Short communication: east meets west: a description of HIV-1 drug resistance mutation patterns of patients failing first line therapy in PEPFAR clinics from Uganda and Nigeria

Prevalence of viral load suppression, predictors of virological failure and patterns of HIV drug resistance after 12 and 48 months on first-line antiretroviral therapy: a national cross-sectional survey in Uganda

Objectives

We implemented the WHO cross-sectional survey protocol to determine rates of HIV viral load (VL) suppression (VLS), and weighted prevalence, predictors and patterns of acquired drug resistance (ADR) in individuals with virological failure (VF) defined as VL ≥1000 copies/mL.

Methods

We enrolled 547 and 1064 adult participants on first-line ART for 12 (±3) months (ADR12) and ≥48 months (ADR48), respectively. Dried blood spots and plasma specimens were collected for VL testing and genotyping among the VFs.

Results

VLS was 95.0% (95% CI 93.4%–96.5%) in the ADR12 group and 87.9% (95% CI 85.0%–90.9%) in the ADR48 group. The weighted prevalence of ADR was 96.1% (95% CI 72.9%–99.6%) in the ADR12 and 90.4% (95% CI 73.6–96.8%) in the ADR48 group, out of the 30 and 95 successful genotypes in the respective groups. Initiation on a zidovudine-based regimen compared with a tenofovir-based regimen was significantly associated with VF in the ADR48 group; adjusted OR (AOR) 1.96 (95% CI 1.13–3.39). Independent predictors of ADR in the ADR48 group were initiation on a zidovudine-based regimen compared with tenofovir-based regimens, AOR 3.16 (95% CI 1.34–7.46) and ART duration of ≥82 months compared with <82 months, AOR 1.92 (95% CI 1.03–3.59).

Conclusions

While good VLS was observed, the high prevalence of ADR among the VFs before they underwent the recommended three intensive adherence counselling (IAC) sessions followed by repeat VL testing implies that IAC prior to treatment switching may be of limited benefit in improving VLS.

Distinct Pattern of Thymidine Analogue Mutations with K65R in Patients Failing Tenofovir-Based Antiretroviral Therapy

Historically, in HIV patients, the K65R mutation and thymidine analogue mutations (TAMs) have been reported to rarely coexist. We retrospectively reviewed genotype data from paired samples in a cohort of HIV-1-infected Nigerian patients failing first-line antiretroviral therapies containing zidovudine (AZT) or tenofovir (TDF). Samples for each patient were taken at initial confirmed virological failure ≥1000 copies/ml (S1) and then at the latest available sample with viral load ≥1000 copies/ml before switch to second line (S2). Among 103 patients failing AZT, 19 (18.4%) had TAM-1s, 29 (28.2%) TAM-2s, and 21 (20.4%) mixed TAMs by S2. In contrast, in the 87 patients failing TDF, drug resistance mutations at S2 included K65R in 56 (64.4%), TAM-1s in 1 (1.1%), and TAM-2s in 25 patients (28.7%). Interestingly, 30.4% of patients with K65R in our study developed TAMs. These were exclusively K219E ± D67N and were not predicted to confer a resistance cost to future AZT-containing regimens.

Phenotype, Genotype, and Drug Resistance in Subtype C HIV-1 Infection

BACKGROUND

Virologic failure in subtype C is characterized by high resistance to first-line antiretroviral (ARV) drugs, including efavirenz, nevirapine, and lamivudine, with nucleoside resistance including type 2 thymidine analog mutations, K65R, a T69del, and M184V. However, genotypic algorithms predicting resistance are mainly based on subtype B viruses and may under- or overestimate drug resistance in non-B subtypes. To explore potential treatment strategies after first-line failure, we compared genotypic and phenotypic susceptibility of subtype C human immunodeficiency virus 1 (HIV-1) following first-line ARV failure.

METHODS

AIDS Clinical Trials Group 5230 evaluated patients failing an initial nonnucleoside reverse-transcriptase inhibitor (NNRTI) regimen in Africa and Asia, comparing the genotypic drug resistance and phenotypic profile from the PhenoSense (Monogram). Site-directed mutagenesis studies of K65R and T69del assessed the phenotypic impact of these mutations.

RESULTS

Genotypic algorithms overestimated resistance to etravirine and rilpivirine, misclassifying 28% and 32%, respectively. Despite K65R with the T69del in 9 samples, tenofovir retained activity in >60%. Reversion of the K65R increased susceptibility to tenofovir and other nucleosides, while reversion of the T69del showed increased resistance to zidovudine, with little impact on other NRTI.

CONCLUSIONS

Although genotype and phenotype were largely concordant for first-line drugs, estimates of genotypic resistance to etravirine and rilpivirine may misclassify subtype C isolates compared to phenotype.