Virological failure to raltegravir in Spain: incidence, prevalence and clinical consequences

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.

Association of low-level viremia with mortality among people living with HIV on antiretroviral therapy in Dehong, Southwest China: A retrospective cohort study

OBJECTIVES

To investigate the association of low-level viremia (LLV) with mortality among people living with HIV (PLHIV) on antiretroviral therapy (ART) in Dehong, Southwest China.

METHODS

We analysed data collected from a cohort of PLHIV on ART in Dehong. PLHIV were enrolled in this cohort after they started ART, with viral load (VL) tested once a year afterwards. Each VL level was then categorized into one of the four groups: <50, 50-199, 200-999 and ≥1000 copies/ml. VL levels of 50-199 and 200-999 copies/ml were defined as LLV. The VL level for each participant was re-categorized and fitted into an extended Cox regression model as a time-varying covariate to examine the associations of VL level with all-cause and AIDS-related deaths.

RESULTS

Among the included 7273 of 8762 PLHIV in this study, median age (interquartile range, IQR) was 36 (30-43) years and 59.9% were male. The patients were followed up for a median duration (IQR) of 6.2 (4.3-8.2) years. Compared with VL <50 copies/ml, LLV 200-999 copies/ml (adjusted hazard ratio [aHR] and 95% confidence interval [95% CI]: 1.56 [1.04, 2.32]) were associated with elevated risk of all-cause mortality and LLV50-199 (aHR [95% CI]: 1.00 [0.68, 1.45]) were not. Similarly, only LLV200-999 copies/ml (aHR [95% CI]: 2.37 [1.36, 4.14]) corresponded to higher risk of AIDS-related mortality.

CONCLUSIONS

This study suggests that PLHIV on ART may have elevated death risks even though the viremia is suppressed at a low level. Interventions targeting PLHIV with LLV should be developed to reduce their mortality.

Impact of pre-existent drug resistance on virological efficacy of single tablet regimens in people living with HIV

Despite the broad use of single tablet regimens (STRs), few real-life data are available regarding the impact of pre-existent drug resistance on virological failure (VF). Through this study we aimed to fill this gap, by analyzing a large cohort of individuals selected from the ARCA database. The impact on VF of pre-existent resistance associated mutations (RAMs) and cumulative genotypic susceptibility score (cGSS) before STR start was evaluated through survival analysis. Potential emergence of resistance at VF was also evaluated. Overall, 3916 individuals were included: 678 treatment-naïve (G1), 2309 treatment-experienced aviremic (G2), and 929 viremic (G3); 65.2% of them was treated with an STR based on efavirenz (35.2%) or rilpivirine (30%). At two years after starting STR, the overall probability of VF was 5.9% in G1, 8.7% in G2, and 20.8% in G3. No impact of pre-existent resistance on VF was found in G1. The probability of VF was higher in patients with cGSS<3 (reduced susceptibility to at least one drug) than in those with cGSS=3 (full susceptibility to STR drugs) in both G2 and G3. A higher probability of VF was also found in presence of pre-existent M184V (alone or in combination with pre-existent thymidine analogue mutations). Among patients who failed STR, a significant emergence of RAMs was found only in those exposed to EFV/FTC/TDF in G3 (specifically K103N and M184V). Our results confirm a high efficacy of STRs in clinical settings. Pre-existent resistance seems to influence virological efficacy of STR in treatment-experienced individuals (both aviremic and viremic).

Primary resistance to integrase strand transfer inhibitors in Spain using ultrasensitive HIV-1 genotyping

BACKGROUND

Transmission of resistance mutations to integrase strand transfer inhibitors (INSTIs) in HIV-infected patients may compromise the efficacy of first-line antiretroviral regimens currently recommended worldwide. Continued surveillance of transmitted drug resistance (TDR) is thus warranted.

OBJECTIVES

We evaluated the rates and effects on virological outcomes of TDR in a 96 week prospective multicentre cohort study of ART-naive HIV-1-infected subjects initiating INSTI-based ART in Spain between April 2015 and December 2016.

METHODS

Pre-ART plasma samples were genotyped for integrase, protease and reverse transcriptase resistance using Sanger population sequencing or MiSeq™ using a ≥ 20% mutant sensitivity cut-off. Those present at 1%-19% of the virus population were considered to be low-frequency variants.

