Pfizer (PFE) and Medivation (MDVN) will stop development of their investigational Alzheimer’s disease drug after it failed to meet the main goals of improving cognition and daily function in a late-stage trial.

The drug companies said Tuesday that while dimebon was generally well tolerated in the study, it did not achieve statistically significant results for either improving cognitive ability or self care and daily function.

The experimental drug also failed an earlier Alzheimer's disease trial in 2010 and a late-stage study for Huntington's disease in 2011. Pfizer and Medivation stopped development on dimebon for Huntington's, a hereditary condition that causes mental deterioration, after that trial failed. 

In addition to ending the development of dimebon, the companies will also terminate the ongoing open label extension study in Alzheimer’s disease.

“We recognize Alzheimer’s is a very complex disease,” said Dr. Steven Romano, head of   Pfizer’s medicines development group. Despite the disappointing results, Romano said Pfizer remains committed to advancing the science of the disease.

The Phase III trial took place over a 12-month period with 1,003 Alzheimer’s patients.

Shares of Medivation were down about 2.5% to $54.37 Tuesday morning. 

The company's shares of been hit hard by dimebon's failures but have gained two-fold over the last two months after its prostate cancer drug, MDV3100, received a positive recommendation from an independent committee. 

Follow Jennifer Booton on Twitter at @Jbooton