Coverage of 2007 ICAAC
(Interscience Conference on Antimicrobial Agents and Chemotherapy)

September 17–20, 2007, Chicago, Illinois

Options continue to increase for first line therapy

September 19, 2007

Results presented at the 47th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) being held in Chicago show that Lexiva (fosamprenavir), when boosted with Norvir (ritonavir), is as effective as Kaletra (lopinavir + ritonavir) for first line anti-HIV treatment.

The KLEAN study compares boosted Lexiva against Kaletra in over 800 people taking anti-HIV drugs for the first time. Everyone also took the fixed-dose combination pill, Epzicom (abacavir + lamivudine). As reported here, results after 48 weeks were reported from KLEAN at the 2006 International AIDS Conference in Toronto. Those results showed Lexiva to be comparable to Kaletra in terms of reducing HIV levels, increasing CD4 cell counts as well as tolerability.

The results presented in Chicago covered almost another year of follow-up on nearly 200 people who stayed on treatment. A very large majority of people still on treatment for two years had HIV levels below 400 copies. There was a small difference, which favored Lexiva (93% vs. 87%), but it was too small to be significant. The same was true for gains in CD4 cell count, where people on Lexiva averaged a gain of 292 cells/mL, while those on Kaletra gained 286.

Importantly, little difference was seen in tolerability and side effects. The most common side effects for both groups were diarrhea and increases in blood fats (cholesterol and triglycerides).

Along with Prezista (darunavir), Reyataz (atazanavir) and perhaps even Invirase (saquinavir), Lexiva can stand side by side with Kaletra as an effective, durable boosted protease inhibitor for first line therapy.

The similar side effect results of these two drugs are likely to disappoint GlaxoSmithKline (GSK), the maker of Lexiva, as people look for more tolerable choices to Kaletra. As suggested by the study’s name, GSK undoubtedly hoped that Lexiva would prove both equally effective and more tolerable (clean) in terms of side effects.

KLEAN is ongoing. Its final results from a total of 144 weeks—almost 3 years—should be presented some time next year. However, these results so far should help open up a growing list of options for people staring at their first HIV regimen with a protease inhibitor.