Low-level viral loads and virological failure in the integrase strand transfer era.

OBJECTIVES: To analyse the occurrence of virological failure (VF) in patients starting ART with an integrase strand transfer inhibitor (INSTI)-based regimen in recent years, in relation with previous episodes of low-level viral load (LLVL). PATIENTS AND METHODS: Patients starting a first ART between 1 January 2015 and 31 December 2020 based on two NRTIs and one INSTI were included if after virological control (two measures of VL < 50 copies/mL) they had a minimum of two additional VL measurements. Cox models adjusted for sex, age, acquisition group, hepatitis B or C coinfection, place of birth, year of ART initiation, CD4+ T cells and VL at ART initiation, duration of known HIV infection and of ART regimen were used to assess the association between the time to VF and the occurrence of LLVL. ART regimen was evaluated as time-varying covariate. RESULTS: LLVL was described in 13.7% and VF in 11% of the 3302 patients. LLVL was associated with VF [adjusted HR (aHR) 1.76, 95% CI 1.28-2.41], as well as age (aHR 0.97/year, 95% CI 0.96-0.98), CD4+ T cell count at ART initiation (aHR 0.93, 95% CI 0.87-0.98), heterosexual transmission (aHR 1.76, 95% CI 1.30-2.37) and being born abroad (aHR 1.50, 95% CI 1.17-1.93). CONCLUSIONS: LLVL was related to VF. Even in the absence of subsequent failure, LLV episodes have a cost. Thus any VL value above 50 copies/mL should lead to enhanced adherence counselling.

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.

Weighted log-rank test to compare two survival functions in the presence of dependent censoring.

Comparing survival functions with the log-rank test in the presence of dependent censoring can produce an invalid test result. We extend our previous work on the estimation of the survival function using prognostic variables to adjust for dependent censoring to the comparison of two survival distributions. In these estimators, the weights of a censored individual is redistributed among either a subset of patients in the risk set or all patients in the risk set but giving more weight to patients having smallest distances from the censored subject. The distance is based on two risk scores obtained from two working models, one for the failure time and one for the censoring time. Based on the estimators, we suggest a weighted log-rank test to compare two survival distributions. A simulation study compared performance of our method with the analysis of the observed data without using auxiliary variables and with a recent method based on multiple imputation (KMIB method). With appropriate parameters, the weighted log-rank approach provides sizes of the test comparable to the nominal value but higher powers than the two other methods. The method is illustrated with data from a breast cancer study.

Factors associated with the emergence of integrase resistance mutations in patients failing dual or triple integrase inhibitor-based regimens in a French national survey.

BACKGROUND: Successful 2-drug regimens (2DRs) for HIV were made possible by the availability of drugs combining potency and tolerability with a high genetic barrier to resistance. How these deal with resistance development/re-emergence, compared with 3DRs, is thus of paramount importance. MATERIALS AND METHODS: A national survey including patients who were either naive or experienced with any 2DR or 3DR but failing integrase strand transfer inhibitor (INSTI)-containing regimens [two consecutive plasma viral load (VL) values >50 copies/mL] was conducted between 2014 and 2019. Genotypic resistance tests were interpreted with the v28 ANRS algorithm. RESULTS: Overall, 1104 patients failing any INSTI-containing regimen (2DRs, n = 207; 3DRs, n = 897) were analysed. Five hundred and seventy-seven (52.3%) patients were infected with a B subtype and 527 (47.3%) with non-B subtypes. Overall, 644 (58%) patients showed no known integrase resistance mutations at failure. In multivariate analysis, factors associated with the emergence of at least one integrase mutation were: high VL at failure (OR = 1.24 per 1 log10 copies/mL increase); non-B versus B subtype (OR = 1.75); low genotypic sensitivity score (GSS) (OR = 0.10 for GSS = 2 versus GSS = 0-0.5); and dolutegravir versus raltegravir (OR = 0.46). Although 3DRs versus 2DRs reached statistical significance in univariate analysis (OR = 0.59, P = 0.007), the variable is not retained in the final model. CONCLUSIONS: This study is one of the largest studies characterizing integrase resistance in patients failing any INSTI-containing 2DR or 3DR in routine clinical care and reveals factors associated with emergence of integrase resistance that should be taken into consideration in clinical management. No difference was evidenced between patients receiving a 2DR or a 3DR.

