Protease Inhibitor Resistance-associated Mutations Research Articles

Increased acquired protease inhibitor drug resistance mutations in minor HIV-1 quasispecies from infected patients suspected of failing on national second-line therapy in South Africa

BackgroundHIV-1C has been shown to have a greater risk of virological failure and reduced susceptibility towards boosted protease inhibitors (bPIs), a component of second-line combination antiretroviral therapy (cART) in South Africa. This study entailed an evaluation of HIV-1 drug resistance-associated mutations (RAMs) among minor viral populations through high-throughput sequencing genotypic resistance testing (HTS-GRT) in patients on the South African national second-line cART regimen receiving bPIs.MethodsDuring 2017 and 2018, 67 patient samples were sequenced using high-throughput sequencing (HTS), of which 56 samples were included in the final analysis because the patient’s treatment regimen was available at the time of sampling. All patients were receiving bPIs as part of their cART. Viral RNA was extracted, and complete pol genes were amplified and sequenced using Illumina HiSeq2500, followed by bioinformatics analysis to quantify the RAMs according to the Stanford HIV Drug Resistance Database.ResultsStatistically significantly higher PI RAMs were observed in minor viral quasispecies (25%; 14/56) compared to non-nucleoside reverse transcriptase inhibitors (9%; 5/56; p = 0.042) and integrase inhibitor RAM (4%; 2/56; p = 0.002). The majority of the drug resistance mutations in the minor viral quasispecies were observed in the V82A mutation (n = 13) in protease and K65R (n = 5), K103N (n = 7) and M184V (n = 5) in reverse transcriptase.ConclusionsHTS-GRT improved the identification of PI and reverse transcriptase inhibitor (RTI) RAMs in second-line cART patients from South Africa compared to the conventional GRT with ≥20% used in Sanger-based sequencing. Several RTI RAMs, such as K65R, M184V or K103N and PI RAM V82A, were identified in < 20% of the population. Deep sequencing could be of greater value in detecting acquired resistance mutations early.

Week 96 subgroup analyses of the phase 3, randomized AMBER and EMERALD trials evaluating the efficacy and safety of the once daily darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) single-tablet regimen in antiretroviral treatment (ART)-naïve and -experienced, virologically-suppressed adults living with HIV-1

Background Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated in AMBER (treatment-naïve adults; NCT02431247) and EMERALD (treatment-experienced, virologically-suppressed adults; NCT02269917). Objective To describe a Week 96 pre-planned subgroup analysis of D/C/F/TAF arms by demographic characteristics (age ≤/>50 years, gender, black/non-black race), and baseline clinical characteristics (AMBER: viral load [VL], CD4+ count, WHO clinical stage, HIV-1 subtype and antiretroviral resistance; EMERALD: prior virologic failure [VF], antiretroviral experience, screening boosted protease inhibitor [PI], and boosting agent). Methods Patients in D/C/F/TAF and control arms could continue on/switch to D/C/F/TAF in a single-arm, open-label extension phase after Week 48 until Week 96. Efficacy endpoints were percentage cumulative confirmed VL ≥50 copies/mL (virologic rebound; EMERALD), and VL <50 (virologic response), or ≥50 copies/mL (VF) (FDA snapshot; both trials). Results D/C/F/TAF demonstrated high Week 96 virologic responses (AMBER: 85% [308/362]; EMERALD: 91% [692/763]) and low VF rates (AMBER: 6% [20/362]; EMERALD: 1% [9/763]). In EMERALD, D/C/F/TAF showed low virologic rebound cumulative through Week 96 (3% [24/763]). Results were consistent across subgroups, including prior antiretroviral experience in EMERALD. No darunavir, primary PI, or tenofovir resistance-associated mutations were observed post-baseline. Study-drug-related serious adverse events (AEs) and AE-related discontinuations were <1% and 2%, respectively (both D/C/F/TAF arms), and similar across subgroups. eGFRcyst and bone mineral density improved or were stable and lipids increased through Week 96 across demographic subgroups, with small changes in total-cholesterol/HDL-cholesterol ratio. Conclusions D/C/F/TAF was effective with a high barrier to resistance and bone/renal safety benefits, regardless of demographic or clinical characteristics for treatment-naïve and treatment-experienced, virologically-suppressed adults.

Virological failure and HIV drug resistance among adults living with HIV on second-line antiretroviral therapy in the Asia-Pacific.

