Suppression of dualtropic human immunodeficiency virus type 1 by the CXCR4 antagonist AMD3100 is associated with efficiency of CXCR4 use and baseline virus composition

Abstract

In a phase I/II evaluation of the CXCR4 antagonist AMD3100, human immunodeficiency virus RNA levels were significantly reduced in a single study subject who harbored CXCR4 (X4)-tropic virus, but not in subjects who harbored either dual/mixed (DM)-tropic or CCR5 (R5)-tropic virus (C. W. Hendrix et al., J. Acquir. Immune Defic. Syndr. 37:1253-1262, 2004). In this study, we analyzed the envelope clones of DM-tropic virus in baseline and treated virus populations from 14 subjects. Ten subjects exhibited significant reductions in CXCR4-mediated infectivity after 10 days of AMD3100 therapy relative to baseline (X4 suppressor group), while four subjects had no reduction of CXCR4-mediated infectivity (X4 nonsuppressor group). The baseline viruses of the X4 suppressor group infected CXCR4-expressing cells less efficiently than those of the X4 nonsuppressor group. Clonal analysis indicated that the baseline viruses from the X4 suppressor group contained a higher proportion of R5-tropic variants mixed with CXCR4-using variants, while the X4 nonsuppressor group was enriched for CXCR4-using variants. AMD3100 suppressed X4-tropic variants in all subjects studied, but not all dualtropic variants. Furthermore, dualtropic variants that used CXCR4 efficiently were suppressed by AMD3100, while dualtropic variants that used CXCR4 poorly were not. This study demonstrated that AMD3100 has the ability to suppress both X4-tropic and certain dualtropic variants in vivo. The suppression of CXCR4-using variants by AMD3100 is dependent on both the tropism composition of the virus population and the efficiency of CXCR4 usage of individual variants.

FIG. 1.

Analysis of tropism of viruses from subjects 35 and 33 before, during, and after treatment with AMD3100. (A and C) The coreceptor tropism of the virus population at baseline and on days 11, 18, and 39 was determined using Trofile. Infectivity in CD4⁺ CCR5⁺ (open bars) and CD4⁺ CXCR4⁺ (solid bars) U87 cells, as measured by luciferase activity (RLU) in a single measurement, is shown. (B and D) Proportions of clones with the indicated tropisms (R5, X4, dual-X, and dual-R), represented as percentages of the total number of functional clones for each time point, are shown. Open bars, R5-tropic clones; solid bars, X4-tropic clones; shaded bars, dual-X-tropic clones; hatched bars, dual-R-tropic clones.

FIG. 2.

Analysis of tropism of viruses from subject 10 before and after treatment with AMD3100. (A) The coreceptor tropism of the virus population at baseline and day 11 was determined using Trofile. Infectivity in CD4⁺ CCR5⁺ (open bars) and CD4⁺ CXCR4⁺ (solid bars) U87 cells, as measured by luciferase activity (RLU) in a single measurement, is shown. (B) Proportions of clones with the indicated tropisms (R5, X4, dual-X, and dual-R), represented as percentages of the total number of functional clones isolated at each time point, are shown. Open bars, R5-tropic clones; solid bars, X4-tropic clones; shaded bars, dual-X-tropic clones; hatched bars, dual-R-tropic clones.

FIG. 3.

Phylogenetic analysis of gp160 env clones isolated at baseline and on days 11, 18, and 39 for subjects 35 and 33. Phylogenetic trees show the association of the time point with the coreceptor tropism at baseline and on days 11, 18, and 39 for subjects 35 (A) and 33 (B). Colored lines represent env clones isolated at baseline (pink), day 11 (gold), day 18 (green), and day 39 (blue). Clones with X4 or dual-X tropism are shown within dashed circles. Asterisks indicate clones with dual-R tropism.