Linezolid-Associated Neurologic Adverse Events in Patients with Multidrug-Resistant Tuberculosis, France.

Linezolid is one of the most effective drugs for treating multidrug-resistant tuberculosis (MDR TB), but adverse effects remain problematic. We evaluated 57 MDR TB patients who had received >1 dose of linezolid during 2011-2016. Overall, patients received 600 mg/day of linezolid for a median of 13 months. In 33 (58%) patients, neurologic or ophthalmologic signs developed, and 18 (32%) had confirmed peripheral neuropathy, which for 78% was irreversible at 12 months after the end of TB treatment despite linezolid withdrawal. Among the 19 patients who underwent ophthalmologic evaluation, 14 patients had optic neuropathy that fully reversed for 2. A total of 16 (33%) of 49 patients had a linezolid trough concentration >2 mg/L, and among these, 14 (88%) experienced adverse effects. No significant association was found between trough concentration and neurologic toxicity. These findings suggest the need to closely monitor patients for neurologic signs and discuss optimal duration of linezolid treatment.

Weighted Kaplan-Meier estimators motivating to estimate HIV-1 RNA reduction censored by a limit of detection.

Measuring the magnitude of reduction in HIV-1 RNA levels accurately is difficult because many patients have a censored reduction due to the limit of detection (LOD) of the virologic assay being employed. The use of censored methods has improved the analysis of such reductions compared with crude methods but implies independent censoring. For HIV-1 RNA reduction data, the value at which a patient's HIV-1 RNA reduction becomes censored is mainly determined by the patient's baseline HIV-1 RNA level. We suggest two possibilities based on modification of the redistribution to the right algorithm to handle the situation of dependence either from a single continuous marker, that is, the baseline HIV-1 RNA level, or from multiple markers. Two series of simulation, one in the HIV-1 RNA setting and one in the classical censoring setting, compared performance of the previous methods with our suggestions. Our proposed estimators show good performances when the dependent censoring is due to LOD. Overall, in the classical censoring setting, our suggestions perform as well as other methods including the Inverse Probability of Censoring Weighted and the Kaplan-Meier imputation with Bootstrap. We applied those estimators to estimate the HIV-1 RNA reduction at week 8 of 502 patients who received a raltegravir-containing regimen and to data from the Mayo Clinic trial in primary biliary cirrhosis.

Anti-gp41 antibody levels reflect HIV viral suppression and cellular reservoir in long-term antiretroviral-treated trial participants.

BACKGROUND: A major challenge to HIV cure strategies is the quantification of persistent reactivation-prone virus in people living with HIV. OBJECTIVES: To determine whether anti-gp41 antibody levels correlate with viral suppression and HIV-1 DNA levels in patients on ART. METHODS: Participants with plasma HIV-1 RNA below 50 copies/mL for >12 months were included from three ANRS cohorts (COPANA, MONOI and APROCO). Antibody levels to gp41 were measured by a low-sensitivity enzyme-linked immunoassay. Correlations with patient and virus characteristics, plasma HIV-1 RNA load (standard and ultrasensitive tests) and cell-associated HIV-1 DNA were assessed. RESULTS: Median age was 41 years and 77.5% of the 683 participants were men. Median CD4+ T cell count was 582 cells/mm3 and median viral suppression duration was 6.6 years (IQR 2.0-9.5). The overall median anti-gp41 antibody titre was 1.3 (IQR 0.6-1.9); median HIV-1 DNA level was 2.6 (IQR 2.1-3.0) log10 copies/106 leucocytes; and HIV-1 RNA was undetectable in 56% of samples. A lower titre of anti-gp41 antibodies correlated with male gender, longer viral suppression and lower HIV-1 DNA burden. Sustained undetectable HIV-1 RNA was associated with lower anti-gp41 levels [median 1.1 (IQR 0.5-1.6) versus 1.4 (IQR 0.7-1.9), P = 0.009]. CONCLUSIONS: Anti-gp41 levels decreased with the duration of antiviral suppression on ART. Lower titres were associated with lower HIV-1 DNA levels and longer duration of viral suppression, reflecting minimal antigen stimulation. Anti-gp41 antibody titration may be a useful biomarker reflecting long-term HIV-1 suppression on ART.

