Efficacy and safety of dolutegravir or darunavir in combination with lamivudine plus either zidovudine or tenofovir for second-line treatment of HIV infection (NADIA): week 96 results from a prospective, multicentre, open-label, factorial, randomised, non-inferiority trial

Pretreatment and acquired HIV drug resistance in Belize-results of nationally representative surveys, 2021-22

BACKGROUND

The rising prevalence of pretreatment drug resistance (PDR) to non-nucleoside reverse-transcriptase inhibitors threatens the effectiveness of ART. In response, the WHO recommends dolutegravir-based ART regimens due to their high genetic barrier to resistance and better treatment outcomes. This is expected to contribute to achieving the Joint United Nations Programme on HIV/AIDS (UNAIDS) target of 95% viral suppression in people on ART.

OBJECTIVES

To estimate the prevalence of PDR among adults initiating ART and assess viral suppression and acquired HIV drug resistance (ADR) among individuals receiving ART in Belize.

PATIENTS AND METHODS

Nationally representative cross-sectional PDR and ADR surveys were conducted between 2021 and 2022. Sixty-seven adults were included in the PDR survey, and 43 children and adolescents and 331 adults were included in the ADR survey. Demographic and clinic data and blood specimens were collected. HIV drug resistance (HIVDR) was predicted using the Stanford HIVdb tool.

RESULTS

The prevalence of PDR to efavirenz or nevirapine in adults was 49.3% (95% CI 42.2%-56.4%) and was significantly higher in those with previous antiretroviral exposure (OR: 7.16; 95% CI 2.71-18.95; P = 0.002). Among children and adolescents receiving ART, 50.0% had viral suppression, with better rates for those receiving dolutegravir-based ART (OR: 5.31; 95% CI 3.02-9.34; P < 0.001). In adults, 79.6% achieved viral suppression. No resistance to integrase inhibitors was observed in those on dolutegravir-based ART.

CONCLUSIONS

Prioritizing dolutegravir-based ART is critical for achieving HIV epidemic control in Belize. Efforts should focus on retention in care and adherence support to prevent HIVDR.

Emergent resistance-associated mutations at first- or second-line HIV-1 virologic failure with second-generation InSTIs in two- and three-drug regimens: the Virostar-1 study

BACKGROUND

Second-generation integrase strand transfer inhibitors (InSTIs) have a high barrier to resistance and potent antiretroviral activity. They are recommended as first- or second-line (FL and SL) options in two- and three-drug regimens (2DR and 3DR) in international treatment guidelines. However, there are limited real-world data on emerging resistance at the time of virological failure (VF) with these regimens.

OBJECTIVES

The Virostar-1 study objective is to analyse the emergence of resistance-associated mutations (RAMs) over 3 years with DTG-based 2DRs and DTG- or bictegravir (BIC)-based 3DRs in people living with HIV (PLWH) experiencing a VF (FL or SL).

METHODS

Retrospective analysis of genotypic resistance detected at the time of a FL or SL VF with BIC/FTC/TAF, DTG/ABC/3TC, DTG/3TC and DTG/RPV between 2019 and 2022 was conducted from a French multicentre database. VF was defined as two consecutive HIV-1 plasma viral loads > 50 c/mL. Sanger assays were performed at VF within standard clinical care. Resistance mutations were reported using the ANRS algorithm. Selection biases prevent group comparisons.

RESULTS

During the period, N = 5986 PLWH were followed either in FL or SL. The VF rate was overall low: BIC/FTC/TAF, 6.8%; DTG/ABC/3TC, 7.5%; DTG/3TC, 5.1%; and DTG/RPV, 2.1%. Some emergent InSTI or NRTI RAMs were detected with BIC/FTC/TAF 4%, DTG/ABC/3TC 8.5%, DTG/3TC 18% and 39% emergent NNRTI RAMs with DTG/RPV. However, a complete absence of dual resistance against NRTIs and InSTIs was observed.

CONCLUSIONS

We detected rare emergent InSTI RAMs and few emergent NRTI RAMs in PLWH failing DTG- or BIC-based regimens in FL or SL. The observed rates of emergent RAMs at VF were 4% with BIC/FTC/TAF, 8.5% with DTG/ABC/3TC, 18% with DTG/3TC and 39% with DTG/RPV.

Heavily treatment-experienced patients with HIV: are new mechanisms of action enough?

Antiretroviral (ARV) drug resistance poses a threat to ending the HIV epidemic. As the rates of integrase resistance continue to increase globally, the availability of options for HIV treatment becomes limited. Heavily treatment-experienced (HTE) people with HIV (PWH) are limited to two or fewer available fully active ARV classes and are more likely to have an AIDS-defining event. Appropriate identification and management of HTE PWH is crucial to improving patient outcomes and reducing the future spread of drug-resistant HIV. As treatment options become more limited owing to drug resistance, the availability of more potent drugs with a marked increase in virologic suppression is needed in the current ART era. The purpose of this narrative review is to review the identification of HTE PWH, novel mechanisms of resistance, and management of HTE PWH in resource-rich and resource-limited settings using novel ARVs and combination ART.

Performance of an in-house multiplex PCR assay for HIV-1 drug resistance testing - A cheaper alternative

BACKGROUND

Currently, most HIV drug resistance PCR assays amplify the protease-reverse transcriptase (PR-RT) fragment separately from the integrase (IN) fragment. The aim of this study was to develop a multiplex PCR assay that simultaneously amplifies PR-RT and IN fragments for HIV-1 drug-resistance testing.

METHODS

The in-house multiplex PCR assay was evaluated on extracted total nucleic acids obtained from the National Health Laboratory Service (NHLS) and Lancet laboratories. Sanger sequencing was performed on amplicons, and HIV-1 drug-resistance mutations (DRMs) were assessed using HIV Stanford drug resistance database.

RESULTS

This study tested 59 patient samples with known HIV-1 viral load and DRM results; 41 from Lancet and 18 from NHLS. In-house multiplex PCR assay detected one or both fragments in most samples but had higher sensitivity for detection of IN fragment (93.2 %) compared to PR-RT fragment (83.1 %). There was 100 % concordance between Lancet assay versus in-house assay sequence data for IN DRMs, but lower concordance with PR-RT (87.0 %). The in-house multiplex PCR assay's precision and reproducibility analysis showed ≥99.9 % sequence similarity and yielded similar DRM results for both PR-RT and IN fragments.

CONCLUSIONS

The in-house multiplex PCR assay demonstrated satisfactory performance and higher sensitivity for IN fragment amplification. This could be a cost-effective method for HIV-1 drug resistance testing as both PR-RT and IN fragments are successfully amplified in one reaction in most samples.

Cost-effectiveness of viral load testing for transitioning antiretroviral therapy-experienced children to dolutegravir in South Africa: a modelling analysis

BACKGROUND

For children with HIV on antiretroviral therapy (ART), transitioning to dolutegravir-containing regimens is recommended. The aim of this study was to assess whether introducing viral load testing to inform new nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs) for children with HIV and viraemia alongside dolutegravir-based ART is beneficial and of good economic value.

METHODS

We used the Cost-Effectiveness of Preventing AIDS Complications-Pediatric model to project clinical and cost implications of three strategies among a simulated cohort of South African children aged 8 years with HIV receiving abacavir-lamivudine-efavirenz: (1) continue current ART (no dolutegravir; abacavir-lamivudine-efavirenz); (2) transition all children with HIV to dolutegravir, keeping current NRTIs (dolutegravir; abacavir-lamivudine-dolutegravir); or (3) transition to dolutegravir based on viral load testing (viral load plus dolutegravir), keeping current NRTIs if virologically suppressed (abacavir-lamivudine-dolutegravir, 70% of cohort) or switching abacavir to zidovudine (zidovudine) if viraemic (zidovudine-lamivudine-dolutegravir, 30%). We assumed 50% of children who had viraemia after abacavir-lamivudine exposure had NRTI resistance; with resistance, we assumed zidovudine-lamivudine-dolutegravir was more effective than abacavir-lamivudine-dolutegravir. We designated a strategy as preferred if it was most effective and least costly or had an incremental cost-effectiveness ratio less than half the South African 2020 gross domestic product per capita.

FINDINGS

Under base-case assumptions, the viral load plus dolutegravir strategy would be the most effective (projected undiscounted life expectancy of 39·72 life-years) and least costly strategy (US$24 600 per person); the no dolutegravir strategy was the least effective (34·49 life-years) and most expensive ($26 480 per person). In sensitivity analyses, the 24-week virological suppression probability and subsequent monthly virological failure risks (ie, late failure) were most influential on cost-effectiveness. Only with a high late-failure risk for zidovudine-lamivudine-dolutegravir (ie, ≥0·3% per month in the base case or >0·5% per month if abacavir also confers low virological suppression probability in the presence of NRTI resistance [65%]) would the dolutegravir strategy become preferred above the viral load plus dolutegravir strategy.

INTERPRETATION

For programmes transitioning to dolutegravir-based regimens, our model predicted that doing so would be more effective and less costly than continuing current ART regimens, regardless of NRTI choice. Whether viral load testing for children with HIV is necessary to inform NRTI choice depends substantially on the comparative outcomes of abacavir and zidovudine after switching to dolutegravir-containing ART.

FUNDING

The Eunice Kennedy Shriver Institute for Child Health and Human Development, the National Institute of Allergy and Infectious Diseases, the Massachusetts General Hospital Executive Committee on Research, the Massachusetts General Hospital, and the Medical Research Council.

