Increased Drug Exposure Research Articles

Clinical study design strategies to mitigate confounding effects of time-dependent clearance on dose optimization of therapeutic antibodies.

Time-dependent pharmacokinetics (TDPK) is a frequent confounding factor that misleads exposure-response (ER) analysis of therapeutic antibodies, where a decline in clearance results in increased drug exposure over time in patients who respond to therapy, causing a false-positive ER finding. The object of our simulation study was to explore the influence of clinical trial designs on the frequency of false-positive ER findings. Two previously published population PK models representative of slow- (pembrolizumab) and fast-onset (rituximab) TDPK were used to simulate virtual patient cohorts with time-dependent clearance and the frequency of false-positive ER findings. The impact of varying the number of dose groups, dose range, and sample size was evaluated over time. Study designs with a single tested dose level showed a high probability of showing a false-positive ER finding. When TDPK has a slow onset, use of exposure measures from early timepoints in ER analysis significantly reduces the risk of a false-positive, while with fast onset it did not. Randomization of patients to two dose levels greatly reduced the risk, with a threefold or greater dose range offering the greatest benefit. The likelihood of false-positive increases with a larger sample size, where greater care should be taken to identify confounding factors. Clinical trial simulation supports that appropriate clinical study design and analysis with adequate dose exploration can reduce but cannot entirely eliminate the risk of misleading ER findings.

Pulmonary delivery of forsythin-phospholipid complexes improves the lung anti-inflammatory efficacy in mice by enhancing dissolution and lung tissue affinity

Forsythin, currently in phase II clinical trials in China for the treatment of the common cold and influenza, faces challenges in achieving adequate lung drug exposure due to its limited dissolution and permeability, thereby restricting its therapeutic efficacy. The objective of this work was to formulate a forsythin-phospholipid complex (FPC) to enhance its dissolution properties and lung affinity with a particular view to improving pulmonary drug exposure and anti-inflammatory response. The results revealed that forsythin reacted with dipalmitoyl-phosphatidylcholine to form a stable, nanosized FPC suspension. This formulation significantly improved the in vitro drug's dissolution, cellular uptake, and lung affinity compared to its uncomplexed form. Intratracheal administration of FPC in a mouse model of acute lung injury induced by lipopolysaccharide (LPS) resulted in a substantial increase in drug exposure to lung tissues (39.6-fold) and immune cells in the epithelial lining fluid (198-fold) compared to intraperitoneal injection. In addition, FPC instillation exhibited superior local anti-inflammatory effects, leading to improved survival rates among mice with LPS-induced acute respiratory distress syndrome, outperforming both instilled forsythin and injected FPC. Overall, this work demonstrated the potential of phospholipid complexes as a viable option for developing inhalation products for drugs with limited solubility and permeability properties.

Analyzing parametric influences driving age-associated changes in absorption using a PBPK-GSA approach

The advanced age population may be susceptible to an increased risk of adverse effects due to increased drug exposure after oral dosing. Factors such as high-interindividual variability and lack of data has led to poor characterization of absorption's role in pharmacokinetic changes in this population. Physiologically based pharmacokinetic (PBPK) models are increasingly being used during the drug development process, as their unique qualities are advantageous in atypical scenarios such as drug-drug interactions or special populations such as older people. Along with relying on various sources of data, auxiliary tools including parameter estimation and sensitivity analysis techniques are employed to support model development and other applications. However, sensitivity analyses have mostly been limited to localized techniques in the majority of reported PBPK models using them. This is disadvantageous, since local sensitivity analyses are unsuitable for risk analysis, which require assessment of parametric interactions and proper coverage of the input space to better estimate and subsequently mitigate the effects of the phenomenon of interest. For this reason, this study seeks to integrate a global sensitivity analysis screening method with PBPK models based in PK-Sim® to characterize the consequences of potential changes in absorption that are often associated with advanced age. The Elementary Effects (Morris) method and visualization of the results are implemented in R and three model drugs representing Biopharmaceutical Classification System classes I-III that are expected to exhibit some sensitivity to three age-associated hypotheses were successfully tested.

Thermally-Induced Supersaturation Approach for Optimizing Drug Loading and Biopharmaceutical Properties of Supersaturated Lipid-Based Formulations: Case Studies with Ibrutinib and Enzalutamide.