Resistance to integrase inhibitors: a national study in HIV-1-infected treatment-naive and -experienced patients.

OBJECTIVES: To describe integrase strand transfer inhibitor (INSTI) resistance profiles and factors associated with resistance in antiretroviral-naive and -experienced patients failing an INSTI-based regimen in clinical practice. METHODS: Data were collected from patients failing an INSTI-containing regimen in a multicentre French study between 2014 and 2017. Failure was defined as two consecutive plasma viral loads (VL) >50 copies/mL. Reverse transcriptase, protease and integrase coding regions were sequenced at baseline and failure. INSTI resistance-associated mutations (RAMs) included in the Agence Nationale de Recherches sur le SIDA genotypic algorithm were investigated. RESULTS: Among the 674 patients, 359 were failing on raltegravir, 154 on elvitegravir and 161 on dolutegravir therapy. Overall, 90% were experienced patients and 389 (58%) patients showed no INSTI RAMs at failure. The strongest factors associated with emergence of at least one INSTI mutation were high VL at failure (OR = 1.2 per 1 log10 copies/mL increase) and low genotypic sensitivity score (GSS) (OR = 0.08 for GSS ≥3 versus GSS = 0-0.5). Patients failing dolutegravir also had significantly fewer INSTI RAMs at failure than patients failing raltegravir (OR = 0.57, P = 0.02) or elvitegravir (OR = 0.45, P = 0.005). Among the 68 patients failing a first-line regimen, 11/41 (27%) patients on raltegravir, 7/18 (39%) on elvitegravir and 0/9 on dolutegravir had viruses with emergent INSTI RAMs at failure. CONCLUSIONS: These results confirmed the robustness of dolutegravir regarding resistance selection in integrase in the case of virological failure in routine clinical care.

Ultrasensitive Human Immunodeficiency Virus Type 1 Viral Load as a Marker of Treatment Choice for Simplification Strategies.

Background: Using 3 randomized Protease inhibitor (PI) monotherapy studies: Kalesolo, Dream and Monoi, we performed a pooled-analysis. Our objective was to determine in PI monotherapy and standard tritherapy: 1) distribution of ultrasensitive viral load (USVL) at week 96 (W96); 2) factors associated with virological failure (VF) at W96 and 3) factors associated with USVL<1 copy at W96. Methods: VF was defined as 2 consecutive measurements of Human Immunodeficiency Virus Type 1 RNA viral load>50 copies/mL and analysed in Intention-To-Treat. A logistic model was used to investigate which variables were predictive of a VF and Fisher test to investigate differences in USVL at W96. Results: Among 609 patients, 73% were male with median age of 44.4 years (IQR 39.8-52.1), baseline CD4/CD8 ratio was 0.8 (IQR 0.6-1.10), baseline CD4 was 564.5/mm3 (IQR 422-707) and 59% presented a baseline USVL<1 copy/mL. At W96, the proportion of USVL<1 copy/mL was significantly different between PI monotherapy and standard tritherapy in pooled-analysis (65% versus 74%; p=0.04). Overall, baseline USVL<1copy/mL, tritherapy and to be a female were associated with USVL<1 copy/mL at W96 (p<0.0001, p=0.049 and p=0.006). In PI monotherapy receiving DRV/r was associated with USVL<1 copy/mL at W96 (p=0.003). Factors associated to virological succes at W96 were higher baseline CD4 (p=0.034) and baseline USVL<1 copy/mL (p=0.0005). Conclusion: Pooled-analysis of 3 PI monotherapy trials showed better efficacy of tritherapy in terms of USVL at W96. Furthermore regarding USVL at W96, to receive LPV/r seems to be more deleterious than DRV/r. Baseline USVL impacts VF at W96 more specifically in tritherapy arm. Clinical Trials Registration: NCT00421551, NCT00946595, and NCT00140751.