Transition to dolutegravir-based ART in 35 low- and middle-income countries: a global survey of HIV care clinics

OBJECTIVE

We studied the transition to dolutegravir-containing antiretroviral therapy (ART) at HIV treatment clinics within the International epidemiology Databases to Evaluate AIDS (IeDEA).

DESIGN

Site-level survey conducted in 2020-2021 among HIV clinics in low- and middle-income countries (LMICs).

METHODS

We assessed the status of dolutegravir rollout and viral load and drug resistance testing practices for persons on ART switching to dolutegravir-based regimens. We used generalized estimating equations to assess associations between clinic rollout of both first- and second-line dolutegravir-based ART regimens (dual rollout) and site-level factors.

RESULTS

Of 179 surveyed clinics, 175 (98%) participated; 137 (78%) from Africa, 30 (17%) from the Asia-Pacific, and 8 (5%) from Latin America. Most clinics (80%) were in low- or lower-middle-income countries, and there were a mix of primary-, secondary- and tertiary-level clinics. Ninety percent reported rollout of first-line dolutegravir, 59% of second-line, 94% of first- or second-line and 55% of dual rollout. The adjusted odds of dual rollout were higher among tertiary-level [adjusted odds ratio (aOR) 4.00; 95% confidence interval (CI) 1.39-11.47] and secondary-level clinics (aOR 3.66; 95% CI 2.19-6.11) than in primary-level clinics. Over half (59%) of clinics that introduced first- or second-line dolutegravir-based ART required recent viral load testing before switching to dolutegravir, and 15% performed genotypic resistance testing at switch.

CONCLUSIONS

Dolutegravir-based ART was rolled out at nearly all IeDEA clinics in LMICs, yet many switched persons to dolutegravir without recent viral load testing and drug resistance testing was rarely performed. Without such testing, drug resistance among persons switching to dolutegravir may go undetected.

Type 1 Human Immunodeficiency Virus (HIV-1) Incidence, Adherence, and Drug Resistance in Individuals Taking Daily Emtricitabine/Tenofovir Disoproxil Fumarate for HIV-1 Pre-exposure Prophylaxis: Pooled Analysis From 72 Global Studies

BACKGROUND

Oral pre-exposure prophylaxis (PrEP) with emtricitabine/tenofovir disoproxil fumarate (F/TDF) has high efficacy against HIV-1 acquisition. Seventy-two prospective studies of daily oral F/TDF PrEP were conducted to evaluate HIV-1 incidence, drug resistance, adherence, and bone and renal safety in diverse settings.

METHODS

HIV-1 incidence was calculated from incident HIV-1 diagnoses after PrEP initiation and within 60 days of discontinuation. Tenofovir concentrations in dried blood spots (DBS), drug resistance, and bone/renal safety indicators were evaluated in a subset of studies.

RESULTS

Among 17 274 participants, there were 101 cases with new HIV-1 diagnosis (.77 per 100 person-years; 95% confidence interval [CI]: .63-.94). In 78 cases with resistance data, 18 (23%) had M184I or V, 1 (1.3%) had K65R, and 3 (3.8%) had both mutations. In 54 cases with tenofovir concentration data from DBS, 45 (83.3%), 2 (3.7%), 6 (11.1%), and 1 (1.9%) had average adherence of <2, 2-3, 4-6, and ≥7 doses/wk, respectively, and the corresponding incidence was 3.9 (95% CI: 2.9-5.3), .24 (.060-.95), .27 (.12-.60), and .054 (.008-.38) per 100 person-years. Adherence was low in younger participants, Hispanic/Latinx and Black participants, cisgender women, and transgender women. Bone and renal adverse event incidence rates were 0.69 and 11.8 per 100 person-years, respectively, consistent with previous reports.

CONCLUSIONS

Leveraging the largest pooled analysis of global PrEP studies to date, we demonstrate that F/TDF is safe and highly effective, even with less than daily dosing, in diverse clinical settings, geographies, populations, and routes of HIV-1 exposure.

Emergence of Acquired Dolutegravir Resistance in Treatment-experienced People With HIV in Lesotho

BACKGROUND

Since 2019, the World Health Organization has recommended dolutegravir-based antiretroviral therapy (ART) as the preferred regimen for human immunodeficiency virus management. Large-scale programmatic transitioning to dolutegravir-based ART was subsequently implemented across Africa, often in the absence of recent viral load testing and without access to genotypic resistance testing (GRT) in case of viremia.

METHODS

This study assessed emerging dolutegravir resistance in the routine care of the Viral Load Cohort North-East Lesotho. We included pediatric and adult participants who changed from nonnucleoside reverse transcriptase inhibitor- to dolutegravir-based ART and had at least 1 viral load assessment before and after the change. We sequenced available samples of participants fulfilling the additional virological criteria of having 2 viremic episodes while taking dolutegravir, with at least 1 viral load ≥500 copies/mL taken ≥18 months after changing to dolutegravir.

RESULTS

Among 15 349 participants, 157 (1.0%) met the virological criteria, and GRT was successful for 85 (0.6%). Among these 85, 8 (9.4%) had dolutegravir resistance, with 2 (2.4%) and 6 (7.1%) predicted to have intermediate- and high-level dolutegravir resistance, respectively. One participant had 2, 2 had 1, and 5 had 0 active drugs in their regimen. A GRT from before the change to dolutegravir was available for 5 of these 8 participants: 4 had 0 and 1 had 1 active drug in their nonnucleoside transcriptase inhibitor-based regimen.

CONCLUSIONS

Nine percent of people with persistent or recurring human immunodeficiency virus viremia ≥18 months after changing to dolutegravir-based ART had dolutegravir resistance. Detection and management of emerging dolutegravir resistance must be addressed across Africa.

Paediatric antiretroviral therapy challenges with emerging integrase resistance

PURPOSE OF REVIEW

Universal antiretroviral (ART) coverage and virological suppression are fundamental to ending AIDS in children by 2030. Availability of new paediatric dolutegravir (DTG)-based ART formulations is a major breakthrough and will undoubtedly help achieve this goal, but treatment challenges still remain.

RECENT FINDINGS

Paediatric formulations remain limited compared to those for adults, especially for young children, those unable to tolerate DTG or with DTG-based first-line ART failure. Tenofovir alafenamide is virologically superior to standard-of-care backbone drugs in second-line, but paediatric formulations are not widely available. The roles of resistance testing and recycling of backbone drugs following first-line ART failure remain to be determined. Results of trials of novel treatment strategies including dual therapy and long-acting agents are awaited. Although numbers are currently small, safe and effective ART options are urgently required for children developing DTG resistance.

SUMMARY

The antiretroviral treatment gap between adults and children persists. The potential benefits from rollout of new paediatric DTG-based fixed-dose combination ART for first-line treatment are considerable. However, children remain disadvantaged when DTG-based first-line ART fails or cannot be used. Research efforts to address this inequity require prioritisation in order to ensure health outcomes are optimised for all ages in all settings.

Optimising Paediatric HIV Treatment: Recent Developments and Future Directions

Treatment options for children living with HIV have historically been less effective, less practical and more difficult to implement compared with those for adults, as the research and development of new drugs for children has lagged behind. Significant progress has been achieved in response to the paediatric HIV epidemic over the last decade. Several optimised paediatric antiretroviral formulations are currently available or in development, including fixed-dose combination tablets containing a complete World Health Organization-recommended regimen. Despite these advancements, virological suppression rates in children are generally lower than in adults. Even when oral fixed-dose combinations with the optimal target profiles are developed, for some children virological suppression is not achievable for reasons such as adherence challenges, intolerance, toxicity and genotypic resistance. New safe, effective, well-tolerated antiretroviral agents from existing and novel classes, as well as innovative administration strategies are essential. To achieve the UNAIDS target of virological suppression in 95% of children receiving antiretroviral therapy, concerted efforts are required. This includes identifying priority drugs in line with latest developments, focusing drug development studies on these priorities, ensuring a timely technical knowledge transfer between originator and generic companies, accelerating regulatory approvals and facilitating procurement and implementation in countries. Success in these efforts depends on collaboration among all stakeholders, including communities, researchers, pharmaceutical companies, guideline and policymakers, governments, funders, regulators and healthcare providers. This review outlines which paediatric antiretroviral therapies are currently available, those which are under development and the future directions of paediatric HIV treatment.

Population Effectiveness of Dolutegravir Implementation in Uganda: A Prospective Observational Cohort Study (DISCO), 48-Week Results

BACKGROUND

Tenofovir/lamivudine/dolutegravir (TLD) is the preferred first-line antiretroviral therapy (ART) regimen for people with HIV (PWH), including those who were previously virologically suppressed on nonnucleoside reverse transcriptase inhibitors (NNRTIs). We sought to estimate the real-world effectiveness of the TLD transition in Ugandan public-sector clinics.

METHODS

We conducted a prospective cohort study of PWH aged ≥18 years who were transitioned from NNRTI-based ART to TLD. Study visits were conducted on the day of TLD transition and 24 and 48 weeks later. The primary end point was viral suppression (<200 copies/mL) at 48 weeks. We collected blood for retrospective viral load (VL) assessment and conducted genotypic resistance tests for specimens with VL >500 copies/mL.

RESULTS

We enrolled 500 participants (median age 47 years; 41% women). At 48 weeks after TLD transition, 94% of participants were in care with a VL <200 copies/mL (n = 469/500); 2% (n = 11/500) were lost from care or died; and only 2% (n = 9/500) had a VL >500 copies/mL. No incident resistance to DTG was identified. Few participants (2%, n = 9/500) discontinued TLD due to adverse events.