Lipid-based formulations (LbFs) have demonstrated success in pharmaceutical applications; however, challenges persist in dissolving entire doses of the drug into defined liquid volumes. In this study, the temperature-induced supersaturation method was employed in LbF to address drug loading and pill burden issues. Supersaturated LbFs (super-LbF) were prepared using the temperature-induced supersaturation method, where the drug load is above its equilibrium solubility. Further, the influence of the drug's physicochemical and thermal characteristics on drug loading and their relevance with an apparent degree of supersaturation (aDS) was studied using two model drugs, ibrutinib and enzalutamide. All the prepared LbFs were evaluated in terms of physical stability, dispersion, and solubilization capacity, as well as pharmacokinetic assessments. Drug re-crystallization was observed in the lipid solution on long-term storage at higher aDS values of 2-2.5. Furthermore, high-throughput lipolysis studies demonstrated a significant decrease in drug concentration across all LbFs (regardless of drug loading) due to a decline in the formulation solvation capacity and subsequent generation of in-situ supersaturation. Further, the in vivo results demonstrated comparable pharmacokinetic parameters between conventional LbF and super-LbF. The short duration of the thermodynamic metastable state limits the potential absorption benefits. However, super-LbFs of Ibr and Enz showed superior profiles, with 1.7-fold and 5.2-fold increased drug exposure compared to their respective crystalline suspensions. In summary, this study emphasizes the potential of temperature-induced supersaturation in LbF for enhancing drug loading and highlights the intricate interplay between drug properties, formulation characteristics, and in vivo performance.

Interactions of bosutinib with drug transporters: In vitro and In vivo inhibition of organic cation transporter 2, multidrug and toxin extrusion protein 1, and breast cancer resistance protein by bosutinib

Bosutinib has been approved for use in patients with chronic myeloid leukemia. Information regarding the effects of bosutinib on clinically important drug transporters is limited, particularly regarding its inhibitory potency on transporters and in vivo effects. Therefore, we conducted a study investigating the in vitro and in vivo effects of bosutinib on drug transporters. Bosutinib showed moderate or strong inhibitory effects on organic cation transporter 2, multidrug and toxin extrusion protein 1, and breast cancer resistance protein with IC50 values of 0.0894, 0.598, and 10.8 µM, respectively. In vivo experiments in rats showed that bosutinib significantly inhibited organic cation transporter 2 and multidrug and toxin extrusion protein 1, leading to a marked reduction in the renal clearance of metformin and an increase in systemic exposure to metformin. Bosutinib increased systemic exposure to sulfasalazine, a probe substrate of breast cancer resistance protein, by 75 % in rats, highlighting its potential to significantly affect intestinal drug efflux. These quantitative changes suggest that bosutinib may alter the in vivo pharmacokinetics of drugs that are substrates of these transporters, potentially leading to increased drug exposure and enhanced or unexpected pharmacological effects.

#2898 Exposure response model describing hematologic changes with chronic treatment of CKD anemia with vadadustat

