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[...]we conducted a pilot study in which we inoculated participants with ART-R P. falciparum parasites harbouring the kelch13 gene mutation R539T (K13R539T strain) [4] to determine the safety, tolerability, and clearance of infection with ART-R parasites. Methods Study design We conducted 2 consecutive phase 1, single-centre, open-label studies: a pilot study and a randomised study. ART-R, artemisinin-resistant; ART-S, artemisinin-sensitive; A/P, atovaquone/proguanil; AS, artesunate; DHA/PQP, dihydroartemisinin/piperaquine phosphate; IV, intravenously; PQ, primaquine; qPCR, quantitative PCR https://doi.org/10.1371/journal.pmed.1003203.g001 Development of parasitaemia was monitored daily from Day 3 (pilot study Participant 1) or Day 4 (pilot study Participant 2 and comparative study) until parasites were detected by qPCR, then twice daily until AS administration. Outcomes A primary outcome of both studies was safety and tolerability of infection with ART-R parasites (and of ART-S parasites in the comparative study only), determined by evaluating adverse events, physical examinations, vital signs, clinical biochemistry, haematology, and urinalysis.

Mycophenolic acid (MPA), the active drug moiety of mycophenolate, is a potent immunosuppressant agent, which is increasingly being used in the treatment of patients with various autoimmune diseases. An understanding of the pharmacokinetics and pharmacodynamics of mycophenolate in this population should assist the clinician with rational dosage decisions. This review aims to provide an overview of the published literature on the clinical pharmacokinetics of mycophenolate in autoimmune disease and a briefer summary of current pharmacodynamic knowledge, and to identify areas of potential future research in this field. A literature search was conducted using PubMed and EMBASE databases as well as bibliographies of relevant articles and ‘on-line early’ pages of key journals. Twenty-six pharmacokinetic/pharmacodynamic studies of mycophenolate in people with autoimmune disease were identified and appraised. Twenty-two of these studies used non-compartmental analysis techniques and four used population modelling methods to estimate mycophenolate pharmacokinetic parameters. Seven studies linked mycophenolate exposure to treatment outcomes. Only four studies measured free (unbound) as well as total mycophenolate exposure and only two studies characterised MPA disposition following enteric-coated mycophenolate sodium (EC-MPS) administration. Across all studies MPA displayed erratic and complex pharmacokinetics with substantial between-subject variability. Based on total drug measurement, the dose-normalised MPA area under the plasma concentration-time curve (AUC) from 0 to 12 h post-dose (AUC 12 ) varied at least five- to ten-fold between subjects. Typical values for apparent oral clearance (CL/ F ) of MPA during nonlinear mixed–effects modelling ranged from 8.3 to 25.3 L/h. Patient renal function, serum albumin levels, sex, ethnicity, food intake, concurrent administration of interacting drugs such as antacids, metal-containing medications and proton pump inhibitors and polymorphisms in genes encoding uridine diphosphate glucuronosyltransferase were identified in some studies as having a significant influence on the pharmacokinetics of mycophenolate. Typical MPA CL/ F values in autoimmune disease patients were generally slightly lower than values published previously in population pharmacokinetic studies involving renal allograft recipients, possibly because of usage of ciclosporin, poorer renal function or lower serum albumin levels in the renal transplant cohort. In a single crossover study involving ten subjects only, significantly higher MPA AUC 12 and maximum MPA concentration ( C max ) and lower MPA CL/ F were reported following EC-MPS administration compared to mycophenolate mofetil administration. MPA exposure correlated well with treatment efficacy in patients with autoimmune disease (response to treatment, active disease and disease markers); however the relationship between MPA exposure and adverse events (infectious episodes, haematological toxicity and gastrointestinal symptoms) was unclear. Further investigation is required in autoimmune diseases such as chronic plaque psoriasis and rheumatoid arthritis and following EC-MPS administration. The extent of within-subject variability in the pharmacokinetics of mycophenolate is largely unknown and potential covariate influences need to be confirmed in studies with large subject numbers. A relationship between MPA and MPA metabolite exposure and toxicity needs to be established. The contribution of pharmacogenetics to the pharmacokinetics and pharmacodynamics of mycophenolate warrants further investigation, as does the utility of therapeutic drug monitoring. Dosing to achieve a target MPA AUC 12 >35 mg·h/L is likely to lead to better efficacy outcomes in patients with autoimmune disease (rather than just giving standard doses, which lead to a wide range of exposures). However, the relationship between mycophenolate exposure and toxicity requires further investigation to determine the upper end of a target AUC range.

