Population Pharmacokinetic Modeling and Determination of Individual Exposure to Avalglucosidase Alfa in Adolescent and Adult Patients With Late-Onset Pompe Disease: Analysis of Pooled Data From Phase I to III Clinical Trials.

BACKGROUND: Pompe disease is a rare genetic disorder caused by a deficiency of a lysosomal enzyme called acid alpha-glucosidase and is classified into infantile and late-onset forms. Since 2006, an enzyme replacement therapy involving alglucosidase alfa has been available. In 2021, a new enzyme replacement therapy involving avalglucosidase alfa demonstrated improved clinical benefits. In this article, the authors describe the pharmacokinetics of avalglucosidase alfa using a population pharmacokinetic approach. METHODS: The population pharmacokinetic model was developed using a data set that included 75 patients and 2042 plasma drug concentrations determined through enzymatic activity assay from 3 studies (phases I/II and III) and involved 3 dose levels (5, 10, and 20 mg/kg). The analysis was performed using NONMEM software. RESULTS: Two sequences were observed in the plasma drug concentration profile: the first kinetic driving exposure, and after 12 hours postdose, a slight rebound addressing very low concentrations that lasted up to 2 weeks. Following model screening, a model with a central compartment with parallel linear and nonlinear elimination and 2 concatenated peripheral compartments was proposed. A putative back-redistribution of a marginal fraction of the drug from the second peripheral compartment to the central compartment may explain the slight rebound in concentration. The final model's mean bias and precision for individual predictions were -2.66% and 30.7%, respectively, and -0.433% and 38.9%, respectively, for population predictions. CONCLUSIONS: A concatenated 3-compartment model was developed to describe the avalglucosidase alfa concentrations in patients with late-onset Pompe disease. None of the covariates tested could explain the interindividual variability.

Population pharmacokinetic modeling and dosing simulation of avalglucosidase alfa for selecting alternative dosing regimen in pediatric patients with late-onset pompe disease.

Avalglucosidase alfa (AVAL) was approved in the United States (2021) for patients with late-onset Pompe disease (LOPD), aged ≥ 1 year. In the present study, pharmacokinetic (PK) simulations were conducted to propose alternative dosing regimens for pediatric LOPD patients based on a bodyweight cut-off. Population PK (PopPK) analysis was performed using nonlinear mixed effect modeling approach on pooled data from three clinical trials with LOPD patients, and a phase 2 study (NCT03019406) with infantile-onset Pompe disease (IOPD: 1-12 years) patients. A total of 2257 concentration-time points from 91 patients (LOPD, n = 75; IOPD, n = 16) were included in the analysis. The model was bodyweight dependent allometric scaling with time varying bodyweight included on clearance and distribution volume. Simulations were performed for two dosing regimens (20 mg/kg or 40 mg/kg) with different bodyweight cut-off (25, 30, 35 and 40 kg) by generating virtual pediatric (1-17 years) and adult patients. Corresponding simulated individual exposures (maximal concentration, Cmax and area under the curve in the 2-week dosing interval, AUC2W), and distributions were calculated. It was found that dosing of 40 mg/kg and 20 mg/kg in pediatric patients < 30 kg and ≥ 30 kg, respectively, achieved similar AVAL exposure (based on AUC2W) to adult patients receiving 20 mg/kg. PK simulations conducted on the basis of this model provided supporting data for the currently approved US labelling for dosing adapted bodyweight in LOPD patients ≥ 1 year by USFDA.

The antimalarial MMV688533 provides potential for single-dose cures with a high barrier to Plasmodium falciparum parasite resistance.

The emergence and spread of Plasmodium falciparum resistance to first-line antimalarials creates an imperative to identify and develop potent preclinical candidates with distinct modes of action. Here, we report the identification of MMV688533, an acylguanidine that was developed following a whole-cell screen with compounds known to hit high-value targets in human cells. MMV688533 displays fast parasite clearance in vitro and is not cross-resistant with known antimalarials. In a P. falciparum NSG mouse model, MMV688533 displays a long-lasting pharmacokinetic profile and excellent safety. Selection studies reveal a low propensity for resistance, with modest loss of potency mediated by point mutations in PfACG1 and PfEHD. These proteins are implicated in intracellular trafficking, lipid utilization, and endocytosis, suggesting interference with these pathways as a potential mode of action. This preclinical candidate may offer the potential for a single low-dose cure for malaria.

