Simultaneous pharmacokinetic modeling of unbound and total darunavir with ritonavir in adolescents: a substudy of the SMILE trial.

Darunavir (DRV) is an HIV protease inhibitor commonly used as part of antiretroviral treatment regimens globally for children and adolescents. It requires a pharmacological booster, such as ritonavir (RTV) or cobicistat. To better understand the pharmacokinetics (PK) of DRV in this younger population and the importance of the RTV boosting effect, a population PK substudy was conducted within SMILE trial, where the maintenance of HIV suppression with once daily integrate inhibitor + darunavir/ritonavir in children and adolescents is evaluated. A joint population PK model that simultaneously used total DRV, unbound DRV, and total RTV concentrations was developed. Competitive and non-competitive models were examined to define RTV's influence on DRV pharmacokinetics. Linear and non-linear equations were tested to assess DRV protein binding. A total of 443 plasma samples from 152 adolescents were included in this analysis. Darunavir PK was best described by a one-compartment model first-order absorption and elimination. The influence of RTV on DRV pharmacokinetics was best characterized by ritonavir area under the curve on DRV clearance using a power function. The association of non-linear and linear equations was used to describe DRV protein binding to alpha-1 glycoprotein and albumin, respectively. In our population, simulations indicate that 86.8% of total and unbound DRV trough concentrations were above 0.55 mg/L [10 times protein binding-adjusted EC50 for wild-type (WT) HIV-1] and 0.0243 mg/L (10 times EC90 for WT HIV-1) targets, respectively. Predictions were also in agreement with observed outcomes from adults receiving 800/100 mg DRV/r once a day. Administration of 800/100 mg of DRV/r once daily provides satisfactory concentrations and exposures for adolescents aged 12 years and older.

Nucleoside/nucleotide reverse transcriptase inhibitor sparing regimen with once daily integrase inhibitor plus boosted darunavir is non-inferior to standard of care in virologically-suppressed children and adolescents living with HIV - Week 48 results of the randomised SMILE Penta-17-ANRS 152 clinical trial.

Background: Integrase inhibitor (INSTI) with boosted darunavir (DRV/r), a regimen with a high-resistance barrier, avoiding NRTI toxicities, might be a switching option in children living with HIV (CLWHIV). Methods: SMILE is a randomised non-inferiority trial evaluating safety and antiviral efficacy of once-daily INSTI + DRV/r vs. continuing on current standard-of-care (SOC) triple ART (2NRTI + boosted PI/NNRTI) in virologically-suppressed CLWHIV aged 6-18 years. The primary outcome is the proportion with confirmed HIV-RNA ≥50 copies/mL by week 48, estimated by Kaplan-Meier method. Non-inferiority margin was 10%. Registration number for SMILE are: ISRCTN11193709, NCT #: NCT02383108. Findings: Between 10th June 2016 and 30th August 2019, 318 participants were enrolled from Africa 53%, Europe 24%, Thailand 15% and Latin America 8%, 158 INSTI + DRV/r [153 Dolutegravir (DTG); 5 Elvitegravir (EVG)], 160 SOC. Median (range) age was 14.7 years (7.6-18.0); CD4 count 782 cells/mm3 (227-1647); 61% female. Median follow-up was 64.3 weeks with no loss to follow-up. By 48 weeks, 8 INSTI + DRV/r vs. 12 SOC had confirmed HIV-RNA ≥50 copies/mL; difference (INSTI + DRV/r-SOC) -2.5% (95% CI: -7.6, 2.5%), showing non-inferiority. No major PI or INSTI resistance mutations were observed. There were no differences in safety between arms. By week 48, difference (INSTI + DRV/r-SOC) in mean CD4 count change from baseline was -48.3 cells/mm3 (95% CI: -93.4, -3.2; p = 0.036). Difference (INSTI + DRV/r-SOC) in mean HDL change from baseline was -4.1 mg/dL (95% CI: -6.7, -1.4; p = 0.003). Weight and Body Mass Index (BMI) increased more in INSTI + DRV/r than SOC [difference: 1.97 kg (95% CI: 1.1, 2.9; p < 0.001), 0.66 kg/m2 (95% CI: 0.3, 1.0; p < 0.001)]. Interpretation: In virologically-suppressed children, switching to INSTI + DRV/r was non-inferior virologically, with similar safety profile, to continuing SOC. Small but significant differences in CD4, HDL-cholesterol, weight and BMI were observed between INSTI + DRV/r vs. SOC although clinical relevance needs further investigation. SMILE data corroborate adult findings and provide evidence for this NRTI-sparing regimen for children and adolescents. Funding: Fondazione Penta Onlus, Gilead, Janssen, INSERM/ANRS and UK MRC. ViiV-Healthcare provided Dolutegravir.

