Mike: GIGHAART I think is important for two reasons. One is that it's the first controlled study of treatment interruptions [versus no interruption in people with heavy drug experience, about to start a multi-drug regimen]. We've had the same intimation from the Royal Free data and from Veronica Miller's data, that having a treatment interruption was virologically beneficial for you in the short-term.
In GIGHAART, 68 patients were followed, and these were very late stage patients, I mean 26 CD4s versus 28 and they had a high-ish viral load. They'd all been multiply experienced, and quite clearly, on whatever analysis you took, having an eight week interruption was virologically beneficial. The viral load drop was 0.4 log drop versus 1.9 log drop. It's kind of difficult to argue against these data. The question is, is that data going to be the same out to 24 weeks, and clearly Christine [Katlama, the study investigator] intimated that it would.
The next thing I'd say is what are the implications of the data for the OPTIMA study? I kind of think either the OPTIMA study has to ignore those data, which I think is difficult because the study was not stopped by the investigators, it was stopped by the DSMB [Data and Safety Monitoring Board] which means that it was considered unethical to continue because of the high benefit; or the OPTIMA study has to say well, eight weeks has been shown to be beneficial, perhaps we should randomise people to do an eight week interruption and then go back on therapy, or do as long an interruption as you wanted. I certainly think that needs to be considered by the OPTIMA steering committee fairly quickly because it's very early in its recruitment phase. One difficulty may be a difference in the UK opinion and the US and Canada's opinion because I think they're very different treating sites.
In terms of where we move with GIGHAART itself, there was a clear issue about what the sensitivity of the virus was under the genotypic testing, and I think one of the questions becomes, and that is being answered in OPTIMA, do you need all those drugs once you go back on therapy?
The final thing that I think links that with the 3D study [which investigated the use of ddI/d4T/efavirenz with or without hydroyurea], is that certainly in the experienced patients in the 3D final 48 week data from Rob Murphy, you had a benefit to hydroxyurea over the naïve patients, and that may be related to an immune activation issue. In GIGHAART seventy-odd per cent had hydroxyurea, and in our salvage data in our cohort at the Royal Free we had a number of people on hydroxyurea, some of whom stopped, blipped, and went back on hydroxyurea and re-suppressed. Now, I would like to look at those data in a much more controlled way because I think the role of hydroxyurea is not yet adequately explained, especially in late stage patients.
Anna: A lot of people dropped hydroxyurea in the GIGHAART study.
Mike: But that may be a good thing, and maybe you only need it for a short period of time. The problem with the 3D study, which really crippled that study is that firstly, people didn't start it immediately, and secondly, it was a continuous dose. I think that quite clearly after a long period of time on hydroxyurea you do get toxicity.
Martin: Another thing that was quite interesting with GIGHAART was that the rationale for performing the study was that people would revert to wild-type virus and that was why they would do well, whereas in actual fact it seems to be the treatment break itself rather than just the switch. Although the people who reverted to wild-type did slightly better, those who had no change in their resistance pattern also did much better than the people who didn't have an interruption. So clearly we don't understand what's going on.