RESULTS

From a total of 214 available samples, 173 (80.8%), 210 (98.1%) and 214 (100.0%) were successfully amplified for integrase, reverse transcriptase and protease genes, respectively. Using a Sanger-like cut-off, the overall prevalence of any TDR, INSTI-, NRTI-, NNRTI- and protease inhibitor (PI)-associated mutations was 13.1%, 1.7%, 3.8%, 7.1% and 0.9%, respectively. Only three (1.7%) subjects had INSTI TDR (R263K, E138K and G163R), while minority variants with integrase TDR were detected in 9.6% of subjects. There were no virological failures during 96 weeks of follow-up in subjects harbouring TDR as majority variants.

CONCLUSIONS

Transmitted INSTI resistance remains rare in Spain and, to date, is not associated with virological failure to first-line INSTI-based regimens.

Clinical use, efficacy, and durability of maraviroc for antiretroviral therapy in routine care: A European survey

OBJECTIVES

The study aimed to survey maraviroc use and assess effectiveness and durability of maraviroc-containing antiretroviral treatment (ART) in routine practice across Europe.

METHODS

Data were retrieved from 26 cohorts in 8 countries comprising adults who started maraviroc in 2005-2016 and had ≥1 follow-up visit. Available V3 sequences were re-analysed centrally for tropism determination by geno2pheno[coreceptor]. Treatment failure (TF) was defined as either virological failure (viral load >50 copies/mL) or maraviroc discontinuation for any reason over 48 weeks. Predictors of TF were explored by logistic regression analysis. Time to maraviroc discontinuation was estimated by Kaplan-Meier survival analysis.

RESULTS

At maraviroc initiation (baseline), among 1,381 patients, 67.1% had experienced ≥3 ART classes and 45.6% had a viral load <50 copies/mL. Maraviroc was occasionally added to the existing regimen as a single agent (7.3%) but it was more commonly introduced alongside other new agents, and was often (70.4%) used with protease inhibitors. Accompanying drugs comprised 1 (40.2%), 2 (48.6%) or ≥3 (11.2%) ART classes. Among 1,273 patients with available tropism data, 17.6% showed non-R5 virus. Non-standard maraviroc use also comprised reported once daily dosing (20.0%) and a total daily dose of 150mg (12.1%). Over 48 weeks, 41.4% of patients met the definition of TF, although the 1-year estimated retention on maraviroc was 82.1% (95% confidence interval 79.9-84.2). Among 1,010 subjects on maraviroc at week 48, the viral load was >50 copies/mL in 19.9% and >200 copies/mL in 10.7%. Independent predictors of TF comprised a low nadir CD4 count, a detectable baseline viral load, previous PI experience, non-R5 tropism, having ≥3 active drugs in the accompanying regimen, and a more recent calendar year of maraviroc initiation.

CONCLUSIONS

This study reports on the largest observation cohort of patients who started maraviroc across 8 European countries. In this overall highly treatment-experienced population, with a small but appreciable subset that received maraviroc outside of standard treatment guidelines, maraviroc was safe and reasonably effective, with relatively low rates of discontinuation over 48 weeks and only 2 cases of serum transaminase elevations reported as reasons for discontinuation.

Simplification of Antiretroviral Treatment from Darunavir/Ritonavir Monotherapy to Darunavir/Cobicistat Monotherapy: Effectiveness and Safety in Routine Clinical Practice

Our aim was to evaluate the effectiveness and safety of darunavir/cobicistat (DRV/c) monotherapy as an antiretroviral treatment simplification strategy in HIV-infected patients already on suppressive darunavir/ritonavir (DRV/r) monotherapy in routine clinical practice. We conducted a retrospective multicenter study including all adult patients switched from DRV/r monotherapy to DRV/c monotherapy while HIV-1 RNA was <50 copies/mL and who had at least one follow-up visit. The primary endpoint was the percentage of patients remaining free of treatment failure (TF), defined as discontinuation of monotherapy for any reason, including loss of follow-up. Virological failure (VF) was defined as a confirmed HIV-1 RNA ≥50 copies/mL or any change in the regimen after a single determination with HIV-1 RNA ≥50 copies/mL. Changes in renal function parameters and lipid profile were also evaluated. Factors associated with VF were analyzed using Cox regression. In this study, 173 subjects were included. The median (interquartile range) time of follow-up was 58 (50-67) weeks. Overall, 90% of patients remained free of TF during follow-up. Ten (6%) patients discontinued DRV/c monotherapy for nonvirological reasons and eight (5%) developed VF. No DRV-related mutations were identified in patients with VF. A decrease in triglyceride levels (p = .006) and estimated glomerular filtration rate (p = .005) were observed during follow-up. The presence of blips and CD4+ nadir <100 cells/mm³ were predictors of VF. In conclusion, switching to DRV/c monotherapy seems to be safe and effective in routine clinical practice in HIV-infected patients undergoing suppressive DRV/r monotherapy.

