MONDAY, April 2 (HealthDay News) -- An experimental drug might lower a marker of Alzheimer's disease seen in the spinal fluid of patients with mild to moderate disease, a small new study finds.

However, whether this new drug -- bapineuzumab -- will have a beneficial effect on slowing or stopping the degenerative process of Alzheimer's isn't known, the researchers said.

And an Alzheimer's expert said it's far too soon to draw conclusions for the preliminary study.

"This is interesting incremental information from a quite small group of subjects, but no conclusions can be drawn at this point," said William Thies, vice president for medical and scientific affairs at the Alzheimer's Association.

Thies, who was not involved in the study, added that "an important question remains whether such changes in spinal fluid markers correlate with clinical benefit."

The study authors said that this issue is being addressed in additional trials of bapineuzumab.

"We are looking forward to seeing phase 3 results later this year," Thies said.

The current study was published online April 2 in the Archives of Neurology.

For the study, an international team led by Dr. Kaj Blennow, of the University of Gothenburg in Sweden, analyzed two trials that included 46 patients with mild to moderate Alzheimer's disease.

Alzheimer disease is a progressive neurodegenerative disease, which has been associated with deposits of beta-amyloid (protein) plaques and fibrous tangles in the brain and abnormal tau protein in the spinal fluid, the researchers noted.

In these trials, 27 patients were treated with bapineuzumab and 19 with a placebo. The researchers looked for the effect of the drug on several markers associated with Alzheimer's disease.

The investigators found that compared with the placebo, bapineuzumab reduced levels of phosphorylated tau in spinal fluid, which may mean that it reduced its level in the brain as well, which might also reduce tangles in the brain, they suggested.

While they found a reduction for total tau, it was not statistically significant, Blennow's group noted.

Bapineuzumab is a drug known as a "monoclonal antibody" that is designed to work against the formation of tangles by attacking the various forms of tau.

A monoclonal antibody is an antibody created to target a specific disease process and is called "monoclonal" because a single cell antibody is cloned again and again to create the drug.

"An important question remains whether such changes in [spinal fluid] biomarkers correlate with clinical benefit," the researchers concluded.

Another Alzheimer's expert urged caution when interpreting the study findings.

"It's interesting, but it's a small group of patients and there was no statistical significance in the conclusion," said Dr. David Langer, a neurosurgeon and director of Cerebrovascular Research at the Cushing Neuroscience Institute, part of the North Shore-LIJ Health System in Manhasset, N.Y.

There's also a question whether tau tangles cause Alzheimer's disease or are only a result of the disease, Langer said. "That still remains controversial," he said.

"It would be nice if we could figure out the cause and, therefore, a way to treat Alzheimer's disease," Langer said. "The conclusion that you reduce the amount of these biomarkers is interesting, but we don't even know if that means anything about the way an Alzheimer's patient would behave or not. We are far away from a cure for Alzheimer's disease based on this study."

The study authors made numerous financial disclosures, a journal editor noted, and the study was funded by Elan (which was acquired by Janssen Alzheimer Immunotherapy) and Wyeth Pharmaceuticals (acquired by Pfizer).

More information

For more information on Alzheimer's disease, visit the Alzheimer's Association.