To assess second-line antiretroviral therapy (ART) virological failure and HIV drug resistance-associated mutations (RAMs), in support of third-line regimen planning in Asia. Adults >18years of age on second-line ART for ≥6months were eligible. Cross-sectional data on HIV viral load (VL) and genotypic resistance testing were collected or testing was conducted between July 2015 and May 2017 at 12 Asia-Pacific sites. Virological failure (VF) was defined as VL >1000 copies/mL with a second VL >1000 copies/mL within 3-6months. FASTA files were submitted to Stanford University HIV Drug Resistance Database and RAMs were compared against the IAS-USA 2019 mutations list. VF risk factors were analysed using logistic regression. Of 1378 patients, 74% were male and 70% acquired HIV through heterosexual exposure. At second-line switch, median [interquartile range (IQR)] age was 37(32-42) years and median (IQR) CD4 count was 103 (43.5-229.5) cells/µL; 93% received regimens with boosted protease inhibitors (PIs). Median duration on second line was 3years. Among 101 patients (7%) with VF, CD4 count >200 cells/µL at switch [odds ratio (OR)=0.36, 95% confidence interval (CI): 0.17-0.77 vs. CD4 ≤50) and HIV exposure through male-male sex (OR=0.32, 95% CI: 0.17-0.64 vs. heterosexual) or injecting drug use (OR=0.24, 95% CI: 0.12-0.49) were associated with reduced VF. Of 41 (41%) patients with resistance data, 80% had at least one RAM to nonnucleoside reverse transcriptase inhibitors (NNRTIs), 63% to NRTIs, and 35% to PIs. Of those with PI RAMs, 71% had two or more. There were low proportions with VF and significant RAMs in our cohort, reflecting the durability of current second-line regimens.

Surveillance of HIV-1 transmitted integrase strand transfer inhibitor resistance in the UK.

BackgroundHIV treatment guidelines have traditionally recommended that all HIV-positive individuals are tested for evidence of drug resistance prior to starting ART. Testing for resistance to reverse transcriptase inhibitors and PIs is well established in routine care. However, testing for integrase strand transfer inhibitor (InSTI) resistance is less consistent.ObjectivesTo inform treatment guidelines by determining the prevalence of InSTI resistance in a national cohort of recently infected individuals.Patients and methodsRecent (within 4 months) HIV-1 infections were identified using a Recent Infection Testing Algorithm of new HIV-1 diagnoses in the UK. Resistance-associated mutations (RAMs) in integrase, protease and reverse transcriptase were detected by ultradeep sequencing, which allows for the sensitive estimation of the frequency of each resistant variant in a sample.ResultsThe analysis included 655 randomly selected individuals (median age = 33 years, 95% male, 83% MSM, 78% white) sampled in the period 2014 to 2016 and determined to have a recent infection. These comprised 320, 138 and 197 samples from 2014, 2015 and 2016, respectively. None of the samples had major InSTI RAMs occurring at high variant frequency (≥20%). A subset (25/640, 3.9%) had major InSTI RAMs occurring only as low-frequency variants (2%–20%). In contrast, 47/588 (8.0%) had major reverse transcriptase inhibitor and PI RAMs at high frequency.ConclusionsBetween 2014 and 2016, major InSTI RAMs were uncommon in adults with recent HIV-1 infection, only occurring as low-frequency variants of doubtful clinical significance. Continued surveillance of newly diagnosed patients for evidence of transmitted InSTI resistance is recommended to inform clinical practice.

Polymorphisms and drug resistance analysis of HIV-1 isolates from patients on first line antiretroviral therapy (ART) in South-eastern Nigeria.

Acquisition of resistance mutations by HIV-1 isolates causes treatment failure among infected patients receiving antiretroviral therapy (ART). This study determined patterns of drug-resistance mutations (DRMs) among HIV-1 isolates from patients receiving first-line ART in South-eastern Nigeria. Blood samples were collected from HIV-1 infected patients accessing antiretroviral treatment centers at General Hospital Awo-Omamma, Imo state, State Hospital Asaba, Delta state and St Joseph's Catholic Hospital Adazi, Anambra state and used for HIV-1 DNA sequencing and phylogenetic analysis. DRMs were scored using combination of Stanford algorithm and the 2015 International Antiviral Society-USA list while drug susceptibility was predicted using Stanford algorithm. Twenty eight of the HIV-1 isolates were sequenced and identified as subtypes G (35.7%), CRF02_AG (57.1%) and unclassifiable, UG (7.1%). Major PI resistance-associated mutations were identified at two sites including M46L (16.7% of subtype G/UG) and V82L (6.3% of CRF02_AG). Minor PI resistance-associated mutations identified among subtype G/UG are L10V/I (8.3%) and K20I (100%) while L10V/I (50%), K20I (100%), L33F (6.3%) and N88D (6.3%) were identified among CRF02_AG. Other polymorphisms found include; I13V/A, E35Q, M36I/L, N37D/S/E/H, R57K/G, L63T/P/S/Q, C67E/S, H69K/R, K70R, V82I and L89M in the range of 28.6% to 100% among the different subtypes. Interpretation based on Stanford algorithm showed that Darunavir/ritonavir is the only regimen whose potency was not compromised by the circulating mutations. Identification of major and minor PI resistance mutations in this study underscores the need for drug resistance testing prior to initiation of second line antiretroviral therapy in Nigeria.