Population pharmacokinetics of unbound and total dolutegravir concentrations in children aged 12†years and older: a PK substudy of the SMILE trial.

BACKGROUND: SMILE, a multicentre randomized trial, compared the efficacy and safety of switching virologically suppressed children and adolescents with HIV to a once-daily dual regimen of dolutegravir plus ritonavir-boosted darunavir versus continuing standard ART. Within a nested pharmacokinetic (PK) substudy, we performed a population PK analysis to describe total and unbound dolutegravir plasma concentrations in children and adolescents receiving this dual therapy. METHODS: Sparse blood samples were obtained during follow-up for dolutegravir quantification. A population PK model was developed to simultaneously describe total and unbound dolutegravir concentrations. Simulations were performed and were compared with the protein-adjusted 90% inhibitory concentration (IC90) and the in vitro IC50, respectively. Dolutegravir exposures in children aged ≥12 years were also compared with values in treatment-experienced adults. RESULTS: Four hundred and fifty-five samples from 153 participants aged between 12 and 18 years were collected for this PK analysis. A one-compartment model with first-order absorption and elimination best described unbound dolutegravir concentrations. The relationship between unbound and total dolutegravir concentrations was best characterized by a non-linear model. Unbound dolutegravir apparent clearance was significantly influenced by total bilirubin concentrations and by Asian ethnicity. All children and adolescents had trough concentrations well above the protein-adjusted IC90 and the in vitro IC50 values. Dolutegravir concentrations and exposures were also similar to those obtained in adults receiving dolutegravir 50 mg once daily. CONCLUSIONS: A once-daily 50 mg dolutegravir dose for children and adolescents produces adequate total and unbound concentrations when used as part of dual therapy with ritonavir-boosted darunavir.

Weekends-off efavirenz-based antiretroviral therapy in HIV-infected children, adolescents and young adults (BREATHER): Extended follow-up results of a randomised, open-label, non-inferiority trial.

BACKGROUND: Weekends off antiretroviral therapy (ART) may help engage HIV-1-infected young people facing lifelong treatment. BREATHER showed short cycle therapy (SCT; 5 days on, 2 days off ART) was non-inferior to continuous therapy (CT) over 48 weeks. Planned follow-up was extended to 144 weeks, maintaining original randomisation. METHODS: BREATHER was an open-label, non-inferiority trial. Participants aged 8-24yrs with virological suppression on efavirenz-based first-line ART were randomised 1:1, stratified by age and African/non-African sites, to remain on CT or change to SCT. The Kaplan-Meier method was used to estimate the proportion of participants with viral rebound (confirmed VL≥50 copies/mL) under intent-to-treat at 48 weeks (primary outcome), and in extended follow-up at 96, 144, and 192 weeks. SCT participants returned to CT following viral rebound, 3 VL blips or discontinuation of efavirenz. FINDINGS: Of 199 participants (99 SCT, 100 CT), 97 per arm consented to extended follow-up. Median follow-up was 185.3 weeks (IQR 160.9-216.1). 69 (70%) SCT participants remained on SCT at last follow-up. 105 (53%) were male, baseline median age 14 years (IQR 12-18), median CD4 count 735 cells/µL (IQR 576-968). 16 SCT and 16 CT participants had confirmed VL≥50 copies/mL by the end of extended follow-up (HR 1.00, 95% CI 0.50-2.00). Estimated difference in percentage with viral rebound (SCT minus CT) by week 144 was 1.9% (90% CI -6.6-10.4; p = 0.72) and was similar in a per-protocol analysis. There were no significant differences between arms in proportions of participants with grade 3/4 adverse events (18 SCT vs 16 CT participants; p = 0.71) or ART-related adverse events (10 vs 12; p = 0.82). 20 versus 8 serious adverse events (SAEs) were reported in 16 SCT versus 4 CT participants, respectively (p = 0.005 comparing proportions between groups; incidence rate ratio 2.49, 95%CI 0.71-8.66, p = 0.15). 75% of SAEs (15 SCT, 6 CT) were hospitalisations for a wide range of conditions. 3 SCT and 6 CT participants switched to second-line ART following viral failure (p = 0.50). CONCLUSIONS: Sustainable non-inferiority of virological suppression in young people was shown for SCT versus CT over median 3.6 years. Standard-dose efavirenz-based SCT is a viable option for virologically suppressed HIV-1 infected young people on first-line ART with 3-monthly VL monitoring. TRIAL REGISTRATION: EudraCT 2009-012947-40 ISRCTN 97755073 ClinicalTrials.gov NCT01641016.

