Integrated Population Exposure-Response of Dolutegravir in HIV-1 Supports Bridging of Clinical Response Influenced by Relevant Intrinsic and Extrinsic Patient Characteristics.

Dolutegravir (DTG) is a human immunodeficiency virus type 1 (HIV-1) integrase strand transfer inhibitor indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults and pediatric subjects aged at least 4 weeks. The present work aimed to characterize the viral response based on a pooled analysis of exposure-response (E-R) from five studies in treatment-experienced and integrase-resistant (INI-r) patients infected with HIV-1. Importantly, model-based simulations of the E-R relationships with DTG provided insight into the clinical relevance of known intrinsic (e.g., sub-population with Q148-driven integrase mutation) and extrinsic (food, enzyme inducers, and metal cation-containing products) factors expected to influence the DTG E-R relationship. Model-based post hoc exposure metrics (Cmin and Cavg) were incorporated into a mechanistic population viral dynamic model describing the short-term effect of DTG on log10 HIV-1 RNA viral load over 8 or 10 days. In addition, the impact of DTG in combination with background ARTs on the 24-week HIV RNA response was also assessed using logistic regression. There was good concordance between model-based predictions and observed virologic response on day 10 and week 24. The E-R model-based simulations exploring the potential impact of a higher dose (100 mg b.i.d.) of DTG in subpopulations experiencing exposure changes due to covariates did not show clinically relevant changes in virological response compared with the approved 50 mg b.i.d. clinical dose. Overall, our study confirmed the current recommendation of dolutegravir 50 mg b.i.d. in the integrase inhibitor-resistant (INI-r) population.

Bridging dolutegravir clinical viral response across doses and formulations using model-based exposure-response analysis in pediatrics.

OBJECTIVE: Dolutegravir (DTG) is a once-daily HIV-1 integrase inhibitor approved for the treatment of HIV-1 infection in adults and children from 4 weeks of age. The posology of DTG in children has been driven by exposure-matching relative to the adult dose for efficacy and safety. However, higher variability in pediatric exposures raises concern that efficacy may not be reliably extrapolated from adult trials. Therefore, we evaluated the relationship between DTG exposure and virologic response in children. DESIGN/METHODS: A population exposure-response analysis using logistic regression for virologic response was undertaken based on DTG exposure and covariate data from 146 pediatric participants with HIV-1 from age at least 4 weeks to less than 18 years treated for up to 48 weeks with DTG in IMPAACT P1093 study. RESULTS: None of the DTG exposure metrics were predictive of virologic response over the range of exposures in this analysis. Of the covariates tested, viral load at least 100 000 copies/ml at enrolment was a significant predictor of virologic response showing a lower probability of achieving a virologic response of HIV-1 RNA less than 50 copies/ml compared with participants with viral load less than 100 000 copies/ml at enrolment. Baseline viral load was also a significant predictor at week 48 whereby the probability of achieving a virologic response at week 48 decreased with increasing baseline viral load. CONCLUSION: This exposure-response analysis suggests that DTG exposures in children are all above the plateau of the exposure-response relationship. These results suggest that matching pediatric pharmacokinetic exposure parameters to those in adults is a reasonable approach for dose determination of DTG-containing formulations in pediatrics.

Sensitive HIV-1 DNA Pol Next-Generation Sequencing for the Characterisation of Archived Antiretroviral Drug Resistance.

Modern HIV-1 treatment effectively suppresses viral amplification in people living with HIV. However, the persistence of HIV-1 DNA as proviruses integrated into the human genome remains the main barrier to achieving a cure. Next-generation sequencing (NGS) offers increased sensitivity for characterising archived drug resistance mutations (DRMs) in HIV-1 DNA for improved treatment options. In this study, we present an ultra-sensitive targeted PCR assay coupled with NGS and a robust pipeline to characterise HIV-1 DNA DRMs from buffy coat samples. Our evaluation supports the use of this assay for Pan-HIV-1 analyses with reliable detection of DRMs across the HIV-1 Pol region. We propose this assay as a new valuable tool for monitoring archived HIV-1 drug resistance in virologically suppressed individuals, especially in clinical trials investigating novel therapeutic approaches.

