Coverage of CROI 2008 (Conference on Retroviruses and Opportunistic Infections)

February 4–6, 2008, Boston, MA

 

HEAT study shows Epzicom as good as
Truvada when paired with Kaletra

February 4, 2008

A poster presented today found that that the widely used fixed-dose combination pills, Epzicom (Ziagen/abacavir + Epivir/lamivudine) and Truvada (Viread/tenofovir + Emtriva/emtricitibine), performed equally well when they’re taken with the boosted protease inhibitor, Kaletra (lopinavir + ritonavir). This head-to-head study, called HEAT, is important because there isn’t much direct comparison data between Epzicom and Truvada, which are the two preferred fixed-dose combination NRTI pills found in the current federal guidelines.

The HEAT study looked at around 700 people who had never taken HIV drugs. They were randomly selected to take either Epzicom or Truvada with Kaletra. About half of the study volunteers were white and 82% were male. The main outcome was the proportion of people with HIV levels below 50 copies/ml after 48 weeks. Data were also collected on side effects and changes in CD4 count.

After 48 weeks, similar percentages of people in both groups (68% for Epzicom vs. 67% for Truvada) had undetectable HIV. People taking Epzicom had slightly larger increases in CD4 cell counts (201 vs. 179), but not to a clinically significant degree. There were also similar levels of side effects among the two groups—with more kidney problems among people on Truvada and more abacavir hypersensitivity reactions (HSR) in people on Epzicom.

The current federal guidelines, released in late January, list both Truvada and Epzicom as the preferred options for first line treatment. To date, there has been little direct comparison data to help people choose between these two options. The results from HEAT suggest that either of them is likely to work well, at least when taken with once daily Kaletra.

There are a couple of secondary but important notes about this study. First, it used Kaletra once a day rather than the more widely used and better supported twice a day schedule. This might explain the higher levels of resistance to NRTIs than is typically seen in clinical studies. Also, HLA testing—which fairly accurately predicts the risk of having an abacavir HSR—was not used in the study. Other studies, like PREDICT and SHAPE, suggest that if HLA testing had been used, then a much lower rate of abacavir HSR would likely have occurred.

The other important note is that this study only compared these combination pills when taken with Kaletra. While Kaletra is widely used in first line therapy, others—notably Sustiva (efavirenz) and Reyataz (atazanavir)—are also common choices for first line therapy. It would be a mistake to interpret these results to mean that other drug combinations are less effective than the two used in HEAT.

HEAT is an important study nonetheless. The best way to compare drugs is in these kinds of head-to-head studies. The results from HEAT presented here suggest that, along with HLA testing, Epzicom is a reasonable option to Truvada, when either is taken with Kaletra.