A phase I study of the HDM2 antagonist SAR405838 combined with the MEK inhibitor pimasertib in patients with advanced solid tumours.

BACKGROUND: This phase I, open-label, dose-escalation study evaluated the safety, pharmacokinetics and pharmacodynamics of combination therapy with the HDM2 inhibitor SAR405838 and the MEK1/2 inhibitor pimasertib administered orally once daily (QD) or twice daily (BID) in locally advanced or metastatic solid tumours (NCT01985191). METHODS: Patients with locally advanced or metastatic solid tumours with documented wild-type TP53 and RAS or RAF mutations were enroled. A 3 + 3 dose-escalation design was employed. The primary objective was to assess maximum tolerated dose (MTD). RESULTS: Twenty-six patients were treated with SAR405838 200 or 300 mg QD plus pimasertib 60 mg QD or 45 mg BID. The MTD was SAR405838 200 mg QD plus pimasertib 45 mg BID. The most common dose-limiting toxicity was thrombocytopenia. The most frequently occurring treatment-related adverse events were diarrhoea (81%), increased blood creatine phosphokinase (77%), nausea (62%) and vomiting (62%). No significant drug-drug interactions were observed. The biomarkers MIC-1 and pERK were, respectively, upregulated and downregulated in response to study treatment. In 24 efficacy-evaluable patients, one patient (4%) had a partial response and 63% had stable disease. CONCLUSIONS: The safety profile of SAR405838 and pimasertib combined was consistent with the safety profiles of both drugs. Preliminary antitumour activity was observed.

A phase I study of SAR405838, a novel human double minute 2 (HDM2) antagonist, in patients with solid tumours.

PURPOSE: In tumours with wild-type TP53, the tumour-suppressive function of p53 is frequently inhibited by HDM2. This phase I, dose-escalating study investigated the maximum tolerated dose (MTD), safety, pharmacokinetics and pharmacodynamics of SAR405838, an HDM2 inhibitor, in patients with advanced solid tumours (NCT01636479). METHODS: In dose escalation, patients with any locally advanced/metastatic solid tumour with TP53 mutation prevalence below 40%, or documented as TP53 wild-type, were eligible. In the MTD expansion cohort, only patients with de-differentiated liposarcoma were included. Primary end-points were MTD and efficacy in the MTD expansion cohort. Secondary end-points included safety, pharmacokinetics and pharmacodynamics biomarkers. RESULTS: Seventy-four patients were treated with SAR405838 (50-800 mg once daily [QD], 800-1800 mg weekly and 1800 mg twice weekly). Two patients treated with SAR405838 400 mg QD had thrombocytopaenia as a dose-limiting toxicity (DLT). The MTD for the QD schedule of SAR405838 was 300 mg QD. No DLTs were observed with the weekly schedule; one patient had a DLT of nausea with the 1800 mg twice-weekly dose. Treatment with SAR405838 was associated with increased plasma MIC-1, reflecting p53 pathway activation. In the de-differentiated liposarcoma MTD cohort, 89% of the patients had HDM2 amplification at baseline and no TP53 mutations were observed; best response was stable disease in 56% and progression-free rate at 3 months was 32%. CONCLUSION: SAR405838 had an acceptable safety profile with limited activity in patients with advanced solid tumours. The MTD of SAR405838 was 300 mg QD; MTD was not reached with the weekly schedule.

HPLC-MS/MS method for the simultaneous determination of clopidogrel, its carboxylic acid metabolite and derivatized isomers of thiol metabolite in clinical samples.

