Virological response and resistance profile in highly treatment-experienced HIV-1-infected patients switching to dolutegravir plus boosted darunavir in clinical practice

Switching to bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) plus darunavir/cobicistat in heavily antiretroviral-experienced, virologically suppressed HIV-infected adults receiving complex regimens

OBJECTIVES

To evaluate the efficacy and safety of the two-pill regimen bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) plus darunavir/cobicistat as a switching strategy in heavily treatment-experienced people living with HIV (PLWH).

METHODS

Multicentre, prospective, single-arm pilot clinical trial. Participants were virologically suppressed adults receiving a stable antiretroviral regimen of at least three pills from at least three drug families due to previous virological failures and/or toxicities with no documented resistance to integrase strand transfer inhibitors or darunavir (≥15 points, Stanford). Clinical and laboratory assessments were performed at 0, 4, 12, 24, 36 and 48 weeks. HIV-1 proviral DNA was amplified and sequenced by Illumina at baseline. Plasma bictegravir concentrations were determined in 22 patients using UHPLC-MS/MS. The primary study endpoint was viral load (VL)< 50 copies/mL at Week 48 (ITT).

RESULTS

We enrolled 63 participants (92% men) with median baseline CD4 count of 515 cells/mm3 (IQR: 334.5-734.5), 24 years on ART (IQR: 15.9-27.8). The median number of pills was 4 (range: 3-10). At baseline, proviral DNA was amplified in 39 participants: 33/39 had resistance mutations. Three participants discontinued owing to toxicity. At 48 weeks, 95% had VL < 50 copies/mL by ITT and 100% by PP analysis. A modest increase was observed in the bictegravir plasma concentration, and a significant decrease in estimated glomerular filtration rate was observed only at Week 4, probably related to interaction with renal transporters.

CONCLUSIONS

Our data suggest that BIC/FTC/TAF + darunavir/cobicistat is an effective, well-tolerated regimen that may improve convenience and, potentially, long-term success in stable heavily pre-treated PLWH.

Evaluation of integrase resistance in individuals who failed a regimen containing dolutegravir in French and Italian clinical settings

BACKGROUND

This work aims to evaluate integrase resistance and its predictors in HIV-1 infected combined antiretroviral therapy (cART) experienced individuals failing a dolutegravir-based regimen.

METHODS

Major resistance mutations (MRM) and genotypic susceptibility score (GSS) of dolutegravir companion drugs were evaluated on plasma genotypic resistance test (GRT) performed at dolutegravir failure. Logistic regression was used to evaluate factors associated to the risk of integrase strand-transfer inhibitors (INSTI)-resistance at dolutegravir failure.

RESULTS

We retrospectively analysed 467 individuals. At failure GRT, individuals had been under dolutegravir for a median (IQR) time of 11 (5-20) months; around half of them had never been exposed to INSTI (52%) and 10.7% were at first-line regimen. Fifty-eight (12.4%) individuals showed ≥1 INSTI MRM. Among them, people INSTI-exposed showed significantly higher prevalence of INSTI resistance compared to those who were INSTI naïve [46 (21.2%) versus 9 (3.9%), P < 0.001].N155H was the most prevalent MRM (5.4%), followed by G140S (4.5%) and Q148H (4.3%). These MRM were more probably present in INSTI-experienced individuals compared to those INSTI naïve. Despite failure, 89.5% of individuals harboured viral strains fully susceptible to dolutegravir and bictegravir and 85.0% to all INSTI. No INSTI exposure before receiving dolutegravir [OR: 0.35 (0.16-0.78), P < 0.010] and a GSS for companion drugs ≥2 (OR: 0.09 [0.04-0.23], P < 0.001) were negatively associated with INSTI resistance at failure.

CONCLUSIONS

In a large set of individuals failing dolutegravir in real-life, INSTI resistance was low and mainly related to previous first-generation INSTI exposure. Surveillance of integrase resistance remains crucial to preserve efficacy of INSTI class in the future.

Virological efficacy of switch to DTG plus 3TC in a retrospective observational cohort of suppressed HIV-1 patients with or without past M184V: the LAMRES study

OBJECTIVES

The aim of this study was to assess the efficacy of dolutegravir plus lamivudine (DTG+3TC) in a large set of virologically suppressed HIV-1 infected individuals with or without past M184V mutation.