CONCLUSIONS

High rates of viral suppression, high tolerability, and lack of emergent drug resistance support use of TLD as the preferred first-line regimen in the region.

CLINICAL TRIALS REGISTRATION

NCT04066036.

HIV-1 infection kinetics, drug resistance, and long-term safety of pre-exposure prophylaxis with emtricitabine plus tenofovir alafenamide (DISCOVER): week 144 open-label extension of a randomised, controlled, phase 3 trial

BACKGROUND

Data characterising the long-term use and safety of emtricitabine plus tenofovir disoproxil fumarate as daily oral pre-exposure prophylaxis (PrEP) are scarce and there are uncertainties regarding the value of routine HIV-1 RNA testing during oral PrEP follow-up.

METHODS

The DISCOVER trial was a randomised, controlled, phase 3 trial in which cisgender men and transgender women aged 18 years and older with a high likelihood of acquiring HIV were recruited from 94 clinics in Europe and North America and randomly assigned to receive either emtricitabine plus tenofovir disoproxil fumarate (200/25 mg) tablets daily, with matched placebo tablets, or emtricitabine plus tenofovir alafenamide (200/300 mg) tablets daily, with matched placebo tablets, for at least 96 weeks. After completion of the trial, participants were offered enrolment in this 48-week open-label extension study of emtricitabine plus tenofovir alafenamide. In participants diagnosed with HIV during the randomised and open-label phases of the study, we characterised HIV-1 test results and measured HIV-1 RNA viral load retrospectively when available. Adherence based on tenofovir diphosphate concentrations in dried blood spots and genotypic resistance were assessed in participants diagnosed with HIV. Safety assessments included adverse events, laboratory parameters, and, in a subset of participants, bone mineral density. HIV-1 incidence in participants initially randomly assigned to receive emtricitabine plus tenofovir alafenamide was estimated using a Poisson distribution. Changes from baseline in safety endpoints were described in participants assigned to received emtricitabine plus tenofovir alafenamide and in those who switched from emtricitabine plus tenofovir disoproxil fumarate during the open-label phase. This trial is registered with ClinicalTrials.gov, NCT02842086, and is ongoing.

FINDINGS

Between Sept 13, 2016, and June 30, 2017, 5399 participants were enrolled and randomly assigned in DISCOVER. 2699 were assigned to receive emtricitabine plus tenofovir disoproxil fumarate and 2700 were assigned to receive emtricitabine plus tenofovir alafenamide, of whom 2693 and 2694, respectively, received at least one dose of study drug. 2115 (79%) assigned to emtricitabine plus tenofovir disoproxil fumarate switched to emtricitabine plus tenofovir alafenamide in the open-label phase, and 2070 (77%) continued with emtricitabine plus tenofovir alafenamide in the open-label phase. As of data cutoff (Dec 10, 2020), after 15 817 person-years of follow-up, 27 new HIV-1 diagnoses were observed across the total study period, with three occurring during the open-label phase. In participants who were initially assigned to emtricitabine plus tenofovir alafenamide, the incidence was 0·13 per 100 person-years (95% CI 0·061-0·23; ten of 2670). Stored plasma samples were available for 23 of 27 participants, including 22 with incident infection. In four (17%) of 23 participants, retrospective testing detected HIV-1 RNA before serological HIV-1 test positivity; one was a suspected baseline infection. Of the three incident cases, all three were non-adherent to PrEP and none developed drug resistance. Among participants taking emtricitabine plus tenofovir alafenamide for up to 144 weeks, markers of glomerular filtration and proximal renal tubule dysfunction (β2-microglobulin to creatinine ratio and retinol-binding protein to creatinine ratio) improved or remained stable at 144 weeks compared with baseline, bone mineral density in hip and lumbar spine increased or remained stable from baseline to week 144 (n=191), cholesterol and glucose concentrations remained stable, and median bodyweight increased by less than 1 kg per year. In participants who switched from emtricitabine plus tenofovir disoproxil fumarate during the open-label phase (2115 [79%] of 2693), markers of glomerular filtration and proximal renal tubule dysfunction improved or remained stable, bone mineral density increased, cholesterol concentrations increased, glucose concentrations were similar, and median bodyweight increased more compared with those who remained on emtricitabine and tenofovir alafenamide.

INTERPRETATION

Routine HIV-1 RNA testing for follow-up of individuals on daily oral PrEP provides modest additional clinical benefit. Long-term use of emtricitabine and tenofovir alafenamide as daily oral PrEP is safe and well tolerated and can be an especially appropriate choice for people with bone or renal morbidities.

FUNDING

Gilead Sciences.

HIV-1 pretreatment and acquired antiretroviral drug resistance before tenofovir/ /lamivudine /dolutegravir (TLD) roll-out in Mozambique

BACKGROUND

The World Health Organization (WHO) recommends that HIV treatment scale-up is accompanied by a robust assessment of drug resistance emergence and transmission. The WHO HIV Drug Resistance (HIVDR) monitoring and surveillance strategy includes HIVDR testing in adults both initiating and receiving antiretroviral therapy (ART). Due to limited information about HIVDR in Mozambique, we conducted two nationally representative surveys of adults initiating and receiving first-line ART regimes to better inform the HIV program.

METHODS

We carried out a cross-sectional study between March 2017 and December 2019. Adults (older than 15 years) living with HIV (PLHIV) initiating ART or receiving first-line ART for between 9-15 months at 25 health facilities across all eleven provinces in Mozambique were included. Genotypic HIVDR was assessed on dried blood spots (DBS) when viral loads were  ≥ 1000 copies/ml. Genotypic resistance for non-nucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs), and protease inhibitors (PIs) was determined using the Stanford HIV database algorithm 9.5 and calibrated population resistance tool 8.1.

RESULTS

Of 828 participants -enrolled, viral load (VL) testing was performed on 408 initiators and 409 ART experienced. Unsuppressed VL was found in 68.1% 419 initiators and 18.8% (77/409) of the ART experienced. Of the 278 initiators and 70 ART experienced who underwent sequencing, 51.7% (144/278) and 75.7% (53/70) were sequenced successfully. Among the new initiators, pretreatment drug resistance (PDR) for NNRTI and PI was found in 16.0% (23/144) and 1.4% (2/144) of the participants, respectively. Acquired drug resistance (ADR) was found in 56.5% (30/53) of the ART-experienced participants of whom 24.5% (13/53) were resistant to both NRTI and NNRTI.

CONCLUSION

High rates of PDR and ADR for NNRTI and ADR for NRTI were observed in our study. These findings support the replacement of NNRTIs with dolutegravir (DTG) but high levels of NRTI resistance in highly treatment-experienced individuals still require attention when transitioning to new regimens. Moreover, the study underlines the need for routine VL testing and HIVDR surveillance to improve treatment management strategies.

Development and Optimization of Oligonucleotide Ligation Assay (OLA) Probes for Detection of HIV-1 Resistance to Dolutegravir

The WHO currently recommends dolutegravir (DTG)-based ART for persons living with HIV infection in resource-limited-settings (RLS). To expand access to testing for HIV drug resistance (DR) to DTG in RLS, we developed probes for use in the oligonucleotide ligation assay (OLA)-Simple, a near-point of care HIV DR kit. Genotypic data from clinical trials and case reports were used to determine the mutations in HIV-1 integrase critical to identifying individuals with DTG-resistance at virologic failure of DTG-based ART. Probes to detect G118R, Q148H/K/R, N155H and R263K in HIV-1 subtypes A, B, C, D and CRF01_AE were designed using sequence alignments from the Los Alamos database and validated using 61 clinical samples of HIV-1 subtypes A, B, C, D, CRF01_AE genotyped by PacBio (n = 15) or Sanger (n = 46). Initial OLA probes failed to ligate for 16/244 (6.5%) codons (9 at G118R and 7 at Q148H/K/R). Probes revised to accommodate polymorphisms interfering with ligation at codons G118R and Q148R reduced indeterminates to 3.7% (5 at G118R and 4 at Q148H/K/R) and detected DTG-mutations with a sensitivity of 96.5% and 100% specificity. These OLA DTG resistance probes appear highly sensitive and specific across HIV-1 subtypes common in RLS with high burden of HIV infection.

Dolutegravir Resistance in African Programmatic Settings Among Patients With Failure of Dolutegravir-based ART

Dolutegravir resistance is emerging in routine clinical contexts in southern Africa, primarily in patients with prior treatment experience failing dolutegravir-based antiretroviral therapy (ART). This potential issue was raised by The Nucleosides and Darunavir/Dolutegravir in Africa trial that compared dolutegravir and boosted protease inhibitor-based therapy as second-line ART, in which new dolutegravir resistance was observed at failure. However, recent data suggest that also at risk are patients who were transitioned to dolutegravir from non-nucleoside reverse transcriptase inhibitor-based ART while viremic. Identifying patients experiencing failure of dolutegravir with resistance will be difficult given current gaps in viral load monitoring and limited capacity for genotypic resistance testing. As a result, in the short term, most patients affected will go unrecognized, with particularly important implications for patients affected who have advanced HIV or who are pregnant/breastfeeding. Prospective research is needed to understand the scope of the problem, identify additional risk factors, and determine best management. In the short term, for most patients with dolutegravir resistance and prior non-nucleoside reverse transcriptase inhibitor exposure, the best option will be a timely switch to a regimen anchored by a boosted protease inhibitor, with a high genetic barrier to resistance.

