Polyethylene glycol-modified interleukin-2 and thymosin alpha(1) in human immunodeficiency virus type 1 infection

The safety and antiviral effects of polyethylene glycolated interleukin-2 (PEG-IL-2) and thymosin alpha(1) in addition to zidovudine were studied in 12 human immunodeficiency virus (HIV)-infected subjects with 50-250 CD4 T cells/mm(3), PEG-IL-2 was administered by intravenous infusions every 2 weeks at 10(6) IU/m(2) for 20 weeks. Thymosin alpha(1) was administered subcutaneously at 400 mu g/m(2) after four doses of PEG-IL-2, escalating to 1600 mu g/m(2) weekly for an additional 2 months. Significant elevations of CD4 T cell numbers of 30%-40% were seen after PEG-IL-2 infusions, but no additional increase in CD4 cell count was observed with thymosin alpha(1). Virologic monitoring by polymerase chain reaction quantitation of proviral DNA and plasma RNA and p24 antigen assays showed no evidence of increased HIV activation during PEG-IL-2 or thymosin alpha(1) therapy. Patients tolerated both PEG-IL-2 and thymosin alpha(1) without significant toxicities.