Risk factors for raltegravir resistance development in clinical practice

Long-term outcomes of highly experienced people with HIV undergoing salvage therapy with raltegravir

Raltegravir and other third-line drugs have shown promise in improving outcomes in treatment-experienced patients. However, the efficacy and tolerability of these agents vary. This study assessed real-life virologic success, long-term survival, and adverse events in patients receiving raltegravir or other third-line drugs as salvage regimens. This retrospective cohort study included adults who experienced treatment failure (human immunodeficiency syndrome-1 RNA plasma viral load >1000 copies/mL) and subsequently initiated raltegravir or other third-line drugs (darunavir/ritonavir, maraviroc, or etravirine). Propensity score matching methods were employed to account for differences at the time of switching from failing antiretroviral therapy regimens. The matched subset was analyzed using the Kaplan-Meier method and Generalized Wilcoxon tests to evaluate the probability of achieving virologic suppression (plasma viral load <50 copies/mL). Mortality rates, toxicity, treatment interruption, virologic failure, and loss to follow-up were determined using Poisson regression. One hundred and sixty-eight patients initiating salvage regimens were included, with 123 receiving raltegravir and 45 other third-line drugs. Propensity score matching resulted in a subset of 90 patients, 45 in each group. During the follow-up period, there were no significant differences observed between the groups in terms of virologic suppression (77.8% vs 82.2%, P = .73), mortality rates (4.04 vs 6.18 persons per 100 person-years [p-y]; P = .67), drug toxicity (0.00 vs 2.06 persons per 100 p-y; P = .49), treatment interruption (8.07 vs 0.00 persons per 100 p-y; P = .06), virologic failure (2.02 vs 4.12 persons per 100 p-y; P = .61), and loss of follow-up (6.05 vs 4.12 persons per 100 p-y; P = .70). Our findings indicate comparable survival and virological success rates between raltegravir and other drugs used in salvage regimens. Similar rates of drug toxicity, treatment interruption, virologic failure, and loss of follow-up were also observed. These results suggest that raltegravir may be a viable option for salvage therapy, demonstrating outcomes comparable to other third-line drugs in real life.

Initial Antiretroviral Therapy in an Integrase Inhibitor Era: Can We Do Better?

With the second-generation integrase inhibitors (dolutegravir and bictegravir) extending the attributes of earlier integrase inhibitors, three-drug regimens containing integrase inhibitors plus two nucleos(t)ide reverse transcriptase inhibitors are now widely recommended for first-line (initial) treatment of human immunodeficiency virus-1 infection. Led by dolutegravir plus lamivudine, two-drug therapy is emerging as a way to reduce antiretroviral therapy cost and adverse effects without compromising treatment options should virologic failure occur. Initial two-drug therapy has limitations, including the relative incompatibility with the coemerging concept of same-day antiretroviral therapy initiation.

Impact of baseline plasma HIV-1 RNA and time to virological suppression on virological rebound according to first-line antiretroviral regimen

Objectives

We investigated the risk of virological rebound in HIV-1-infected patients achieving virological suppression on first-line combined ART (cART) according to baseline HIV-1 RNA, time to virological suppression and type of regimen.

Patients and methods

Subjects were 10 836 adults who initiated first-line cART (two nucleoside or nucleotide reverse transcriptase inhibitors + efavirenz, a ritonavir-boosted protease inhibitor or an integrase inhibitor) from 1 January 2007 to 31 December 2014. Cox proportional hazards models with multiple adjustment and propensity score matching were used to investigate the effect of baseline HIV-1 RNA and time to virological suppression on the occurrence of virological rebound.

Results

During 411 436 patient-months of follow-up, risk of virological rebound was higher in patients with baseline HIV-1 RNA ≥100 000 copies/mL versus <100 000 copies/mL, in those achieving virological suppression in > 6 months versus <6 months, and lower with efavirenz or integrase inhibitors than with ritonavir-boosted protease inhibitors. Baseline HIV-1 RNA >100 000 copies/mL was associated with virological rebound for ritonavir-boosted protease inhibitors but not for efavirenz or integrase inhibitors. Time to virological suppression >6 months was strongly associated with virological rebound for all regimens.