Abstract Background and Aims Vadadustat (VADA) is an oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor, a class of drugs that stabilize HIF and stimulate endogenous erythropoietin production, increasing iron mobilization and red blood cell production. VADA is approved in 36 countries globally and is indicated in the European Union for the treatment of symptomatic anaemia associated with chronic kidney disease (CKD) in adults on chronic maintenance dialysis and is an alternative to treatment with erythropoiesis-stimulating agents (ESAs). The aim of this work was to develop a predictive, semi-mechanistic model to understand the effects of VADA and erythropoiesis-stimulating agents (ESAs) on hemoglobin response and to evaluate the impact of intrinsic and extrinsic patient characteristics on that response for non-dialysis dependent (NDD) and dialysis-dependent (DD) patient populations. Method A predictive semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for VADA and ESA treatment was developed using nonlinear mixed effects methods. The model describes changes in reticulocyte count (RETICs), mature erythrocytes (RBCs) and hemoglobin (Hb) as a function of drug exposure and subject-specific characteristics. The dataset was based on data from 7 Phase 1 to Phase 3 studies (Table 1; N = 894 for VADA; N = 560 for ESA modeling) in healthy volunteers and subjects with NDD- or DD-CKD who were either ESA-naïve or ESA experienced but not receiving treatment at screening. Prior population PK modeling of VADA provided estimated drug exposures for VADA-treated subjects, while dose normalized to standard units (IU/kg/wk) was used as the exposure metric for subjects on ESA. Each of these exposure metrics could vary with time, as the dose was adjusted according to observed Hb response. This work evaluated alternative model structures, as well as covariate effects affecting Hb individual response. Results A predictive semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for VADA and ESA treatment was developed using nonlinear mixed effects methods. The model describes changes in reticulocyte count (RETICs), mature erythrocytes (RBCs) and hemoglobin (Hb) as a function of drug exposure and subject-specific characteristics. The dataset was based on data from 7 Phase 1 to Phase 3 studies (Table 1; N = 894 for VADA; N = 560 for ESA modeling) in healthy volunteers and subjects with NDD- or DD-CKD who were either ESA-naïve or ESA experienced but not receiving treatment at screening. Prior population PK modeling of VADA provided estimated drug exposures for VADA-treated subjects, while dose normalized to standard units (IU/kg/wk) was used as the exposure metric for subjects on ESA. Each of these exposure metrics could vary with time, as the dose was adjusted according to observed Hb response. This work evaluated alternative model structures, as well as covariate effects affecting Hb individual response. A similar model structure was found to describe early changes in RETICs and longer-term changes in Hb for both VADA and ESAs. In each case, the magnitude of response increases with increased drug exposure up to a maximum value (Emax), and the Emax values were similar between VADA and ESAs. Subject intrinsic predictors of response included eGFR, subject age, BMI, and serum albumin, while extrinsic factors affecting response included geographic region, limits on acceptable Hb values (which also differ by geographic region) and the presence of previous ESA treatment. Interestingly, Hb responses were also correlated with changes in serum hepcidin, a key regulator of iron homeostasis, following both VADA and ESA treatment. Differences between the response to VADA and ESA were also described, including differences in temporal changes in RETICs and Hb. Conclusion This model showed an exposure-response relationship between VADA or ESA treatment and changes in RETICs and Hb for ESA naïve or ESA-experienced CKD subjects. The model will be used to inform dosage recommendations for VADA based on patient characteristics.

Absorption of cinnarizine from type II lipid-based formulations: Impact of lipid chain length, supersaturation, digestion, and precipitation inhibition

Lipid-based formulations (LBFs) are an enabling-formulation approach for lipophilic poorly water-soluble compounds. In LBFs, drugs are commonly pre-dissolved in lipids, and/or surfactants/cosolvents, hereby avoiding the rate-limiting dissolution step. According to the Lipid formulation classification system, proposed by Pouton in 2006, in type II LBFs a surfactant with an HLB-value lower than 12 is added to the lipids. If high drug doses are required, e.g. for preclinical toxicity studies, supersaturated LBFs prepared at elevated temperatures may be a possibility to increase drug exposure. In the present study, the impact of digestion on drug absorption in rats was studied by pre-dosing of the lipase inhibitor orlistat. The lipid chain length of the type II LBFs was varied by administration of a medium-chain- (MC) and a long-chain (LC)-based formulation. Different drug doses, both non-supersaturated and supersaturated, were applied. Due to an inherent precipitation tendency of cinnarizine in supersaturated LBFs, the effect of the addition of the precipitation inhibitor Soluplus® was also investigated. The pharmacokinetic results were also evaluated by multiple linear regression. In most cases LC-based LBFs did not perform better in vivo, in terms of a higher area under the curve (AUC0–24 h) and maximal plasma concentration (Cmax), than MC-based LBFs. The administration of supersaturated LBFs resulted in increased AUC0–24 h (1.5 – 3.2-fold) and Cmax (1.1 – 2.6-fold)-values when compared to the non-supersaturated equivalents. Lipase inhibition led to a decreased drug exposure in most cases, especially for LC formulations (AUC0–24 h reduced to 47 – 67%, Cmax to 46 – 62%). The addition of Soluplus® showed a benefit to drug absorption from supersaturated type II LBFs (1.2 – 1.7-fold AUC0–24 h), due to an increased solubility of cinnarizine in the formulation. Upon dose-normalization of the pharmacokinetic parameters, no beneficial effect of Soluplus® could be demonstrated.

