HIV-1-infected patients with advanced disease failing a raltegravir-containing salvage regimen in São Paulo, Brazil

Real-world prevalence of integrase inhibitor resistance and virological failure since adoption as guideline-preferred therapy

Background

Limited data reporting real-world prevalence of integrase strand transfer inhibitor resistance (INSTI-R) in the USA are available because their recommendation as first-line treatment in 2017. Reported national surveillance data in the USA estimated INSTI-R to be 6.3% as of 2018. This article aims to describe estimated prevalence of INSTI-R within a single clinic network in Chicago, IL, USA, and identify risk factors for resistance and virological failure (VF).

Methods

This was a retrospective, single-centre study of adults with HIV starting an INSTI-containing regimen between September 2017 and 2020. The primary endpoint was the difference in INSTI-R of the sample population compared with the national prevalence. Other outcomes included VF and documented INSTI-R mutations.

Results

Of 948 participants screened, 321 were included. Eight people had baseline INSTI-R testing results available, of which five had INSTI-R at baseline for an estimated prevalence of 1.6%. This estimation was significantly less than the national estimated prevalence of 6.3% (p<0.001). VF occurred in 26 (7.8%) individuals. Because no participants acquired INSTI-R during the study period, investigators were unable to identify risk factors associated with the development of INSTI-R. People with high pre-treatment viral loads had 1.21 (95% CI 1.05-1.39) higher odds of VF.

Conclusions

Amongst participants on INSTI-containing regimens, INSTI-R rates were estimated to be lower than the estimated national prevalence. Detectable pre-switch viral loads were more associated with VF than undetectable viral loads.

HIV-1 integrase genotyping is reliable and reproducible for routine clinical detection of integrase resistance mutations even in patients with low-level viraemia

OBJECTIVES

Integrase drug resistance monitoring deserves attention because of the increasing number of patients being treated with integrase strand-transfer inhibitors. Therefore, we evaluated the integrase genotyping success rate at low-level viraemia (LLV, 51-1000 copies/mL) and resistance in raltegravir-failing patients.

METHODS

An integrase genotypic resistance test (GRT) was performed on 1734 HIV-1 samples collected during 2006-13. Genotyping success rate was determined according to the following viraemia levels: 51-500, 501-1000, 1001-10 000, 10 001-100 000 and >100 000 copies/mL. The reproducibility of integrase GRT was evaluated in 41 plasma samples processed in duplicate in two reference centres. The relationship between LLV and resistance prevalence was evaluated in a subset of 120 raltegravir-failing patients.

RESULTS

Overall, the integrase genotyping success rate was 95.7%. For viraemia levels 51-500 and 501-1000 copies/mL, the rate of success was 82.1% and 94.0%, respectively. GRT was reproducible, producing sequences with a high similarity and an equal resistance profile regardless of the sequencing centre or viraemia level. Resistance was detected both at LLV and at viraemia >1000 copies/mL (51-500 copies/mL = 18.2%; 501-1000 = 37.5%; 1001-10 000 = 53.7%; 10 001-100 000 = 30.0%; and >100 000 = 30.8%). At viraemia ≤500 copies/mL, Q148H/K/R and N155H had the same prevalence (9.1%), while the Y143C/H/R was completely absent. At early genotyping (within 3 months of raltegravir treatment), Q148H/K/R and N155H mutations were detected regardless of the viraemia level, while Y143C/H/R was observed only in samples with viraemia >1000 copies/mL.

CONCLUSIONS

Our findings prove the reliability of HIV-1 integrase genotyping and reinforce the concept that this assay may be useful in the management of failures even at LLV.

High frequency of dolutegravir resistance in patients failing a raltegravir-containing salvage regimen

OBJECTIVES

Dolutegravir is a second-generation integrase strand transfer inhibitor (InSTI) that has been recently approved by the FDA to treat antiretroviral therapy-naive as well as treatment-experienced HIV-infected individuals, including those already exposed to the first-generation InSTI. Despite having a different mutational profile, some cross-resistance mutations may influence its susceptibility. The aim of this study was to evaluate the impact of a raltegravir-containing salvage regimen on dolutegravir activity.

PATIENTS AND METHODS

Blood samples of 92 HIV-infected individuals with virological failure (two or more viral loads >50 copies/mL after 6 months of treatment) using raltegravir with optimized background therapy were sequenced and evaluated according to the Stanford University HIV Drug Resistance Database algorithm.

RESULTS

Among the 92 patients analysed, 32 (35%) showed resistance to dolutegravir, in most cases associated with the combination of Q148H/R/K with G140S/A mutations. At genotyping, patients with resistance to dolutegravir had viral load values closer to the highest previously documented viral load.

CONCLUSIONS

Changes in viraemia during virological failure may indicate the evolution of raltegravir resistance and may predict the emergence of secondary mutations that are associated with a decrease in dolutegravir susceptibility. Early discontinuation of raltegravir from failing regimens might favour subsequent salvage with dolutegravir, but further studies are necessary to evaluate this issue.