2482. Clinical Outcomes of Once-Daily Darunavir in Treatment-Experienced Patients with Darunavir Resistance Associated Mutations Through 48 Weeks of Treatment

BackgroundDarunavir (DRV) is a well-tolerated, potent protease inhibitor used once-daily in patients with no DRV resistance-associated mutations (RAMs) and twice-daily in those with DRV RAMs. Treatment guidelines encourage use of once-daily regimens to optimize patient adherence, convenience and tolerability. Several studies suggest that once-daily DRV retains efficacy in the setting of 1–2 DRV RAMs whereas 3 or more DRV RAMs (with multiple background PI RAMs) is needed for DRV resistance. Currently, there is little clinical data to support the long-term use of once-daily DRV in patients with DRV RAMs.MethodsThis is a retrospective study evaluating the 48-week clinical outcomes of 22 treatment-experienced patients with DRV RAMs switched to once-daily DRV between 2014 and 2017 at the Orlando Immunology Center. The primary endpoint was the proportion with virologic suppression (HIV-1 RNA< 50 copies/mL) at Week 48. Adherence, adverse events (AEs) and laboratory parameters were analyzed throughout the study.ResultsThe median age (range) of the sample was 53 (21–77) years, median baseline CD4+ count was 609 cells/mm3, 18 (82%) had baseline HIV-1 RNA <50 copies/mL, 15 (69%) had previously used 1 or more PIs and median number (range) of baseline DRV RAMs was 2 (1–5) (Table 1). At Week 48, 20 (91%) had HIV-1 RNA <50 copies/mL; 2 (9%) virologic non-responders had HIV-1 RNA of 82 and 59,637 copies/mL and reported noncompliance (Figure 1). There was no significant change in median CD4+ count from baseline to Week 48 (+22, 95% confidence interval (CI): [−116.5; 56.0]). Once-daily DRV was associated with a significant median increase in HDL cholesterol (+82, 95% CI: [37.0; 101.0]) and a significant median decrease in LDL cholesterol (-60, 95% CI: [-89.5; -31.0]). There were no significant changes in the proportion of patients on lipid lowering therapy at baseline and week 48 (p = 0.33). There were no self-reported AEs or Grade 3–4 lab abnormalities through Week 48.ConclusionOnce-daily DRV maintained virologic control in this cohort of treatment-experienced patients with 1 or more baseline DRV RAMs and was safe and well-tolerated. This suggests that once-daily DRV may be effective in this population however further data are needed to validate this as a viable treatment option. Disclosures All authors: No reported disclosures.

Week 96 efficacy and safety results of the phase 3, randomized EMERALD trial to evaluate switching from boosted-protease inhibitors plus emtricitabine/tenofovir disoproxil fumarate regimens to the once daily, single-tablet regimen of darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) in treatment-experienced, virologically-suppressed adults living with HIV-1

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg was investigated through 96 weeks in EMERALD (NCT02269917).Virologically-suppressed, HIV-1-positive treatment-experienced adults (previous non-darunavir virologic failure [VF] allowed) were randomized (2:1) to D/C/F/TAF or boosted protease inhibitor (PI) plus emtricitabine/tenofovir-disoproxil-fumarate (F/TDF) over 48 weeks. At week 52 participants in the boosted PI arm were offered switch to D/C/F/TAF (late-switch, 44 weeks D/C/F/TAF exposure). All participants were followed on D/C/F/TAF until week 96. Efficacy endpoints were percentage cumulative protocol-defined virologic rebound (PDVR; confirmed viral load [VL] ≥50 copies/mL) and VL < 50 copies/mL (virologic suppression) and ≥50 copies/mL (VF) (FDA-snapshot analysis).Of 1141 randomized patients, 1080 continued in the extension phase. Few patients had PDVR (D/C/F/TAF: 3.1%, 24/763 cumulative through week 96; late-switch: 2.3%, 8/352 week 52–96). Week 96 virologic suppression was 90.7% (692/763) (D/C/F/TAF) and 93.8% (330/352) (late-switch). VF was 1.2% and 1.7%, respectively. No darunavir, primary PI, tenofovir or emtricitabine resistance-associated mutations were observed post-baseline. No patients discontinued for efficacy-related reasons. Few discontinued due to adverse events (2% D/C/F/TAF arm). Improved renal and bone parameters were maintained in the D/C/F/TAF arm and observed in the late-switch arm, with small increases in total cholesterol/high-density-lipoprotein-cholesterol ratio. A study limitation was the lack of a control arm in the week 96 analysis.Through 96 weeks, D/C/F/TAF resulted in low PDVR rates, high virologic suppression rates, very few VFs, and no resistance development. Late-switch results were consistent with D/C/F/TAF week 48 results. EMERALD week 96 results confirm the efficacy, high genetic barrier to resistance and safety benefits of D/C/F/TAF.

Prevalence of Darunavir Resistance in the United States from 2010 to 2017.