Emergence of Resistance in HIV-1 Integrase with Dolutegravir Treatment in a Pediatric Population from the IMPAACT P1093 Study.

P1093 is a multicenter, open-label, phase I/II study of pharmacokinetics, safety, and tolerability of dolutegravir plus an optimized background regimen in pediatric participants aged 4 weeks to <18 years with HIV-1. Most participants were highly treatment experienced. We report the mechanisms of emergent integrase strand transfer inhibitor (INSTI) resistance among adolescents and children receiving dolutegravir. Plasma was collected at screening and near protocol-defined virologic failure (PDVF) for population-level and, for some samples, clonal-level integrase genotyping, phenotyping, and replication capacity. HIV-1 RNA was assessed in all available plasma samples. Phylogenetic analysis of clonal integrase sequences and homology modeling of HIV-1 intasome complexes containing resistance-associated substitutions were performed. Treatment-emergent INSTI resistance was detected in 8 participants who met PDVF criteria. The rare INSTI resistance-associated substitution G118R or R263K developed in 6 participants. The on-study secondary integrase substitution E157Q or L74I was observed in 2 participants. G118R reduced dolutegravir susceptibility and integrase replication capacity more than R263K and demonstrated greater reduction in susceptibility and integrase replication capacity when present with specific secondary integrase substitutions, including L74M, T66I, and E138E/K. Continuing evolution after R263K acquisition led to reduced dolutegravir susceptibility and integrase replication capacity. Structural examination revealed potential mechanisms for G118R- and R263K-mediated INSTI resistance. G118R and R263K INSTI resistance substitutions, which are distinct to second-generation INSTIs, were detected in adolescents and children with prior virologic failure who received dolutegravir. This study provides additional molecular and structural characterization of integrase to aid in the understanding of INSTI resistance mechanisms in antiretroviral-experienced populations. (This study has been registered at ClinicalTrials.gov under identifier NCT01302847.).

Long-Term Safety and Efficacy of Dolutegravir in Treatment-Experienced Adolescents With Human Immunodeficiency Virus Infection: Results of the IMPAACT P1093 Study.

BACKGROUND: P1093 is an ongoing phase I/II multicenter open-label study of dolutegravir plus an optimized background regimen in age-defined pediatric cohorts; here we report the long-term safety and virologic efficacy outcomes for the oldest cohort. METHODS: The study enrolled human immunodeficiency virus type 1 (HIV-1)-infected treatment-experienced adolescents aged 12 to <18 years, with an HIV-1 RNA level ≥1000 copies/mL . Cumulative safety and HIV-1 RNA outcomes were assessed once the last enrolled participant reached 144 weeks of follow-up. RESULTS: Among 23 adolescents enrolled, 16 remained in the study at least 144 weeks; the median follow-up was 153 weeks (range, 55-193 weeks). Dolutegravir was well tolerated, with grade 3 clinical adverse events in 5 participants, grade 3 laboratory abnormalities in 3, and grade 4 laboratory abnormalities in 1; none of the adverse events or abnormalities were judged to be treatment related. In an-intent-to-treat analysis, an HIV-1 RNA level <400 copies/mL at week 144 was achieved in 43% (10 of 23 participants; 95% confidence interval, 23.2%-65.5%); in addition, 35% (8 of 23; 16.4%-57.3%) had an HIV-1 RNA level <50 copies/mL. Nine participants (39%) discontinued study treatment before 144 weeks, but none because of adverse events or drug intolerance. All participants with sustained virologic control had excellent adherence; most who experienced virologic failure had adherence levels <90%. HIV-1 genotypic drug resistance testing was available at time of failure from 6 participants; 1 had evolution in integrase resistance with E138T, S147G, and R263K mutations at week 192 and phenotypic dolutegravir resistance of a 5.1-fold change. CONCLUSIONS: Dolutegravir plus an optimized background regimen seemed safe, well tolerated, and efficacious in this cohort of treatment-experienced HIV-1-infected adolescents. Adherence remains problematic in this population. CLINICAL TRIALS REGISTRATION: NCT01302847.