Antiretroviral-treated HIV-1 patients can harbour resistant viruses in CSF despite an undetectable viral load in plasma.

Background: HIV therapy reduces the CSF HIV RNA viral load (VL) and prevents disorders related to HIV encephalitis. However, these brain disorders may persist in some cases. A large population of antiretroviral-treated patients who had a VL > 1.7 log 10 copies/mL in CSF with detectable or undetectable VL in plasma associated with cognitive impairment was studied, in order to characterize discriminatory factors of these two patient populations. Methods: Blood and CSF samples were collected at the time of neurological disorders for 227 patients in 22 centres in France and 1 centre in Switzerland. Genotypic HIV resistance tests were performed on CSF. The genotypic susceptibility score was calculated according to the last Agence Nationale de Recherche sur le Sida et les hépatites virales Action Coordonnée 11 (ANRS AC11) genotype interpretation algorithm. Results: Among the 227 studied patients with VL > 1.7 log 10 copies/mL in CSF, 195 had VL detectable in plasma [median (IQR) HIV RNA was 3.7 (2.7-4.7) log 10 copies/mL] and 32 had discordant VL in plasma (VL < 1.7 log 10 copies/mL). The CSF VL was lower (median 2.8 versus 4.0 log 10 copies/mL; P < 0.001) and the CD4 cell count was higher (median 476 versus 214 cells/mm 3 ; P < 0.001) in the group of patients with VL < 1.7 log 10 copies/mL in plasma compared with patients with plasma VL > 1.7 log 10 copies/mL. Resistance to antiretrovirals was observed in CSF for the two groups of patients. Conclusions: Fourteen percent of this population of patients with cognitive impairment and detectable VL in CSF had well controlled VL in plasma. Thus, it is important to explore CSF HIV (VL and genotype) even if the HIV VL is controlled in plasma because HIV resistance may be observed.

Accuracy of predictive ability measures for survival models.

One aspect of an analysis of survival data based on the proportional hazards model that has been receiving increasing attention is that of the predictive ability or explained variation of the model. A number of contending measures have been suggested, including one measure, R2 (ß), which has been proposed given its several desirable properties, including its capacity to accommodate time-dependent covariates, a major feature of the model and one that gives rise to great generality. A thorough study of the properties of available measures, including the aforementioned measure, has been carried out recently. In that work, the authors used bootstrap techniques, particularly complex in the setting of censored data, in order to obtain estimates of precision. The motivation of this work is to provide analytical expressions of precision, in particular confidence interval estimates for R2 (ß). We use Taylor series approximations with and without local linearizing transforms. We also consider a very simple expression based on the Fisher's transformation. This latter approach has two great advantages. It is very easy and quick to calculate, and secondly, it can be obtained for any of the methods given in the recent review. A large simulation study is carried out to investigate the properties of the different methods. Finally, three well-known datasets in breast cancer, lymphoma and lung cancer research are given as illustrations. Copyright © 2017 John Wiley & Sons, Ltd.

Improved darunavir genotypic mutation score predicting treatment response for patients infected with HIV-1 subtype B and non-subtype B receiving a salvage regimen.

