A disappointment came in after Alzheimer's disease drug by Pfizer Inc. and a partner failed at a late-stage study being conducted for treating Alzheimer’s.

Pfizer and partner Medivation Inc. on Wednesday reported that the drug called Dimebon could not fulfill its primary and secondary goals.

It was being tested for improving thinking ability and overall daily function over six months in patients who had mild to moderate Alzheimer's disease.

Experts state that failing this test does not spell end for Dimebon.

Three studies are still in progress by Medivation and Pfizer, the world's biggest drugmaker by revenue, that might be able to prove that Dimebon helps patients when used for a longer duration or in combination with other Alzheimer's drugs.

There were promising results at the initial stages of the study and doctors thought that the study would be able to give some hope to stop or reverse the disease.

Dr Ronald Petersen, chairman of the Alzheimer's Association's medical and scientific advisory council, said, "It's a setback, because it was the drug nearest to approval. It could have been on the market in two years, and anything else will take much longer.”

Shares of Medivation and Pfizer went down following the news.

Petersen however was hopeful as other studies of Dimebon continue.