Fixed-dose combination dolutegravir, abacavir, and lamivudine versus ritonavir-boosted atazanavir plus tenofovir disoproxil fumarate and emtricitabine in previously untreated women with HIV-1 infection (ARIA): week 48 results from a randomised, open-label, non-inferiority, phase 3b study.

BACKGROUND: Dolutegravir is a once-daily integrase strand transfer inhibitor with no need for pharmacokinetic boosting that is approved for the treatment of HIV-1 infection. Because women are often under-represented in HIV clinical trials, we addressed the safety and efficacy of dolutegravir in women with HIV-1. METHODS: The ARIA study is a randomised, open-label, multicentre, active-controlled, parallel-group, non-inferiority phase 3b study done in 86 hospital and university infectious disease clinics, local health clinics, and private infectious disease clinics in 12 countries and one US territory, in North America, South America, Europe, Africa, and Asia. Eligible participants were women aged 18 years or older who had HIV-1 RNA viral loads of 500 copies per mL or greater, had received 10 days or less of previous antiretroviral therapy, and had tested negative for the HLA-B*5701 allele. Pregnant women were excluded. Eligible women were randomly assigned (1:1) to receive either a single-tablet regimen of dolutegravir plus abacavir and lamivudine once a day (dolutegravir group) or a three-tablet combination of ritonavir-boosted atazanavir plus coformulated tenofovir disoproxil fumarate and emtricitabine once a day (atazanavir group). Random treatment group assignment was stratified by plasma HIV-1 RNA viral loads and CD4 cell count at baseline. The primary endpoint was the proportion of participants with HIV-1 RNA viral loads of less than 50 copies per mL at week 48 in all participants who received at least one dose of study medication (intention-to-treat exposed population). We used a non-inferiority margin of -12%. Investigators monitored adverse events to assess safety. This study is registered with ClinicalTrials.gov, number NCT01910402. FINDINGS: Between Aug 22, 2013, and Sept 22, 2015, of 705 women assessed, 499 were randomly assigned to either the dolutegravir group (n=250) or the atazanavir group (n=249); two participants from each group were randomised to treatment but did not receive study medication. At week 48, 203 (82%) of 248 participants in the dolutegravir group compared with 176 (71%) of 247 in the atazanavir group had HIV-1 RNA viral loads of less than 50 copies per mL (mean difference 10·5%, 95% CI 3·1-17·8, p=0·005). One participant in the atazanavir group had nucleoside reverse transcriptase inhibitor-associated resistance that led to reduced emtricitabine susceptibility. Adverse events were similar between the dolutegravir and atazanavir groups; the most common were nausea (46 [19%] of 248 in the dolutegravir group vs 49 [20%] of 247 in the atazanavir group) and headache (28 [11%] vs 32 [13%]). Fewer participants in the dolutegravir group than the atazanavir group reported drug-related adverse events (83 [33%] vs 121 [49%]) or adverse events that led to discontinuation (ten [4%] vs 17 [7%]). One death was reported in each treatment group, but neither was considered related to the study medications. INTERPRETATION: The non-inferior efficacy and similar safety profile of the dolutegravir combined regimen compared with the atazanavir regimen support the use of dolutegravir for HIV-1 infection in treatment-naive women. FUNDING: ViiV Healthcare.

Dolutegravir versus placebo in subjects harbouring HIV-1 with integrase inhibitor resistance associated substitutions: 48-week results from VIKING-4, a randomized study.

