Solanezumab is a story that won't go away. Eli Lilly's antibody therapy for Alzheimer's is the subject of a lot of arguing among investors: some people (and I'm one of them) think that there is no strong evidence for its efficacy, not yet, and that the amount of time and effort devoted to finding that out means that there likely isn't any meaningful efficacy to be found. Others are more optimistic, which is why Lilly's stock has risen in recent months.
The latest point of contention is an independent analysis of biomarker data which came out this week at a conference in Monaco. This suggests that there was a meaningful change in the amount of circulating beta-amyloid after treatment, which could mean that the antibody was working as planned to increase clearance of soluble amyloid, thus altering the amyloid balance in the CNS. It should be noted that this line of attack depends on several factors - first among them, that amyloid is a causative factor in Alzheimer's, and secondly, that clearing it from the periphery can affect its concentration and distribution inside the brain. There's evidence for both of these, and there's evidence against both of them. Such questions can only be answered in the clinic, and I'm glad that Lilly, Roche/Genentech, and others are trying to answer them.
What I want to focus on today, though, is an issue that comes up in passing in the Fierce Biotech link above:
Biomarkers and pooled data may help support further studies of the drug, as well as other programs that rest on the beta amyloid hypothesis, but they don't prove that solanezumab works as hoped. Nevertheless, the first sign of success in this field has fueled tremendous enthusiasm that something in the pipeline could eventually work--perhaps even pushing regulators to approve new therapies with something less than clear efficacy data. And any newly approved drug would find a massive market of millions of desperate patients.
That's a big "perhaps", one that's worth tens of billions of dollars. What I worry about is pressure building for the FDA to approve an Alzheimer's therapy (solanezumab or something else) based on these hints of mechanistic efficacy. The problem is, solanezumab hasn't shown much promise of improving the lives of actual Alzheimer's patients. Lilly's own trials showed a possible improvement in a measure of cognitive decline, but this did not show up again in a second patient group, even when they specifically modified the endpoints of the trial to look for it. And neither group showed any functional effects at all, which I think are what most Alzheimer's patients (and their family members) would really want to see.
But there really is such a huge demand for something, anything, with any hint of hope. People would line up to buy anything that got FDA approval, no matter how tenuous the evidence was. And that puts the agency in a very tough position, similar to the one it was in with the Avastin breast cancer issue. Update: there was, to be sure, more of a safety question with Avastin at the same time. You can argue that one of the main purposes of the agency is to make sure that medicines that people can be prescribed in this country will actually do some good, rather than raise hopes for nothing. You could also argue that responsible adults - and their physicians, and their insurance companies - should be able to make such choices for themselves, and should be able to spend their time and money in the ways that they best see fit. You could argue that companies with marginally effective (or ineffective) therapies face a huge moral hazard, in that their incentives are to get such treatments onto the market whether they do anyone else any good or not. None of these are foolish positions, but they are also, in places, mutually incompatible. Alzheimer's disease might well turn into the next place in which we thrash them out.