Dolutegravir plus boosted darunavir versus recommended standard-of-care antiretroviral regimens in people with HIV-1 for whom recommended first-line non-nucleoside reverse transcriptase inhibitor therapy has failed (D2EFT): an open-label, randomised, phase 3b/4 trial

BACKGROUND

Randomised comparative data on efficacy and safety of second-line antiretroviral therapy (ART) after failure of non-nucleoside reverse transcriptase inhibitors (NNRTIs) across diverse geographical settings are scarce. The aim of this study was to evaluate optimal second-line ART for people with HIV.

METHODS

D2EFT is a completed international, randomised, open-label, phase 3b/4 trial evaluating three second-line ART strategies in adults (aged ≥18 years) with HIV-1 for whom first-line NNRTI therapy has failed. The study was done at 28 sites across 14 countries in Asia, Africa, and Latin America. It was originally designed to compare recommended standard of care (ritonavir-boosted darunavir [800 mg darunavir plus 100 mg ritonavir once daily] plus two nucleoside reverse transcriptase inhibitors [NRTIs; dosed once or twice daily]) with a novel nucleoside sparing regimen of dolutegravir (50 mg once daily) with ritonavir-boosted darunavir. The study was adapted during the first year to add a third arm of dolutegravir (50 mg once daily) with fixed tenofovir disoproxil fumarate (300 mg once daily) plus either lamivudine (300 mg once daily) or emtricitabine (200 mg once daily). Participants were randomly assigned with a computer-generated, blocked randomisation scheme (block size of two) stratified by site, previous tenofovir disoproxil fumarate use, and HIV viral load. The trial was designed to evaluate non-inferiority of either interventional arm against standard of care for the primary outcome of virological suppression, as determined by HIV RNA load of less than 50 copies per mL at 48 weeks. The prespecified non-inferiority margin was 12%. Comparisons were made with a modified intention-to-treat population, including all participants randomly assigned but excluding administrative withdrawals. This study is registered with ClinicalTrials.gov, NCT03017872.

FINDINGS

1190 individuals were screened; 828 participants were enrolled between Nov 1, 2017, and Dec 31, 2021. Two participants were unable to receive their assigned regimen for administrative reasons; and 826 participants were included in analyses. Median age was 39 years (IQR 33-46), and 450 (54%) participants were female. Baseline median CD4 count was 206 cells per μL (23-354) and median HIV RNA was 15 400 copies per mL (3600-65 986). The proportion of participants with HIV RNA of less than 50 copies per mL at 48 weeks was 194 (75%) of 257 in the ritonavir-boosted darunavir plus two NRTIs group, 222 (84%) of 264 in the ritonavir-boosted darunavir plus dolutegravir group, and 227 (78%) of 291 in the dolutegravir with tenofovir disoproxil fumarate plus either lamivudine or emtricitabine group. Compared with ritonavir-boosted darunavir plus two NRTIs, the difference in virological suppression was 8·6% (95% CI 1·7 to 15·5; p=0·016) for dolutegravir plus ritonavir-boosted darunavir and 6·7% (-1·2 to 14·4; p=0·093) for dolutegravir with tenofovir disoproxil fumarate plus either lamivudine or emtricitabine. Six deaths occurred, none of which were related to treatment. 19 pregnancies (11 livebirths) occurred with no congenital defects.

INTERPRETATION

In individuals experiencing failure of an NNRTI-based first-line ART, a switch to either dolutegravir plus ritonavir-boosted darunavir or dolutegravir with tenofovir disoproxil fumarate plus either lamivudine or emtricitabine, without universal access to genotyping, was non-inferior in achieving viral suppression compared with ritonavir-boosted darunavir plus two NRTIs. These global data support the most recent WHO treatment guidelines.

FUNDING

UNITAID; National Institute of Allergy and Infectious Diseases, USA; National Health and Medical Research Council, Australia; ViiV Healthcare; and Janssen.

Optimising HIV drug resistance testing laboratory networks in Kenya: insights from systems engineering modelling

BACKGROUND

HIV drug resistance (DR) is a growing threat to the durability of current and future HIV treatment success. DR testing (DRT) technologies are very expensive and specialised, relying on centralised laboratories in most low and middle-income countries. Modelling for laboratory network with point-of-care (POC) DRT assays to minimise turnaround time (TAT), is urgently needed to meet the growing demand.

METHODS

We developed a model with user-friendly interface using integer programming and queueing theory to improve the DRT system in Kisumu County, Kenya. We estimated DRT demand based on both current and idealised scenarios and evaluated a centralised laboratory-only network and an optimised POC DRT network. A one-way sensitivity analysis of key user inputs was conducted.

RESULTS

In a centralised laboratory-only network, the mean TAT ranged from 8.52 to 8.55 working days, and the system could not handle a demand proportion exceeding 1.6%. In contrast, the mean TAT for POC DRT network ranged from 1.13 to 2.11 working days, with demand proportion up to 4.8%. Sensitivity analyses showed that expanding DRT hubs reduces mean TAT substantially while increasing the processing rate at national labs had minimal effect. For instance, doubling the current service rate at national labs reduced the mean TAT by only 0.0%-1.9% in various tested scenarios, whereas doubling the current service rate at DRT hubs reduced the mean TAT by 37.5%-49.8%. In addition, faster batching modes and transportation were important factors influencing the mean TAT.

CONCLUSIONS

Our model offers decision-makers an informed framework for improving the DRT system using POC in Kenya. POC DRT networks substantially reduce mean TAT and can handle a higher demand proportion than a centralised laboratory-only network, especially for children and pregnant women living with HIV, where there is an immediate push to use DRT results for patient case management.

Prevalence of Emergent Dolutegravir Resistance Mutations in People Living with HIV: A Rapid Scoping Review

BACKGROUND

Dolutegravir (DTG) is a cornerstone of global antiretroviral (ARV) therapy (ART) due to its high efficacy and favorable tolerability. However, limited data exist regarding the risk of emergent integrase strand transfer inhibitor (INSTI) drug-resistance mutations (DRMs) in individuals receiving DTG-containing ART.

METHODS

We performed a PubMed search using the term "Dolutegravir", last updated 18 December 2023, to estimate the prevalence of VF with emergent INSTI DRMs in people living with HIV (PLWH) without previous VF on an INSTI who received DTG-containing ART.

RESULTS

Of 2131 retrieved records, 43 clinical trials, 39 cohorts, and 6 cross-sectional studies provided data across 6 clinical scenarios based on ART history, virological status, and co-administered ARVs: (1) ART-naïve PLWH receiving DTG plus two NRTIs; (2) ART-naïve PLWH receiving DTG plus lamivudine; (3) ART-experienced PLWH with VF on a previous regimen receiving DTG plus two NRTIs; (4) ART-experienced PLWH with virological suppression receiving DTG plus two NRTIs; (5) ART-experienced PLWH with virological suppression receiving DTG and a second ARV; and (6) ART-experienced PLWH with virological suppression receiving DTG monotherapy. The median proportion of PLWH in clinical trials with emergent INSTI DRMs was 1.5% for scenario 3 and 3.4% for scenario 6. In the remaining four trial scenarios, VF prevalence with emergent INSTI DRMs was ≤0.1%. Data from cohort studies minimally influenced prevalence estimates from clinical trials, whereas cross-sectional studies yielded prevalence data lacking denominator details.

CONCLUSIONS

In clinical trials, the prevalence of VF with emergent INSTI DRMs in PLWH receiving DTG-containing regimens has been low. Novel approaches are required to assess VF prevalence with emergent INSTI DRMs in PLWH receiving DTG in real-world settings.

HIV epidemiology, prevention, treatment, and implementation strategies for public health

The global HIV response has made tremendous progress but is entering a new phase with additional challenges. Scientific innovations have led to multiple safe, effective, and durable options for treatment and prevention, and long-acting formulations for 2-monthly and 6-monthly dosing are becoming available with even longer dosing intervals possible on the horizon. The scientific agenda for HIV cure and remission strategies is moving forward but faces uncertain thresholds for success and acceptability. Nonetheless, innovations in prevention and treatment have often failed to reach large segments of the global population (eg, key and marginalised populations), and these major disparities in access and uptake at multiple levels have caused progress to fall short of their potential to affect public health. Moving forward, sharper epidemiologic tools based on longitudinal, person-centred data are needed to more accurately characterise remaining gaps and guide continued progress against the HIV epidemic. We should also increase prioritisation of strategies that address socio-behavioural challenges and can lead to effective and equitable implementation of existing interventions with high levels of quality that better match individual needs. We review HIV epidemiologic trends; advances in HIV prevention, treatment, and care delivery; and discuss emerging challenges for ending the HIV epidemic over the next decade that are relevant for general practitioners and others involved in HIV care.

Clinical outcomes with second-line dolutegravir in people with virological failure on first-line non-nucleoside reverse transcriptase inhibitor-based regimens in South Africa: a retrospective cohort study

BACKGROUND

Dolutegravir (DTG) is recommended for second-line antiretroviral therapy (ART) after virological failure on first-line non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens in people living with HIV in low-income and middle-income countries. We compared the effectiveness of DTG versus the previously recommended ritonavir-boosted lopinavir (LPV/r) regimen for second-line treatment in South Africa.

METHODS

In this retrospective observational cohort study, we used routinely collected, de-identified data from 59 primary health-care facilities in eThekwini Municipality, KwaZulu-Natal, South Africa. We included people living with HIV aged 15 years or older with virological failure (defined as two consecutive viral loads of ≥1000 copies per mL at least 56 days apart) on first-line NNRTI-based ART containing tenofovir disoproxil fumarate (TDF) and who switched to second-line ART. Our primary outcomes were retention in care and viral suppression (<50 copies per mL) at 12 months after starting second-line treatment. We used modified Poisson regression models to compare these outcomes between second-line regimens (zidovudine [AZT]/emtricitabine or lamivudine [XTC]/DTG; TDF/XTC/DTG; and AZT/XTC/LPV/r).