Abstract 3737: Molecular and early clinical characterization of the anti-CD73 antibody S095024 (Sym024)

Abstract Background: Adenosine signaling is a central immunosuppressive mechanism affecting a broad set of immune cell types. Adenosine is generated from extracellular ATP by a group of ectonucleotidases including CD39 and CD73. Suppressing the adenosine pathway via CD73 blockade may enhance the potential of checkpoint inhibitor therapies.S095024 (Sym024) is a fully human, effector-function attenuated antibody that binds to human and cynomolgus CD73 with sub-nM affinity. Methods: Preclinically, the stoichiometry and conformational structure of the binding interaction between CD73 and S095024 was assessed by SEC-MALS and cryo-EM and the ability of S095024 to inhibit CD73 activity was done in vitro covering 3-, 6- and 24-hour incubation periods. The clinical safety, tolerability, pharmacokinetics, and pharmacodynamics of S095024 alone or in combination with Sym021, an anti-PD1 antibody, was investigated in a first-in-human study (NCT04672434) in patients with selected types of advanced solid tumors. Following assessment of single agent S095024 (100 to 1500 mg IV Q2W) in part I, the safety and tolerability of S095024 (300 to 1500 mg IV Q2W) was assessed in combination with Sym021 (200 mg IV Q2W) in part II. A part IIa was added: patients received 3000 mg IV Q2W of S095024 in Cycle 1, followed by 3000 mg S095024 + 200 mg Sym021 from Cycle 2 onwards. Results: Structural data indicate that S095024 binds to CD73 in a unique configuration by bridging the two monomers of the molecule, interacting in a 1:1 stoichiometry and effectively preventing the conformational state cycling required for catalysis. Functional data using a 20x cell line panel harboring a broad range of CD73 expression levels demonstrates that this interaction modus results in deep enzymatic inhibition. As of 12 Oct 2023, 43 patients have been treated with, S095024 in the FIH study. S095024, as a single agent (N=18) and in combination with PD-1 blockade (N=25) was well tolerated across all dose levels. The most frequent treatment emergent adverse events (≥15% patients) were fatigue, nausea, diarrhea, dyspnea, and vomiting. A dose proportional increase in drug exposure, both in monotherapy and combination, was observed starting at 900 mg. Target engagement assessed both peripherally (free soluble CD73) and intra-tumorally (enzymatic activity), showed a sustained decrease in free soluble CD73 in blood at dose levels ≥1500 mg and dose-dependent CD73 modulation, with >80% inhibition reached at ≥1500 mg in tumor biopsies. Conclusions: These findings reveal the potential of S095024 (Sym024) to prevent adenosine-mediated tumor evasion and support further clinical investigation. Citation Format: Anna Spreafico, Jordi R. Ahnert, David Sommerhalder, Maria Almena-Carrasco, Najah Harouki Crochemore, Xenophon Ianopulos, Janus S. Jakobsen, Emily Armbruster, Audrey Delmas, Amédée des Georges, Camilla Fröhlich, Julia Geronimi, Michael M. Grandal, Randi W. Hansen, Johan Lantto, Julie Legrand, Franck Levasseur, Matteo Riva, Christelle Rodrigues, Vanessa Seif, Vasileios Askoxylakis, Nehal Lakhani. Molecular and early clinical characterization of the anti-CD73 antibody S095024 (Sym024) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3737.

Abstract 6510: BPI-511966,a potent and selective HPK1 inhibitor with robust single-agent efficacy for cancer immunotherapy