The emergence and transmission of antiretroviral drug resistance have been and remain a concern among people living with human immunodeficiency virus (HIV)-1 infection. The protease inhibitor (PI) darunavir has been approved for use in the United States for more than 10 years and has demonstrated a high barrier to resistance. Previous analyses identified significant reductions in the prevalence of samples with darunavir resistance-associated mutations (RAMs) and with phenotypic resistance to darunavir and other PIs between 2006 and 2012. This analysis extends those findings by evaluating darunavir and PI resistance among clinical samples submitted for routine drug resistance testing (combined genotyping and phenotyping) in the United States from 2010 to 2017. Frequencies of 11 darunavir and 23 primary PI RAMs, and phenotypic susceptibility, were assessed yearly among all samples and in a subset of samples with distinct phenotypic resistance to one or more PIs. Among all samples (N = 60,760), the proportion with 0 darunavir RAMs was 91.7% in 2010 and 95.8% in 2017. The proportions of all samples with phenotypic susceptibility to darunavir, atazanavir, and lopinavir were, respectively, 97.4%, 94.2%, and 94.7% in 2010 and 98.6%, 97.7%, and 97.5% in 2017. Among the 4,799 samples with phenotypic resistance to one or more PIs, the proportions with phenotypic susceptibility to darunavir, atazanavir, and lopinavir were, respectively, 73.3%, 41.5%, and 46.0% in 2010 and 70.7%, 53.7%, and 48.8% in 2017. The prevalence of darunavir RAMs among commercially tested HIV-1 samples remained low and generally stable from 2010 to 2017, and high proportions showed phenotypic darunavir susceptibility.

A Surveillance on Protease Inhibitor Resistance-Associated Mutations Among Iranian HIV-1 Patients

Background: Drug resistance is emerging as one of the greatest challenges in the development of effective treatment for HIV infection. The importance of clinical studies in this field stems from the world wide growing of treatment drug-resistant mutations. Objectives: This study was performed to determine the HIV subtype and the resistance mutations to the protease inhibitors in both untreated HIV patients and patients under treatment with protease inhibitors (PIs) in Iran. Methods: The study was conducted on two groups of participants. The first group consisted of 25 HIV patients who did not receive any antiretroviral treatment. The second group included 25 HIV patients who have being treated with a combination of protease inhibitors. After genome extraction, a nested polymerase chain reaction was performed to amplify the protease gene. Upon confirmation using electrophoresis, the amplicons or PCR products were sequenced and analyzed to determine the drug resistance mutations as well as the viral subtypes. Results: No mutations were found in the first group; however, 32% of the samples in the second group had PI related drug-resistance mutations. The major mutations were V82A and M46I, which were seen in 12% of the samples, while the minor mutation F53L was seen in 16% of the samples. The subtype analysis showed that 94% of the samples were subtype CRF35_AD, and 6% were of defined as subtype A. Conclusions: The present study reports updates on the mutations related to protease resistance in Iranian HIV patients receiving treatment. Our data, as well as existing reports, support the need for the optimization of treatment to prevent emergence of resistant viruses and a search for new antiretroviral drug candidates for HIV patients.

HIV-1 Drug Resistance and Third-Line Therapy Outcomes in Patients Failing Second-Line Therapy in Zimbabwe.

ObjectivesTo analyze the patterns and risk factors of HIV drug resistance mutations among patients failing second-line treatment and to describe early treatment responses to recommended third-line antiretroviral therapy (ART) in a national referral HIV clinic in Zimbabwe.MethodsPatients on boosted protease inhibitor (PI) regimens for more than 6 months with treatment failure confirmed by 2 viral load (VL) tests >1000 copies/mL were genotyped, and susceptibility to available antiretroviral drugs was estimated by the Stanford HIVdb program. Risk factors for major PI resistance were assessed by logistic regression. Third-line treatment was provided as Darunavir/r, Raltegravir, or Dolutegravir and Zidovudine, Abacavir Lamivudine, or Tenofovir.ResultsGenotypes were performed on 86 patients who had good adherence to treatment. The median duration of first- and second-line ART was 3.8 years (interquartile range [IQR], 2.3–5.1) and 2.6 years (IQR, 1.6–4.9), respectively. The median HIV viral load and CD4 cell count were 65 210 copies/mL (IQR, 8728–208 920 copies/mL) and 201 cells/mm3 (IQR, 49–333 cells/mm3). Major PI resistance-associated mutations (RAMs) were demonstrated in 44 (51%) non-nucleoside reverse transcriptase inhibitor RAMs in 72 patients (83%) and nucleoside reverse transcriptase inhibitors RAMs in 62 patients (72%). PI resistance was associated with age >24 years (P = .003) and CD4 cell count <200 cells/mm3 (P = .007). In multivariable analysis, only age >24 years was significantly associated (adjusted odds ratio, 4.75; 95% confidence interval, 1.69–13.38; P = .003) with major PI mutations. Third-line DRV/r- and InSTI-based therapy achieved virologic suppression in 29/36 patients (81%) after 6 months.ConclusionsThe prevelance of PI mutations was high. Adolescents and young adults had a lower risk of acquiring major PI resistance mutations, possibly due to poor adherence to ART. Third-line treatment with a regimen of Darunavir/r, Raltegravir/Dolutegravir, and optimized nucleoside reverse transcriptase inhibitors was effective.

The Second-Generation Maturation Inhibitor GSK3532795 Maintains Potent Activity Toward HIV Protease Inhibitor-Resistant Clinical Isolates.