Transmission blocking activity is an important characteristic of antimalarial drugs, and can be evaluated in malaria volunteer infection studies (VIS). We undertook a pilot VIS to evaluate the suitability of a recently manufactured Plasmodium falciparum 3D7 bank (3D7-MBE-008) for evaluating transmission blocking interventions. Four adults were inoculated with P. falciparum 3D7-MBE-008 infected erythrocytes and administered piperaquine on days 8 and 10 to clear asexual parasitemia while permitting gametocyte development. On day 25, participants were randomised (1:1) to receive either 0.25 mg/kg primaquine (primaquine group) or no intervention (control group). Transmissibility was assessed by enriched membrane feeding assays on days 25, 29, 32, and 39, with transmission intensity (proportion of mosquitoes infected) determined by 18S qPCR. All participants were infective on day 25, with a median 94% (range, 12–100%) of mosquitoes positive for oocysts, and 76% (range, 8–94%) positive for sporozoites. In the primaquine group, mosquito infectivity decreased substantially between days 25 and 29. In the control group, mosquito infectivity remained high up to day 32, and persisted to day 39 in one participant. The P. falciparum 3D7-MBE-008 parasite bank induced blood-stage infections that were highly transmissible to mosquitoes and is therefore suitable for evaluating transmission blocking interventions. Trial registration anzctr.org.au (registration number: ACTRN12622001097730), registered 08/08/2022.

Background The combination antimalarial artefenomel-piperaquine failed to achieve target efficacy in a phase 2b study in Africa and Vietnam. We retrospectively evaluated whether characterizing the pharmacological interaction of this antimalarial combination in a volunteer infection study (VIS) would have enabled prediction of the phase 2b study results. Methods Twenty-four healthy adults enrolled over three consecutive cohorts were inoculated with Plasmodium falciparum -infected erythrocytes on day 0. Participants were randomized within each cohort to one of seven dose combination groups and administered a single oral dose of artefenomel-piperaquine on day 8. Participants received definitive antimalarial treatment with artemether-lumefantrine upon parasite regrowth or on day 42 ± 2. The general pharmacodynamic interaction (GPDI) model implemented in the Bliss Independence additivity criterion was developed to characterize the pharmacological interaction between artefenomel and piperaquine. Simulations based on the model were performed to predict the outcomes of the phase 2b combination study. Results For a dose of 800 mg artefenomel administered with 640 mg, 960 mg, or 1440 mg piperaquine, the simulated adequate parasitological response at day 28 (APR 28 ), incorporating actual patient pharmacokinetic (PK) data from the phase 2b trial, was 69.4%, 63.9%, and 74.8%, respectively. These results closely matched the observed APR 28 in the phase 2b trial of 67.0%, 65.5%, and 75.4%, respectively. Conclusions These results indicate that VIS offer an efficient means for informing antimalarial combination trials conducted in the field, potentially expediting clinical development. Trial registration This study was registered on ClinicalTrials.gov on 11 May 2018 with registration number NCT03542149.