Abstract Although immune checkpoint inhibitors (ICIs) have become the standard treatment for many types of cancers, a large proportion of patients fail to respond to ICIs. Hematopoietic progenitor kinase 1 (HPK1) has been validated as a negative intracellular immune checkpoint that constrains T-cell activation. Genetic or pharmacological ablation of HPK1 induces a robust anti-cancer immune response in vivo, highlighting the potential of HPK1 as a next-generation target for cancer immunotherapy. Herein, we reported the discovery of BPI-511966, a highly potent ATP-competitive HPK1 inhibitor. The compound strongly inhibited HPK1 kinase with an IC50 of 2.3 nM at physiologically relevant ATP concentration (1 mM) and reduced phosphorylation of SLP-76, a substrate adaptor of HPK1, in Jurkat T cells in vitro, with an IC50 value of 11 nM. Development of an optimal HPK1 inhibitor requires not only high potency for target engagement but also high selectivity to spare other kinases that are essential for T cell activation. BPI-511966 showed >100-fold higher IC50 (364 nM) against MAP4K3/GLK, an HPK1 homology kinase promoting T-cell activation, and also demonstrated weak inhibition in a panel of other immune-related kinases. The remarkable potency and selectivity of BPI-511966 translate into robust T cell-enhancing efficacy in vitro. Treatment with BPI-511966 promoted both IL-2 and IFN-γ production by Jurkat T cell and human PBMC in a dose-dependent manner. The on-target action of BPI-511966 was validated in HPK1-KO Jurkat T cells, in which no significant impacts on SLP-76 phosphorylation and IL-2 secretion were observed. In vivo, single dose escalation of BPI-511966 in mice leads to dose-proportional increases in drug exposure, accompanied by inhibition of SLP-76 phosphorylation in peripheral CD3+ T cells. Furthermore, repeated oral administration of BPI-511966 as a single agent significantly suppressed CT-26 tumor growth in immune-competent mice (92% TGI), correlating with increased infiltration of CD45+ CD8+ cells and enhanced cytokine production in tumor. Notably, the efficacy of BPI-511966 is abrogated in immune-compromised mice, suggesting its vital role in promoting anti-cancer immunity. In summary, this study presents a novel, highly potent, and selective HPK1 inhibitor BPI-511966. The robust single-agent activity of BPI-511966 makes it a promising small molecule I/O agent to address ICI resistance as monotherapy or in combination. Citation Format: Yong Zhang, Xiaoguan Zhu, Wenmao Wu, Zhifang Xia, Zhengyao Zou, Han Han, Cheng Yang, Haibo Chen, Tianyi Ma, Xiaoyun Liu, Jing Guo, Hao Wu, Hong Lan, Lieming Ding, Jiabing Wang, Quan Zhou. BPI-511966,a potent and selective HPK1 inhibitor with robust single-agent efficacy for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6510.

Exposure-efficacy and exposure-safety analyses of ropeginterferon alfa-2b treatment in patients with polycythaemia vera.

To investigate the exposure-response (E-R) relationship, including exposure-efficacy and exposure-safety, of ropeginterferon alfa-2b treatment in patients with polycythaemia vera (PV). Based on the results of the phase II trial A20-202 regarding ropeginterferon alfa-2b in patients with PV, E-R analyses were performed to evaluate the efficacy and safety of the given dosing regimen. The E-R analyses were based on logistic and linear regression and the relationship between exposure to ropeginterferon alfa-2b and key efficacy and safety variables. The key efficacy variables included complete haematologic response (CHR) and reduction of the driver mutation JAK2V617F. The safety variable was treatment-related adverse events (TRAEs). A clear relationship between the exposure to ropeginterferon alfa-2b and CHR was observed, with an increase in drug exposure resulting in an increased probability of achieving CHR. Similar CHR probabilities were observed in the third and fourth quantiles of the average concentration at Week 24. The results from the exposure-JAK2V617F model indicated that the JAK2V617F allele burden decreased with increasing exposure to ropeginterferon alfa-2b and baseline body surface area. Exposure-safety analysis revealed a risk of AEs associated with transaminase abnormalities, which were not associated with clinical significance. Our analyses have shown that patients with PV treated with ropeginterferon alfa-2b had an increased probability of achieving CHR and a molecular response with acceptable safety risks at the 250-350-500 μg titration dosing regimen. This study has provided the relevant data for the application of a biologics licence of ropeginterferon alfa-2b for PV treatment in China.

Flavonoids as CYP3A4 Inhibitors In Vitro.

