The AAPS Journal最新文献

Abstract

The clinical use of therapeutic monoclonal antibodies (mAbs) for the treatment of cancer, inflammation, and other indications has been successfully established. A critical aspect of drug-antibody pharmacokinetics is immunogenicity, which triggers an immune response via an anti-drug antibody (ADA) and forms drug/ADA immune complexes (ICs). As a consequence, there may be a reduced efficacy upon neutralization by ADA or an accelerated drug clearance. It is therefore important to understand immunogenicity in biological therapies. A drug-like immunoglobulin G (IgG) was radiolabeled with tritium, and ICs were formed using polyclonal ADA, directed against the complementary-determining region of the drug-IgG, to investigate in vivo biodistribution in rodents. It was demonstrated that 65% of the radioactive IC dose was excreted within the first 24 h, compared with only 6% in the control group who received non-complexed ³H-drug. Autoradiographic imaging at the early time point indicated a deposition of immune complexes in the liver, lung, and spleen indicated by an increased radioactivity signal. A biodistribution study confirmed the results and revealed further insights regarding excretion and plasma profiles. It is assumed that the immune complexes are readily taken up by the reticuloendothelial system. The ICs are degraded proteolytically, and the released radioactively labeled amino acids are redistributed throughout the body. These are mainly renally excreted as indicated by urine measurements or incorporated into protein synthesis. These biodistribution studies using tritium-labeled immune complexes described in this article underline the importance of understanding the immunogenicity induced by therapeutic proteins and the resulting influence on biological behavior.

Abstract

Special populations, like geriatric patients, experience altered paracetamol pharmacokinetics (PK), complicating pain management. More PK research is essential to optimize paracetamol (acetaminophen) dosing. Yet, the reference method ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is not readily available. Therefore, we aimed to evaluate the agreement between UPLC-MS/MS and the more accessible colorimetric Roche acetaminophen (ACETA) assay in quantifying paracetamol plasma concentrations, to facilitate PK studies and therapeutic drug monitoring for pain management. Patient data and plasma samples were obtained from a prospective study including geriatric patients admitted to the geriatric wards. ACETA and UPLC-MS/MS assays were performed in two separate laboratories. Bland–Altman plot and Passing-Bablok regression were used to assess agreement. Accuracy was evaluated using the McNemar test for a threshold value of 10 mg/L. Population PK modeling was employed to bridge PK data obtained from both methods (NONMEM 7.5). A total of 242 plasma sample pairs were available from 40 geriatric patients (age range, 80–95 years). Paracetamol plasma concentrations from ACETA (median 9.8 [interquartile range 6.1–14.4] mg/L) and UPLC-MS/MS (9.5 [6.2–14.8] mg/L) did not differ significantly (P > 0.05). No significant proportional nor additive bias was observed between both assay methods. The classification accuracy (at threshold 10 mg/L) was 85% (P = 0.414). The conversion factor between ACETA and UPLC-MS/MS was estimated at 1.06 (relative standard error 5%), yet with a 13.4% (relative standard error 23%) interindividual variability. ACETA assay showed no systematic bias in comparison with the UPLC-MS/MS assay in determining paracetamol exposure in geriatric blood samples despite the imprecision.

There are examples in the literature demonstrating different approaches to defining the item characteristic functions (ICF) and characterizing the latent variable time-course within a pharmacometrics item response theory (IRT) framework. One such method estimates both the ICF and latent variable time-course simultaneously, and another method establishes the ICF first then models the latent variable directly. To date, a direct comparison of the “simultaneous” and “sequential” methodologies described in this work has not yet been systematically investigated. Item parameters from a graded response IRT model developed from Parkinson’s Progression Marker Initiative (PPMI) study data were used as simulation parameters. Each method was evaluated under the following conditions: (i) with and without drug effect and (ii) slow progression rate with smaller sample size and rapid progression rate with larger sample size. Overall, the methods performed similarly, with low bias and good precision for key parameters and hypothesis testing for drug effect. The ICF parameters were well determined when the model was correctly specified, with an increase in precision in the scenario with rapid progression. In terms of drug effect, both methods had large estimation bias for the slow progression rate; however, this bias can be considered small relative to overall progression rate. Both methods demonstrated type 1 error control and similar discrimination between model with and without drug effect. The simultaneous method was slightly more precise than the sequential method while the sequential method was more robust towards longitudinal model misspecification and offers practical advantages in model building.

Inhibiting MerTK on macrophages is a promising therapeutic strategy for augmenting anti-tumor immunity. However, blocking MerTK on retinal pigment epithelial cells (RPEs) results in retinal toxicity. Bispecific antibodies (bsAbs) containing an anti-MerTK therapeutic and anti-PD-L1 targeting arm were developed to reduce drug binding to MerTK on RPEs, since PD-L1 is overexpressed on macrophages but not RPEs. In this study, we present a modeling framework using in vitro receptor occupancy (RO) and pharmacokinetics (PK) data to predict efficacy, toxicity, and therapeutic index (TI) of anti-MerTK bsAbs. We first used simulations and in vitro RO data of anti-MerTK monospecific antibody (msAb) to estimate the required MerTK RO for in vivo efficacy and toxicity. Using these estimated RO thresholds, we employed our model to predict the efficacious and toxic doses for anti-MerTK bsAbs with varying affinities for MerTK. Our model predicted the highest TI for the anti-MerTK/PD-L1 bsAb with an attenuated MerTK binding arm, which was consistent with in vivo efficacy and toxicity observations. Subsequently, we used the model, in combination with sensitivity analysis and parameter scans, to suggest an optimal molecular design of anti-MerTK bsAb with the highest predicted TI in humans. Our prediction revealed that this optimized anti-MerTK bsAb should contain a MerTK therapeutic arm with relatively low affinity, along with a high affinity targeting arm that can bind to a low abundance target with slow turnover rate. Overall, these results demonstrated that our modeling framework can guide the rational design of bsAbs.

