Responses to Switching to Maraviroc-Based Antiretroviral Therapy in Treated Patients with Suppressed Plasma HIV-1-RNA Load

Maraviroc reactivates HIV with potency similar to that of other latency reversing drugs without inducing toxicity in CD8 T cells

Human immunodeficiency virus (HIV) remains incurable due to latent reservoirs established in non-activated CD4 T cells. Current efforts to achieve a functional cure rely on immunomodulatory strategies focused on enhancing the functions of cytotoxic cells. Implementation of these actions requires a coordinated activation of the viral transcription in latently infected cells so that the reservoir became visible and accessible to cytotoxic cells. As no latency reversing agent (LRA) has been shown to be completely effective, new combinations are of increasing importance. Recent data have shown that maraviroc is a new LRA. In this work, we have explored how the combination of maraviroc with other LRAs influences on HIV reactivation using in vitro latency models as well as on the cell viability of CD8 T cells from ART-treated patients. Maraviroc reactivated HIV with a potency similar to other LRAs. Triple combinations resulted toxic and were rejected. No dual combination was synergistic. The combination with panobinostat or disulfiram maintained the effect of both drugs without inducing cell proliferation or toxicity. Maraviroc does not alter the viability of CD8 T cells isolated from patients under antiretroviral treatment. This finding enhances the properties of maraviroc as a LRA.

Genotypic Tropism Testing in HIV-1 Proviral DNA Can Provide Useful Information at Low-Level Viremia

The possibility of performing genotypic tropism testing (GTT) with proviral DNA (pvDNA) even during suppressed viremia would facilitate the use of CCR5 inhibitors as part of switching, simplification, or intensification strategies. Thus, we aimed to evaluate the tropism concordance between plasma RNA and pvDNA samples and to assess which factors could affect possible discrepancies between the two compartments. GTT was performed using both plasma RNA and pvDNA from 55 sample pairs from drug-experienced patients. Potential differences between the two compartments were evaluated by analyzing coreceptor usage and genetic variability. Paired samples were also stratified in three levels of viremia (<50, 51 to 500, and >500 copies/ml). Overall, Geno2Pheno comparisons of false-positive rates in the two compartments showed good correlation (r = 0.72). A high level of concordance in tropism predictions for the two compartments was found (46/55 sample pairs [83.6%]). Among the 9 sample pairs with discordant tropisms, a larger proportion of pvDNA samples harboring CXCR4/dual-mixed-tropic viruses was found, in comparison with plasma RNA samples (88.9% versus 11.1%; P = 0.0034). Discordant samples were characterized by greater genetic variability than were concordant samples. With stratification of the paired samples according to viremia levels, the prevalence of discordant samples decreased with increasing viremia (<50 copies/ml, 21.4%; 51 to 500 copies/ml, 15.4%; >500 copies/ml, 6.7%; P = 0.2). Our findings confirm that prediction of viral tropism using pvDNA is feasible even in low-level viremia and provides useful information for therapy optimization for patients with low or suppressed viremia.

HIV co-receptor tropism prediction remains stable over time in treatment-naïve patients

HIV co-receptor tropism determination is essential before prescribing the CCR5 antagonist maraviroc. British HIV Association guidelines suggest tropism testing may remain valid for only 90 days in antiretroviral-naïve patients. We aimed to determine the accuracy of this figure. Tropism was assessed in 26 antiretroviral-naïve patients with ongoing viral replication, sampled yearly from first clinic visit. The V3 region of HIV-1 was sequenced in triplicate, then tropism predicted using the Geno2Pheno system. Baseline tropism prediction remained valid for a median of 52 months (range 7-81). For 19/26 individuals baseline tropism remained unchanged throughout a median of 54 months follow-up; 18 R5 tropic and 1 X4 tropic. In seven patients (27%) baseline tropism switched at least once (range 1-4 switches) during follow-up; however, their baseline tropism prediction remained valid for a median of 45 months. Co-receptor tropism in treatment-naïve patients with ongoing viral replication appears highly stable over time, suggesting that baseline genotypic tropism prediction may be valid for a longer duration in patients delaying ART initiation. In this study, baseline tropism prediction remained valid for a median of 52 months, suggesting current guidelines recommending repeat testing after 90 days may be excessively conservative in their assessment of tropism stability.