Flavonoids, a diverse group of polyphenolic compounds found abundantly in fruits, vegetables, and beverages like tea and wine, offer a plethora of health benefits. However, they have a potential interaction with drug metabolism, particularly through the inhibition of the cytochrome P450 3A4 enzyme, the most versatile and abundant enzyme in the liver. CYP3A4 is responsible for metabolizing approximately 50% of clinically prescribed drugs across diverse therapeutic classes, so these interactions have raised concerns about potential adverse effects. This review delves into the scientific evidence surrounding flavonoid-mediated CYP3A4 inhibition, exploring the inhibitory potential of investigated flavonoids and future implications. Kusehnol I, chrysin, leachianone A, and sophoraflavone G showed the largest inhibitory potentials and lowest IC50 values. While the clinical significance of flavonoid-mediated CYP3A4 inhibition in dietary contexts is generally considered low due to moderate intake and complex interactions, it poses a potential concern for individuals consuming high doses of flavonoid supplements or concurrently taking medications metabolized by CYP3A4. This can lead to increased drug exposure, potentially triggering adverse reactions or reduced efficacy.

Utilization of Lipophilic Salt and Phospholipid Complex in Lipid-Based Formulations to Modulate Drug Loading and Oral Bioavailability of Pazopanib.

Pazopanib hydrochloride (PAZ) displays strong intermolecular interaction in its crystal lattice structure, limiting its solubility and dissolution. The development of lipid-based formulations (LbFs) resulted in reduced PAZ loading due to solid-state mediated low liposolubility. This study aims to enhance our understanding of PAZ crystallinity by synthesizing a lipophilic salt and phospholipid complex and investigating its impact on the drug loading in LbFs. The synthesized pazopanib lipophilic salt and phospholipid complex were extensively characterized. The solid form of pazopanib docusate (PAZ-DOC) and pazopanib phospholipid complex (PAZ-PLC) indicates a reduction in characteristic diffraction peaks of crystalline PAZ. The lipid formulations were prepared using synthesized PAZ-DOC and PAZ-PLC, where PAZ-DOC demonstrated sixfold higher drug solubility than the commercial salt form and twice that of the PAZ-PLC due to differences in the crystallinity. Further, the impact of salt and complex formation was assessed on the aqueous drug solubilization using lipolysis and multimedia dissolution experiments. Moreover, the LbFs showed notably faster dissolution compared to the crystalline PAZ and marketed tablet. In terms of in vivo pharmacokinetics, the PAZ-DOC LbF exhibited a remarkable 11-fold increase in AUC value compared to the crystalline PAZ and a 2.5-fold increase compared to Votrient®. Similarly, PAZ-PLC LbF showed an approximately ninefold increase in drug exposure compared to the crystalline PAZ, and a 2.2-fold increase compared to Votrient®. These findings suggest that disrupting the crystallinity of drugs and incorporating them into LbF could be advantageous for enhancing drug loading and overcoming limitations related to drug absorption.

Species-specific Bioactivation of Morpholines as a Causative of Drug Induced Liver Injury Observed in Monkeys.

Everolimus, an allosteric mechanistic target of rapamycin (mTOR) inhibitor, recently demonstrated the therapeutic value of mTOR inhibitors for Central Nervous System (CNS) indications driven by hyperactivation of mTOR. A newer, potent brain-penetrant analog of everolimus, referred to as (1) in this manuscript [(S)-3-methyl-4-(7-((R)-3-methylmorpholino)-2- (thiazol-4-yl)-3H-imidazo[4,5-b]pyridin-5-yl)morpholine,(1)] catalytically inhibits mTOR function in the brain and increases the lifespan of mice with neuronal mTOR hyperactivation. Early evaluation of the safety of 1 was conducted in cynomolgus monkeys in which oral doses were administered to three animals in a rising-dose fashion (from 2 to 30 mg/kg/day). 1 produced severe toxicity including the evidence of hepatic toxicity, along with non-dose proportional increases in drug exposure. Investigations of cross-species hepatic bioactivation of 1 were conducted to assess whether the formation of reactive drug metabolites was associated with the mechanism of liver toxicity. 1 contained two morpholine rings known as structural alerts and can potentially form reactive intermediates through oxidative metabolism. Bioactivation of 1 was investigated in rat, human and monkey liver microsomes fortified with trapping agents such as methoxylamine or potassium cyanide. Our results suggest that bioactivation of the morpholine moieties to reactive intermediates may have been involved in the mechanism of liver toxicity observed with 1. Aldehyde intermediates trappable by methoxylamine were identified in rat and monkey liver microsomal studies. In addition, a total of four cyano conjugates arising from the formation of iminium ion intermediates were observed and identified. These findings may potentially explain the observed monkey toxicity. Interestingly, methoxylamine or cyano adducts of 1 were not observed in human liver microsomes. The bioactivation of 1 appears to be species-specific. Circumstantial evidence for the toxicity derived from 1 point to the formation of iminium ion intermediates trappable by cyanide in monkey liver microsomes. The cyano conjugates were only observed in monkey liver microsomes, potentially pointing to cause at least the hepatotoxicity observed in monkeys. In contrast, methoxylamine conjugates were detected in both rat and monkey liver microsomes, with only a trace amount in human liver microsomes. Cyano conjugates were not observed in human liver microsomes, challenging the team on the drugability and progressivity of 1 through drug development. The mechanisms for drug-induced liver toxicity are multifactorial. These results are highly suggestive that the iminium ion may be an important component in the mechanism of liver toxicity 1 observed in the monkey.

