Levels of a protein believed to be a main cause of Alzheimer's disease rose in the blood of patients treated with Eli Lilly's experimental drug in late-stage trials, suggesting the protein, beta amyloid, was removed from the brain as intended, researchers said on Monday.
Lilly in August disclosed that its drug solanezumab did not significantly arrest progression of the memory-robbing disease in the pair of Phase III studies, which tested patients with mild to moderate symptoms of Alzheimer's.
But the company later said an analysis of combined data from the two trials suggested the drug significantly slowed cognitive decline in patients with only mild symptoms, although it did not slow the decline of their physical function.
The finding from the pooled trial data helped restore some faith in the closely followed Lilly drug - that it might hold promise in treating patients who have not yet developed symptoms or who are in the very earliest stages of the disease.
Researchers on Monday, attending the Clinical Trials in Alzheimer's Disease (CTAD) annual scientific meeting in Monaco, said an independent analysis of the trial data suggested that beta amyloid was removed from the brain into the bloodstream of patients taking solanezumab.
"The results support continued interest in amyloid as a therapeutic target in Alzheimer's disease research," CTAD said in a release.
Rachelle Doody, an Alzheimer's disease researcher from Baylor School of Medicine who led the analysis, said the removal of amyloid from the brain into the blood - and slight cognitive improvement seen - lend credence to amyloid as a culprit in the disease.
"The beta amyloid biomarker results in the trial support the small, yet significant cognitive benefit" seen with the anti-amyloid approach, Doody said.
Researchers said the studies support the earlier use of drugs like solanezumab, which target toxic amyloid plaques in the brain, to prevent symptoms of the disease. One such prevention study is slated to begin next year at Washington University in St. Louis, and includes use of the Lilly drug.
Researchers in Monaco said no changes were seen in any other major biomarkers - proteins or tissue changes believed associated with the disease - including another suspected leading culprit protein called tau.
Credit-Suisse analyst Catherine Arnold said data so far, including the amyloid findings presented on Monday, are "encouraging" for solanezumab. But she predicted Lilly would have to complete another big late-stage trial to win approval of the drug for patients with milder symptoms.
"While there continue to be many points of debate on solanezumab, there is little debate the drug has an active and safe profile," she said in a research note.
Arnold said the drug could be introduced in 2017 and achieve eventual annual peak sales of $2.5 billion, if a new big trial supports its marketing approval.
Wall Street has taken an intense interest in solanezumab because Lilly badly needs big-selling new medicines to cushion plunging sales of its Zyprexa schizophrenia drug, now facing cheaper generics, and sales declines of other Lilly medicines that will go up against generics by 2014.
Alzheimer's is a progressive and ultimately fatal disease affecting an estimated 35 million people worldwide, CTAD said, adding the number is expected to exceed 115 million if nothing is done to slow or prevent the disease.