BACKGROUND: The Phase III VIKING-3 study demonstrated that dolutegravir (DTG) 50 mg twice daily was efficacious in antiretroviral therapy (ART)-experienced subjects harbouring raltegravir- and/or elvitegravir-resistant HIV-1. VIKING-4 (ING116529) included a placebo-controlled 7-day monotherapy phase to demonstrate that short-term antiviral activity was attributable to DTG. METHODS: VIKING-4 is a Phase III randomized, double-blind study in therapy-experienced adults with integrase inhibitor (INI)-resistant virus randomized to DTG 50 mg twice daily or placebo while continuing their failing regimen (without raltegravir or elvitegravir) for 7 days (clinicaltrials.gov identifier NCT01568892). At day 8, all subjects switched to open-label DTG 50 mg twice daily and optimized background therapy including ≥1 fully active drug. The primary end point was change from baseline in plasma HIV-1 RNA at day 8. RESULTS: The study population (n=30) was highly ART-experienced with advanced HIV disease. Patients had extensive baseline resistance to all approved antiretroviral classes. Adjusted mean change in HIV-1 RNA at day 8 was -1.06 log10 copies/ml for the DTG arm and 0.10 log10 copies/ml for the placebo arm (treatment difference -1.16 log10 copies/ml [-1.52, -0.80]; P<0.001). Overall, 47% and 57% of subjects had plasma HIV-1 RNA <50 and <400 copies/ml at week 24, and 40% and 53% at week 48, respectively. No discontinuations due to drug-related adverse events occurred in the study. CONCLUSIONS: The observed day 8 antiviral activity in this highly treatment-experienced population with INI-resistant HIV-1 was attributable to DTG. Longer-term efficacy (after considering baseline ART resistance) and safety during the open-label phase were in-line with the results of the larger VIKING-3 study.

Dolutegravir in antiretroviral-experienced patients with raltegravir- and/or elvitegravir-resistant HIV-1: 24-week results of the phase III VIKING-3 study.

BACKGROUND: The pilot phase IIb VIKING study suggested that dolutegravir (DTG), a human immunodeficiency virus (HIV) integrase inhibitor (INI), would be efficacious in INI-resistant patients at the 50 mg twice daily (BID) dose. METHODS: VIKING-3 is a single-arm, open-label phase III study in which therapy-experienced adults with INI-resistant virus received DTG 50 mg BID while continuing their failing regimen (without raltegravir or elvitegravir) through day 7, after which the regimen was optimized with ≥1 fully active drug and DTG continued. The primary efficacy endpoints were the mean change from baseline in plasma HIV-1 RNA at day 8 and the proportion of subjects with HIV-1 RNA <50 c/mL at week 24. RESULTS: Mean change in HIV-1 RNA at day 8 was -1.43 log10 c/mL, and 69% of subjects achieved <50 c/mL at week 24. Multivariate analyses demonstrated a strong association between baseline DTG susceptibility and response. Response was most reduced in subjects with Q148 + ≥2 resistance-associated mutations. DTG 50 mg BID had a low (3%) discontinuation rate due to adverse events, similar to INI-naive subjects receiving DTG 50 mg once daily. CONCLUSIONS: DTG 50 mg BID-based therapy was effective in this highly treatment-experienced population with INI-resistant virus. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov (NCT01328041) and http://www.gsk-clinicalstudywww.gsk-clinicalstudyregister.com (112574).

Prevalent polymorphisms in wild-type HIV-1 integrase are unlikely to engender drug resistance to dolutegravir (S/GSK1349572).

The majority of HIV-1 integrase amino acid sites are highly conserved, suggesting that most are necessary to carry out the critical structural and functional roles of integrase. We analyzed the 34 most variable sites in integrase (>10% variability) and showed that prevalent polymorphic amino acids at these positions did not affect susceptibility to the integrase inhibitor dolutegravir (S/GSK1349572), as demonstrated both in vitro (in site-directed mutagenesis studies) and in vivo (in a phase IIa study of dolutegravir monotherapy in HIV-infected individuals). Ongoing clinical trials will provide additional data on the virologic activity of dolutegravir across subject viruses with and without prevalent polymorphic substitutions.