Conclusions

In HIV-1-infected patients starting cART, risk of virological rebound was lower with efavirenz or integrase inhibitors than with ritonavir-boosted protease inhibitors. These data, from a very large observational cohort, in addition to the more rapid initial virological suppression obtained with integrase inhibitors, reinforce the positioning of this class as the preferred one for first-line therapy.

Dolutegravir as monotherapy in HIV-1-infected individuals with suppressed HIV viraemia

BACKGROUND

Reducing drug burden is a key challenge for achieving lifelong suppressive HIV therapy. Dolutegravir, with a high potency, long half-life and high genetic barrier, offers potential for monotherapy.

METHODS

This observational single-centre study enrolled all patients with HIV RNA (viral load) <50 copies/mL for at least 12 months, with CD4 >350 cells/mm(3) and with no failure under integrase inhibitor therapy who had switched from suppressive ART to dolutegravir monotherapy (50 mg/day). Primary outcome was proportion of patients with viral load <50 copies/mL at week 24.

RESULTS

Twenty-eight patients treated for a median ART duration of 17 years (IQR 11-20), virally suppressed for a median of 79 months (IQR 42-95) and with a median CD4 count of 624 cells/mm(3) (IQR 524-761), were enrolled. Baseline ART consisted of a three-drug (n = 10), two-drug (n = 10) or single-drug (n = 8) regimen with integrase inhibitor exposure in 13 patients. The proportion of patients maintaining viral load <50 copies/mL was 96% (95% CI 79%-100%) at week 4, 100% (95% CI = 85%-100%) at week 8, 93% (95% CI 76%-99%) at week 12 and 92% (75-99) at week 24. Three patients (3.70%; 95% CI 3.4%-10.8%) with prior integrase inhibitor experience had HIV RNA rebound with the presence of resistance mutations. Genotyping of HIV DNA using the Sanger method or ultradeep sequencing showed no integrase inhibitor resistance-associated mutations (RAMs) except for the mutation 74I in a patient on a suppressive elvitegravir regimen. The median within- and between-subject variability of dolutegravir C24 was 25% and 34%, respectively. Nine patients with a year of follow-up remained virally suppressed.

CONCLUSIONS

Dolutegravir has the potency to be further investigated as a single ART in randomized studies, particularly in patients with no prior exposure to integrase inhibitors.

Antiretroviral resistance at virological failure in the NEAT 001/ANRS 143 trial: raltegravir plus darunavir/ritonavir or tenofovir/emtricitabine plus darunavir/ritonavir as first-line ART

OBJECTIVES

To describe the pattern of drug resistance at virological failure in the NEAT001/ANRS143 trial (first-line treatment with ritonavir-boosted darunavir plus either tenofovir/emtricitabine or raltegravir).

METHODS

Genotypic testing was performed at baseline for reverse transcriptase (RT) and protease genes and for RT, protease and integrase (IN) genes for patients with a confirmed viral load (VL) >50 copies/mL or any single VL >500 copies/mL during or after week 32.

RESULTS

A resistance test was obtained for 110/805 (13.7%) randomized participants qualifying for resistance analysis (61/401 of participants in the raltegravir arm and 49/404 of participants in the tenofovir/emtricitabine arm). No resistance-associated mutation (RAM) was observed in the tenofovir/emtricitabine plus darunavir/ritonavir arm, and all further analyses were limited to the raltegravir plus darunavir arm. In this group, 15/55 (27.3%) participants had viruses with IN RAMs (12 N155H alone, 1 N155H + Q148R, 1 F121Y and 1 Y143C), 2/53 (3.8%) with nucleotide analogue RT inhibitor RAMs (K65R, M41L) and 1/57 (1.8%) with primary protease RAM (L76V). The frequency of IN mutations at failure was significantly associated with baseline VL: 7.1% for a VL of <100,000 copies/mL, 25.0% for a VL of ≥100,000 copies/mL and <500,000 copies/mL and 53.8% for a VL of ≥500,000 copies/mL (PTREND = 0.007). Of note, 4/15 participants with IN RAM had a VL < 200 copies/mL at time of testing.

