VIVITROL – FDA Advisory Committee Meeting

On September 16, 2010, an FDA Advisory Committee will review Alkermes application to extend the VIVITROL indication to include treatment of opioid abuse in addition to the alcohol dependency it currently has.   When we first heard of this, we thought this was a slam dunk.  Early indicators were that the clinical trial was statistically significant and the adverse event profile was not much different from what was seen with the patients who were being treated for alcohol dependency.  But now we’ve seen the FDA Briefing document and things aren’t so clear.  For one, the application is based on a single relatively small study conducted in Russia.  In very guarded terms, the FDA has asked the Advisory Committee to determine if the study is applicable to the US patients.  Why so?  Because the patient population in the Russian study is very lean on people of color, only 2 Asians, the rest >99% are white.  So, does it represent the patient population that will use the drug in the US?  The short answer is NO.  The “margin of efficacy” (our term, not theirs) is only a 12% difference in efficacy between the placebo patients and the Vivitrol treated patients.  So, it is conceivable that if the drug is less effective in treating people of color then the “margin of efficacy” could disappear in a clinical trial population that represents the US patient population.  And that we don’t know because Alkermes didn’t consider that in setting up the trial in Russia.

It is difficult to predict with any degree of accuracy how the Advisory Committee will go but the lack of data in a representative US patient population for whom the drug is intended is a major regulatory obstacle.  If this study was done in the US, would the FDA accept the demographics?  Probably not.  Is this drug better than anything else that’s out there now for treating opioid dependency?  Is it better than immediate release naltrexone for treating opioid dependency?