FINDINGS

We included 1214 participants in our study, of whom 729 (60%) were female and 485 (40%) were male, and whose median age was 36 years (IQR 30-42). 689 (57%) were switched to AZT/XTC/LPV/r, 217 (18%) to AZT/XTC/DTG, and 308 (25%) to TDF/XTC/DTG. Compared with AZT/XTC/LPV/r (75%), retention in care was higher with AZT/XTC/DTG (86%, adjusted risk ratio [aRR]=1·14, 95% CI 1·03-1·27; adjusted risk difference [aRD]=10·89%, 95% CI 2·01 to 19·78) but similar with TDF/XTC/DTG (77%, aRR=1·01, 0·94-1·10; aRD=1·04%, -5·03 to 7·12). Observed retention in care was lower with TDF/XTC/DTG than with AZT/XTC/DTG, although in multivariable analysis evidence for a difference was weak (aRR=0·89, 0·78-1·01, p=0·060; aRD=-9·85%, -20·33 to 0·63, p=0·066). Of 799 participants who were retained in care with a 12-month viral load test done, viral suppression was higher with AZT/XTC/DTG (59%; aRR=1·25, 1·06-1·47; aRD=11·57%, 2·37 to 20·76) and higher with TDF/XTC/DTG (61%; aRR=1·30, 1·14-1·48; aRD=14·16%, 7·14 to 21·18) than with AZT/XTC/LPV/r (47%).

INTERPRETATION

These findings from routine care support further implementation of WHO's recommendation to use DTG instead of LPV/r in people living with HIV who experience virological failure while receiving first-line NNRTI-based ART.

FUNDING

Bill & Melinda Gates Foundation.

TRANSLATION

For the isiZulu translation of the abstract see Supplementary Materials section.

Virological Findings and Treatment Outcomes of Cases That Developed Dolutegravir Resistance in Malawi's National HIV Treatment Program

Millions of Africans are on dolutegravir-based antiretroviral therapy (ART), but few detailed descriptions of dolutegravir resistance and its clinical management exist. We reviewed HIV drug resistance (HIVDR) testing application forms submitted between June 2019 and October 2022, data from the national HIVDR database, and genotypic test results. We obtained standardized ART outcomes and virological results of cases with dolutegravir resistance, and explored associations with dolutegravir resistance among individuals with successful integrase sequencing. All cases were on two nucleoside reverse transcriptase inhibitors (NRTIs)/dolutegravir, and had confirmed virological failure, generally with prolonged viremia. Among 89 samples with successful integrase sequencing, 24 showed dolutegravir resistance. Dolutegravir resistance-associated mutations included R263K (16/24), E138K (7/24), and G118R (6/24). In multivariable logistic regression analysis, older age and the presence of high-level NRTI resistance were significantly associated with dolutegravir resistance. After treatment modification recommendations, four individuals (17%) with dolutegravir resistance died, one self-discontinued ART, one defaulted, and one transferred out. Of the 17 remaining individuals, 12 had follow-up VL results, and 11 (92%) were <1000 copies/mL. Twenty-four cases with dolutegravir resistance among 89 individuals with confirmed virological failure suggests a considerable prevalence in the Malawi HIV program. Successful management of dolutegravir resistance was possible, but early mortality was high. More research on the management of treatment-experienced individuals with dolutegravir resistance is needed.

Outcomes and characteristics of patients on protease inhibitors at a tertiary level antiretroviral clinic

Background

Protease inhibitors (PIs) have been recommended as World Health Organization second-line antiretroviral therapy (ART) for low- to middle-income countries for two decades. As dolutegravir-based regimens have become widely available, the future role of PIs is uncertain.

Objectives

To describe the characteristics of patients on PI-based ART (in first-line and second-line regimens), double-boosted protease inhibitors (DBPI) and patients who received recycled nucleoside reverse transcriptase inhibitors (NRTI) in second-line regimens at a tertiary level ART clinic.

Method

We conducted a descriptive retrospective record review of adult patients on PI-based ART who attended Nthabiseng Adult Infectious Diseases Clinic at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa, between January 2021 and April 2022.

Results

Of the 900 patients sampled, 543 (60.3%) were female, the median age was 45 and 703 (79.1%) had viral loads (VL) below 1000 copies/mL. In contrast, 21 (58.3%) of 36 vertically infected patients had VLs below 1000 copies/mL. Thirty-seven (4.1%) patients were on DBPIs. The commonest reason for DBPI use in 24 (64.9%) patients was drug resistance test (DRT)-guided switch after virological failure. Forty-nine (5.4%) patients were on recycled NRTIs with no DRT, and 24 (2.6%) patients were on NRTIs to which there was documented resistance. Outcomes for these patients were similar to the total sample.

Conclusion

PIs have long been a cornerstone of second-line ART. This study demonstrates the real-world utility of PIs, as well as their disadvantages. There was no difference in the outcomes of patients who received recycled NRTIs in second-line regimens.

Integrase inhibitors: current protagonists in antiretroviral therapy

Since HIV was identified as the etiological agent of AIDS, there have been significant advances in antiretroviral therapy (ART) that has reduced morbidity/mortality. Still, the viral genome's high mutation rate, suboptimal ART regimens, incomplete adherence to therapy and poor control of the viral load generate variants resistant to multiple drugs. Licensing over 30 anti-HIV drugs worldwide, including integrase inhibitors, has marked a milestone since they are potent and well-tolerated drugs. In addition, they favor a faster recovery of CD4+ T cells. They also increase the diversity profile of the gut microbiota and reduce inflammatory markers. All of these highlight the importance of including them in different ART regimens.

HIV-1 drug resistance in people on dolutegravir-based antiretroviral therapy: a collaborative cohort analysis

BACKGROUND

The widespread use of the integrase strand transfer inhibitor (INSTI) dolutegravir in first-line and second-line antiretroviral therapy (ART) might facilitate emerging resistance. The DTG RESIST study combined data from HIV cohorts to examine patterns of drug resistance mutations (DRMs) and identify risk factors for dolutegravir resistance.

METHODS

We included cohorts with INSTI resistance data from two collaborations (ART Cohort Collaboration, International epidemiology Databases to Evaluate AIDS in Southern Africa), and the UK Collaborative HIV Cohort. Eight cohorts from Canada, France, Germany, Italy, the Netherlands, Switzerland, South Africa, and the UK contributed data on individuals who were viraemic on dolutegravir-based ART and underwent genotypic resistance testing. Individuals with unknown dolutegravir initiation date were excluded. Resistance levels were categorised using the Stanford algorithm. We identified risk factors for resistance using mixed-effects ordinal logistic regression models.

FINDINGS

We included 599 people with genotypic resistance testing on dolutegravir-based ART between May 22, 2013, and Dec 20, 2021. Most had HIV-1 subtype B (n=351, 59%), a third had been exposed to first-generation INSTIs (n=193, 32%), 70 (12%) were on dolutegravir dual therapy, and 18 (3%) were on dolutegravir monotherapy. INSTI DRMs were detected in 86 (14%) individuals; 20 (3%) had more than one mutation. Most (n=563, 94%) were susceptible to dolutegravir, seven (1%) had potential low, six (1%) low, 17 (3%) intermediate, and six (1%) high-level dolutegravir resistance. The risk of dolutegravir resistance was higher on dolutegravir monotherapy (adjusted odds ratio [aOR] 34·1, 95% CI 9·93-117) and dolutegravir plus lamivudine dual therapy (aOR 9·21, 2·20-38·6) compared with combination ART, and in the presence of potential low or low (aOR 5·23, 1·32-20·7) or intermediate or high-level (aOR 13·4, 4·55-39·7) nucleoside reverse transcriptase inhibitor (NRTI) resistance.

INTERPRETATION

Among people with viraemia on dolutegravir-based ART, INSTI DRMs and dolutegravir resistance were rare. NRTI resistance substantially increased the risk of dolutegravir resistance, which is of concern, notably in resource-limited settings. Monitoring is important to prevent resistance at the individual and population level and ensure the long-term sustainability of ART.

FUNDING

US National Institutes of Health, Swiss National Science Foundation.

Virologic Response to Dolutegravir Plus Lamivudine in People With Suppressed Human Immunodeficiency Virus Type 1 and Historical M184V/I: A Systematic Literature Review and Meta-analysis

Background

To investigate the impact of the M184V/I mutation on virologic response to dolutegravir plus lamivudine (DTG + 3TC) in suppressed-switch populations, a meta-analysis was performed using virologic outcomes from people with human immunodeficiency virus type 1 (PWH) with and without M184V/I before DTG + 3TC switch in real-world studies identified via systematic literature review. Sensitivity analyses were performed using data from PWH with M184V/I in interventional studies identified via targeted literature review.

Methods

Single-arm meta-analyses using common- and random-effects models were used to estimate proportions of PWH with virologic failure (VF) among real-world populations with and without M184V/I and interventional study participants with M184V/I at 24, 48, and 96 weeks.