Adherence to antiretroviral therapy and acceptability of planned treatment interruptions in HIV-infected children.

There have been no paediatric randomised trials describing the effect of planned treatment interruptions (PTIs) of antiretroviral therapy (ART) on adherence, or evaluating acceptability of such a strategy. In PENTA 11, HIV-infected children were randomised to CD4-guided PTIs (n = 53) or continuous therapy (CT, n = 56). Carers, and children if appropriate, completed questionnaires on adherence to ART and acceptability of PTIs. There was no difference in reported adherence on ART between CT and PTI groups; non-adherence (reporting missed doses over the last 3 days or marking <100 % adherence since the last clinical visit on a visual analogue scale) was 18 % (20/111) and 14 % (12/83) on carer questionnaires in the CT and PTI groups respectively (odds ratios, OR (95 % CI) = 1.04 (0.20, 5.41), χ(2) (1) = 0.003, p = 0.96). Carers in Europe/USA reported non-adherence more often (31/121, 26 %) than in Thailand (1/73, 1 %; OR (95 % CI) = 54.65 (3.68, 810.55), χ(2) (1) = 8.45, p = 0.004). The majority of families indicated they were happy to have further PTIs (carer: 23/36, 64 %; children: 8/13, 62 %), however many reported more clinic visits during PTI were a problem (carer: 15/36, 42 %; children: 6/12, 50 %).

Outcomes after reinitiating antiretroviral therapy in children randomized to planned treatment interruptions.

BACKGROUND: Excess risks for death/opportunistic disease in adults randomized to CD4-driven planned treatment interruption (PTI) in the Strategies for Management of Antiretroviral Therapy (SMART) trial remained after antiretroviral therapy (ART) re-initiation. Risks for children following PTI were evaluated in long-term follow-up of children in the PENTA 11 trial. METHODS: Children with HIV RNA below 50 copies/ml and CD4 at least 30% (2-6 years) or at least 500 cells/µl (7-15 years) were randomized to continuous ART (cART) or PTI in PENTA 11 (ISRCTN 36694210). After the end of the trial, all were recommended to resume ART. Data were collected annually and analysed up to the second year of visit. RESULTS: One hundred and one (51 cART, 50 PTI; median baseline age 9.2 years) children had median overall follow-up 4.6 (range 3.7-5.0) years. During 2-year post-trial period, there were no deaths or new Centers for Disease Control and Prevention (CDC) stage B/C events. Rate of clinical grade of at least two events was similar between PTI and cART [relative risk (RR) 1.03; 95% confidence interval (CI) 0.43, 2.50; P = 0.94]. At 2 years, difference in absolute CD4% between PTI and cART was -1.6% (-4.5%; 1.3%; P = 0.27), and proportions with HIV RNA below 50 copies/ml were 82 versus 86% (P = 0.57), respectively; no differences in growth or fasting lipids were observed. Key predictors of greater CD4% recovery after re-initiating ART were higher CD4% at baseline (P < 0.001) and longer time since ART re-initiation (P < 0.001). During overall follow-up, 4 (8%) PTI versus 5 (10%) CT children switched ART for failure (P = 0.75) and 9 (18%) versus 1 (2%) (P = 0.008) substituted ART for simplification. CONCLUSIONS: No adverse clinical, immunological or virological consequences of PTI were observed 2 years after the end of PENTA 11 trial. Although ART interruption is not generally recommended, it may be an acceptable option for children, particularly when there is high risk of unplanned treatment interruptions.