20. What are the response, duration and durability for the three hepatitis B treatments?

Here’s a summary for the three drugs that are available. I’ll just go through these slowly for you one at a time. So this is, first of all, the published data in the one-year response, e-Positive, and here’s the wild type, e-Negative (precore and core promoter mutants). Now the response for the e-Positive is defined as loss of e-antigen, development of e-antibody, and a low DNA. That occurs in about 20% with interferon, 16%-18% in four different studies for lamivudine, and 12% in the Gilead adefovir studies for one year of therapy. So these are relatively low rates, and as you’ll see later, if you treat longer than a year, these numbers go up. Now the e-Negative, here there’s a different end point. They’re already e-Negative to begin with, so the end point is only the DNA. And so the DNA comes down low, and that occurs commonly with e-Negative. All of these therapies will lower the DNA level. The problem, if you skip down to the third box, is the durability. For e-Positive hepatitis B, if you treat for a year and you stop when there is loss of e-antigen, development of e-antibody, it’s durable for 80%-90%, for lamivudine it is a little lower, 60%-80%-there’s a higher relapse rate. This data was just published also in Berlin; it was 91% with Gilead for adefovir. So, you stop therapy the patients will have a persistently inactive virus. For e-Negative, it’s very very low. In other words, these patient’s DNA will always come back up again. Duration of therapy for interferon has four to six months for e-Positive. There is new information suggesting that one year of interferon therapy may actually get a fairly good sustained response rate. I think we’re going to see some renewed interest, although we use a lot of oral agents. The pegylated interferons are a little better tolerated and for those with e-Negative, we’re starting to see some better results. And for the two oral agents, we just simply treat long-term.