Safety and efficacy of dolutegravir in treatment-experienced subjects with raltegravir-resistant HIV type 1 infection: 24-week results of the VIKING Study.

BACKGROUND: Dolutegravir (DTG; S/GSK1349572), a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, has limited cross-resistance to raltegravir (RAL) and elvitegravir in vitro. This phase IIb study assessed the activity of DTG in HIV-1-infected subjects with genotypic evidence of RAL resistance. METHODS: Subjects received DTG 50 mg once daily (cohort I) or 50 mg twice daily (cohort II) while continuing a failing regimen (without RAL) through day 10, after which the background regimen was optimized, when feasible, for cohort I, and at least 1 fully active drug was mandated for cohort II. The primary efficacy end point was the proportion of subjects on day 11 in whom the plasma HIV-1 RNA load decreased by ≥0.7 log(10) copies/mL from baseline or was <400 copies/mL. RESULTS: A rapid antiviral response was observed. More subjects achieved the primary end point in cohort II (23 of 24 [96%]), compared with cohort I (21 of 27 [78%]) at day 11. At week 24, 41% and 75% of subjects had an HIV-1 RNA load of <50 copies/mL in cohorts I and II, respectively. Further integrase genotypic evolution was uncommon. Dolutegravir had a good, similar safety profile with each dosing regimen. CONCLUSION: Dolutegravir 50 mg twice daily with an optimized background provided greater and more durable benefit than the once-daily regimen. These data are the first clinical demonstration of the activity of any integrase inhibitor in subjects with HIV-1 resistant to RAL.

Similar virologic and immunologic efficacy with fosamprenavir boosted with 100 mg or 200 mg of ritonavir in HIV-infected patients: results of the LESS trial.

PURPOSE: ritonavir (RTV) effectively boosts most protease inhibitors but is associated with significant dose-dependent adverse events (AEs). In an effort to better manage toxicities through a reduced dose of RTV, this study compared fosamprenavir (FPV) boosted with RTV 100 mg (FPV/r100) or with RTV 200 mg (FPV/r200) daily. METHODS: this 24-week, open-label study enrolled patients taking a FPV/r 200-containing regimen who had HIV RNA <400 copies/mL and randomized them 1:2 to continue that regimen or simplify to FPV/r100 once daily. Other medications were not altered. The primary endpoint was the percentage of patients without suspected or confirmed virologic failure (HIV RNA ≥ 400 copies/mL) through week 24 by a missing/discontinuation equals failure (M/D=F) analysis. Noninferiority criteria were demonstrated if the lower bound of the 95% confidence interval (CI) for the difference in the primary endpoint rates between groups was greater than -12. RESULTS: the 2 regimens met prespecified noninferiority criteria (FPV/r100, 92%; FPV/r 200, 94%; 95% CI, -9.36 to 5.12). At week 24, the percentage of patients with HIV RNA <50 copies/mL by M/ D=F was 83% in the FPV/r100 group and 85% in the FPV/r 200 group. Drug-related grade 2-4 AEs were uncommon (FPV/r100, 4%; FPV/r 200, 7%). Median changes in lipids were similar in both groups, with the exception of triglycerides (FPV/r100, -21 mg/dL; FPV/r 200, -2 mg/dL). CONCLUSIONS: this 24-week study demonstrated that among previously suppressed patients, once-daily FPV/r100 was similar to FPV/r 200 in virologic and immunologic effects but was associated with greater decreases from baseline in triglyceride levels.

Randomized comparison of renal effects, efficacy, and safety with once-daily abacavir/lamivudine versus tenofovir/emtricitabine, administered with efavirenz, in antiretroviral-naive, HIV-1-infected adults: 48-week results from the ASSERT study.