Sialic Acid Mediated Endothelial and Hepatic Uptake: A Mechanism based Mathematic Model Elucidating the Complex Pharmacokinetics and Pharmacodynamics of Efmarodocokin Alfa, a Variably Glycosylated Fusion Protein

Sialic acid (SA) is crucial for protecting glycoproteins from clearance. Efmarodocokin alfa (IL-22Fc), a fusion protein agonist that links IL-22 to the crystallizable fragment (Fc) of human IgG4, contains 8 N-glycosylation sites and exhibits heterogeneous and variable terminal sialylation biodistribution. This presents a unique challenge for Pharmacokinetic (PK) and Pharmacodynamic (PD) analysis and cross-species translation. In this study, we sought to understand how varying SA levels and heterogeneous distribution contribute to IL-22Fc's complex PKPD properties. We initially used homogenous drug material with varying SA levels to examine PKPD in mice. Population PKPD analysis based on mouse data revealed that SA was a critical covariate simultaneously accounting for the substantial between subject variability (BSV) in clearance (CL), distribution clearance (CLd), and volume of distribution (Vd). In addition to the well-established mechanism by which SA inhibits ASGPR activity, we hypothesized a novel mechanism by which decrease in SA increases the drug uptake by endothelial cells. This decrease in SA, leading to more endothelial uptake, was supported by the neonatal Fc receptor (FcRn) dependent cell-based transcytosis assay. The population analysis also suggested in vivo EC50 (IL-22Fc stimulating Reg3β) was independent on SA, while the in-vitro assay indicated a contradictory finding of SA-in vitro potency relationship. We created a mechanism based mathematical (MBM) PKPD model incorporating the decrease in SA mediated endothelial and hepatic uptake, and successfully characterized the SA influence on IL-22Fc PK, as well as the increased PK exposure being responsible for increased PD. Thereby, the MBM model supported that SA has no direct impact on EC50, aligning with the population PKPD analysis. Subsequently, using the MBM PKPD model, we employed 5 subpopulation simulations to reconstitute the heterogeneity of drug material. The simulation accurately predicted the PKPD of heterogeneously and variably sialylated drug in mouse, monkey and human. The successful prospective validation confirmed the MBM's ability to predict IL-22Fc PK across variable SA levels, homogenous to heterogeneous material, and across species (R2=0.964 for clearance prediction). Our model prediction suggests an average of 1 mol/mol SA increase leads to a 50% increase in drug exposure. This underlines the significance of controlling sialic acid levels during lot-to-lot manufacturing.

Abstract C079: H. pylori eradication for mitigating gastro-duodenal cancers: Modeling pharmacokinetics of levofloxacin niosomes in Sprague-Dawley rats

