Sanofi-Aventis basically has their future riding on their obesity therapy Acomplia (rimonabant), which was (until a day or two ago) expected to be approved before the middle of this year. But the FDA gave them one of those "Approvable, But. . ." letters which sow fear and confusion whenever they arrive.
The fear is self-explanatory, and the confusion comes because the letters don't have to be made public. No one knows what the FDA's concerns are, because Sanofi-Aventis doesn't have to say - yet. But in the case of a drug that was expected to be this big, and one that S-A's management was telling everyone just the other day was in fine, fine shape, they're going to have to come out with something soon or risk a complete loss of confidence and credibility.
There are quite a few possibilities, as this post at Pharmagossip lays out. I have to say, rimonabant has always made me a bit nervous, and that's not just hindsight talking. Back in 2004 I wrote about some possible bad side effects of the drug, and last year I worried in general about the problems of taking such a drug (huge buildup, huge market, totally new mechanism of action) to market.
You see, the problem is, I did the first half of my career in CNS drug discovery. Drugs that act on central nervous system receptors can do all kinds of odd stuff, and we most definitely do not know enough about brain chemistry to predict what those interesting surprises might be. The endocannabinoid receptor that rimonabant targets is very much an evolving story - it's even less worked out than the other brain targets. The thought of a CNS drug whose target is relatively less well understood than the others should be enough to make anyone gaze thoughtfully out the window for a bit.
The field has other brisk and tangy qualities. For example, the patient population tends to have an alarmingly heterogeneous response to CNS drugs, as a look at the antipsychotic and antidepressant markets will show you. Drugs that work fine for one person do nothing for another, and we don't yet know why. I can see no reason why rimonabant should be any different.
This FDA action may have borne out some of these fears, or it may be that Sanofi is just involved in an argument about a too-aggressive labeling proposal. Here's betting that they fill in some details real soon now. The longer they wait, the worse it'll be for them. By. . .Wednesday, I'd say?