New Alzheimer's Drug on Horizon? A Solid Maybe...

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Contributed by: Dennis Fortier, President, Medical Care Corporation

A new Alzheimer's drug, being co-developed by Biogen and Easai, has completed a Phase II FDA trial with seemingly positive results. The drug (BAN2401) is a monoclonal antibody that binds to certain forms of amyloid protein, which is considered by many in the field to be a key culprit in the onset and progression of Alzheimer's disease. When the antibody is flushed out of the system, it takes the harmful amyloid protein with it. Over the past five years, several similar drugs have shown glimmers of promise before ultimately failing in Phase III FDA trials.

For perspective, Phase II studies are generally smaller (fewer people enrolled) with the purpose of determining safety for various doses of a drug along with any possible side-effects at each dose of the drug. Phase III studies are generally larger, often longer, and usually a final step prior to "market approval".

Biogen recently presented a snapshot of the data from their Phase II FDA trial at the Alzheimer's Association International Conference in Chicago. While the results showed a reduction in amyloid among subjects receiving the higher doses and a possible slowing of cognitive decline at some stages, the presentation lacked details and many questions remain unanswered.

The primary questions were related to the trial design which appeared to have lower-risk patients in the high dose group and higher risk patients in the untreated (placebo) group. If this was the case, then it would be easier to show that the treatment group fared better (perhaps on both amyloid deposition and cognition) than the placebo group. In defense of this approach, it was taken as a safety measure, not as an attempt to show efficacy through some deceptive trial design. With that in mind, the results are encouraging.

Secondarily, some in the field questioned the validity of the instrument used to measure cognition. The instrument (the ADCOMS) is a composite measure that pulls certain items from various other, well-validated instruments and combines them in a new instrument specifically designed to detect subtle changes. Given the well-documented mediocrity of the instruments historically used to measure cognitive change in FDA clinical trials,  concerns about the ADCOMS should be somewhat tempered because the new instrument may not be significantly better than previous instruments, but it is probably no worse either. With this perspective, lingering angst about the ADCOMS may possibly be over-blown.

Overall, the trial results are both PROMISING and PREMATURE. While there is reason for a fair amount of optimism, one should not carry that optimism with an unrealistic amount of conviction.

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