Protease inhibitor (PI)-resistant HIV-1 isolates with primary substitutions in protease (PR) and secondary substitutions in Gag could potentially exhibit cross-resistance to maturation inhibitors. We evaluated the second-generation maturation inhibitor, GSK3532795, for activity toward clinical isolates with genotypic and phenotypic characteristics associated with PI resistance (longitudinal). Longitudinal clinical isolates from 15 PI-treated patients and 7 highly PI-resistant (nonlongitudinal) viruses containing major and minor PI resistance-associated mutations were evaluated for GSK3532795 sensitivity. Phenotypic sensitivity was determined using the PhenoSense Gag/PR assay (Monogram Biosciences) or in-house single- and multiple-cycle assays. Changes from baseline [CFB; ratio of post- to pre-treatment FC-IC50 (fold-change in IC50 versus wild-type virus)] <3 were considered to be within the no-effect level. All nonlongitudinal viruses tested were sensitive to GSK3532795 (FC-IC50 range 0.16-0.68). Among longitudinal isolates, all post-PI treatment samples had major PI resistance-associated mutations in PR and 17/21 had PI resistance-associated changes in Gag. Nineteen of the 21 post-PI treatment samples had GSK3532795 CFB <3. Median (range) CFB was 0.83 (0.05-27.4) [Monogram (11 patients)] and 1.5 (1.0-2.2) [single-cycle (4 patients)]. The 2 post-PI treatment samples showing GSK3532795 CFB >3 (Monogram) were retested using single- and multiple-cycle assays. Neither sample had meaningful sensitivity changes in the multiple-cycle assay. Gag changes were not associated with an increased GSK3532795 CFB. GSK3532795 maintained antiviral activity against PI-resistant isolates with emergent PR and/or Gag mutations. This finding supports continued development of GSK3532795 in treatment-experienced patients with or without previous PI therapy.

Naturally occurring hepatitis C virus protease inhibitors resistance-associated mutations among chronic hepatitis C genotype 1b patients with or without HIV co-infection

The aim of this study was to measure the frequency of natural mutations in hepatitis C virus (HCV) mono-infected and HIV/HCV co-infected protease inhibitor (PI)-naive patients. Population sequence of the non-structural (NS)3 protease gene was evaluated in 90 HCV mono-infected and 96 HIV/HCV co-infected PI treatment-naive patients. The natural prevalence of PI resistance mutations in both groups was compared. Complete HCV genotype 1b NS3 sequence information was obtained for 152 (81.72%) samples. Seven sequences (8.33%) of the 84 HCV mono-infected patients and 21 sequences (30.88%) of the 68 HIV/HCV co-infected patients showed amino acid substitutions associated with HCV PI resistance. There was a significant difference in the natural prevalence of PI resistance mutations between these two groups (P = 0.000). The mutations T54S, R117H and N174F were observed in 1.19%, 5.95% and 1.19% of HCV mono-infected patients. The mutations F43S, T54S, Q80K/R, R155K, A156G/V, D168A/E/G and V170A were found in 1.47%, 4.41%, 1.47%/1.47%, 2.94%, 23.53%/1.47%, 1.47%/1.47%/1.47% and 1.47% of HIV/HCV co-infected patients, respectively. In addition, the combination mutations in the NS3 region were detected only in HIV/HCV genotype 1b co-infected patients. Naturally occurring HCV PI resistance mutations existed in HCV mono-infected and HIV/HCV co-infected genotype 1b PI-naive patients. HIV co-infection was associated with a greater frequency of PI resistance mutations. The impact of HIV infection on baseline HCV PI resistance mutations and treatment outcome in chronic hepatitis C (CHC) patients should be further analyzed.

Prevalence of HIV-1 drug resistance among patients failing first-line ART in Monrovia, Liberia: a cross-sectional study.

To assess the prevalence of acquired drug resistance in HIV-1-infected patients living in Monrovia, Liberia, who had clinical and/or immunological failure of first-line ART according to WHO criteria. Patients receiving ART for >1 year with clinical and/or immunological failure were included. Sequencing of protease and reverse transcriptase regions was performed using Agence Nationale de Recherche sur le SIDA et les hépatites virales (ANRS) procedures and sequences were interpreted using the ANRS resistance algorithm. Ninety patients were enrolled. They had been receiving ART for a median time of 42 months and half were receiving zidovudine/lamivudine/nevirapine. Seventy-five per cent of patients were infected with CRF02_AG. Twenty-seven per cent of patients displayed a plasma viral load <50 copies/mL. Among the 66 patients with detectable viraemia, the median viral load was 4.7 log10 copies/mL (IQR = 3.0-5.6). The prevalence of NRTI and NNRTI resistance-associated mutations (RAMs) was 63% and 71%, respectively; and the median number of NRTI and NNRTI RAMs was 2 and 3, respectively. Two patients (4%) displayed viruses with PI RAMs. Regarding NRTI drug resistance, 29%, 38%, 63%, 29% and 25% of patients had viruses resistant to zidovudine, stavudine, lamivudine/emtricitabine, abacavir and tenofovir, respectively. Regarding the NNRTI drug class, 56%, 65%, 33% and 42% of patients had viruses resistant to efavirenz, nevirapine, etravirine and rilpivirine, respectively. The high prevalence of acquired drug resistance in patients followed in two centres of the Liberian capital city, documented after a median of 3 years on a first-line ART regimen, jeopardizes the activity of second-line regimens and highlights the need for virological monitoring in these settings.