A fast and reproducible HPLC-MS/MS method was developed for the simultaneous determination of clopidogrel (CLP), its carboxylic acid derivative (CLPM), derivatized thiol metabolite isomers MP-H3 and the active MP-H4 in incurred human plasma. CLP, CLPM, MP-H3 and MP-H4 isomers together with the internal standard piroxicam were extracted from plasma samples using a simple protein precipitation with acetonitrile. The analytes were separated on HPLC Zorbax Plus C18 column via gradient elution with water and acetonitrile, both containing 0.1% (v/v) formic acid. Detection of the analytes were performed on a triple-quadrupole MS with multiple-reaction-monitoring via electrospray ionization. Calibration curves of the analytes prepared in 250µL plasma were found to be linear in ranges: 0.25-5.00ng/mL for CLP, 0.25-50.00ng/mL for MP-H3 and MP-H4 isomers and 50-10,000ng/mL for CLPM. The lower limit of quantitation was 0.25ng/mL for CLP, MP-H3, MP-H4 and 50.00ng/mL for CLPM. Intra- and inter-assay precision, expressed as relative standard deviation, was ≤18.1% for CLP, ≤15.2% for CLPM, ≤10.1% for MP-H3 and ≤19.9% for MP-H4. Intra- and inter-day accuracy of the method, expressed as relative error, was ≤16%. The analytes were stable in samples stored for 6h in autosampler, in plasma samples for 24h at room temperature and for 3 months at -25°C. Resolution of CLP, CLPM and MP-H3 and MP-H4 isomers of thiol metabolite during one analytical run was reported in patient plasma. The HPLC-MS/MS method was applied for pharmacokinetic studies of CLP and its metabolites in patients treated with daily dose of 75mg CLP.

An improved method for specific and quantitative determination of the clopidogrel active metabolite isomers in human plasma.

Pharmacokinetic analyses of clopidogrel are hampered by the existence of multiple active metabolite isomers (H1 to H4) and their instability in blood. We sought to retest the pharmacodynamic activities of the four individual active metabolite isomers in vitro, with the ultimate aim of determining the isomers responsible for clopidogrel activity in vivo. In vitro activity was evaluated by measuring binding of [³³P]-2-methylthio-ADP on P2Y12-expressing Chinese hamster ovary (CHO) cells and human platelets in platelet-rich plasma (PRP). A stereoselective method that used reverse-phase ultra high-performance liquid chromatography (UHPLC) and tandem mass spectrometry (MS) was developed to measure individual concentrations of the stable 3'-methoxyacetophenone (MP) derivatives of H1-H4. The new method was used to analyze plasma samples from clopidogrel-treated subjects enrolled in a phase I clinical trial. In vitro binding assays confirmed the previously observed biological activity of H4 (IC50: CHO-P2Y12: 0.12 µM; PRP: 0.97 µM) and inactivity of H3, and demonstrated that H1 was also inactive. Furthermore, H2 demonstrated approximately half of the biological activity in vitro compared with H4. Optimisation of UHPLC conditions and MS collision parameters allowed the resolution and detection of the four derivatised active metabolite isomers (MP-H1 to MP-H4). The stereoselective assay was extensively validated, and was accurate and precise over the concentration range 0.5-250 ng/ml. Only MP-H3 and MP-H4 were quantifiable in incurred clinical samples. Based on in vitro pharmacodynamic data and found concentrations, the active metabolite isomer H4 is the only diastereoisomer of clinical relevance for documenting the pharmacokinetic profile of the active metabolite of clopidogrel.

Molecularly imprinted polymers for the clean-up of a basic drug from environmental and biological samples.

A molecularly imprinted polymer (MIP) was synthesized and evaluated to selectively extract an alpha-blocker, i.e. alfuzosin, from human plasma. The synthesis of the MIP was performed in dichloromethane with methacrylic acid as monomer and the target drug as template. A first series of experiments was carried out in dichloromethane to estimate the potential of the MIP in its specific recognition medium, i.e. dichloromethane, by developing a selective procedure and by measuring the capacity of the sorbent. An optimized procedure was developed for the selective extraction of alfuzosin with a recovery close to 100% in this medium and a specific capacity of 1.3 micromol g(-1) of MIP was measured. A study in aqueous media was also carried out by a comprehensive approach of the retention mechanism in order to build a selective procedure of extraction. The effects of the amount and of the charge of cations were studied and an optimal pH value was defined to limit matrix effects. Then, the alfuzosin MIP was then directly used to selectively extract the target drug from human plasma with an extraction recovery of 60%. Lastly, a soil was extracted by a pressurized solvent and the resulting extract was cleaned up on the MIP, showing the possibility to use this selective sorbent for the sample treatment of various complex matrices.