Abbott presented 48-week findings comparing an HIV regimen of its protease inhibitor (PI), Kaletra (lopinavir/ritonavir), and Merck's integrase inhibitor, Isentress (raltegravir), to a traditional HIV regimen of Kaletra and the nucleotide/nucleoside reverse transcriptase inhibitors (NRTIs) in Truvada (tenofovir and emtricitabine) in antiretroviral-naive adult patients. Efficacy data were collected over the first 48 weeks of the 96-week PROGRESS (PROtease/InteGRasE Simplification Study) study. These data met the primary efficacy endpoint, which measured whether a similar proportion of treatment-naive HIV-infected patients reached undetectable viral loads. The results were presented at the 28th International AIDS Conference in Vienna, Austria.

"The 48-week PROGRESS study results, while not definitive, suggest that the nucleoside-sparing HIV regimen of Kaletra and Isentress may be an alternative treatment option for patients new to HIV therapy, when compared to a standard HIV regimen. This further advances our research into new HIV treatment classes and explores the use of alternative drug combinations for patients," said Jacques Reynes, M.D., professor of medicine, head of the Infectious and Tropical Disease Department at the University Hospital Center of Montpellier, France, and a presenting author of the PROGRESS study.

HIV treatment regimens are typically drawn from approximately 20 approved antiretroviral medications in six classes. Standard regimens for treatment-naive patients generally consist of two NRTIs plus either a PI or a non-nucleoside reverse transcriptase inhibitor (NNRTI).

PROGRESS is a global, multicenter, 96-week open-label study of approximately 200 HIV-infected patients. Physicians should use caution when interpreting these results of the PROGRESS study.

Key findings through week 48 include: A similar proportion of patients had HIV-1 RNA levels less than 40 copies/mL (defined as undetectable) when treated with Kaletra and Isentress, compared to Kaletra and Truvada; Both groups, on average, had a similar positive immune response, measured by their increase in CD4+ T-cell counts ; The safety and tolerability, including incidences of treatment-emergent moderate-to-severe medication-related adverse events, were generally similar between regimens. Lipid (cholesterol and triglyceride) elevations were observed more frequently in the Kaletra and Isentress group.

"Kaletra is one of the most widely-studied protease inhibitors available, and Abbott believes it is important to look at new ways of combining Kaletra with other HIV medications to explore additional treatment options for patients," said Scott C. Brun, M.D., divisional vice president, infectious disease development, Global Pharmaceutical Research and Development, Abbott. "The PROGRESS study is another step toward understanding the science behind potential new treatment approaches to help people living with HIV and demonstrates Abbott's continued commitment to HIV research."

PROGRESS is an open-label, 96-week study evaluating the efficacy and safety of Kaletra in combination with Isentress, compared to Kaletra and Truvada in antiretroviral-naive patients. Merck supplied Isentress for the PROGRESS study.

Kaletra (lopinavir/ritonavir) is a prescription anti-HIV-1 medicine called a protease inhibitor that contains lopinavir and ritonavir. Kaletra is used with other anti-HIV-1 medicines to increase the chance of treatment response in people with human immunodeficiency virus (HIV-1) infection. It is not known if Kaletra is safe and effective in children under 14 days old.

Kaletra does not cure HIV-1 infection or AIDS and does not stop people from passing HIV-1 to others. People taking Kaletra may still get opportunistic infections or other conditions that happen with HIV-1.

Do not take Kaletra if you are allergic to any of its ingredients, including lopinavir or ritonavir. Do not take Kaletra with certain medicines, as they can cause serious problems, death, or make Kaletra less effective against HIV. Some patients taking Kaletra can develop inflammation of the pancreas and liver problems, which can cause death. Patients may develop changes in heart rhythm, large increases in triglycerides and cholesterol, diabetes, high blood sugar, changes in body fat, and/or increased bleeding in people with hemophilia. Some patients may develop signs and symptoms of serious infections they already have after starting anti-HIV medicines. Please see the Important Safety Information for more details.

Isentress is the first medicine to be approved in a new class of antiretroviral medications called integrase inhibitors. Isentress is approved for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in adult patients new to treatment and adult patients who have previously taken antiretroviral therapy. The safety and efficacy of Isentress have not been established in pediatric patients. Isentress works by inhibiting the insertion of HIV-1 DNA into human DNA by the integrase enzyme. Inhibiting integrase from performing this essential function limits the ability of the virus to replicate and infect new cells.

Abbott has been a leader in HIV/AIDS research since the early years of the epidemic. In 1985, the company developed the first licensed test to detect HIV antibodies in the blood and remains a leader in HIV diagnostics. Abbott retroviral and hepatitis tests are used to screen more than half of the world's donated blood supply.