Limited evolution of inferred HIV-1 tropism while viremia is undetectable during standard HAART therapy

Background

HIV patients on suppressive antiretroviral therapy have undetectable viremia making it impossible to screen plasma HIV tropism if regimen change is required during suppression. We investigated the prevalence and predictors of tropism switch from CCR5-using (“R5”) to non-CCR5-using (“non-R5”) before and after viral suppression in the initially therapy-naïve HOMER cohort from British Columbia, Canada.

Methods

We compared pre-therapy and post-suppression viral genotypic tropism in patients who initiated on PI/NNRTI-based antiretroviral regimens between 1996-1999 (n = 462). Virologic suppression was defined as having two consecutive viral loads of <500 copies/mL, which was the sensitivity limit of most viral load assays at the time. Viral tropism was inferred by V3-loop-population-sequencing and geno2pheno_[coreceptor] with cutoff at 5.75% false positive rate (FPR).

Results

When virologic suppression was defined as two-consecutive viral loads <500 copies/mL, 34 (9%) of the 397 patients with pre-therapy R5-virus switched to non-R5 at viral load rebound after a median of 19 months (IQR 8–41 months) of undetectable viremia. Duration of viral load suppression was not a predictor of switch, but lower CD4 count during suppression (median 400 versus 250 cells/mL) and an increased prevalence of pre-therapy non-R5 HIV by “deep” sequencing (median 0.2% versus 3.2%) were independently associated with switch (p = 0.03 and p<0.0001, respectively).

Conclusion

R5-to-non-R5 tropism switches in plasma virus after undetectable viremia were relatively rare events especially among patients with higher CD4 counts during virologic suppression. Our study supports the use of pre-suppression tropism results if maraviroc is being considered during virologic suppression in this subgroup of patients.

Stability of unfrozen whole blood DNA for remote genotypic analysis of HIV-1 coreceptor tropism

Background

Maraviroc is an HIV-1 coreceptor antagonist that has shown good efficacy and tolerability in treatment-naive and treatment-experienced patients harboring CCR5-tropic virus. The use of Maraviroc in treatment simplification in patients with suppressed plasma HIV-1 RNA requires analysis of HIV-1 DNA. Coreceptor tropism testing is often performed remotely at reference laboratories. In this study paired whole blood stored at + 4°C and at−20°C were compared as a source for genotypic coreceptor tropism testing.

Methods

Two hundred paired whole blood samples from different patients were analysed. Each sample was stored in two different conditions: one aliquot was stored at−20°C until spin column DNA extraction (WB20) and one aliquot was stored at +4°C for two weeks and then placed at room temperature (22-24°C) for two days before DNA extraction (WB4). Subsequently, a fragment encompassing the HIV-1 gp120 V3 domain was amplified by a singlicate nested PCR followed by triplicate nested PCR in the negative samples. A randomly selected panel of 20 paired WB4 and WB20 duplicate amplification products were sequenced and coreceptor tropism was inferred by geno2pheno [coreceptor].

Results

WB20 yielded a higher amount of DNA than WB4 (median [IQR] values 332.5 ng/μl [117.5-401] and 107 ng/μl [56.6-318], respectively; P < 0.001). However, the DNA purity was higher for WB4 than for WB20 (median distance from the optimal OD_260/280 ratio, 0.14 [0.07-0.79] and 0.96 [0.36-1.10], respectively; P < 0.0001). The number of samples successfully amplified was 152 (76.0%) for WB20 and 155 (77.5%) for WB4 with the first PCR and 179 (89.5%) for WB20 and 181 (90.5%) for WB4 (P = ns) following subsequent triplicate analysis. The inferred coreceptor tropism was concordant in 18 out of 20 paired WB4 and WB20 samples. Two samples yielded discordant results, consistent with the discordance rate within duplicates from the same sample source (2/20 with WB4 and 1/20 with WB20) due to the inherent gp120 V3 variability.