Purpose This study aims to determine if continuous infusion (CI) is associated with better clinical and pharmacokinetic/pharmacodynamic (PK/PD) outcomes compared to intermittent bolus (IB) dosing in critically ill patients with severe sepsis. Methods This was a two-centre randomised controlled trial of CI versus IB dosing of beta-lactam antibiotics, which enrolled critically ill participants with severe sepsis who were not on renal replacement therapy (RRT). The primary outcome was clinical cure at 14 days after antibiotic cessation. Secondary outcomes were PK/PD target attainment, ICU-free days and ventilator-free days at day 28 post-randomisation, 14- and 30-day survival, and time to white cell count normalisation. Results A total of 140 participants were enrolled with 70 participants each allocated to CI and IB dosing. CI participants had higher clinical cure rates (56 versus 34 %, p  = 0.011) and higher median ventilator-free days (22 versus 14 days, p  < 0.043) than IB participants. PK/PD target attainment rates were higher in the CI arm at 100 % fT >MIC than the IB arm on day 1 (97 versus 70 %, p  < 0.001) and day 3 (97 versus 68 %, p  < 0.001) post-randomisation. There was no difference in 14-day or 30-day survival between the treatment arms. Conclusions In critically ill patients with severe sepsis not receiving RRT, CI demonstrated higher clinical cure rates and had better PK/PD target attainment compared to IB dosing of beta-lactam antibiotics. Continuous beta-lactam infusion may be mostly advantageous for critically ill patients with high levels of illness severity and not receiving RRT. Malaysian National Medical Research Register ID: NMRR-12-1013-14017.

New antimalarials with novel mechanisms of action are needed to combat the emergence of drug resistance. Triaminopyrimidines comprise a novel antimalarial class identified in a high-throughput screen against asexual blood-stage Plasmodium falciparum. This first-in-human study aimed to characterise the safety, pharmacokinetics, and antimalarial activity of the triaminopyrimidine ZY-19489 in healthy volunteers. A three-part clinical trial was conducted in healthy adults (aged 18–55 years) in Brisbane, QLD, Australia. Part one was a double-blind, randomised, placebo-controlled, single ascending dose study in which participants enrolled into one of six dose groups (25, 75, 150, 450, 900, or 1500 mg) were randomly assigned (3:1) to ZY-19489 or placebo. Part two was an open-label, randomised, two-period cross-over, pilot food-effect study in which participants were randomly assigned (1:1) to a fasted-fed or a fed-fasted sequence. Part three was an open-label, randomised, volunteer infection study using the P falciparum induced blood-stage malaria model in which participants were enrolled into one of two cohorts, with participants in cohort one all receiving the same dose of ZY-19489 and participants in cohort two randomly assigned to receive one of two doses. The primary outcome for all three parts was the incidence, severity, and relationship to ZY-19489 of adverse events. Secondary outcomes were estimation of ZY-19489 pharmacokinetic parameters for all parts; how these parameters were affected by the fed state for part two only; and the parasite reduction ratio, parasite clearance half-life, recrudescent parasitaemia, and pharmacokinetic–pharmacodynamic modelling parameters for part three only. This trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12619000127101, ACTRN12619001466134, and ACTRN12619001215112). 48 participants were enrolled in part one (eight per cohort for 25–1500 mg cohorts), eight in part two (four in each group, all dosed with 300 mg), and 15 in part three (five dosed with 200 mg, eight with 300 mg, and two with 900 mg). In part one, the incidence of drug-related adverse events was higher in the 1500 mg dose group (occurring in all six participants) than in lower-dose groups and the placebo group (occurring in one of six in the 25 mg group, two of six in the 75 mg group, three of six in the 150 mg group, two of six in the 450 mg group, four of six in the 900 mg group, and four of 12 in the placebo group), due to the occurrence of mild gastrointestinal symptoms. Maximum plasma concentrations occurred 5–9 h post-dosing, and the elimination half-life was 50–97 h across the dose range. In part two, three of seven participants had a treatment-related adverse event in the fed state and four of eight in the fasted state. Dosing in the fed state delayed absorption (maximum plasma concentration occurred a median of 12·0 h [range 7·5–16·0] after dosing in the fed state vs 6·0 h [4·5–9·1] in the fasted state) but had no effect on overall exposure (difference in area under the concentration–time curve from time 0 [dosing] extrapolated to infinity between fed and fasted states was −0·013 [90% CI −0·11 to 0·08]). In part three, drug-related adverse events occurred in four of five participants in the 200 mg group, seven of eight in the 300 mg group, and both participants in the 900 mg group. Rapid initial parasite clearance occurred in all participants following dosing (clearance half-life 6·6 h [95% CI 6·2–6·9] for 200 mg, 6·8 h [95% CI 6·5–7·1] for 300 mg, and 7·1 h [95% CI 6·6–7·6] for 900 mg). Recrudescence occurred in four of five participants in the 200 mg group, five of eight in the 300 mg group, and neither of the two participants in the 900 mg group. Simulations done using a pharmacokinetic–pharmacodynamic model predicted that a single dose of 1100 mg would clear baseline parasitaemia by a factor of 109. The safety, pharmacokinetic profile, and antimalarial activity of ZY-19489 in humans support the further development of the compound as a novel antimalarial therapy. Cadila Healthcare and Medicines for Malaria Venture.