CONCLUSIONS

In the NEAT001/ANRS143 trial, there was no RAM at virological failure in the standard tenofovir/emtricitabine plus darunavir/ritonavir regimen, contrasting with a rate of 29.5% (mostly IN mutations) in the raltegravir plus darunavir/ritonavir NRTI-sparing regimen. The cumulative risk of IN RAM after 96 weeks of follow-up in participants initiating ART with raltegravir plus darunavir/ritonavir was 3.9%.

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.

Cross-resistance to elvitegravir and dolutegravir in 502 patients failing on raltegravir: a French national study of raltegravir-experienced HIV-1-infected patients

OBJECTIVES

The objectives of this study were to determine the prevalence and patterns of resistance to integrase strand transfer inhibitors (INSTIs) in patients experiencing virological failure on raltegravir-based ART and the impact on susceptibility to INSTIs (raltegravir, elvitegravir and dolutegravir).

PATIENTS AND METHODS

Data were collected from 502 treatment-experienced patients failing a raltegravir-containing regimen in a multicentre study. Reverse transcriptase, protease and integrase were sequenced at failure for each patient. INSTI resistance-associated mutations investigated were those included in the last ANRS genotypic algorithm (v23).

RESULTS

Among the 502 patients, at failure, median baseline HIV-1 RNA (viral load) was 2.9 log10 copies/mL. Patients had been previously exposed to a median of five NRTIs, one NNRTI and three PIs. Seventy-one percent harboured HIV-1 subtype B and the most frequent non-B subtype was CRF02_AG (13.3%). The most frequent mutations observed were N155H/S (19.1%), Q148G/H/K/R (15.4%) and Y143C/G/H/R/S (6.7%). At failure, viruses were considered as fully susceptible to all INSTIs in 61.0% of cases, whilst 38.6% were considered as resistant to raltegravir, 34.9% to elvitegravir and 13.9% to dolutegravir. In the case of resistance to raltegravir, viruses were considered as susceptible to elvitegravir in 11% and to dolutegravir in 64% of cases. High HIV-1 viral load at failure (P < 0.001) and low genotypic sensitivity score of the associated treatment with raltegravir (P < 0.001) were associated with the presence of raltegravir-associated mutations at failure. Q148 mutations were selected more frequently in B subtypes versus non-B subtypes (P = 0.004).

CONCLUSIONS

This study shows that a high proportion of viruses remain susceptible to dolutegravir in the case of failure on a raltegravir-containing regimen.

A cohort study of treatment-experienced HIV-1-infected patients treated with raltegravir: factors associated with virological response and mutations selected at failure

This study aimed to identify factors associated with virological response (VR) to raltegravir (RAL)-containing regimens in 468 treatment-experienced but integrase inhibitor-naive HIV-1 patients receiving a RAL-containing regimen. VR was defined at Month 6 (M6) as HIV-1 RNA viral load (VL) <50 copies/mL. The impacts on VR of baseline integrase mutations, VL, CD4 count, genotypic sensitivity score for nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors and protease inhibitors, and the number of new antiretrovirals used for the first time associated with RAL were investigated. For patients with VL >50 copies/mL at M6, integrase mutations selected were characterised. Median baseline VL was 4.2 log(10)copies/mL (IQR 3.3-4.9 log(10) copies/mL) and CD4 count was 219 cells/mm(3) (IQR 96-368 cells/mm(3)). At M6, 71% of patients were responders. In multivariate analysis, baseline VL and CD4 count and ≥ 2 new antiretrovirals among darunavir, etravirine, maraviroc and enfuvirtide were associated with VR to RAL. Neither HIV-1 subtype nor baseline integrase polymorphisms were associated with VR to RAL. Among 63 failing patients at M6, selection of ≥ 1 change in the integrase gene was observed in 49 (77.8%), and 27/63 (42.9%) were considered as RAL-associated resistance mutations. Factors independently associated with the occurrence of ≥ 1 RAL-associated resistance mutation were VL at failure >3 log(10) and having no new drugs associated with RAL. RAL showed great potency in treatment-experienced patients. The number of new drugs associated with RAL was an important factor associated with VR. HIV-1 subtype and baseline integrase polymorphisms do not influence the RAL VR.