Graphical Abstract

The FDA initiated a cross-sectional, statistically based sampling and testing study to characterize the quality of marketed alcohol-based hand sanitizer (ABHS) by evaluating the alcohol content and impurities present in ABHS products manufactured by establishments that registered with the FDA during March–April 2020. A stratified sampling design divided the population of manufacturers into independent groups based on each establishment’s level of experience with FDA oversight and its geographic location. ABHS products were collected and analyzed by spatially offset Raman spectroscopy and gas chromatography with mass spectrometry (GC–MS). The GC–MS results for 310 products, from 196 newly registered domestic manufacturers, showed that 71.6% (± 5.7%) of these manufacturers had violative products. In 104 (33.5%) cases, the alcohol content did not meet label claim assay specifications but still fell within CDC efficacy ranges. Ethanol ABHS products failed more often overall (assay and impurities) (84.3%) and for impurities (84.3%), than isopropanol ABHS products (11.2% and 6.2%, respectively). Differences in test results across active ingredients were statistically significant. Ethanol ABHS products often (63.5% of cases) failed due to the presence of acetal or acetaldehyde, particularly in products with pH ≤ 6. Other impurities were also detected in several ABHS products, suggesting the use of low-grade alcohol in the manufacture of these products. Evidence was insufficient to conclude that having experience manufacturing FDA-regulated products, or lack thereof, influenced product-level violative results. This study highlights the importance of sourcing and testing active pharmaceutical ingredients to produce quality drug products.

Graphical Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal interstitial lung disease that affects three million patients worldwide and currently without an effective cure. Zinpentraxin alfa, a recombinant human pentraxin-2 (rhPTX-2) protein, has been evaluated as a potential drug candidate for the treatment of IPF. Clinical pharmacokinetic analysis of zinpentraxin alfa has been challenging historically due to interference from serum amyloid P component (SAP), an endogenous human pentraxin-2 protein. These molecules share an identical primary amino acid sequence and glycan composition; however, zinpentraxin alfa possesses α2,3-linked terminal sialic acid residues while SAP is an α2,6-linked isomer. By taking advantage of this only structural difference, we developed a novel assay strategy where α2,3-sialidase was used to selectively hydrolyze α2,3-linked sialic acid residues, resulting in desialylated zinpentraxin alfa versus unchanged sialylated SAP, following an immunoaffinity capture step. Subsequent tryptic digestion produced a unique surrogate asialo-glycopeptide from zinpentraxin alfa and allowed specific quantification of the biotherapeutic in human plasma. In addition, a common peptide shared by both molecules was selected as a surrogate to determine total hPTX-2 concentrations, i.e., sum of zinpentraxin alfa and SAP. The quantification methods for both zinpentraxin alfa and total hPTX-2 were validated and used in pharmacokinetic assessment in IPF patients. The preliminary results suggest that endogenous SAP levels remained largely constant in IPF patients throughout the treatment with zinpentraxin alfa. Our novel approach provides a general bioanalytical strategy to selectively quantify α2,3-sialylated glycoproteins in the presence of their corresponding α2,6-linked isomers.

Graphical Abstract

Recent publications by Benet and coworkers, Korzekwa and Nagar, and Rowland et al. signal disagreement regarding the use of Kirchhoff’s laws in combining pharmacokinetic parameters, especially clearances and rate constants. Here, it is pointed out that Kirchhoff’s laws as applied to pharmacokinetics simply assert that concentrations are well defined and that molar or mass balances hold. The real issue is how to combine parameters for clearance processes in sequence, which may be reversible, irreversible, or even active in either or both directions. It is also demonstrated that Kirchhoff’s laws cannot be used to resolve contradictory results observed in liver transport and clearance. Finally, a simple argument is provided relating nonlinear clearance to apparently anomalous bioavailability observations.

Graphical Abstract

SHetA2 is a promising, orally active small molecule with anticancer properties that target heat shock proteins. In this study, we aimed to investigate the pharmacodynamic (PD) effects of SHetA2 using preclinical in vitro and in vivo models of ovarian cancer and establish a physiologically based pharmacokinetic (PBPK)/PD model to describe their relationships with SHetA2 concentrations in mice. We found that daily oral administration of 60 mg/kg SHetA2 for 7 days resulted in consistent plasma PK and tissue distribution, achieving tumor drug concentrations required for growth inhibition in ovarian cancer cell lines. SHetA2 effectively induced cyclin D1 degradation in cancer cells in a dose-dependent manner, with up to 70% reduction observed and an IC₅₀ of 4~5 µM. We identified cyclin D1 as a potential PD marker for SHetA2, based on a well-correlated time profile with SHetA2 PK. Additionally, we examined circulating levels of ccK18 as a non-invasive PD marker for SHetA2-induced apoptotic activity and found it unsuitable due to high variability. Using a PBPK/PD model, we depicted SHetA2 levels and their promoting effects on cyclin D1 degradation in tumors following multiple oral doses. The model suggested that twice-daily dosing regimens would be effective for sustained reduction in cyclin D1 protein. Our study provides valuable insights into the PK/PD of SHetA2, facilitating future clinical trial designs and dosing schedules.