Conclusions

Storing whole blood at +4°C for up to two weeks and shipping at room temperature is a convenient method for obtaining HIV-1 gp120 V3 sequence information via testing at a remote laboratory in patients with suppressed viremia.

Longitudinal analysis of HIV-1 coreceptor tropism by single and triplicate HIV-1 RNA and DNA sequencing in patients undergoing successful first-line antiretroviral therapy

Objectives

Maraviroc has been shown to be effective in patients harbouring CCR5-tropic HIV-1. While this CCR5 antagonist has initially been used in salvage therapy, its excellent safety profile makes it ideal for antiretroviral treatment simplification strategies in patients with suppressed plasma viraemia. The aim of this study was to compare HIV-1 tropism as detected in baseline plasma RNA and peripheral blood mononuclear cell (PBMC) DNA prior to first-line therapy and to analyse tropism evolution while on successful treatment.

Methods

HIV-1 tropism was determined using triplicate genotypic testing combined with geno2pheno[coreceptor] analysis at a 10% false positive rate in 42 patients. Paired pre-treatment plasma RNA and PBMC DNA and two subsequent PBMC DNA samples (the first obtained after reaching undetectable plasma HIV-1 RNA and the second after at least 2 years of suppression of plasma viraemia) were evaluated.

Results

Coreceptor tropism was completely concordant in paired pre-treatment RNA and DNA, with 26.2% of HIV-1 sequences predicted to be non-CCR5-tropic. During follow-up, coreceptor tropism switches were detected in 4 (9.5%) patients without any preferential direction. Although false positive rate discrepancies within triplicates were common, the rate of discordance of coreceptor tropism assignment among triplicate results in this mostly CCR5-tropic dataset was only 2.1%, questioning the added value of triplicate testing compared with single testing.

Conclusions

HIV-1 coreceptor tropism changes during virologically successful first-line treatment are infrequent. HIV-1 DNA analysis may thus support the choice of a CCR5 antagonist in treatment switch strategies; however, maraviroc treatment outcome data are required to confirm this option.

Use of cellular HIV DNA to predict virologic response to maraviroc: performance of population-based and deep sequencing

BACKGROUND

A tropism test is required before administration of the antiretroviral drug maraviroc. However, plasma RNA testing is not possible in patients with undetectable plasma viral loads. Here we assess genotypic testing of cellular human immunodeficiency virus (HIV) DNA from peripheral blood mononuclear cells (PBMCs) to predict virologic responses in treatment-experienced patients beginning maraviroc-containing regimens.

METHODS

PBMC samples from 181 maraviroc recipients at study entry in MOTIVATE or A4001029 (51% R5 by original Trofile). The V3 loop was amplified in triplicate from cellular HIV DNA, and matching plasma RNA (n = 156). Sequencing was performed using standard population-based methods and next-generation deep sequencing, with tropism assessment as previously defined.

RESULTS

Genotypic DNA-based tropism testing from the cellular compartment had 78%-81% sensitivity relative to RNA-based Trofile at the same time point. Cell-based genotypic tropism methods and plasma-based phenotypic and genotypic methods were predictive of virologic response. However, when classifications were discordant, the outcomes favored the plasma predictions over the DNA ones.

CONCLUSIONS

Genotypic determination of HIV tropism can be performed using cell-derived viral DNA, and is a predictor of virologic success on maraviroc in therapy-experienced patients. However, the PBMC compartment appears to be a suboptimal predictor compared to plasma.