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Background: Dolutegravir (DTG)-based antiretroviral therapy (ART) is highly effective and well-tolerated in adults and is rapidly being adopted globally. We describe the design of the ODYSSEY trial which evaluates the efficacy and safety of DTG-based ART compared with standard-of-care in children and adolescents. The ODYSSEY trial includes nested pharmacokinetic (PK) sub-studies which evaluated pragmatic World Health Organization (WHO) weight-band-based DTG dosing and opened recruitment to children < 14 kg while dosing was in development., Methods: ODYSSEY (Once-daily DTG based ART in Young people vS. Standard thErapY) is an open-label, randomised, non-inferiority, basket trial comparing the efficacy and safety of DTG + 2 nucleos(t) ides (NRTIs) versus standard-of-care (SOC) in HIV-infected children < 18 years starting first-line ART (ODYSSEY A) or switching to second-line ART (ODYSSEY B). The primary endpoint is clinical or virological failure by 96 weeks., Results: Between September 2016 and June 2018, 707 children weighing ≥14 kg were enrolled; including 311 ART-naïve children and 396 children starting second-line. 47% of children were enrolled in Uganda, 21% Zimbabwe, 20% South Africa, 9% Thailand, 4% Europe. 362 (51%) participants were male; median age [range] at enrolment was 12.2 years [2.9-18.0]. 82 (12%) children weighed 14 to < 20 kg, 135 (19%) 20 to < 25 kg, 206 (29%) 25 to < 35 kg, 284 (40%) ≥35 kg. 128 (18%) had WHO stage 3 and 60 (8%) WHO stage 4 disease. Challenges encountered include: (i) running the trial across high- to low-income countries with differing frequencies of standard-of-care viral load monitoring; (ii) evaluating pragmatic DTG dosing in PK sub-studies alongside FDA- and EMA-approved dosing and subsequently transitioning participants to new recommended doses; (iii) delays in dosing information for children weighing 3 to < 14 kg and rapid recruitment of ART-naïve older/heavier children, which led to capping recruitment of participants weighing ≥35 kg in ODYSSEY A and extending recruitment (above 700) to allow for ≥60 additional children weighing between 3 to < 14 kg with associated PK; (iv) a safety alert associated with DTG use during pregnancy, which required a review of the safety plan for adolescent girls., Conclusions: By employing a basket design, to include ART-naïve and -experienced children, and nested PK sub-studies, the ODYSSEY trial efficiently evaluates multiple scientific questions regarding dosing and effectiveness of DTG-based ART in children., Trial Registration: NCT, NCT02259127 , registered 7th October 2014; EUDRACT, 2014-002632-14, registered 18th June 2014 ( https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-002632-14/ES ); ISRCTN, ISRCTN91737921 , registered 4th October 2014.

Background: Enzalutamide is a potent androgen-signaling receptor inhibitor and is licensed for the treatment of metastatic castration-resistant prostate cancer. N-desmethylenzalutamide is the active metabolite of enzalutamide. A method to quantitate enzalutamide and its active metabolite was developed and validated according to the European Medicine Agency guidelines., Methods: Enzalutamide and N-desmethylenzalutamide were extracted by protein precipitation, separated on a C18 column with gradient elution and analyzed with tandem quadrupole mass spectrometry in positive ion mode. A stable deuterated isotope (D6-enzalutamide) was used as an internal standard. The method was tested and stability was studied in real-life patients with metastatic castration-resistant prostate cancer patients treated with enzalutamide., Results: The calibration curve covered the range of 500-50,000 ng/mL. Within- and between-day precisions were <8% and accuracies were within 108% for both enzalutamide and N-desmethylenzalutamide. Precisions for lower limit of quantification level were <10% and accuracies within 116% for enzalutamide and N-desmethylenzalutamide. Enzalutamide and N-desmethylenzalutamide stability was proven for 24 hours for whole blood at ambient temperature and 23 days for plasma at both ambient temperature and 2-8°C. Long-term patient plasma stability was shown for 14 months at -40°C., Conclusions: This bioanalytical method was successfully validated and applied to determine plasma concentrations of enzalutamide and N-desmethylenzalutamide in clinical studies and in routine patient care.

Objective: To describe the pharmacokinetics of tenofovir and emtricitabine in the third trimester of pregnant HIV-infected women and at postpartum., Design: A nonrandomized, open-label, multicentre phase IV study in HIV-infected pregnant women recruited from HIV treatment centres in Europe., Methods: HIV-infected pregnant women treated with the nucleotide/nucleoside analogue reverse transcriptase inhibitors (NRTIs) tenofovir disoproxil fumarate (TDF 300 mg; equivalent to 245 mg tenofovir disoproxil) and/or emtricitabine (FTC 200 mg) were included in the study. Twenty-four-hour pharmacokinetic curves were recorded in the third trimester (preferably week 33) and postpartum (preferably week 4-6). Collection of a cord blood sample and maternal sample at delivery was optional. Pharmacokinetic parameters were calculated using WinNonlin software version 5.3. Statistical analysis was conducted using SPSS version 16.0., Results: Thirty-four women were included in the analysis. Geometric mean ratios of third trimester vs. postpartum [90% confidence interval (CI)] were 0.77 (0.71-0.83) for TDF area under the curve (AUC0-24 h); 0.81 (0.68-0.96) for TDF Cmax and 0.79 (0.70-0.90) for TDF C24 h and 0.75 (0.68-0.82) for FTC AUC0-24 h; and 0.87 (0.77-0.99) for FTC Cmax and 0.77 (0.52-1.12) for FTC C24 h. The viral load close to delivery was less than 200  copies/ml in all but one patient, the average gestational age at delivery was 38 weeks. All children were tested HIV-negative and no congenital abnormalities were reported., Conclusion: Although pharmacokinetic exposure of the NRTIs TDF and FTC during pregnancy is approximately 25% lower, this was not associated with virological failure in this study and did not result in mother-to-child transmission.

