Immunologic and virologic effects of subcutaneous interleukin 2 in combination with antiretroviral therapy: A randomized controlled trial.

CONTEXT: While interleukin 2 (IL-2) is capable of inducing a marked expansion of the CD4 T-lymphocyte pool, limited data exist on whether IL-2 treatment can add significantly to the immunologic and virologic effects of potent antiretroviral therapy (ART). OBJECTIVE: To determine the rate and magnitude of CD4 cell recovery and viral suppression when using a combination therapy of IL-2 and ART compared with ART alone. DESIGN AND SETTING: Randomized, controlled multicenter trial conducted from April 1996 through April 1998 at 8 clinical sites in the United States. PATIENTS: Eighty-two adult outpatients who were infected with human immunodeficiency virus (HIV) and had baseline CD4 cell counts of 200 x 10(6)/L to 500 x 10(6)/L and baseline RNA levels of fewer than 10,000 copies/mL were randomized; 78 completed the study. INTERVENTIONS: Thirty-nine patients were randomly assigned to receive a combination therapy of subcutaneous IL-2 (administered in 5-day courses every 8 weeks at a starting dosage of 7.5 mIU twice per day) and ART; 43 were to receive ART therapy alone. MAIN OUTCOME MEASURES: Interleukin 2 safety and differential effects on CD4 cell counts, CD4 cell percentages, and plasma HIV RNA levels. RESULTS: The mean (SD) percentage increase in CD4 cell counts at 1 year for patients who received IL-2 was 112% (113%) compared with 18% (35%) in recipients of ART alone (P<.001). Both groups had mean (SD) increases in CD4 cell percentage: from 20.4% (6.3%) to 32.3% (12.4%) for the combination therapy group compared with 20.4% (5.1%) to 23.0% (7.2%) for recipients of ART alone (P<.001). Using a sensitive viral RNA assay, mean viral load changes were -0.28 and 0.09 log(10) copies for IL-2 recipients and control patients, respectively (P=.03). Twenty (67%) of 30 evaluable patients receiving IL-2 achieved final viral loads of fewer than 50 copies/mL compared with 13 (36%) of 36 control patients (P=.02). Toxic effects were common among patients who received IL-2 and were managed with antipyretics, hydration, rest, and dosage reduction as needed. CONCLUSIONS: Intermittent therapy with IL-2 and ART produced a substantially greater increase in CD4 cells and was associated with a larger decrease in viral load than ART alone. Clinical end-point trials will be necessary to determine whether the enhanced viral suppression and CD4 cell increases associated with IL-2 therapy will translate into improved clinical outcomes. JAMA. 2000;284:183-189

Indinavir concentrations and St John's wort.

St John's wort reduced the area under the curve of the HIV-1 protease inhibitor indinavir by a mean of 57% (SD 19) and decreased the extrapolated 8-h indinavir trough by 81% (16) in healthy volunteers. A reduction in indinavir exposure of this magnitude could lead to the development of drug resistance and treatment failure.

A randomized trial of high- versus low-dose subcutaneous interleukin-2 outpatient therapy for early human immunodeficiency virus type 1 infection.

Forty-nine outpatients infected with human immunodeficiency virus with baseline CD4 cell counts >/=500/mm3, who were on stable antiretroviral therapy, were randomized to receive 5-day cycles of either low-dose (1.5 million IU [MIU] twice a day) or high-dose (7.5 MIU twice a day) subcutaneous (sc) interleukin (IL)-2 every 4 or every 8 weeks. High-dose recipients experienced mean slopes of +116.1 cells/month and +2.7 %/month in CD4 cells and percents, respectively, whereas low-dose recipients displayed mean slopes of +26.7 and +1.3% in the same parameters. At month 6, high-dose recipients achieved a 94.8% increase in mean CD4 cells over baseline compared with a 19.0% increase in low-dose recipients. While high-dose recipients encountered more constitutional side effects, these were generally not dose-limiting. High-dose scIL-2 therapy in outpatients with early HIV-1 infection was well tolerated and induced dramatic, sustained rises in CD4 cells.

