Antiviral drugs are one of those big unmet medical needs that we talk about in the drug industry. The reason we talk about them is, of course, that from a business standpoint - and this is a business, for sure - "unmet need" is equivalent to "unmade profit".
The problem is, the reason that some of these big opportunities are unclaimed is that they're not easy to address. As I've said here before, one big problem with antivirals is that there are a very limited number of good targets for drugs. After all, viruses are pretty stripped-down to start with: they do a limited number of things, but they do them very well indeed. Compared to a relatively target-rich therapeutic area like cancer, infectious disease is a desert.
One well-known oasis, though, contains the viral proteases. Many viruses carry these as a key part of their machinery, to help "unpack" necessary proteins from larger precursors. Famously, that's how many of the anti-HIV drugs work, and the same general strategy should be applicable to several other viral types.
Hepatitis C has been one of the big targets for many years now. Various development programs have come and gone, but no one has been able to really nail this one. Vertex is now in the middle of trying to, and as Adam Feuerstein points out, they're really betting a large part of the company on the attempt. Over the next few months, results should start coming out for their PROVE trials of telaprevir (VX-950), and for Vertex's sake, the drug had better work. A herd of competitors, probably led by Schering-Plough, is ready to take over should anything slip.
"Work" is defined as "work well enough so that people don't have to take injections of interferon". That'll depend, as always, on the balance of efficacy and toxicity, and it's the side effect profile that everyone will be watching, since it's widely assumed that the drug will in fact do some good against the disease. The nerve-wracking thing about working for a small-to-medium sized company has always been that your future ends up depending on single events like this, and I wish everyone at Vertex good luck. (Of course, as people at Pfizer will tell you, your future even at a gigantic company can end up depending on the results of one clinical trial - this industry is getting altogether too exciting for a lot of people to take).