Gag-protease coevolution analyses define novel structural surfaces in the HIV-1 matrix and capsid involved in resistance to Protease Inhibitors

Despite the major role of Gag in establishing resistance of HIV-1 to protease inhibitors (PIs), very limited data are available on the total contribution of Gag residues to resistance to PIs. To identify in detail Gag residues and structural interfaces associated with the development of HIV-1 resistance to PIs, we traced viral evolution under the pressure of PIs using Gag-protease single genome sequencing and coevolution analysis of protein sequences in 4 patients treated with PIs over a 9-year period. We identified a total of 38 Gag residues correlated with the protease, 32 of which were outside Gag cleavage sites. These residues were distributed in 23 Gag-protease groups of coevolution, with the viral matrix and the capsid represented in 87% and 52% of the groups. In addition, we uncovered the distribution of Gag correlated residues in specific protein surfaces of the inner face of the viral matrix and at the Cyclophilin A binding loop of the capsid. In summary, our findings suggest a tight interdependency between Gag structural proteins and the protease during the development of resistance of HIV-1 to PIs.

HIV drug resistance against strand transfer integrase inhibitors

Integrase strand transfer inhibitors (INSTIs) are the newest class of antiretroviral drugs to be approved for treatment and act by inhibiting the essential HIV protein integrase from inserting the viral DNA genome into the host cell’s chromatin. Three drugs of this class are currently approved for use in HIV-positive individuals: raltegravir (RAL), elvitegravir (EVG), and dolutegravir (DTG), while cabotegravir (CAB) and bictegravir (BIC) are currently in clinical trials. RAL and EVG have been successful in clinical settings but have relatively low genetic barriers to resistance. Furthermore, they share a high degree of cross-resistance, which necessitated the development of so-called second-generation drugs of this class (DTG, CAB, and BIC) that could retain activity against these resistant variants. In vitro selection experiments have been instrumental to the clinical development of INSTIs, however they cannot completely recapitulate the situation in an HIV-positive individual. This review summarizes and compares all the currently available information as it pertains to both in vitro and in vivo selections with all five INSTIs, and the measured fold-changes in resistance of resistant variants in in vitro assays. While the selection of resistance substitutions in response to RAL and EVG bears high similarity in patients as compared to laboratory studies, there is less concurrence regarding the “second-generation” drugs of this class. This highlights the unpredictability of HIV resistance to these inhibitors, which is of concern as CAB and BIC proceed in their clinical development.

Effectiveness and Risk Factors for Virological Outcome of Raltegravir-Based Therapy for Treatment-Experienced HIV-Infected Patients

Objective

We evaluated the effectiveness of a raltegravir (RAL)-containing regimen plus an optimized background regimen in HIV-1 highly treatment-experienced patients.

Design

A retrospective cohort, multicentre study was conducted.

Methods

Adult (>16 years old) HIV treatment-experience patients starting therapy with a RAL-containing regimen were included. Effectiveness was evaluated as the percentage of patients with an undetectable HIV-1 RNA viral load (<50 and <200 copies/mL) after 48 weeks, and changes in CD4+ cell counts. We evaluated the risk factors associated with treatment failure.

Results

Of the 107 patients in the cohort, 86% were men, the median age was 45 years [interquartile range (IQR) 40–52] and the median number of previous regimens was six (IQR 4–7). After 48 weeks of treatment, 73% (IQR 63–80%) of patients (n = 78) had a viral load of <50 copies/mL and 85% (IQR 77–90%) (n = 91) had <200 copies/mL. In a logistic regression model, risk factors associated with a virological outcome of HIV-1 RNA of <200 copies/mL were age >40 years [odds ratio (OR) 5.61; 95% confidence interval (CI) 1.61–18.84; P = 0.006] and use of tenofovir in the regimen (OR 0.16; 95% CI 0.03–0.80; P = 0.026).

