Immunologic benefits of enfuvirtide in patients enrolled in a drug assistance program.

Background: Randomized clinical trials have demonstrated that enfuvirtide plus an optimized background regimen can cause a significant increase in CD4+ cell counts and a reduction in HIV RNA levels.

Objective: To describe and analyze CD4+ cell count and HIV RNA changes in HIV-infected patients receiving enfuvirtide and a prescribed background regimen (PBR) in a primarily clinical setting.

Methods: A retrospective review from September 1998 through August 2005 of CD4+ cell counts and HIV RNA changes from baseline was conducted in patients receiving enfuvirtide. Data were stratified and analyzed according to baseline CD4+ cell count and HIV RNA.

Results: A mean CD4+ cell count increase of approximately 102 cells/mm(3)was observed, regardless of baseline CD4+ cell count, in 187 patients receiving enfuvirtide during a mean of 19.4 months of follow-up. During 3 years of follow-up, patients initiating enfuvirtide at CD4+ cell counts less than 100 cells/mm(3)never achieved absolute CD4+ cell counts comparable to the counts in patients starting enfuvirtide at CD4+ cell counts of 100 cells/mm(3)or more. In 38.3% of patients achieving an undetectable HIV RNA level, a mean CD4+ cell count increase of 185 cells/mm(3)was observed. An unexpected finding was that a mean CD4+ cell count increase of 76 cells/mm(3)occurred in 61.7% of patients not achieving complete viral suppression.

Conclusions: Immunologic benefits were observed in subjects continuing enfuvirtide plus a PBR irrespective of baseline CD4+ cell count, complete viral suppression, or antiretroviral susceptibility data. Data suggest that initiation of enfuvirtide at CD4+ cell counts greater than 100 cells/mm(3)may be immunologically advantageous and independent of complete virologic response.