Mycophenolic acid (MPA) is a potent immunosuppressant agent, which is increasingly being used in the treatment of patients with various autoimmune diseases. Dosing to achieve a specific target MPA area under the concentration–time curve from 0 to 12 h post-dose (AUC 12 ) is likely to lead to better treatment outcomes in patients with autoimmune disease than a standard fixed-dose strategy. This review summarizes the available published data around concentration monitoring strategies for MPA in patients with autoimmune disease and examines the accuracy and precision of methods reported to date using limited concentration–time points to estimate MPA AUC 12 . A total of 13 studies were identified that assessed the correlation between single time points and MPA AUC 12 and/or examined the predictive performance of limited sampling strategies in estimating MPA AUC 12 . The majority of studies investigated mycophenolate mofetil (MMF) rather than the enteric-coated mycophenolate sodium (EC-MPS) formulation of MPA. Correlations between MPA trough concentrations and MPA AUC 12 estimated by full concentration–time profiling ranged from 0.13 to 0.94 across ten studies, with the highest associations ( r 2  = 0.90–0.94) observed in lupus nephritis patients. Correlations were generally higher in autoimmune disease patients compared with renal allograft recipients and higher after MMF compared with EC-MPS intake. Four studies investigated use of a limited sampling strategy to predict MPA AUC 12 determined by full concentration–time profiling. Three studies used a limited sampling strategy consisting of a maximum combination of three sampling time points with the latest sample drawn 3–6 h after MMF intake, whereas the remaining study tested all combinations of sampling times. MPA AUC 12 was best predicted when three samples were taken at pre-dose and at 1 and 3 h post-dose with a mean bias and imprecision of 0.8 and 22.6 % for multiple linear regression analysis and of −5.5 and 23.0 % for maximum a posteriori (MAP) Bayesian analysis. Although mean bias was less when data were analysed using multiple linear regression, MAP Bayesian analysis is preferable because of its flexibility with respect to sample timing. Estimation of MPA AUC 12 following EC-MPS administration using a limited sampling strategy with samples drawn within 3 h post-dose resulted in biased and imprecise results, likely due to a longer time to reach a peak MPA concentration ( t max ) with this formulation and more variable pharmacokinetic profiles. Inclusion of later sampling time points that capture enterohepatic recirculation and t max improved the predictive performance of strategies to predict EC-MPS exposure. Given the considerable pharmacokinetic variability associated with mycophenolate therapy, limited sampling strategies may potentially help in individualizing patient dosing. However, a compromise needs to be made between the predictive performance of the strategy and its clinical feasibility. An opportunity exists to combine research efforts globally to create an open-source database for MPA (AUC, concentrations and outcomes) that can be used and prospectively evaluated for AUC target-controlled dosing of MPA in autoimmune diseases.