BACKGROUND: Abacavir/lamivudine and tenofovir/emtricitabine fixed-dose combinations are commonly used first-line antiretroviral therapies, yet few studies have comprehensively compared their safety profiles. METHODS: Forty-eight-week data are presented from this multicenter, randomized, open-label study comparing the safety profiles of abacavir/lamivudine and tenofovir/emtricitabine, both administered with efavirenz, in HLA-B*5701-negative HIV-1-infected adults. RESULTS: Three hundred eighty-five subjects were enrolled in the study. The overall rate of withdrawal was high (28%). Changes in estimated glomerular filtration rate from baseline were similar between arms [difference 0.953 mL.min.1.73 m (95% confidence interval: -1.445 to 3.351), P = 0.435]. Urinary excretion of retinol-binding protein and beta-2 microglobulin increased significantly more in the tenofovir/emtricitabine arm (+50%; +24%) compared with the abacavir/lamivudine arm (no change; -47%) (P < 0.0001). A lower proportion achieved viral load <50 copies per milliliter in the abacavir/lamivudine arm (114 of 192, 59%) compared with the tenofovir/emtricitabine arm (137 of 193, 71%) [difference 11.6% (95% confidence interval: 2.2 to 21.1)]. The overall virological failure rate was low. The adverse event rate was similar between arms (except drug hypersensitivity, reported more in the abacavir/lamivudine arm). CONCLUSIONS: The study showed no difference in estimated glomerular filtration rate between the arms, however, increases in markers of tubular dysfunction were observed in the tenofovir/emtricitabine arm, the long-term consequence of which is unclear. A significant difference in efficacy favoring tenofovir/emtricitabine was observed.

Randomized, double-blind, placebo-matched, multicenter trial of abacavir/lamivudine or tenofovir/emtricitabine with lopinavir/ritonavir for initial HIV treatment.

BACKGROUND: Abacavir sulfate/lamivudine (ABC/3TC) and tenofovir DF/emtricitabine (TDF/FTC) are widely used nucleoside reverse transcriptase inhibitors for initial HIV-1 treatment. This is the first completed, randomized clinical trial to directly compare the efficacy, safety, and tolerability of these agents, each in combination with lopinavir/ritonavir in antiretroviral-naive patients. METHODS: Six hundred and eighty-eight antiretroviral-naive, HIV-1-infected patients were randomized in this double-blind, placebo-matched, multicenter, noninferiority study to receive a once-daily regimen of either ABC/3TC 600 mg/300 mg or TDF/FTC 300 mg/200 mg, both with lopinavir/ritonavir 800 mg/200 mg. Primary endpoints were the proportion of patients with HIV-1 RNA below 50 copies/ml at week 48 (missing = failure, switch included analysis) and the proportion of patients experiencing adverse events over 96 weeks. RESULTS: At week 48, 68% in the ABC/3TC group vs. 67% in the TDF/FTC group achieved an HIV-1 RNA below 50 copies/ml (intent-to-treat exposed missing = failure, 95% confidence interval on the difference -6.63 to 7.40, P = 0.913), demonstrating the noninferiority of ABC/3TC to TDF/FTC at week 48. Noninferiority of the two regimens was sustained at week 96 (60% vs. 58%, respectively, 95% confidence interval -5.41 to 9.32, P = 0.603). In addition, efficacy of both regimens was similar in patients with baseline HIV-1 RNA >or= 100 000 copies/ml or CD4 cell counts below 50 cells/microl. Median CD4 recovery (ABC/3TC vs. TDF/FTC, cells/microl) was +250 vs. +247 by week 96. Premature study discontinuation due to adverse events occurred in 6% of patients in both groups. Protocol-defined virologic failure occurred in 14% of patients in both groups. CONCLUSION: Both ABC/3TC and TDF/FTC provided comparable antiviral efficacy, safety, and tolerability when each was combined with lopinavir/ritonavir in treatment-naive patients.