Efficacy of Once Daily Darunavir/Ritonavir in PI-Naïve, NNRTI-Experienced Patients in the ODIN Trial.

Background. An exploratory subanalysis of the ODIN trial was performed to evaluate the efficacy of darunavir/ritonavir (DRV/r) 800/100 mg OD versus 600/100 mg BID in patients who were NNRTI-experienced but PI-naïve. Methods. ODIN was a phase III, 48-week study comparing DRV/r OD versus BID in 590 treatment-experienced patients with no DRV resistance-associated mutations (RAMs) at screening. Patients received DRV/r 800/100 mg OD or DRV/r 600/100 mg BID plus ≥2 NRTIs. Of the 590 patients randomized, 272 (46%) were NNRTI-experienced but PI-naïve. Results. Overall, 272 patients received DRV/r OD (n = 135) or BID (n = 137) plus ≥2 optimised NRTIs. The mean age was 39 years; 35% were female; 27% were Black, 24% Caucasian, 26% Oriental/Asian, and 23% other races; 17% were recruited in South Africa; and 48% had non-B HIV-1 subtypes. Mean baseline plasma HIV-1 RNA load was 4.10 log10⁡ copies/mL; median CD4 cell count was 258 cells/μL. At week 48, 111/135 (82%) of DRV/r OD and 109/137 (80%) of DRV/r BID patients achieved an HIV-1 RNA load <50 copies/mL. No patient developed primary PI RAMs. Conclusion. DRV/r 800/100 mg OD in combination with ≥2 optimised NRTIs led to virological suppression <50 copies/mL in 82% of NNRTI-experienced, PI-naïve patients by week 48.

Darunavir: A Review of Its Use in the Management of HIV-1 Infection

The latest HIV-1 protease inhibitor (PI) darunavir (Prezista™) has a high genetic barrier to resistance development and is active against wild-type HIV and HIV strains no longer susceptible to some older PIs. Ritonavir-boosted darunavir, as a component of antiretroviral therapy (ART), is indicated for the treatment of HIV-1 infection in adult and paediatric patients (aged ≥3years), with or without treatment experience (details vary depending on region of approval). Several open-label or partially-blinded trials have evaluated the efficacy of ritonavir-boosted darunavir ART regimens for up to 192weeks in these settings. In treatment-naïve adults, once-daily boosted darunavir was no less effective in establishing virological suppression than once- or twice-daily boosted lopinavir, yet was more effective at maintaining suppression long term. Moreover, treatment-experienced adults with no darunavir resistance-associated mutations (RAMs) had no less effective viral load suppression with once-daily than with twice-daily boosted darunavir. In treatment-experienced adults, including some with multiple major PI RAMs, twice-daily boosted darunavir was more effective than twice-daily boosted lopinavir or boosted control PIs in reducing viral load, and provided virological benefit as part of a salvage regimen in those with few remaining treatment options. Boosted darunavir also reduced viral load when administered once-daily in treatment-naïve adolescents or twice-daily in treatment-experienced children and adolescents. Boosted darunavir is generally well tolerated, with gastrointestinal disturbances and lipid abnormalities among the most common tolerability issues. It has a lipid profile more favourable than that of boosted lopinavir in terms of total cholesterol and triglyceride changes and, when administered once daily, its lipid effects are generally similar to those of boosted atazanavir. Thus, boosted darunavir is a useful option for the ART regimens of adult and paediatric patients with HIV-1 infection.

Virological Analysis of Once-Daily and Twice-Daily Darunavir/Ritonavir in the Odin Trial of Treatment-Experienced Patients

The aim of this analysis was to characterize viral resistance in the Phase III, randomized ODIN trial, which demonstrated non-inferiority of once-daily darunavir/ritonavir (DRV/r) 800/100 mg to DRV/r 600/100 mg twice daily, each combined with an optimized background regimen in treatment-experienced patients with no DRV resistance-associated mutations (RAMs) at screening. Virological failure (VF) was defined as never achieving or losing confirmed virological suppression after week 12, with patients being classed as 'never suppressed' (never achieved HIV-1 RNA<50 copies/ml) or 'rebounders' (achieved two consecutive HIV-1 RNA<50 copies/ml but then ≥ 50 copies/ml). Phenotypes and genotypes of plasma HIV-1 viruses, using population-based sequencing and Antivirogram(®), were determined at screening/baseline and on samples from VFs with HIV-1 RNA ≥ 50 copies/ml. Mean baseline HIV-1 RNA was 4.16 log10 copies/ml and 53.9% of patients were protease inhibitor (PI)-experienced at enrolment. VF rate was similar in both arms. A similar proportion of virologically failing patients in both arms developed PI RAMs (11.7% versus 9.5%, respectively) or nucleoside reverse transcriptase inhibitor RAMs (6.7% versus 7.1%). One patient with VF (once-daily arm) developed four primary PI mutations, three of which were also DRV RAMs. This patient was also the only VF to lose susceptibility to DRV. Loss of susceptibility to other PIs (once daily 3.4%; twice daily 0%) and nucleoside reverse transcriptase inhibitors (once daily 13.6%; twice daily 9.8%) in VF patients was infrequent and comparable between treatment arms. These analyses showed once-daily DRV/r 800/100 mg was associated with similar rates of VF and emergence of resistance as DRV/r 600/100 mg twice daily in treatment-experienced patients with no DRV RAMs.

