I previously blogged on Torcetrapib because of my interest in causality and in a similar vein, the cholesterol hypothesis. And I was surprised and delighted when the ILLUMINATE trial showed that Torcetrapib, in spite of doubling HDL, failed miserably. Surprised because like so many others I couldn't really believe that if you double HDL that on balance wonderful things wouldn't happen; and delighted because of the possible insights this might give into the cholesterol hypothesis and causality. (See this post: http://medicalevidence.blogspot.com/2007/11/torcetrapib-torpedoed-sunk-by-surrogate.html )
I must have been too busy skiing when this article on Anacetrapib came out last year: http://www.nejm.org/doi/full/10.1056/NEJMoa1009744 . You may recall that after Torcetrapib was torpedoed, the race was on for apologists to find reasons it didn't work besides the obvious one, that it doesn't work. It raised blood pressure and does things to aldosterone synthesis, etc. Which I find preposterous. Here is an agent with profound effects on HDL and mild effects on other parameters (at least the parameters we can measure) and I am supposed to believe that the minor effects outweigh the major ones when it comes time to measure final outcomes? Heparin also affects aldosterone synthesis, but to my knowledge, when used appropriately to treat patients with clots, its major effects prevail over its minor effects and thus it doesn't kill people.
This is no matter to the true believers. Anacetrapib doesn't have these pesky minor effects, and it too doubles HDL, so the DEFINE investigators conducted a safety study to see if its lack of effects on aldosterone synthesis and the like might finally allow its robust effects on HDL to shine down favorably on cardiovascular outcomes (or at least not kill people.) The results are favorable, and there is no increase in blood pressure or changes in serum electrolytes, so their discussion focuses on all the reasons that this agent might be that Holy Grail of cholesterol lowering agents after all. All the while they continue to ignore the lack of any positive signal on cardiovascular outcomes at 72 weeks with this HDL-raising miracle agent, and what I think may be a secret player in this saga: CRP levels.
Only time and additional studies will tell, but I'd like to be on the record as saying that given the apocalyptic failure of Torcetrapib, the burden of evidence is great to demonstrate that this class will have positive effects on cardiovascular outcomes. I don't think it will. And the implications for the cholesterol hypothesis will perhaps be the CETP inhibitors' greatest contributions to science and medicine.
This is discussion forum for physicians, researchers, and other healthcare professionals interested in the epistemology of medical knowledge, the limitations of the evidence, how clinical trials evidence is generated, disseminated, and incorporated into clinical practice, how the evidence should optimally be incorporated into practice, and what the value of the evidence is to science, individual patients, and society.
Sunday, April 3, 2011
If at first you don't succeed, try, try again: Anacetrapib picks up where Torcetrapib left off
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