Results

Literature reviews identified 5 real-world studies from 3907 publications and 51 abstracts meeting inclusion criteria and 5 interventional studies from 1789 publications and 3 abstracts. All time points had low VF incidence in PWH with M184V/I (real-world: 1.43%-3.81%; interventional: 0.00%) and without (real-world: 0.73%-2.37%). Meta-analysis-estimated proportions (95% confidence interval) with VF were low at weeks 24, 48, and 96, respectively, for PWH with M184V/I (real-world: 0.01 [.00-.04], 0.03 [.01-.06], and 0.04 [.01-.07]; interventional: 0.00 [.00-.02], 0.00 [.00-.01], and 0.00 [.00-.03]) and without (real-world: 0.00 [.00-.02], 0.02 [.01-.04], and 0.02 [.00-.05]). One real-world study (n = 712) reported treatment-emergent M184V at VF in 1 of 652 (0.15%) PWH without prior M184V/I.

Conclusions

Results suggest that prior M184V/I has minimal impact on virologic suppression after switching to DTG + 3TC and provide reassurance when considering switching regimens in virologically suppressed PWH with incomplete treatment history or limited treatment options.

Current drugs for HIV-1: from challenges to potential in HIV/AIDS

The human immunodeficiency virus (HIV) persists in latently infected CD4+T cells and integrates with the host genome until cell death. Acquired immunodeficiency syndrome (AIDS) is associated with HIV-1. Possibly, treating HIV/AIDS is an essential but challenging clinical goal. This review provides a detailed account of the types and mechanisms of monotherapy and combination therapy against HIV-1 and describes nanoparticle and hydrogel delivery systems. In particular, the recently developed capsid inhibitor (Lenacapavir) and the Ainuovirine/tenofovir disoproxil fumarate/lamivudine combination (ACC008) are described. It is interestingly to note that the lack of the multipass transmembrane proteins serine incorporator 3 (SERINC3) and the multipass transmembrane proteins serine incorporator 5 (SERINC5) may be one of the reasons for the enhanced infectivity of HIV-1. This discovery of SERINC3 and SERINC5 provides new ideas for HIV-1 medication development. Therefore, we believe that in treating AIDS, antiviral medications should be rationally selected for pre-exposure and post-exposure prophylaxis to avoid the emergence of drug resistance. Attention should be paid to the research and development of new drugs to predict HIV mutations as accurately as possible and to develop immune antibodies to provide multiple guarantees for the cure of AIDS.

Virologic Outcomes and ARV Switch Profiles 2 Years After National Rollout of Dolutegravir to Children Less Than 15 Years in Southern Mozambique

BACKGROUND

Dolutegravir (DTG) was scaled up globally to optimize treatment for children living with HIV. We evaluated the rollout and virological outcomes after DTG introduction in Mozambique.

METHODS

Data from children 0-14 years with visits from September 2019 to August 2021 were extracted from records in 16 facilities in 12 districts. Among children ever on DTG, we report treatment switches, defined as changes in anchor drug, regardless of changes to nucleoside reverse transcriptase inhibitor (NRTI) backbones. Among those on DTG for ≥6 months, we described viral load suppression rates by children newly initiating and switching to DTG and by the NRTI backbone at the time of the DTG switch.

RESULTS

Overall, 3,347 children were ever on DTG-based treatment (median age 9.5 years; 52.8% female). Most children (3,202, 95.7%) switched to DTG from another antiretroviral regimen. During the 2-year follow-up, 9.9% never switched from DTG; 52.7% had 1 regimen change, of which 97.6% were switched to DTG. However, 37.2% of children experienced ≥2 anchor drug changes. Overall median time on DTG was 18.6 months; nearly all children ≥5 years (98.6%) were on DTG at the last visit. Viral suppression was 79.7% (63/79) for children newly initiating DTG and 85.8% (1,775/2,068) for those switching to DTG. Suppression rates were 84.8% and 85.7% among children who switched and maintained NRTI backbones, respectively.

CONCLUSIONS

Viral suppression rates of ≥80% with minor variations by backbone were achieved during the 2-year DTG rollout. However, there were multiple anchor drug switches for over one-third of children, which may be attributable in part to drug stockouts. Long-term pediatric HIV management will only be successful with immediate and sustainable access to optimized child-friendly drugs and formulations.

Association of cytokine gene polymorphisms with peripheral neuropathy susceptibility in people living with HIV in Greece

Relatively little research has been done in recent years to understand what leads to the unceasingly high rates of HIV sensory neuropathy despite successful antiretroviral treatment. In vivo and in vitro studies demonstrate neuronal damage induced by HIV and increasingly identified ART neurotoxicity involving mitochondrial dysfunction and innate immune system activation in peripheral nerves, ultimately all pathways resulting in enhanced pro-inflammatory cytokine secretion. Furthermore, many infectious/autoimmune/malignant diseases are influenced by the production-profile of pro-inflammatory and anti-inflammatory cytokines, due to inter-individual allelic polymorphism within cytokine gene regulatory regions. Associations of cytokine gene polymorphisms are investigated with the aim of identifying potential genetic markers for susceptibility to HIV peripheral neuropathy including ART-dependent toxic neuropathy. One hundred seventy-one people living with HIV in Northern Greece, divided into two sub-groups according to the presence/absence of peripheral neuropathy, were studied over a 5-year period. Diagnosis was based on the Brief Peripheral Neuropathy Screening. Cytokine genotyping was performed by sequence-specific primer-polymerase chain reaction. Present study findings identify age as an important risk factor (p < 0.01) and support the idea that cytokine gene polymorphisms are at least involved in HIV peripheral-neuropathy pathogenesis. Specifically, carriers of IL1a-889/rs1800587 TT genotype and IL4-1098/rs2243250 GG genotype disclosed greater relative risk for developing HIV peripheral neuropathy (OR: 2.9 and 7.7 respectively), while conversely, carriers of IL2+166/rs2069763 TT genotype yielded lower probability (OR: 3.1), all however, with marginal statistical significance. The latter, if confirmed in a larger Greek population cohort, may offer in the future novel genetic markers to identify susceptibility, while it remains significant that further ethnicity-oriented studies continue to be conducted in a similar pursuit.

Effectiveness of second-generation integrase strand-transfer inhibitor-based regimens for antiretroviral-experienced people with HIV who had viral rebound

BACKGROUND

Antiretroviral regimens containing a second-generation integrase strand-transfer inhibitor (INSTI) plus 2 nucleos(t)ide reverse-transcriptase inhibitors (NRTIs) are the recommended therapy for people with HIV (PWH) who are antiretroviral-naïve or on stable antiretroviral therapy (ART) with viral suppression. Real-world data on the virologic effectiveness of co-formulated bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) among PWH with virologic failure while receiving other ART remain sparse.

METHODS

We retrospectively reviewed the medical records of PWH who had viral rebound with plasma HIV RNA >1000 copies/mL and were switched to either dolutegravir combined with 2 NRTIs or BIC/FTC/TAF. The primary end point was re-achieving viral suppression within the first 48 weeks of switch. The association between NRTI-related resistance-associated mutations (RAMs) and virologic effectiveness was examined.

RESULTS

Seventy-nine PWH with viral rebound while receiving other antiretroviral regimens were included. Within the first 48 weeks of switch, the overall probability of re-achieving viral suppression was 79.7% (82.5% [33/40] and 76.9% [30/39] for BIC/FTC/TAF and dolutegravir-based regimens, respectively, p = 0.78). PWH with a higher CD4 lymphocyte count (adjusted odds ratio, per 100-cell/mm3 increase, 1.41; 95% confidence interval, 1.02-1.95) were more likely to re-achieve viral suppression. Among PWH switching to BIC/FTC/TAF who had pre-existing RAMs to NRTIs before switch, 14 of 15 (93.3%) successfully achieved viral suppression.

CONCLUSIONS

Switching to BIC/FTC/TAF and dolutegravir-based regimens could re-achieve viral suppression in four-fifth of the PWH who experienced viral rebound during treatment with other antiretroviral regimens. Pre-existing NRTI-related RAMs did not have adverse impact on the effectiveness of dolutegravir combined with 2 NRTIs or BIC/FTC/TAF.

Treatment Emergent Dolutegravir Resistance Mutations in Individuals Naïve to HIV-1 Integrase Inhibitors: A Rapid Scoping Review

Background: Dolutegravir (DTG)-based antiretroviral therapy (ART) rarely leads to virological failure (VF) and drug resistance in integrase strand transfer inhibitor (INSTI)-naïve persons living with HIV (PLWH). As a result, limited data are available on INSTI-associated drug resistance mutations (DRMs) selected by DTG-containing ART regimens. Methods: We reviewed studies published through July 2023 to identify those reporting emergent major INSTI-associated DRMs in INSTI-naïve PLWH receiving DTG and those containing in vitro DTG susceptibility results using a standardized assay. Results: We identified 36 publications reporting 99 PLWH in whom major nonpolymorphic INSTI-associated DRMs developed on a DTG-containing regimen and 21 publications containing 269 in vitro DTG susceptibility results. DTG-selected DRMs clustered into four largely non-overlapping mutational pathways characterized by mutations at four signature positions: R263K, G118R, N155H, and Q148H/R/K. Eighty-two (82.8%) viruses contained just one signature DRM, including R263K (n = 40), G118R (n = 24), N155H (n = 9), and Q148H/R/K (n = 9). Nine (9.1%) contained ≥1 signature DRM, and eight (8.1%) contained just other DRMs. R263K and G118R were negatively associated with one another and with N155H and Q148H/K/R. R263K alone conferred a median 2.0-fold (IQR: 1.8-2.2) reduction in DTG susceptibility. G118R alone conferred a median 18.8-fold (IQR:14.2-23.4) reduction in DTG susceptibility. N155H alone conferred a median 1.4-fold (IQR: 1.2-1.6) reduction in DTG susceptibility. Q148H/R/K alone conferred a median 0.8-fold (IQR: 0.7-1.1) reduction in DTG susceptibility. Considerably higher levels of reduced susceptibility often occurred when signature DRMs occurred with additional INSTI-associated DRMs. Conclusions: Among INSTI-naïve PLWH with VF and treatment emergent INSTI-associated DRMs, most developed one of four signature DRMs, most commonly R263K or G118R. G118R was associated with a much greater reduction in DTG susceptibility than R263K.

