18. What drug therapies are currently in development for treatment of HBV?

The last slide is about looking ahead. I've talked to you about the importance of immunizations and the importance of inoculating infants and Asian and population and preventing maternal transmission. From the point of view of blood supply, we’ve cleaned that up and that’s not really a source. As we pointed out, dialysis units have been cleaned up and that’s not a source. IV drug abuse, you do what you can do with that, but that’s not really a major source in the United States fortunately at the moment. In terms of drug therapies, there are currently three licensed drugs in the United States now. One is lamivudine, which is called Epivir, which is a very effective drug, easy to take, relatively cheap, but developed resistance in the end of two to three years in two-thirds of the people who are resistant to it. The second drug is Adefovir, called Hepsera, which is the newer drug that seems to have an extremely low incidence of resistance. Its a little more expensive. It’s been studied lets say for up to five years. There has been an occasional case of drug resistance that’s come up after two to three years of therapy. it goes out over five to ten years, there may be further. The third drug is Interferon. So I think these points we’ve made, new and better treatments and immunization. Interferon is an immune stimulant. Its the treatment for hepatitis C because hepatitis C is an RNA virus and the kind of oral drugs that work for hepatitis B don’t work for C. Interferon is a drug that stimulates the body’s immune system to fight the virus as opposed to inhibiting the replication of the virus. It’s a very difficult drug to take since you have to take it by injection. It has many, many side effects and its incredibly expensive. So it hasn’t been a popular drug up to now and really the evidence that it works hasn’t been very strong. Because it’s an immune booster, it tends to work in patients who are immune competent to begin with. The big problem with hepatitis B is the chronicity in people who are immunoincompetent who got it when they were a baby and their own immune system couldn’t overcome it - that’s why they’re chronic. So the question is whether Interferon can stimulate these people to stimulate them to overcome the virus on their own by taking the Interferon injections. We’ve all been kind of pessimistic about Interferon. In addition, its extremely expensive. There’s another drug therapy called Entecavir which is about to be approved by the FDA and there are at least a half a dozen others on the horizon. The antiviral treatment may wind up being a combination of these drugs in the same way you treat HIV. Fortunately you’re probably going to need two or three and not a whole armamentarium. You may have to take the drugs for the rest of your life, but by taking one or two pills a day it may help prevent you from getting liver failure and cancer.