I've written several times about the NIH's NCATS program, their foray into "translational medicine". Now comes this press release that the first compound from this effort has been picked up for development by a biopharma company.
The company is AesRx (recently acquired by Baxter), and the compound is AES-103. This came from the rare-disease part of the initiative, and the compound is targeting sickle cell anemia - from what I've seen, it appears to have come out of a phenotypic screening effort to identify anti-sickling agents. It appears to work by stabilizing the mutant hemoglobin into a form where it can't polymerize, which is the molecular-level problem underlying the sickle-cell phenotype. For those who don't know the history behind it, Linus Pauling and co-workers were among the first to establish that a mutation in the hemoglobin protein was the key factor. Pauling coined the term "molecular disease" to describe it, and should be considered one of the founding fathers of molecular biology for that accomplishment, among others.
So what's AES-103? Well, you'll probably be surprised: it's hydroxymethyl furfural, which I would not have put high on my list of things to screen. That page says that the NIH screened "over 700 compounds" for this effort, which I hope is a typo, because that's an insanely small number. I would have thought that detecting the inhibition of sickling would be something that could be automated. If you were only screening 700 compounds, would this be one of them?
For those outside the business, I base that opinion on several things. Furans in general do not have a happy history in drug development. They're too electron-rich to play well in vivo, for the most part. This one does have an electron-withdrawing aldehyde on it, but aldehydes have their own problems. They're fairly reactive, and they tend to have poor pharmacokinetics. Aldehydes are, for example, well-known as protease inhibitors in vitro, but most attempts to develop them as drugs have ended in failure. And the only thing that's left on the molecule, that hydroxymethyl, is problematic, too. Having a group like that next to an aromatic ring has also traditionally been an invitation to trouble - they tend to get oxidized pretty quickly. So overall, no, I wouldn't have bet on this compound. There must be a story about why it was tested, and I'd certainly like to know what it is.
But for all I know, those very properties are what are making it work. It may well be reacting with some residue on hemoglobin and stabilizing its structure in that way. The compound went into Phase I in 2011, and into Phase II last year, so it does have real clinical data backing it up at this point, and real clinical data can shut me right up. The main worry I'd have at this point is idiosyncratic tox in Phase III, which is always a worry, and more so, I'd think, with a compound that looks like this. We'll see how it goes.