Darunavir Resistance in HIV Infecting Protease Inhibitor-Experienced Mexican Patients

Background: Darunavir (DRV) is a useful antiretroviral treatment in the salvage therapy of multiclass-resistant HIV-infected patients. This study’s aim was to determine the frequency and risk factors for DRV resistance-associated mutations (DRV-RAM) among DRV-naive Mexican patients with virologic failure after extensive antiretroviral treatment and exposure to at least one protease inhibitor (PI). Methods: HIV-infected patients with a history of at least 2 failed regimes were included and their clinical histories and genotype resistance tests were analyzed. Major PI resistance-associated mutations (PI-RAM), DRV-RAM and resistance to DRV were defined according to the IAS-USA criteria. Previous exposure to PI was compared between patients with DRV-resistant HIV and DRV-susceptible HIV-infected controls. Results: The median number of major PI-RAM was 2 (IQR = 0 - 3). In 54.7% (95% CI = 50.0% - 59.4%) of 631 subjects, no DRV-RAM were found on viral genotyping and 6.7% (95% CI = 4.8% - 8.6%) had 3 or more DRV-RAM. The two most frequently found DRV-RAM were in codons I84V (in 22.7% of cases) and L33F (in 20% of cases) in the viral protease gene. The number of major PI-RAM (as a surrogate marker of duration and number of PI used) and previous exposure to (fos) amprenavir or tipranavir were independently associated with DRV-resistant HIV infection. Conclusions: In this Mexican population, despite a high prior PI exposure, HIV-DRV resistance rate is relatively low and successful viral control with DRV-containing combined salvage therapy is expected in most patients.

Antiviral activity of dolutegravir in subjects with failure on an integrase inhibitor‐based regimen: week 24 phase 3 results from VIKING‐3

BackgroundVIKING-3 aimed to examine efficacy and safety of dolutegravir (DTG) 50 mg twice daily in patients with resistance to multiple ARV classes, including integrase inhibitors (INI).MethodsRAL and/or EVG-resistant (current or historical) adult subjects with screening plasma HIV-1 RNA ≥500 c/mL and resistance to ≥2 other ART classes received open-label DTG 50 mg BID while continuing their failing regimen (without RAL/EVG). At Day 8 the background regimen was optimised and DTG continued. Activity of the optimized background regimen (OBR) was determined by Monogram Net Assessment. Primary endpoints were antiviral efficacy at Day 8 and Week 24.Results183 subjects enrolled, 124 with INI-resistance at screening and 59 with historical (but no screening) resistance. Population was advanced: at BL, median CD4 140, prior ART 13 yrs, 56% CDC Class C; 79% had >2 NRTI, 75% >1 NNRTI, and 70% >2 PI resistance-associated mutations, and 61% had non-R5 HIV detected. Of the 114 subjects who had the opportunity to complete 24 weeks on study before data cutoff, 72 (63%) had <50 c/mL RNA at Week 24 (SNAPSHOT algorithm). Mean HIV RNA declined by 1.4 log10 c/mL (95% CI: 1.3, 1.5; p < 0.001) at Day 8; response differed by genotype pathway (Table).Primary INI mutations at BLNMean HIV RNA (log 10) Change from BL (SD) at Day 8%>1 log HIV RNA decline of <50 c/mL at Day 8TOTAL183−1.4 (0.61)82%T661−1.9100%Y14328−1.7 (0.42)96%N15533−1.4 (0.51)82%Q148 + ≤1 secondary mutation# 32−1.1 (0.51)69%Q148 + ≥2 secondary mutations# 20−1.0 (0.81)48%≥2 primary mutations8−1.4 (0.76)75%No primary mutations60−1.6 (0.55)95%#Key secondary mutations comprised G140_ACS, L741, E138_AKT.In subjects with Q148 pathway mutations, virologic response decreased with increasing number of secondary mutations. Background overall susceptibility score (OSS) was not associated with Wk 24 response: % <50 c/mL were 83%, 63%, 59% and 69% for OSS 0, 1, 2 and >2, respectively. Discontinuations due to adverse events were uncommon (6/183, 3%); the most common drug-related AEs were diarrhoea, nausea and headache, each reported in only 5% of subjects.ConclusionA majority of the highly treatment-experienced subjects in VIKING-3 achieved suppression with DTG-based therapy. Responses were associated with Baseline IN genotype but not OSS, highlighting the importance and independence of DTG antiviral activity. DTG had a low rate of discontinuation due to adverse events at 50 mg BID in this advanced patient population.

