I mentioned that Amgen had a rough time with their leptin program, but there are people who benefit tremendously from the protein. There are some people (very few, actually) who are similar to the ob/ob mouse, in that they have a mutation in their leptin protein gene. They tend to have a lot of metabolic troubles, starting with morbid obesity and a terrible blood lipid profile. Administration of the human protein works wonders for them.
So leptin, therapeutically, is an orphan drug. And the identification of patients who can benefit from it is a harbinger of the era of "personalized medicine" that everyone says is coming. They're probably right, because we're actually learning to pick up on more and more cues like this, and finding them is an area of frantic research (and frantic funding.) The push is on to identify things in both directions: positive (who will benefit from Drug X?) and negative (who will show nasty side effects from Drug X?)
That second category could have saved a lot of drugs that have disappeared from advanced clinical trials, or even some that have disappeared from the market. It's quite possible that we'll see some of these brought back from cold storage in some fashion, when we find ways to get around their bad low-incidence problems. This sort of thing (toxicogenomics) is what many drug industry researchers think of when they think of the promise of genomics - who could blame them?
But it's that first category, pharmacogenomics, that'll make life interesting. Look, for example, at some of the cancer therapies in the clinic now. Even though things like Iressa and Erbitux seem to work dramatically in some patients, they completely fail in others. There's no way to tell which group a new patient will end up in - if you could sort them out, you'd only give it to the dramatic-recovery crowd, and tell the others not to waste their time (or their money.)
Or their money. . .there's the rub. What happens when we get to this point, when we can predict who will respond to our new drugs and who won't? The customers sure will be happy - but there won't be nearly as many of them. Face it, when a new therapy for a grave disease (cancer, AIDS, diabetes, etc.) hits the market now, everyone's going to try it out. Even as it fails in a certain percent of users, everyone's going to. . .well. . .buy it. And that's figured into industry calculations. When you think about the potential market for your new drug, you aim for the biggest number of possible patients/customers.
What if you cut that market in half? Or more? What if the only people who buy your drug are the ones that it's certain to work for? You've now got a smaller market. A well-served one, that's for sure, but smaller all the same. But developing your drug didn't cost any less than it did when you developed it for the whole crowd, hit or miss, and it just might have cost even more. So how are you going to do it, selling it to a smaller group?
Well, as far as I can see, the price will go up. It'll have to. No one will care for this one bit, but that's what's going to have to happen. That'll be the surcharge for making sure that the drug does what it's supposed to. And those of us in research will have to get used to the idea that we're going to have to develop even more new drugs as we do now, to make sure that we cover all the patient groups in what used to be larger, less differentiated markets. Given the struggles we're having to develop things as they stand, that's going to be a lively undertaking indeed.