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Hi, this is Paul Sax from Brigham and Women's Hospital and Harvard Medical School. Today I would like to continue my review of the recent International AIDS Society meeting that just took place in Rome.

For today's summary, I would like to summarize 3 studies, all on investigational antiretrovirals. They are (1) lersivirine, an investigational nonnucleoside reverse transcriptase inhibitor (NNRTI); (2) elvitegravir, an investigational integrase inhibitor; and (3) dolutegravir, another integrase inhibitor.

I'll start with lersivirine. Lersivirine is a once-daily NNRTI that was compared with efavirenz in a phase 2 trial,[1] with everyone also receiving the nucleoside tenofovir/emtricitabine. Let me just cut to the chase. The bottom line is that lersivirine was almost as good as efavirenz in this study. It was dosed in both 500 mg and 750 mg once-daily doses. Looking at the breakdown by baseline viral load, it appeared to be that activity was greater in the efavirenz arm. In addition, more gastrointestinal side effects occurred in the lersivirine arm, so overall it was almost as good.

By contrast, let's take a look at dolutegravir. Dolutegravir was compared with efavirenz in a phase 2 study.[2] We saw 16-week data last year, and this year we saw the 48-week data. These patients were treated with dolutegravir in various doses vs efavirenz, and the results were outstanding. At 48 weeks, about 90% of the dolutegravir treatment group had an undetectable viral load. Of interest, even in patients who had virologic failure on dolutegravir, there was no integrase resistance, suggesting that this drug potentially has a very high genetic barrier.

The third study,[3] which was a full phase 3 study, compared elvitegravir to raltegravir in treatment-experienced patients. You might recall that elvitegravir in phase 2 actually had some difficulties because the study design did not initially allow patients to have boosted protease inhibitors in their background.[4] Here, all patients received a boosted protease inhibitor. The good news is that in this study, elvitegravir was comparably active with raltegravir in these treatment-experienced patients. The side-effect profile was very similar, with a bit more diarrhea in the elvitegravir group and a bit more liver function test abnormality in the raltegravir group.

This is encouraging news, certainly both on dolutegravir and elvitegravir, whereas the data on lersivirine looked actually only so-so. Keep an eye out for these drugs going forward. That summarizes the most important of the investigational drug studies at the International AIDS Society meeting this year.