A phase 4, single‐arm, open‐label, pilot study of maraviroc, raltegravir and darunavir/r in HIV‐1 adults with triple class failure: TERCETO study

The purpose of this phase 4, single‐arm, open‐label study was to evaluate the safety, tolerability, efficacy, antiviral and immunological activity of maraviroc (MVC) in combination with raltegravir (RGV) and darunavir/r (DRV/r) in adult HIV‐1 infected patients (pts) with limited treatment options. HIV‐1 pts with documented virologic triple class failure or multi‐drug class resistance defined as the presence of Q151 complex, 69 insertion complex and/or≥3 TAMs for NRTIs and K103N, G190S+Y181C or Y188L mutants for NNRTIs and≥3 RAMs (L10F/I/R/V; M46I/L; I54V/M/L; V82A/F/T/S; I84V; L90M) for protease inhibitors (PIs) were offered a triple drug regimen consisting of MVC 150 mg BID, RGV 400 mg BID and DRV/r 600/100 mg BID. Safety, lipid profile and virologic efficacy were evaluated at week 4, 12, 24, 36 and 48. Between January 2010 and March 2012, 27 pts were enrolled. Screening failure rate was 52% due to undetectable viral load (pVL) or non R5 tropism type (Trofile™). Despite being heavily pre‐treated pts, only 26% had negative tropism test at SCR. Baseline characteristics of 13 included pts were: 77% male, median age 43 years (IQR: 40.1–48.6), 38% had a prior AIDS‐defining condition. Median BSL pVL was 23,350 cps/mL (4.4 log10) (IQR: 11,236–55,785) and median CD4 was 222 cells/mm3 (IQR: 179–318). Median time on NRTIs, NNRTIs and PIs were 10.7 (8.6–13.7), 1.7 (1.3–7.6) and 5.4 (4.7–10) years respectively. Pts had received a median of 2 PIs (IQR: 2–3). 8/13 pts showed thymidine analogue‐associated mutations (TAMs), and≥2 were present in 5/13. Detectable NNRTI resistance‐associated mutations (RAMs) were present in 10/13 patients. 9/13 had≥4 primary PI RAMs. At 48 weeks, 2 pts had discontinued therapy (OIs related death (cryptococcal meningitis)=1, withdrawn from the study on W36 due to blips despite not achieving criteria for virologic failure=1) and the remaining pts (11/13) achieved undetectable pVL and increased CD4 in 133 cell/mm3 from BSL (IQR: 81–174.5). Median total cholesterol levels increased from 162 mg/dL (IQR: 135‐188) to 215 mg/dL (IQR: 182–237) between BSL/W48; median change in cholesterol levels: 40 mg/dL (IQR: 6.5‐66). Salvage therapy including MVC, RGV and DRV/r achieved sustained reductions in pVL (&lt;50 copies/mL) through 48 weeks of therapy in this pilot study with no treatment limiting toxicity.AcknowledgementsTERCETO study was sponsored through an investigator‐initiated research (IIR) grant from Pfizer Inc. Merck provided raltegravir.

Dynamics of gag-pol minority viral populations in naive HIV-1-infected patients failing protease inhibitor regimen

Recently, we have reported the role of baseline gag cleavage site mutations on the virological outcome of a dual-boosted protease inhibitor regimen in antiretroviral-naive patients (2IP-ANRS 127 trial). The objective of this substudy was to characterize, in patients experiencing virological failure, from the 2IP-ANRS 127 trial, the viral quasispecies present at baseline and at virological failure in gag cleavage site, in gag-pol frameshift and in protease-coding region. In four patients, we analysed by clonal analysis the viral population in gag cleavage site (p17/p24, p24/p2, p2/p7, p7/p1, p1/p6(gag)), in p6(gag), in gag-pol frameshift [p1/transframe protein (TFP)/p6(pol)] and in protease-coding region. Clonal analysis of protease-coding region failed to detect major as well as minor protease inhibitor resistance-associated mutations in all four patients. In one patient, a I15V-mutated variant increased from 13 to 100% between baseline and week 24. Clonal analysis of gag and gag-pol cleavage site showed an increase in specific viral populations in p2/p7 cleavage site between baseline and virological failure in three patients. Among them, we described in one patient, that the predominant population at virological failure harboured in p2/p7 and TFP/p6(pol)-specific genotypic profiles associated with duplication of the P(T)APP motif in p6(gag) and the I15V protease mutation on the same individual molecular clones. We highlighted the emergence of minority viral populations in the p2/p7 cleavage site between baseline and virological failure. In addition, we showed the association of a specific protease mutation with gag and gag-pol cleavage site substitutions, suggesting their possible role in virological outcome.