Pharmacokinetic modeling of recombinant interleukin-2 in patients with human immunodeficiency virus infection.

A novel model was developed to characterize the time-varying clearance of recombinant interleukin-2 (IL-2). Sixty-eight patients with human immunodeficiency virus infection received 83 cycles of IL-2 either by continuous infusion or by subcutaneous injection for 5 days. IL-2 concentrations after intravenous infusions peaked at 24 hours and then declined by 55% to 78% during the remainder of the infusion. Soluble IL-2 receptors increased greater than 10-fold before gradually returning to baseline. Subcutaneous administration showed a dose-dependent decrease in area under the concentration-time curve (AUC) between days 1 and 5. A model was developed in 9 patients who had IL-2 concentrations and soluble IL-2 receptors determined by ELISA. Concentrations were fitted by an indirect stimulatory pharmacodynamic model. An additional 59 patients with only IL-2 concentrations were fitted to a simplified empiric model. Both models provided an overall r2 of 0.99 for the plot of observed versus fitted concentrations. The time-dependent increase in IL-2 clearance, likely receptor-mediated, was well described with use of an indirect-effects pharmacokinetic-pharmacodynamic model.

Subcutaneous administration of interleukin-2 in human immunodeficiency virus type 1-infected persons.

The safety and efficacy were assessed of 5-day cycles of subcutaneous (sc) interleukin-2 (IL-2) every 8 weeks in human immunodeficiency virus type 1-infected outpatients with >200 CD4 cells/mm3. Immunologic, virologic, and toxicity parameters were measured in 18 patients receiving standard antiretrovirals plus 5-day courses of sc IL-2 (3-18 MIU/day) every 2 months. Systemic toxicities established the maximally tolerated dose (MTD) of IL-2 as 15 MIU/day. CD4 cell responses appeared to correlate directly with baseline CD4 cell counts, with several patients experiencing a dramatic rise after 3 cycles. Virus load increased only transiently in the peri-injection period. It was concluded that serial cycles of outpatient sc IL-2 can be administered safely, with an MTD of 15 MIU/day. Patients with higher baseline counts appear to have a greater CD4 cell response to sc IL-2 therapy.

Randomized, controlled phase I/II, trial of combination therapy with delavirdine (U-90152S) and conventional nucleosides in human immunodeficiency virus type 1-infected patients.

Delavirdine mesylate (DLV) is a potent nonnucleoside reverse transcriptase inhibitor with activity specific for human immunodeficiency virus type 1. In the present phase I/II study we evaluated the safety, toxicity, pharmacokinetics, and antiretroviral activities of two-drug and three-drug combinations of DLV and conventional doses of nucleoside analogs compared with those of both DLV monotherapy and two-drug nucleoside analog therapy. A total of 85 human immunodeficiency virus type 1 infected patients with CD4 counts of 100 to 300 cells per mm3 were enrolled in two periods: in the first period patients were randomized to receive either zidovudine (ZDV) plus didanosine (group 1) or ZDV plus didanosine plus escalating doses (400 to 1,200 mg/day) of DLV (group 2). In the second period, patients were randomized to receive either 1,200 mg of DLV alone per day (group 3) or ZDV plus 1,200 mg of DLV per day (group 4). DLV demonstrated good oral bioavailability at all five doses tested. The major toxicity was a transient mild rash which appeared in 44% of all DLV recipients. Overall, group 2 patients demonstrated more sustained improvements in CD4 counts, percent CD4 cells, branched DNA levels, p24 antigen levels, and virus titers in plasma than group 1, 3, or 4 patients. The magnitude of the response correlated with the intensity of prior nucleoside analog treatment, the non-syncytium-inducing or syncytium-inducing viral phenotype at baseline, and the presence of a wild-type codon at amino acid position 215 in the baseline reverse transcriptase genotype. Despite a transient rash, DLV therapy was well tolerated. Combination therapy with DLV and nucleoside analogs appears promising, with the three-drug combination appearing to be more potent that either two-drug combinations or monotherapy.