OBJECTIVES: The objective of this study was to improve the prediction of the impact of HIV-1 protease mutations in different viral subtypes on virological response to darunavir. METHODS: Darunavir-containing treatment change episodes (TCEs) in patients previously failing PIs were selected from large European databases. HIV-1 subtype B-infected patients were used as the derivation dataset and HIV-1 non-B-infected patients were used as the validation dataset. The adjusted association of each mutation with week 8 HIV RNA change from baseline was analysed by linear regression. A prediction model was derived based on best subset least squares estimation with mutational weights corresponding to regression coefficients. Virological outcome prediction accuracy was compared with that from existing genotypic resistance interpretation systems (GISs) (ANRS 2013, Rega 9.1.0 and HIVdb 7.0). RESULTS: TCEs were selected from 681 subtype B-infected and 199 non-B-infected adults. Accompanying drugs were NRTIs in 87%, NNRTIs in 27% and raltegravir or maraviroc or enfuvirtide in 53%. The prediction model included weighted protease mutations, HIV RNA, CD4 and activity of accompanying drugs. The model's association with week 8 HIV RNA change in the subtype B (derivation) set was R(2) = 0.47 [average squared error (ASE) = 0.67, P < 10(-6)]; in the non-B (validation) set, ASE was 0.91. Accuracy investigated by means of area under the receiver operating characteristic curves with a binary response (above the threshold value of HIV RNA reduction) showed that our final model outperformed models with existing interpretation systems in both training and validation sets. CONCLUSIONS: A model with a new darunavir-weighted mutation score outperformed existing GISs in both B and non-B subtypes in predicting virological response to darunavir.

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.

Antiretroviral-naive and -treated HIV-1 patients can harbour more resistant viruses in CSF than in plasma.

OBJECTIVES: The neurological disorders in HIV-1-infected patients remain prevalent. The HIV-1 resistance in plasma and CSF was compared in patients with neurological disorders in a multicentre study. METHODS: Blood and CSF samples were collected at time of neurological disorders for 244 patients. The viral loads were >50 copies/mL in both compartments and bulk genotypic tests were realized. RESULTS: On 244 patients, 89 and 155 were antiretroviral (ARV) naive and ARV treated, respectively. In ARV-naive patients, detection of mutations in CSF and not in plasma were reported for the reverse transcriptase (RT) gene in 2/89 patients (2.2%) and for the protease gene in 1/89 patients (1.1%). In ARV-treated patients, 19/152 (12.5%) patients had HIV-1 mutations only in the CSF for the RT gene and 30/151 (19.8%) for the protease gene. Two mutations appeared statistically more prevalent in the CSF than in plasma: M41L (P=0.0455) and T215Y (P=0.0455). CONCLUSIONS: In most cases, resistance mutations were present and similar in both studied compartments. However, in 3.4% of ARV-naive and 8.8% of ARV-treated patients, the virus was more resistant in CSF than in plasma. These results support the need for genotypic resistance testing when lumbar puncture is performed.

Safety and efficacy of coformulated efavirenz/emtricitabine/tenofovir single-tablet regimen in treatment-naive patients infected with HIV-1.

