I’m going to expand on one of the points brought up yesterday, about the reported drug industry executive who was confident that his company’s Alzheimer’s therapy was ready to go out and make billions of dollars. It was that word “confident” that set me off, I think.
Because that’s not a word that you hear much of in this industry. The strongest form that you’ll come across is something like “fairly confident”, which is how you feel when you send in a compound that’s a minor change off something that’s already active, or how you feel about screening a target that’s a close homologue of something you already have plenty of ligands for. You can be pretty sure in those cases that something’s going to hit – but you’ll note that both of those are pretty far upstream in the drug discovery process. As you move toward animals, that confidence begins to look pretty ragged, and depending on the disease, it can just flat-out evaporate.
Despite all our efforts to avoid the expensive little beasts, there is still no way to be sure about how your compound is going to act in an animal until you’ve put it into an animal. That goes for predicting its peak blood levels, its half-life, its metabolites, and the duration and degree of its efficacy. You can have your compounds all ranked in order of how you think they’ll perform, and that list will, every time, be reordered after a first round of animal testing.
And when you go further, you really have no idea. As I’ve said here before, if you don’t cross your fingers when you take a compound into two-week toxicity testing, you haven’t been doing this stuff very long. Despite all efforts to avoid this expensive step, two-week (and four-week and longer) tox testing in animals will always, always tell you things you didn’t know. (Most of the time it’ll tell you things you didn’t particularly want to hear). No one worth their salary will ever use the adjective “confident” before the first multiweek tox data come in.
So much for animals: how about people? Well, despite all our efforts, there are still surprises in Phase I dosing, the tip-toe clinical stage where you look for blood levels in healthy volunteers. The animal pharmacokinetic data tell you where to start the doses in humans, but you can still get ambushed. I worked on a receptor agonist project once where the human blood levels came back at just about 10% of what we’d predicted, so back to the drawing board we went. No, I’ve never heard anyone describe themselves as “confident” before Phase I.
And that’s an easy step compared to Phase II, where for the first time you put your drug into sick patients. The failure rate in Phase II is just abominable, and stands as an indictment of just how little we understand about the biochemistry of human disease and how to modify it. When you consider a central nervous system disease like Alzheimer's, the source of the "confident" quote that started this digression, the failure rate is over 90%. Our understanding of the causes and progression of Alzheimer's is very poor. That's as opposed to a more well-worked-out condition like, say, hypertension, where our understanding is merely quite inadequate.
But if you make it through that fine sieve, you move on to Phase III, a larger and more real-world look at the patient population. If your Phase II trial was designed to provide a robust test, rather than just to make you and your investors feel good, you can hope that your Phase III will work out. But the whole time it's going on, the prudent drug developer will remember that the biggest, most well-funded, and most competent research organizations in the world have all taken huge cratering dives in Phase III. You know a lot more about your compound by this stage, so these disasters don't happen as often - but that means that when they do, they rise right up out of the floor in front of you. No, you can feel better by Phase III, but "confident" is pushing it.
How about when your drug goes to the FDA? Try asking any drug company executive if they'd like to go on record as being "confident" of regulatory approval. And when your drug actually goes to market? Is anyone really confident about those projections from the people in marketing? Pfizer sure talked a good game about Exubera, remember. Don't forget, too, that nasty side effects can always be waiting out there in the larger patient population. Even after your drug goes out and starts earning a living, it can be completely torpedoed at any time. Baycol, Vioxx, Avandia - you can name more.
So that's the story: you can never kick back and relax in this business. For all the perception that some people have of the drug industry as a sure-fire money machine, it sure doesn't look that way from inside. Anyone who describes themselves as "confident" about their new experimental medication is trying to fool their listeners. Or themselves. Maybe both.