Low Prevalence of Pre-Treatment and Acquired Drug Resistance to Dolutegravir among Treatment Naïve Individuals Initiating on Tenofovir, Lamivudine and Dolutegravir in Zimbabwe

Dolutegravir (DTG) use in combination with tenofovir and lamivudine (TLD) is scaling up in Africa. However, HIV drug resistance (HIVDR) data to DTG remain scarce in Zimbabwe. We assessed the prevalence and genetic mechanisms of DTG resistance in people living with HIV initiating on TLD. A prospective cohort study was conducted between October 2021 and April 2023 among antiretroviral therapy (ART) naïve adults (≥18 years) attending care at an HIV clinic in Zimbabwe. Pre-treatment drug resistance (PDR) was assessed prior to TLD initiation and viral load (VL) outcome and acquired drug resistance (ADR) to TLD were described after 24 weeks follow-up. In total, 172 participants were enrolled in the study. The median (IQR) age and log10 VL were 39 (29-48) years and 5.41 (4.80-5.74) copies/mL, respectively. At baseline, no PDR to DTG was found. However, as previously reported, PDR to non-nucleotide reverse transcriptase inhibitor (NNRTI) was high (15%) whilst PDR to NRTI was low (4%). After a median duration of 27 (25-30) weeks on TLD, virological suppression (VL < 1000 copies/mL) was 98% and among the 2 participants with VL ≥ 1000 copies/mL, no ADR was found. HIVDR to DTG is rare among ART naïve individuals. DTG is more likely to address the problems of HIVDR in Africa.

HIV infection

The AIDS epidemic has been a global public health issue for more than 40 years and has resulted in ~40 million deaths. AIDS is caused by the retrovirus, HIV-1, which is transmitted via body fluids and secretions. After infection, the virus invades host cells by attaching to CD4 receptors and thereafter one of two major chemokine coreceptors, CCR5 or CXCR4, destroying the host cell, most often a T lymphocyte, as it replicates. If unchecked this can lead to an immune-deficient state and demise over a period of ~2-10 years. The discovery and global roll-out of rapid diagnostics and effective antiretroviral therapy led to a large reduction in mortality and morbidity and to an expanding group of individuals requiring lifelong viral suppressive therapy. Viral suppression eliminates sexual transmission of the virus and greatly improves health outcomes. HIV infection, although still stigmatized, is now a chronic and manageable condition. Ultimate epidemic control will require prevention and treatment to be made available, affordable and accessible for all. Furthermore, the focus should be heavily oriented towards long-term well-being, care for multimorbidity and good quality of life. Intense research efforts continue for therapeutic and/or preventive vaccines, novel immunotherapies and a cure.

Clinical outcomes after the introduction of dolutegravir for second-line antiretroviral therapy in South Africa: a retrospective cohort study

Background

Dolutegravir is now recommended for second-line anti-retroviral therapy (ART) in low- and middle-income countries. We compared outcomes with dolutegravir (DTG) versus the previous lopinavir/ritonavir (LPV/r) regimen in South Africa.

Methods

We used routinely collected, de-identified data from 59 South African clinics. We included people living with HIV aged ≥ 15 years with virologic failure (two consecutive viral loads ≥1000 copies/mL) on first-line tenofovir disoproxil fumarate (TDF)-based ART and switched to second-line ART. We used modified Poisson regression models to compare outcomes of 12-month retention-in-care and viral suppression (<50 copies/ml) after switching to second-line regimens of zidovudine (AZT), emtricitabine/lamivudine (XTC), DTG and TDF/XTC/DTG and AZT/XTC/LPV/r.

Findings

Of 1214 participants, 729 (60.0%) were female, median age was 36 years (interquartile range 30 to 42), 689 (56.8%) were switched to AZT/XTC/LPV/r, 217 (17.9%) to AZT/XTC/DTG and 308 (25.4%) to TDF/XTC/DTG. Retention-in-care was higher with AZT/XTC/DTG (85.7%, adjusted risk ratio (aRR) 1.14, 95% confidence interval (CI) 1.03 to 1.27; adjusted risk difference (aRD) 10.89%, 95%CI 2.01 to 19.78) but not different with TDF/XTC/DTG (76.9%, aRR 1.01, 95%CI 0.94 to 1.10; aRD 1.04%, 95%CI -5.03 to 7.12) compared to AZT/XTC/LPV/r (75.2%). Retention-in-care with TDF/XTC/DTG was not statistically significantly different from AZT/XTC/DTG (aRR 0.89, 95%CI 0.78 to 1.01; aRD -9.85%, 95%CI -20.33 to 0.63). Of 799 participants who were retained-in-care with a 12-month viral load, viral suppression was higher with AZT/XTC/DTG (59.3%, aRR 1.25, 95%CI 1.06 to 1.47; aRD 11.57%, 95%CI 2.37 to 20.76) and TDF/XTC/DTG (60.7%, aRR 1.30, 95%CI 1.14 to 1.48; aRD 14.16%, 95%CI 7.14 to 21.18) than with the AZT/XTC/LPV/r regimen (46.7%).

Interpretation

DTG-based second-line regimens were associated with similar or better retention-in-care and better viral suppression than the LPV/r-based regimen. TDF/XTC/DTG had similar viral suppression compared to AZT/XTC/DTG.

Funding

Bill & Melinda Gates Foundation, Africa Oxford Initiative.

Advancing HIV Drug Resistance Technologies and Strategies: Insights from South Africa's Experience and Future Directions for Resource-Limited Settings

Monitoring of HIV drug resistance (HIVDR) remains critical for ensuring countries attain and sustain the global goals for ending HIV as a public health threat by 2030. On an individual patient level, drug resistance results assist in ensuring unnecessary treatment switches are avoided and subsequent regimens are tailored on a case-by-case basis, should resistance be detected. Although there is a disparity in access to HIVDR testing in high-income countries compared to low- and middle-income countries (LMICS), more LMICs have now included HIVDR testing for individual patient management in some groups of patients. In this review, we describe different strategies for surveillance as well as where HIVDR testing can be implemented for individual patient management. In addition, we briefly review available technologies for HIVDR testing in LMICs, including Sanger sequencing, next-generation sequencing, and some point-of-care options. Finally, we describe how South Africa has implemented HIVDR testing in the public sector.

Second-Line Switch to Dolutegravir for Treatment of HIV Infection

BACKGROUND

Data to inform the switch from a ritonavir-boosted protease inhibitor (PI) to dolutegravir in patients living with human immunodeficiency virus (HIV) infection who do not have genotype information and who have viral suppression with second-line therapy containing a ritonavir-boosted PI have been limited.

METHODS

In a prospective, multicenter, open-label trial conducted at four sites in Kenya, we randomly assigned, in a 1:1 ratio, previously treated patients without genotype information who had viral suppression while receiving treatment containing a ritonavir-boosted PI to either switch to dolutegravir or continue the current regimen. The primary end point was a plasma HIV type 1 RNA level of at least 50 copies per milliliter at week 48, assessed on the basis of the Food and Drug Administration snapshot algorithm. The noninferiority margin for the between-group difference in the percentage of participants who met the primary end point was 4 percentage points. Safety up to week 48 was assessed.

RESULTS

A total of 795 participants were enrolled, with 398 assigned to switch to dolutegravir and 397 assigned to continue taking their ritonavir-boosted PI; 791 participants (397 in the dolutegravir group and 394 in the ritonavir-boosted PI group) were included in the intention-to-treat exposed population. At week 48, a total of 20 participants (5.0%) in the dolutegravir group and 20 (5.1%) in the ritonavir-boosted PI group met the primary end point (difference, -0.04 percentage points; 95% confidence interval, -3.1 to 3.0), a result that met the criterion for noninferiority. No mutations conferring resistance to dolutegravir or the ritonavir-boosted PI were detected at the time of treatment failure. The incidence of treatment-related grade 3 or 4 adverse events was similar in the dolutegravir group and the ritonavir-boosted PI group (5.7% and 6.9%, respectively).

CONCLUSIONS

In previously treated patients with viral suppression for whom there were no data regarding the presence of drug-resistance mutations, dolutegravir treatment was noninferior to a regimen containing a ritonavir-boosted PI when the patients were switched from a ritonavir-boosted PI-based regimen. (Funded by ViiV Healthcare; 2SD ClinicalTrials.gov number, NCT04229290.).

Bictegravir/emtricitabine/tenofovir alafenamide plus doravirine in highly treatment-experienced men with multidrug-resistant HIV

OBJECTIVE

To evaluate the safety and efficacy of switching highly treatment-experienced people with HIV (HTE PWH) from rilpivirine/emtricitabine/tenofovir alafenamide (RPV/FTC/TAF) plus dolutegravir (DTG) to bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) plus doravirine (DOR). A pharmacokinetic (PK) analysis was conducted to assess the potential interaction between BIC and DOR.