Due to the differences between bioavailability of efavirenz (EFV) and tenofovir (TDF), the single-tablet regimen of EFV/emtricitabine (FTC)/TDF is not approved as initial antiretroviral therapy (ART) in Europe by the European Medical Agency. To compare clinical, immunological, and virological outcomes between co-formulated TDF/FTC+EFV and the co-formulated EFV/FTC/TDF single-tablet regimen in patients infected with HIV-1 naive to ART, the data of patients (n = 231) who initiated either TDF/FTC+EFV (n = 155) or EFV/FTC/TDF (n = 76) between January 1, 2007 and June 1, 2010 were analyzed. Changes from baseline to week 48 (TDF/FTC+EFV vs. EFV/FTC/TDF) in HIV plasma load (- 3.25 log vs. -3.32 log) and CD4+ T cell count (+180 vs. +138 cells/mm3) were similar in the two groups. Treatment discontinuation was recorded in 50 (22%) patients (40 on TDF/FTC+EFV and 10 on EFV/FTC/TDF, P = 0.03) but time to discontinuation did not differ between the two groups. Only patients on TDF/FTC+EFV discontinued treatment because of neurological symptoms. Virological failure occurred in 11 (4.7%) patients (seven on TDF/FTC+EFV and four on EFV/FTC/TDF, P = 0.75) with new resistance-associated mutations in five among the six with successful resistance genotype tests. Only baseline resistance-associated mutations was a risk factor for virological failure (P = 0.0146). These data show comparable outcomes between TDF/FTC+EFV or EFV/FTC/TDF used in patients infected with HIV-1 and not treated previously, consistent with a low rate of virological failure in the absence of pretreatment resistance. This would suggest that the European Medical Agency should approve co-formulated EFV/FTC/TDF single-tablet regimen for patients naive to ART.

Factors associated with a low HIV reservoir in patients with prolonged suppressive antiretroviral therapy.

OBJECTIVES: The relevance of low-level HIV DNA in patients who have undergone prolonged therapy is not well understood. The objective of this study was to determine factors that influence the establishment of low-level HIV DNA in long-term treated patients (excluding treatment since acute infection). METHODS: This was a cross-sectional study involving 243 patients receiving highly active antiretroviral therapy (HAART) for ≥6 months (median: 9 years of treatment) with plasma HIV RNA <50 copies/mL at the study timepoint, for whom total DNA measurements were performed. Patients treated since early acute infection or receiving cancer chemotherapeutic/immunosuppressive agents were excluded from the study. RESULTS: Overall, the median HIV DNA was 372 copies/10(6) peripheral blood mononuclear cells (PBMCs). Forty-seven patients had levels of HIV DNA below the limit of detection and 58 patients had low-level HIV DNA (<100 copies/10(6) PBMCs). In multivariate analysis, a low total HIV DNA in HAART-treated patients was clearly associated with a low HIV RNA pre-therapeutic viral load (P < 0.0001), regardless of the cut-off used. CONCLUSIONS: These results may be helpful to identify candidates for future trials aiming at a functional cure of HIV infection, since low total HIV DNA levels will most likely be a prerequisite of successful immunological control of HIV replication.

Switching to darunavir/ritonavir 800/100 mg once-daily containing regimen maintains virological control in fully suppressed pre-treated patients infected with HIV-1.

The objective of this study was to evaluate the switch to once-daily darunavir/ritonavir 800/100 mg in treatment-experienced patients with suppressed HIV-1 replication on a twice-daily ritonavir-boosted protease-inhibitor (bid PI/r) containing regimen, that is in a setting where genotypic resistance test cannot be performed. In this open label, non-comparative, multicenter study, patients on a bid PI/r-containing triple combination, with suppressed viral replication, were switched to once-daily darunavir/r 800/100 mg containing triple combination. The primary endpoint was the proportion of patients with plasma HIV-RNA < 50 copies/ml 24 weeks after the switch. Intensive darunavir pharmacokinetic evaluation was performed at Week 4 (W4) in 11 patients. Eighty-five patients were enrolled. All had HIV-RNA < 50 copies/ml at screening with a pre-exposure to a median of 2 PI/r (1-5). By intent-to-treat analysis (missing = failure), 78/85 patients (92%, 95% CI [83;96]) maintained an HIV-RNA < 50 copies/ml at W24. Seven patients experienced protocol-defined treatment failure between baseline and W24: Two had confirmed low-level viral rebound, one discontinued study treatment for adverse event, three withdrew their consent, and one was lost to follow-up. By on-treatment analysis, 78/80 patients (97%, 95% CI [91;99]) maintained an HIV-RNA < 50 copies/ml at W24. Results were similar at Week 48. The median area under the darunavir plasma concentration-time curve measured in 11 patients was 61,380 ng hr/ml; darunavir median trough concentration 1,340 ng/ml and darunavir half-life was 12.2 hr. Tolerability of once-daily darunavir/r 800/100 mg was excellent. Optimally suppressed, treatment-experienced patients can switch safely from a twice-daily PI/r regimen to a once-daily darunavir/r 800/100 mg containing regimen.

