By: Ed Susman

WASHINGTON, DC – An antiretroviral regimen that does not include nucleoside reverse transcriptase inhibitors (NRTIs) appears to be as effective as standard antiretroviral therapy for patients with HIV, researchers reported at the 19th International AIDS Conference.

The nucleoside-sparing regimen combines treatment with the cell entry inhibitor maraviroc and the protease inhibitor atazanavir, boosted with ritonavir.

In the pilot study, 46 of 59 (78%) patients assigned to treatment with maraviroc and boosted atazanavir achieved undetectable status (<400 copies/mL) after 96 weeks of treatment compared with a regimen of boosted atazanavir, emtricitabine, and tenofovir, in which 51 of 61 patients (83.6%) achieved undetectable viral loads at 96 weeks.

“This was an exploratory, pilot study of a once-daily low pill burden therapy,” said Anthony Mills, MD, private practice, Los Angeles, California, during his oral presentation.

In addition to the similar outcomes in suppressing the virus, “no phenotypic resistance, relevant genotypic change or change in tropism developed,” he added.

Maraviroc targets the CCR5 coreceptor on cells that the virus uses as a gateway. In some studies, researchers have observed the virus is able to enter cells by switching its tropism to another coreceptor CXCR4, allowing it to escape maraviroc.

Dr. Mills also reported that CD4-positive cells count increased similarly with regimens, increasing 239.8 cells with maraviroc and 264 cells from baseline with the nucleoside regimen.

In the phase 2b, randomised, open-label study, 60 patients were randomised to treatment with maraviroc 150 mg day and 61 patients were assigned to tenofovir/emtricitabine 200/300 mg once daily plus atazanavir/ritonavir 300/100 mg once daily. Initially the treatment was for 48 weeks, but then was extended to 96 weeks. The study was not powered to demonstrate a treatment difference and therefore the researchers did not perform statistical testing.

Dr. Mills said that researchers are recruiting 804 patients for a phase 3 study of the treatment regimen.

Patients in the study had to have CCR5 tropism. He said 220 patients were screened to find 121 individuals for inclusion in the study. Of the patients, 90% were men and 75% were white. Median baseline CD4-positive cell counts were around 350.

- MFP Wire Services
- 08-09-2012