Studies of maraviroc (MVC) intensification in HIV-infected individuals have suggested that exposure to MVC is associated with increased gut-associated lymphoid tissue (GALT) T cell activation as well as increased HIV-coreceptor (CCR5) expression. Neither of these outcomes would be desirable for a PrEP regimen and so a tissue substudy was added to the HPTN 069/ACTG A5305 study to evaluate GALT responses to four antiretroviral (ART) regimens (MVC, MVC + emtricitabine (FTC), MVC + tenofovir (TDF), and TDF + FTC) and to determine whether ART exposure was associated with suppression of ex vivo / in vitro colorectal explant HIV infection.
CCR5 genotype was characterized from blood sample derived DNA using PCR. Participants received 48 weeks of ART. Colorectal tissue was collected by flexible sigmoidoscopy at Baseline, +24 weeks, +48 weeks, and +49 weeks. Biopsies were enzymatically digested using 2-3 rounds of collagenase II and mechanical disassociation. Mucosal mononuclear cells were stained with antibodies to cell surface markers (CD45, CD3, CD4, CD8, CCR5, CXCR4, CD38, HLA-DR, and CD69) and the Ki-67 intracellular activation marker and run on a BD LSRFortessa flow cytometer. Four biopsies from each participant/per time point were challenged with 105 TCID50 of HIV-1BaL for two hours, washed, and incubated for 2 weeks with supernatant collection at Days 4, 7, 10, and 14 (± 1 day). Day 14 supernatant HIV-1 p24 was quantified using the Alliance assay.
Of the 55 men enrolled in the tissue substudy (MVC [n=13]; MVC + FTC [n=19]; MVC + TDF [n=13]; and TDF + FTC [n=10]), 51 participants were CCR5 wild type and four were heterozygotes (MVC + FTC [n=2]; TDF + FTC [n=2]). There were no significant differences in CD4 T cell activation phenotypes (CD38, HLA-DR, CD69, or Ki-67) between Baseline and Week 24/48 samples or in CCR5 phenotype in any study arm. While significant Day 14 explant viral suppression was seen between Baseline and Week 24 with all the PrEP study regimens, at Week 48 no significant suppression was seen in samples from those randomized to MVC alone.
Increased GALT T cell activation or CCR5 phenotype was not seen in any of the study arms. The explant data suggest that MVC alone may be less effective than combination ART regimens. These observations need to be correlated with pharmacokinetic adherence data. It is also possible that reduced explant viral suppression with MVC may be due to previously reported limitations of testing MVC in the explant model.