Resistant minority species are rarely observed in patients on darunavir/ritonavir monotherapy.

OBJECTIVES: To analyse the emergence of resistant viruses in patients failing darunavir monotherapy, including minority species, and to investigate the impact of baseline reverse transcriptase (RT), protease (PR) and gag resistance mutations on virological failure (VF) occurrence. METHODS: Nine of the 225 HIV-1-infected patients enrolled in the MONOI trial (darunavir/ritonavir monotherapy or darunavir/ritonavir + two nucleoside reverse transcriptase inhibitors in a switch strategy) experienced VF, defined as two plasma HIV-1 viral loads >400 copies/mL at least 2 weeks apart. Among these nine patients with VF, five were in the darunavir/ritonavir monotherapy arm and four were in the darunavir/ritonavir triple therapy arm. Bulk sequences of the PR, RT and gag genes at baseline (on DNA) and at the time of VF (on RNA) were determined for all patients with two viral loads >50 copies/mL at least 2 weeks apart (n = 47). PR and gag gene clonal analysis was performed on plasma samples of the nine patients with VF. RESULTS: There was no association between mutations in RT, PR and gag genes in DNA and VF occurrence. None of the patients demonstrated selection of darunavir resistance mutations among the 47 patients with a viral load >50 copies/mL at least 2 weeks apart. The virus of one of the nine patients with VF presented minority variants with darunavir resistance mutations at positions 32, 47 and 50. Clonal analysis of the gag region for the nine patients with VF did not show any selection of minority variants. CONCLUSIONS: In patients with failure on darunavir/ritonavir monotherapy we did not find any selection of darunavir resistance mutations using standard genotype testing. However, the virus of one patient among nine failures presented minority variants plus darunavir resistance mutations.

Risk factors for raltegravir resistance development in clinical practice.

OBJECTIVES: To investigate the best conditions of raltegravir use to avoid the selection of resistance mutations in the three main genetic pathways: 148, 155 and 143. METHODS: A total of 161 patients failing on raltegravir with two consecutive HIV-1 viral loads >20 copies/mL were studied. Ten parameters [HIV-1 RNA and CD4 at baseline and failure, genotypic sensitivity score (GSS) of treatment associated with raltegravir, protease inhibitors used, time spent on raltegravir, subtype, sex and age] were tested in univariate and multivariate logistic regression analyses and compared with the emergence of resistance mutations to raltegravir at failure. Phenotypic susceptibility to raltegravir was studied in 16 patients without the main resistance mutations to raltegravir at failure. RESULTS: At raltegravir failure, 46/161 patients (28.6%) had integrase resistance mutations, whereas 115/161 (71.4%) had no resistance mutations. High HIV-1 viral load level at failure (OR = 2.81, 95% CI 1.8-4.6, P < 0.001) and low GSS of treatment associated with raltegravir (OR = 11.6, 95% CI 4.5-36.4, P < 0.001) were independently associated with the selection of raltegravir mutations. The percentages of patients with integrase resistance mutations were 7.7% (6/78) versus 48.1% (40/83) when viral load is ≤200 or >200 copies/mL and 47.5% (39/82) versus 8.9% (7/79) when GSS is <2 or ≥2. Among patients without main resistance mutations, two patients showed raltegravir phenotypic resistance, one naturally with F121Y at baseline and the other acquiring G118R at failure. CONCLUSIONS: Our results show that to avoid the selection of raltegravir resistance mutations, patients have to be treated with at least two active drugs in combination with raltegravir and to maintain a viral load ≤200 copies/mL.