo patients.
In the ongoing Phase 3 studies, carriers of the ApoE4 allele are being treated with a lower dose to minimize the risk of vasogenic edema. The Companies believe that the overall safety findings from this Phase 2 trial support their prior decision to move to Phase 3 studies.