Background: Co1nflicting data exist regarding the effect of efavirenz (EFV) plasma concentrations on central nervous system (CNS) toxicity. We aimed to determine whether patients with high EFV plasma concentrations have an increased likelihood of toxicity-driven EFV discontinuations., Methods: EFV plasma concentrations were measured from patients in the EuroSIDA study starting EFV after 1 January 1999. Patients with a plasma concentration available were divided into those that discontinued EFV because of any toxicity or by the choice of the patient or physician within 2 years (TOXPC group) and those that continued EFV for > or = 2 years (no toxicity group). Multivariable logistic regression modelling was used to investigate the effects of the EFV plasma concentration and those of other potentially relevant factors on the risk of toxicity-induced EFV discontinuations., Results: A total of 843 patients were included. Of these patients, 138 patients (16.4%) discontinued EFV because of TOXPC and 705 (83.6%) patients continued EFV for 22 years. A total of 20 (14.5%) patients in the TOXPC group had high EFV plasma concentrations (>4.0 mg/l) compared with 99 (14.0%) patients in the no toxicity group (P = 0.890). A positive hepatitis C status (P = 0.026), but not the EFV plasma concentration, was an independent predictor of toxicity-driven EFV discontinuations., Conclusions: No association was found between EFV plasma concentrations and the risk of EFV discontinuations because of (CNS) toxicity. This result questions the designation of EFV plasma concentrations >4.0 mg/l as being 'toxic', at least when defined by treatment discontinuation.

Objective: To evaluate the longer-term utility of genotypic resistance testing in HIV-1-infected children with virological failure., Methods: Children aged 3 months-18 years switching antiretroviral therapy (ART) with HIV-1 RNA > 2,000 copies/ml were randomized between genotypic testing (Virtual Phenotype) and no testing at baseline and subsequent virological failures. Children were followed to at least 96 weeks., Results: One hundred and seventy eligible children, from 24 clinical centres in six countries, were randomized to resistance testing (n = 87) or no testing (n = 83) between June 2000-July 2003. At baseline, mean HIV-1 RNA and CD4+ T-cell percentage were 4.7 log10 copies/ml and 20%, respectively. Children had taken ART for a mean of 5 years; 24% had received all three classes, 53% nucleoside reverse transcriptase inhibitors (NRTIs)+protease inhibitors (PIs), 9% NRTIs+non-nucleoside reverse transcriptase inhibitors (NNRTIs) and 14% NRTIs only. There was no difference between the arms in the drug classes or the individual PIs/NNRTIs prescribed. However, 49% in the resistance test arm (RT) versus 19% in the no-test arm (NT) continued at least one NRTI from their failing regimen; 56% versus 19% were prescribed didanosine+stavudine as their NRTI backbone. Adjusting for baseline HIV-1 RNA, mean reductions in HIV-1 RNA at 48 weeks were 1.51 log10 copies/ml in the RT arm and 1.23 in the NT arm (P = 0.3); the difference between the arms was smaller at week 96 (RT: 1.50, NT: 1.47; P = 0.9)., Conclusion: In this first paediatric trial of resistance testing, we observed a substantial difference in NRTI-prescribing behaviour across arms. However statistically significant evidence of a long-term virological or immunological benefit was not observed. This trial is registered as an International Standard Randomised Controlled Trial, number ISRCTN14367816.

Since 1999 an ongoing international interlaboratory quality control program has analyzed antiretroviral drugs in plasma. Results of the third round of this program are presented. Quality control samples were prepared by spiking drug-free plasma with varying concentrations of the currently available protease inhibitors and the nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine. Thirty-three laboratories participated in the program and were requested to analyze the quality control samples. Results were from 30 laboratories. Of all measurements, 82% were performed within 80%-120% accuracy limits. Only 3 laboratories performed all their measurements within these limits, and 12 participants reported at least 90% of their analyses within the acceptance range. Mean accuracy for low drug concentrations was worse than for medium and high concentrations. The percentage of satisfactory measurements for the 6 laboratories that participated for the third time in the program increased from 54% in the first round to 85% in the third round. The program revealed a large variability in the laboratories' ability to measure antiretroviral drugs accurately. This variability may have important implications for therapeutic drug monitoring of these drugs and for pharmacokinetic studies. Interlaboratory testing is useful to alert laboratories to previously undetected analytical problems.

An international interlaboratory quality control program for measurement of antiretroviral drugs was initiated. The first round was confined to protease inhibitors and showed large variability in the performance of participating laboratories. The results demonstrate the need for and utility of an ongoing quality control program in this area of bioanalysis.