Conclusions

In this Mexican cohort, RAL achieved high rates of virological suppression and an increase in CD4+ cell count in highly treatment-experienced patients infected with HIV-1. Age >40 years was associated with a good virological outcome, contrary to tenofovir use, which was associated with a poor virological outcome.

Role of phenotypic investigation in the era of routine genotypic HIV-1 drug resistance testing

The emergence of drug resistance can seriously compromise HIV type-1 therapy and decrease therapeutic options. Resistance testing is highly recommended to guide treatment decisions and drug activity can be accurately predicted in the clinical setting through genotypic assays. While phenotypic systems are not suitable for monitoring drug resistance in routine laboratory practice, genotyping can misclassify unusual or complex mutational patterns, particularly with recently approved antivirals. In addition, phenotypic assays remain fundamental for characterizing candidate antiretroviral compounds. This review aims to discuss how phenotypic assays contributed to and still play a role in understanding the mechanisms of resistance of both licensed and investigational HIV type-1 inhibitors.

Prevalence of Integrase Strand Transfer Inhibitors (INSTI) Resistance Mutations in Taiwan

Antiretroviral therapy containing an integrase strand transfer inhibitor (INSTI) plus two NRTIs has become the recommended treatment for antiretroviral-naive HIV-1-infected patients in the updated guidelines. We aimed to determine the prevalence of INSTI-related mutations in Taiwan. Genotypic resistance assays were performed on plasma from ARV-naïve patients (N = 948), ARV-experienced but INSTI-naive patients (N = 359), and raltegravir-experienced patients (N = 63) from 2006 to 2015. Major INSTI mutations were defined according to the IAS-USA list and other substitutions with a Stanford HIVdb score ≧ 10 to at least one INSTI were defined as minor mutations. Of 1307 HIV-1 samples from patients never exposed to INSTIs, the overall prevalence of major resistance mutations to INSTIs was 0.9% (n = 12), with an increase to 1.2% in 2013. Of these 12 sequences, 11 harboured Q148H/K/R, one Y143R, and none N155H. Of 30 sequences (47.6%) with INSTI-resistant mutations from raltegravir-experienced patients, 17 harboured Q148H/K/R, 8 N155H, and 6 Y143C/R. Other than these major mutations, the prevalence of minor mutations were 5.3% and 38.1%, respectively, in ARV-naive and raltegravir-experienced patients. The overall prevalence of INSTI mutations remains low in Taiwan. Surveillance of INSTI resistance is warranted due to circulation of polymorphisms contributing to INSTI resistance and expected increasing use of INSTIs.

Short Communication: Efficacy and Safety of Treatment Simplification to Lopinavir/Ritonavir or Darunavir/Ritonavir Monotherapy: A Randomized Clinical Trial

Antiretroviral treatment simplification strategies based on monotherapy with darunavir/ritonavir (DRV/r) or lopinavir/ritonavir (LPV/r) have not been directly compared in clinical trials. We evaluated the 48-week efficacy and safety of DRV/r versus LPV/r monotherapy as a treatment simplification strategy in a multicenter, randomized open-label study. Maintenance of viral suppression in cerebrospinal fluid (CSF) and semen was also explored. An intention to treat efficacy analysis was performed considering missing equals to failure (ITT:M = F). Virological failure (VF) was defined as a confirmed increase in plasma HIV-1 RNA >50 copies/mL. A total of 75 patients were enrolled: 40 were allocated to DRVr and 33 to LPVr. In the ITT: M = F analysis, 77.5% of patients on DRV/r and 66.6% of patients on LPV/r maintained HIV-1 RNA <50 copies/mL at week 48 (p = .302, treatment difference 10.8% [95% CI,-12.6 to 34.2]). In the DRV/r arm, no patients developed VF and 15.0% discontinued treatment due to adverse events. In the LPV/r arm, 2 (6.1%) patients developed VF and 18.2% discontinued monotherapy due to adverse events. Gastrointestinal disturbances were experienced by 18.2% and 2.5% of patients in the LPV/r and DRV/r arms, respectively (p = .019). Two patients had detectable HIV-1 RNA ≥50 copies/mL in CSF or semen. Monotherapy with LPV/r or DRV/r seems to be virologically effective in selected HIV-1-infected patients with sustained viral suppression. Differences between both regimens seem driven mainly by the better tolerability profile of DRV/r.