The End of Dimebon

Contributed by: Dennis Fortier, President, Medical Care Corporation

Dimebon, an experimental Alzheimer's treatment, has failed its Phase III clinical trial, and will not be further developed by its co-sponsors, Pfizer and Medivation.

The Associated Press article reporting on this failure described it as a "major setback" but it really comes as no surprise to those who have followed the trajectory of this potential new drug.

As we described in an earlier post, Dimebon failed its initial trial showing no cognitive benefits and no improvement of function among those research subjects who took it.  Undaunted by the initial failure, the drug's sponsors pushed forward with three additional trials: one measuring the drug's effect over a longer period, one measuring the drug's effect as poly-therapy in conjunction with Aricept, and one measuring the drug's effect in patients with Huntington's disease.  All three trials have now failed.

This is not good news for the field but I think it important to comment on how this might effect attitudes toward further research.  By and large, even the first Dimebon failure in March of 2010 was expected by most experts who follow this space.  Despite the fact that Pfizer and Medivation chose to push forward and complete three additional studies, consensus was that the drug was unlikely to be effective, and success in those trials was considered an absolute long-shot.

Now, those expectations have been met, and no one is really surprised.  Research will continue at a cautious but steady pace, perpetually fueled by the lucrative potential of success.