Low-frequency pre-treatment HIV drug resistance: effects on 2-year outcome of first-line efavirenz-based antiretroviral therapy.

OBJECTIVES: Assess the impact of pre-treatment high-frequency and low-frequency drug-resistant HIV variants on long-term outcomes of first-line efavirenz-based antiretroviral therapy (ART). DESIGN: Prospective observational study. METHODS: Participants' pre-treatment plasma RNA had two sections of HIV pol encoding reverse transcriptase sequenced (Illumina, MiSeq) using unique molecular identifiers to detect wild-type (pre-treatment drug-resistant variants less than 1% of viral quasispecies), low-frequency (1-9%) or high-frequency drug-resistant variants (10-100%). Associations between pre-treatment drug resistance and virologic outcomes over 24 months of efavirenz-based ART were assessed for the number and frequency of mutations by drug class and other resistance parameters. RESULTS: Virologic failure was detected in 30 of 352 (9%) and pre-treatment drug-resistant variants were detected in the viral quasispecies of 31 of 352 (9%) participants prescribed efavirenz-based ART. Survival analyses revealed statistically significant associations between pre-treatment drug resistance at low (P < 0.0001) and high (P < 0.001) frequencies, at oligonucleotide ligation assay (OLA) (P < 0.00001) and non-OLA (P < 0.01) codons, to a single-antiretroviral class (P < 0.00001), and a shorter time to virologic failure of efavirenz-based ART. Regression analyses detected independent effects across resistance categories, including both low-frequency (P < 0.01) and high-frequency (P < 0.001) drug-resistant variants. CONCLUSION: We observed that pre-treatment HIV drug resistance detected at low frequencies increased the risk of virologic failure over 24 months of efavirenz-based ART, but that most failures, regardless of drug-resistant variants' frequencies, were detected within a year of ART initiation. These observations suggest that when efavirenz-based ART is prescribed, screening for pre-treatment drug resistance by an assay capable of detecting low-frequency variants, including OLA, may guide clinicians to prescribe more effective ART.

Pre-treatment HIV-drug resistance associated with virologic outcome of first-line NNRTI-antiretroviral therapy: A cohort study in Kenya.

BACKGROUND: Pre-treatment HIV-drug-resistance (PDR) to WHO-recommended 1st-line non-nucleoside reverse transcriptase inhibitors (NNRTI)-based antiretroviral treatment (ART) is increasing in low-resource communities. We evaluated the risk of PDR on treatment failure if detected at single or multiple codons, at minority (2-9%) or higher (≥10%) frequencies during efavirenz- vs. nevirapine-ART. METHODS: We conducted a pooled analysis across three cohorts of Kenyans initiating 1st-line NNRTI-ART between 2006 and 2014. Mutations K103N, Y181C, G190A, M184V and K65R were detected by an oligonucleotide ligation assay (OLA) and confirmed by Sanger and next-generation sequencing (NGS). PDR was defined as detection of any mutation by OLA when confirmed by NGS. Treatment failure, defined as plasma HIV RNA ≥400 copies/mL at month-12 of ART, was compared by PDR genotypes. FINDINGS: PDR was detected in 59/1231 (4·8%) participants. Compared to wild-type genotypes, PDR in participants prescribed nevirapine-ART was associated with increased treatment failure [PDR 69·2% (27/39) vs. wild-type 10·4% (70/674); p = 0·0001], whether detected as minority [66·7% (4/6)] or higher [69·7% (23/33)] frequencies in an individual's HIV quasispecies (p = 0·002 and p < 0·0001, respectively), or mutations at single [50·0% (12/24)] or multiple [100·0% (15/15)] codons (p < 0·0001). During efavirenz-ART, PDR was also associated with increased virologic failure [PDR 25·0% (5/20) vs. wild-type 5·0% (25/498); p = 0·005], but only if detected at multiple drug-resistant codons [50·0% (3/6); p = 0·003] or high frequencies PDR [33·3% (5/15); p = 0·001]. INTERPRETATION: The risk that PDR confers for treatment failure varies by number of mutant codons and their frequency in the quasispecies, with a lower risk for efavirenz- compared to nevirapine-based regimens. PDR detection and management could extend the effective use of efavirenz-ART in low-resource settings. FUNDING: NIH, PEPFAR.

Implementation of a point mutation assay for HIV drug resistance testing in Kenya.

OBJECTIVES: An increasing prevalence of HIV pretreatment drug resistance (PDR) has been observed in Africa, which could decrease the effectiveness of antiretroviral therapy (ART) programs. We describe our experiences, the costs and challenges of implementing an oligonucleotide ligation assay (OLA) for management of PDR in Nairobi, Kenya. DESIGN: An observational report of the implementation of OLA in a Kenyan laboratory for a randomized clinical trial evaluating whether onsite use of OLA in individuals initiating ART would decrease rates of virologic failure. METHODS: Compared detection of mutations and proportion of mutants in participants' viral quasispecies by OLA in Kenya vs. Seattle. Reviewed records of laboratory workflow and performance of OLA. Calculated the costs of laboratory set-up and of performing the OLA based on equipment purchase receipts and supplies and labor utilization, respectively. RESULTS: OLA was performed on 492 trial participants. Weekly batch-testing of median of seven (range: 2-13) specimens provided test results to Kenyan clinicians within 10-14 days of sample collection at a cost of US$ 42 per person tested. Cost of laboratory setup was US$ 32 594. Challenges included an unreliable local supply chain for reagents and the need for an experienced molecular biologist to supervise OLA performance. CONCLUSION: OLA was successfully implemented in a Kenyan research laboratory. Cost was twice that projected because of fewer than predicted specimens per batch because of slow enrollment. OLA is a potential simple, low-cost method for PDR testing in resource-limited settings (RLS). Ongoing work to develop a simplified kit could improve future implementation of OLA in RLS.