METHODS

This observational study included individuals who switched to DTG+3TC with ≥1 genotype before switch. Survival analysis was used to evaluate the role of past M184V on virological rebound (VR) or blips after DTG+3TC switch.

RESULTS

A total of 712 individuals followed in several clinical centres in France, Italy and Spain were analysed. Past M184V was present in 60 (8.4%) individuals. By 3 years after switch, the overall probability of VR and blips was 6.7% and 6.9%, respectively, without any statistical significance according to the presence/absence of past M184V. A significantly higher probability of VR was found in individuals harbouring M184V before DTG+3TC with a duration of virological suppression (Ts) ≤.3.5 years compared to others (M184V+Ts ≤.3.5 years: 22.7%; M184M+Ts ≤.3.5 years: 9.0%; M184V+Ts >3.5 years: 7.8%; M184M+Ts >3.5 years: 4.9%; P = 0.007). This finding was not confirmed in multivariable models adjusting for behavioural and demographic variables. Genotypic resistance test after VR under DTG+3TC was available for 8/39 individuals; one poorly adherent individual developed M184V. No resistance to INIs was found.

CONCLUSION

In this retrospective observational study, the probability of VR and blips in patients switching to DTG+3TC was very low after 3 years of treatment regardless M184V. The effect of a short duration of previous virological suppression in individuals with M184V remains troubling and needs ad hoc clinical trials to be confirmed.

Two-drug regimens for HIV treatment

Combination therapy with three antiretroviral agents has been integral to successful HIV-1 treatment since 1996. Although the efficacy, adverse effects, and toxicities of contemporary three-drug regimens have improved, even the newest therapies have potential adverse effects. The use of two-drug regimens is one way to reduce lifetime exposure to antiretroviral drugs while maintaining the benefits of viral suppression. Multiple large, randomised trials have shown the virological non-inferiority of certain two-drug regimens versus three-drug comparators, including adverse effect differences that reflect known profiles of the antiretroviral drugs in the respective regimens. Two-drug combinations are now recommended in treatment guidelines and include the first long-acting antiretroviral regimen for the treatment of HIV-1. Recommended two-drug regimens differ in their risks for, and factors associated with, virological failure and emergent resistance. The tolerability, safety, metabolic profiles, and drug interactions of two-drug regimens also vary by the constituent drugs. No current two-drug regimen is recommended for people with chronic hepatitis B virus as none include tenofovir. Two-drug regimens have increased options for individualised care.

HIV-1 Subtype C Drug Resistance Mutations in Heavily Treated Patients Failing Integrase Strand Transfer Inhibitor-Based Regimens in Botswana

There are limited real-world mutational and virological outcomes data of treatment-experienced persons diagnosed with HIV-1 subtype C (HIV-1 C) who are failing Integrase Strand Transfer Inhibitor-based regimens. Requisition forms sent for HIV-1 genotypic resistance testing (GRT) between May 2015 and September 2019 were reviewed and participants experiencing virologic failure while on dolutegravir (DTG) or raltegravir (RAL) cART at sampling recruited. Sanger sequencing of the HIV-1 Pol gene was performed from residual plasma samples and drug resistance mutational (DRM) analysis performed using the Stanford University HIV drug resistance database. 40 HIV-1C integrase sequences were generated from 34 individuals, 24 of whom were on DTG cART, three on RAL cART and seven on an unknown (DTG or RAL)-anchored cART at time of GRT. 11/34 (32%) individuals had DRMs to DTG and other integrase inhibitors. 7/11 (64%) patients had exposure to a RAL-based cART at the time of sampling. Out of the 11 individuals with DRMs, one (9%) had 2-class, 6 (55%) had 3-class, and 4 (36%) had 4-class multidrug-resistant HIV-1C. 7/11 individuals (64%) are currently virologically suppressed. Of the four individuals not virologically suppressed, three had extensive DRMs involving 4-classes of ARV drugs and one individual has demised. Resistance to DTG occurs more often in patients exposed to RAL cART. Individuals with 4-class DRMs plus integrase T97 and E157Q mutations appear to have worse outcomes. There is a need for frequent VL monitoring and GRT amongst treatment-experienced HIV-1C diagnosed individuals.