Immunologic Benefits of Enfuvirtide in Patients Enrolled in a Drug Assistance Program

Background:Randomized clinical trials have demonstrated that enfuvirtide plus anoptimized background regimen can cause a significant increase in CD4+ cellcounts and a reduction in HIV RNA levels.Objective:To describe and anaiyze CD4+ cell count and HIV RNA changes in HIV-infectedpatients receiving enfuvirtide and a prescribed background regimen (PBR) ina primarily clinical setting.Methods:A retrospective review from September 1998 through August 2005 of CD4+ cellcounts and HIV RNA changes from baseline was conducted in patients receivingenfuvirtide. 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 wasobserved, regardless of baseline CD4+ cell count, in 187 patients receivingenfuvirtide during a mean of 19.4 months of follow-up. During 3 years offollow-up, patients initiating enfuvirtide at CD4+ cell counts less than 100cells/mm 3 never achieved absolute CD4+ cell counts comparableto the counts in patients starting enfuvirtide at CD4+ cell counts of 100cells/mm 3 or more. In 38.3% of patients achieving anundetectable HIV RNA level, a mean CD4+ cell count increase of 185cells/mm 3 was observed. An unexpected finding was that a meanCD4+ cell count increase of 76 cells/mm 3 occurred in 61.7% ofpatients not achieving complete viral suppression.Conclusions:Immunologic benefits were observed in subjects continuing enfuvirtide plus aPBR irrespective of baseline CD4+ cell count, complete viral suppression, orantiretroviral susceptibility data. Dala suggest that initiation ofenfuvirtide at CD4+ cell counts greater than 100 celis/mm 3 may beimmunologically advantageous and independent of complete virologicresponse.