DESIGN AND METHODS

This open-label switch trial enrolled HTE PWH from a primary care private practice in the United States. Eligible participants were male, aged ≥45 years, with documented viral resistance to protease inhibitors, nucleoside reverse transcriptase inhibitors, and/or nonnucleoside reverse transcriptase inhibitors but no resistance to RPV or DOR, and no K65R or T69 insertion mutations. Virologic suppression (≤50 copies/ml) while on RPV/FTC/TAF plus DTG for ≥6 months was required prior to enrollment. The primary endpoint of the study was virologic suppression (<50 and <200 copies/ml) at 48 weeks. Secondary endpoints included safety, tolerability, changes in body mass index (BMI), and identification of PK parameters of BIC and DOR.

RESULTS

Twenty males [median age: 65 years (range, 46-74), median time since HIV diagnosis: 37 years (range, 12-42)] completed the study. BIC/FTC/TAF plus DOR was well tolerated with no serious or treatment-related adverse events reported and no appreciable changes in BMI from baseline to Week 48. At Week 48, 100% of participants had <50 viral copies/ml. PK parameters for BIC and DOR ( n  = 10) were consistent with published data.

CONCLUSIONS

Switching from RPV/FTC/TAF plus DTG to BIC/FTC/TAF plus DOR was well tolerated and efficacious in HTE men aged ≥45 years with HIV.

Initial Supplementary Dose of Dolutegravir in Second-Line Antiretroviral Therapy: A Noncomparative, Double-Blind, Randomized Placebo-Controlled Trial

BACKGROUND

Dolutegravir concentrations are reduced by efavirenz induction effect necessitating twice-daily dolutegravir dosing when coadministered. Efavirenz induction persists for several weeks after stopping, which could potentially select for dolutegravir resistance if switching occurred with unsuppressed human immunodeficiency virus type 1 (HIV-1) RNA levels and standard dolutegravir dosing. We evaluated the need for a lead-in supplementary dolutegravir dose in adults failing first-line tenofovir-emtricitabine-efavirenz (TEE).

METHODS

We conducted a randomized, double-blind, placebo-controlled, phase 2 trial in Khayelitsha, South Africa. Eligible patients had virologic failure (2 consecutive HIV-1 RNA ≥1000 copies/mL) on first-line TEE. Participants were randomly assigned (1:1) to switch to tenofovir-lamivudine-dolutegravir (TLD) with a supplementary 50 mg dolutegravir dose or placebo taken 12 hours later for 14 days. Primary outcome was proportion with HIV-1 RNA <50 copies/mL at week 24. This study was not powered to compare arms.

RESULTS

One hundred thirty participants were randomized (65 to each arm). Median baseline HIV-1 RNA was 4.0 log10 copies/mL and 76% had baseline resistance to both tenofovir and lamivudine. One participant died and 2 were lost to follow-up. At week 24, 55 of 64 (86% [95% confidence interval {CI}: 75%-93%]) in the supplementary dolutegravir arm and 53 of 65 (82% [95% CI: 70%-90%]) in the placebo arm had HIV-1 RNA <50 copies/mL. Grade 3 or 4 adverse events were similar in frequency between arms. None of 6 participants (3 in each arm) eligible for resistance testing by 24 weeks developed dolutegravir resistance.

CONCLUSIONS

Our findings do not support the need for initial dolutegravir dose adjustment in patients switching to TLD who failed first-line TEE.

CLINICAL TRIALS REGISTRATION

NCT03991013.

The G118R plus R263K Combination of Integrase Mutations Associated with Dolutegravir-Based Treatment Failure Reduces HIV-1 Replicative Capacity and Integration

Human immunodeficiency virus (HIV) treatment with antiretroviral regimens containing integrase strand transfer inhibitors such as dolutegravir (DTG) and bictegravir (BIC) offers high levels of protection against the development of drug resistance mutations. Despite this, resistance to DTG and BIC can occur through the development of the R263K integrase substitution. Failure with DTG has also been associated with the emergence of the G118R substitution. G118R and R263K are usually found separately but have been reported together in highly treatment-experienced persons who experienced treatment failure with DTG. We used cell-free strand transfer and DNA binding assays and cell-based infectivity, replicative capacity, and resistance assays to characterize the G118R plus R263K combination of integrase mutations. R263K reduced DTG and BIC susceptibility ~2-fold, in agreement with our previous work. Single-cycle infectivity assays showed that G118R and G118R plus R263K conferred ~10-fold resistance to DTG. G118R alone conferred low levels of resistance to BIC (3.9-fold). However, the G118R plus R263K combination conferred high levels of resistance to BIC (33.7-fold), likely precluding the use of BIC after DTG failure with the G118R plus R263K combination. DNA binding, viral infectivity, and replicative capacity of the double mutant were further impaired, compared to single mutants. We propose that impaired fitness helps to explain the scarcity of the G118R plus R263K combination of integrase substitutions in clinical settings and that immunodeficiency likely contributes to its development.

Impact of rilpivirine cross-resistance on long-acting cabotegravir-rilpivirine in low and middle-income countries

Baseline rilpivirine drug resistance mutations (DRMs) are a risk factor for virological failure in patients treated with long-acting cabotegravir and rilpivirine (CAB/RPV LA). We investigated rilpivirine cross-resistance in treatment-naive and experienced patients in South Africa. One in 10 treatment-naive patients and 74.5% of patients failing treatment presented with rilpivirine DRMs. Our data suggest targeted genotyping may be required for patients initiating CAB/RPV LA, which significantly complicates the currently used public health approach.

Recycling Tenofovir in Second-line Antiretroviral Treatment With Dolutegravir: Outcomes and Viral Load Trajectories to 72 weeks

BACKGROUND

Recycling tenofovir and lamivudine/emtricitabine with dolutegravir (TLD) after failure of non-nucleoside transcriptase inhibitor first-line antiretroviral therapy is more tolerable and scalable than dolutegravir plus optimized nucleoside reverse transcriptase inhibitors. Studies have demonstrated TLD's efficacy as second line, but long-term follow-up is limited.

METHODS

ARTIST is a single arm, prospective, interventional study conducted in Khayelitsha, South Africa, which switched 62 adults with 2 viral loads >1000 copies/mL from tenofovir, lamivudine/emtricitabine, and an non-nucleoside transcriptase inhibitor to TLD. We report efficacy to 72 weeks and, in a post hoc analysis, evaluated viral load trajectories of individuals with viremic episodes.

RESULTS

Virologic suppression was 86% [95% confidence interval (CI) 74 to 93], 74% (95% CI: 61 to 84), and 75% (95% CI: 63 to 86) <50 copies/mL and 95%, 84%, and 77% <400 copies/mL at week 24, 48, and 72, respectively, with 89% (50/56) resistant (Stanford score ≥15) to tenofovir and/or lamivudine preswitch. No participants developed integrase-inhibitor resistance. Of the 20 participants not suppressed at week 24 and/or 48, 2 developed virologic failure, 1 switched regimen (adverse event), 2 were lost to follow-up, 1 missed the visit, 1 transferred out, 9 resuppressed <50 copies/mL with enhanced adherence counseling, and 4 remained viremic (3 with <200 copies/mL) at week 72.

CONCLUSIONS

Recycling NRTIs with dolutegravir was effective for most participants to 72 weeks. Most with viremia did not develop virologic failure and subsequently suppressed with enhanced adherence counseling or continued to have low-level viremia. No integrase-inhibitor resistance was detected despite low-level viremia in a minority of participants.

Efficacy of Dolutegravir versus Darunavir in Antiretroviral First-Line Regimens According to Resistance Mutations and Viral Subtype

Background: Dolutegravir (DTG)-based first-line regimens have shown superior efficacy versus darunavir (DRV)-based ones in randomized trials. We compared these two strategies in clinical practice, particularly considering the role of pre-treatment drug resistance mutations (DRMs) and of the HIV-1 subtype. Materials and methods: The multicenter Antiretroviral Resistance Cohort Analysis (ARCA) database was queried to identify HIV-1-positive patients starting a first-line therapy with 2NRTIs plus either DTG or DRV between 2013 and 2019. Only adult (≥18 years) patients with a genotypic resistance test (GRT) prior to therapy and with HIV-1 RNA ≥1000 copies/mL were selected. Through multivariable Cox regressions, we compared DTG- versus DRV-based regimens in the time to virological failure (VF) stratifying for pre-treatment DRMs and the viral subtype. Results: A total of 649 patients was enrolled, with 359 (55.3%) and 290 (44.7) starting DRV and DTG, respectively. In 11 months of median follow-up time, there were 41 VFs (8.4 in 100 patient-years follow-up, PYFU) and 15 VFs (5.3 per 100 PYFU) in the DRV and DTG groups, respectively. Compared with a fully active DTG-based regimen, the risk of VF was higher with DRV (aHR 2.33; p = 0.016), and with DTG-based regimens with pre-treatment DRMs to the backbone (aHR 17.27; p = 0.001), after adjusting for age, gender, baseline CD4 count and HIV-RNA, concurrent AIDS-defining event and months since HIV diagnosis. Compared with patients harboring a B viral subtype and treated with a DTG-based regimen, patients on DRV had an increased risk of VF, both in subtype B (aHR 3.35; p = 0.011), C (aHR 8.10; p = 0.005), CRF02-AG (aHR 5.59; p = 0.006) and G (aHR 13.90; p < 0.001); DTG also demonstrated a reduced efficacy in subtypes C (versus B, aHR 10.24; p = 0.035) and CRF01-AE (versus B; aHR 10.65; p = 0.035). Higher baseline HIV-RNA and a longer time since HIV diagnosis also predicted VF. Conclusions: In line with randomized trials, DTG-based first-line regimens showed an overall superior efficacy compared with DRV-based regimens. GRT may still play a role in identifying patients more at risk of VF and in guiding the choice of an antiretroviral backbone.