The KLEAN study of fosamprenavir-ritonavir versus lopinavir-ritonavir, each in combination with abacavir-lamivudine, for initial treatment of HIV infection over 48 weeks: a randomised non-inferiority trial.

BACKGROUND: Lopinavir-ritonavir is a preferred protease inhibitor co-formulation for initial HIV-1 treatment. Fosamprenavir-ritonavir has shown similar efficacy and safety to lopinavir-ritonavir when each is combined with two nucleoside reverse transcriptase inhibitors. We compared the two treatments directly in antiretroviral-naive patients. METHODS: This open-label, non-inferiority study included 878 antiretroviral-naive, HIV-1-infected patients randomised to receive either fosamprenavir-ritonavir 700 mg/100 mg twice daily or lopinavir-ritonavir 400 mg/100 mg twice daily, each with the co-formulation of abacavir-lamivudine 600 mg/300 mg once daily. Primary endpoints were proportion of patients achieving HIV-1 RNA less than 400 copies per mL at week 48 and treatment discontinuations because of an adverse event. The intent-to-treat analysis included all patients exposed to at least one dose of randomised study medication. This study is registered with ClinicalTrials.gov, number NCT00085943. FINDINGS: At week 48, non-inferiority of fosamprenavir-ritonavir to lopinavir-ritonavir (95% CI around the treatment difference -4.84 to 7.05) was shown, with 315 of 434 (73%) patients in the fosamprenavir-ritonavir group and 317 of 444 (71%) in the lopinavir-ritonavir group achieving HIV-1 RNA less than 400 copies per mL. Treatment discontinuations due to an adverse event were few and occurred with similar frequency in the two treatment groups (fosamprenavir-ritonavir 53, 12%; lopinavir-ritonavir 43, 10%). Diarrhoea, nausea, and abacavir hypersensitivity were the most frequent drug-related grade 2-4 adverse events. Treatment-emergent drug resistance was rare; no patient had virus that developed reduced susceptibility to fosamprenavir-ritonavir or lopinavir-ritonavir. INTERPRETATION: Fosamprenavir-ritonavir twice daily in treatment-naive patients provides similar antiviral efficacy, safety, tolerability, and emergence of resistance as lopinavir-ritonavir, each in combination with abacavir-lamivudine.

Fosamprenavir clinical study meta-analysis in ART-naïve subjects: rare occurrence of virologic failure and selection of protease-associated mutations.

BACKGROUND: In recent ritonavir-boosted protease inhibitor (PI) studies, high efficacy rates have been observed, with few PI mutations detected. METHOD: To better understand the types of mutations observed and their phenotypic impact and the likelihood of virologic failure (VF) on a regimen that includes either a ritonavir-boosted or unboosted PI, fosamprenavir, a meta-analysis of three studies (NEAT, SOLO, and KLEAN) of 922 ART-naïve participants receiving boosted (FPV/r) or unboosted fosamprenavir (FPV) plus abacavir/lamivudine was performed. 70% of participants by the missing and discontinuation equals failure analysis and 95% by the observed analysis had HIV-RNA <400 copies/mL through 48 weeks. Paired genotypes (baseline and follow-up) were obtained for 74/85 participants meeting VF analysis criteria. RESULTS: FPV-associated resistance mutations were detected in 5/74 patients with VF, with 4/5 receiving unboosted FPV; in four patients viruses developed I54L or M and one developed the V32I+I47V combination. No virus from patients with VF receiving FPV/r had reduced FPV susceptibility (RS), whereas virus from 3/4 of participants with VF who received unboosted FPV and who acquired FPV mutations had FPV RS. Little PI cross-resistance was detected in the VF virus; RS was observed for lopinavir, saquinavir, nelfinavir, atazanavir, and indinavir in 0, 0, 2, 0, and 1 of 5 subjects, respectively. CONCLUSION: These data suggest that inclusion of FPV as part of an initial HIV-treatment regimen is associated with low rates of VF. Selection of FPV resistance-associated mutations is unlikely, especially for FPV/r-containing regimens. If selection of FPV-associated mutations does occur, a second-line PI-containing regimen can be easily constructed.

