Trouble With a Boron-Containing Drug Candidate

There have been all kinds of boronic acid-based enzyme inhibitors over the years, but they’ve been mostly locked in the spacious closet labeled “tool compounds”. That’s as opposed to drugs. After all these years, Velcade is still the only marketed boron-containing drug that I know of.
There’s been a good attempt to change that in antibacterials, with the development of what’s commonly referred to as “GSK ‘052″, short for GSK2251052. That’s a compound that originally came from Anacor about ten years ago, then was picked up by GlaxoSmithKline, and it’s an oxaborole heterocycle that inhibits leucyl tRNA synthetase. (Here’s a review on that whole idea, if you’re interested).

Unfortunately, last month came word that the Phase II trial of the drug had been suspended. All that anyone’s saying is that there’s a “microbiological finding”, which isn’t too informative when it’s applied to y’know, an antibacterial trial. (At least it doesn’t sound like a general safety or tox problem, at any rate).
Anacor is continuing to exploit boron-containing compounds, although opinion looks divided about their prospects. I always have a sneaking fondness for odd compounds and elements, though, so I’d have to root for them just on that basis.