Abacavir and lamivudine fixed-dose combination tablet once daily compared with abacavir and lamivudine twice daily in HIV-infected patients over 48 weeks (ESS30008, SEAL).

BACKGROUND: Abacavir (ABC) and lamivudine (3TC) administered twice daily were compared with an ABC + 3TC fixed-dose combination (Epzicom, Kivexa; EPZ) administered once daily, both in combination with a protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor (NNRTI). METHODS: Two hundred sixty HIV-infected subjects with more than 6 months of ABC and 3TC administered twice daily plus a PI or NNRTI with an HIV-1 RNA level less than 400 copies/mL for more than 3 months and a CD4 count greater than 50 cells/mm were randomized 1:1 to ABC + 3TC administered twice daily or EPZ administered once daily. RESULTS: At baseline, median time on ABC and 3TC administered twice daily was 22 months, and median CD4 count and HIV-1 RNA level were 554 cells/mm and <50 copies/mL, respectively. EPZ administered once daily was established as not inferior to ABC + 3TC administered twice daily based on the proportion of nonvirologic failures (confirmed HIV-1 RNA level > or =1265 copies/mL; 90% confidence interval: -3.4 to 6.4; (intent to treat [ITT]: missing [M] = failure [F]). Proportions with an HIV-1 RNA level <50 copies/mL were 81% of those taking EPZ once daily and 82% of those taking ABC + 3TC twice daily at week 48 (ITT: M = F). Virologic failure was rare (2 patients taking the once-daily regimen, 4 patients taking the twice-daily regimen). There was a low incidence of grade 2 through 4 adverse events (AEs) and no drug-related serious AEs or hypersensitivity reactions. CONCLUSIONS: EPZ administered once daily was established as not inferior to ABC + 3TC administered twice daily in a regimen containing an NNRTI or a PI over 48 weeks. A dual-nucleoside backbone of ABC and 3TC administered once or twice daily is effective, durable, and well tolerated.

Mutations linked to drug resistance, human immunodeficiency virus type 1 biologic phenotype and their association with disease progression in children receiving nucleoside reverse transcriptase inhibitors.

BACKGROUND: Few data are available concerning the impact of antiretroviral resistance in response to antiviral therapy in children. We evaluated the development of antiretroviral genotypic resistance and clinical outcome in a subgroup of children involved in a prospective antiretroviral therapy trial (Pediatric AIDS Clinical Trials Group Protocol 152). DESIGN: We studied 26 matched case/control pairs. A case was defined as having clinical disease progression during the study period; controls did not have disease progression. Cases and controls were matched by age and CD4+ cell count at baseline. Matched pairs received treatment with zidovudine (9 pairs), didanosine (12 pairs) or combined therapy (5 pairs). Multiple codons of the reverse transcriptase coding region (41, 67, 70, 74, 151, 184, 210, 215 and 219) were analyzed. Patients were evaluated for CD4+ cell count, HIV-1 viral load and HIV-1 biologic phenotype at baseline and clinical endpoint. RESULTS: The presence of mutations associated with resistance after nucleoside antiretroviral therapy (P = 0.039) and syncytium-inducing phenotype (P = 0.031), were significantly associated with increased risk of clinical disease progression. The mean difference in HIV-1 RNA levels between cases and their matched controls after nucleoside antiretroviral therapy was 0.77 log10 copies/ml higher for cases (P = 0.003). The median difference between cases and controls for CD4+ cell count after nucleoside antiretroviral therapy was 349 cells/mm3 lower for cases (P < 0.001). CONCLUSIONS: In this small prospective study of HIV-infected children, mutations in the reverse transcriptase coding region, syncytium-inducing viral phenotype, higher HIV-1 RNA load and lower CD4+ cell count were significantly correlated with increased risk of HIV clinical disease progression.