Abstract Eradication of Helicobacter pylori (H. pylori) and, hence, control of its associated conditions (peptic ulcer, gastric cancer, and lymphoma) still constitute major challenge to therapeutics. H. pylori has been implicated in 60% of gastric and 90 % of duodenal ulcers and has been classified as a Class 1 carcinogen in human by the International Agency for Research on Cancer and the World health Organization (Enerson et al, 2016; Vogiatzi et al, 2007; WHO). It affects 4million people world-wide of which 0.5million is from the US and 70% are of 25-64 y/o (Chung & Shelat, 2017). Presently, gastric cancer is the second leading cause of neoplastic mortality globally (Contreras et al, 2014; Owen et al, 2018). The efficacy of currently used antibiotics (erythromycin, clarithromycin, levofloxacin, and azithromycin) in triple or quadruple combinations with proton pump inhibitor (PPI) is decreasing due to resistance development via lipopolysaccharide modification, increased drug efflux, and reduced porin pathway. Adaptive response by bacteria to specific signal due to antibacterial presence in its environment, leading to up-regulation of the efflux system (MexXY/OprM), and down-regulation of porin pathway (OprD) has been recognized as key factor in the resistance manifestation. In an earlier study, we reported that encapsulation of an anti-H. pylori drug (levofloxacin) molecules in niosomes (nano-size lipid vesicles) improved its molecular assimilation by drug-resistant E. coli and Ps. aeruginosa and produced approximately 50 % reduction in their minimum inhibitory concentrations (MIC) (Jankie et al, 2012). In this study, we investigated the in vivo bioavailability of levofloxacin niosomes administered intraperitoneally to Sprague Dawley rats. Plasma data modelling in Gastroplus PKTM for non-compartmental through 3-compartmental models, using Hooke & Jeeves pattern search, indicated that pure levofloxacin obeyed two-compartment kinetic model, while levofloxacin niosomes demonstrated one-compartmental model. In addition, niosome encapsulation increased drug exposure (AUC) about 5 folds and duration of action (mean residence time, MRT) about 1.6 folds. Thus, niosome encapsulation changed distribution pattern and the values of PK parameter supported 2-compartmental and 1-compartmental models for levofloxacin and its niosomes respectively. The knowledge of in vivo rodent PK generated in this study is vital for the determination of test doses in a higher animal species and, subsequent, for the calculation of thee first in human dose of levofloxacin using allometric equations. Generally, the potential is quite high for niosomes encapsulation to enhance the efficacy of other anti-H. pylori drugs against drug-resistant bacterial strains and needs to be investigated. Citation Format: Amusa S. Adebayo, Satish Jankie. H. pylori eradication for mitigating gastro-duodenal cancers: Modeling pharmacokinetics of levofloxacin niosomes in Sprague-Dawley rats [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C079.

Long-Term Intake of Linezolid Elevates Drug Exposure and Reduces Drug Clearance and Elimination in Adults With Drug-Resistant Pulmonary Tuberculosis.

Pharmacokinetic (PK) studies are critical for dose optimization, and there is a paucity of linezolid (LZD) PK data for prolonged use in drug-resistant tuberculosis (DR-TB). Therefore, the authors evaluated the pharmacokinetics of LZD at two-time intervals in DR-TB during long-term use. PK evaluation of LZD was performed at the end of the 8th and 16th weeks of treatment in a randomly selected subset of adult pre-extensively drug-resistant pulmonary tuberculosis patients (n = 18) from a multicentric interventional study (Building Evidence to Advance Treatment of TB/BEAT study; CTRI/2019/01/017310), wherein a daily dose of 600 mg LZD was used for 24 weeks. Plasma LZD levels were measured using a validated high-pressure liquid chromatography (HPLC) method. The LZD median plasma C max was comparable between the 8th and 16th weeks [18.3 mg/L, interquartile range (IQR: 15.5-20.8 and 18.8 mg/L, IQR: 16.0-22.7, respectively)]. However, the trough concentration increased significantly in the 16th week (3.16 mg/L, IQR: 2.30-4.76), compared with the 8th week (1.98 mg/L, IQR: 0.93-2.75). Furthermore, compared with the 8th week, in the 16th week, there was a significant increase in drug exposure (AUC 0-24 = 184.2 mg*h/L, IQR: 156.4-215.8 versus 233.2 mg*h/L, IQR: 187.9-277.2), which corroborated with a longer elimination half-life (6.94 hours, IQR: 5.55-7.99 versus 8.47 hours, IQR:7.36-11.35) and decreased clearance (2.91 L/h, IQR: 2.45-3.33 versus 2.19 L/h, IQR: 1.49-2.78). Long-term daily intake of 600 mg LZD resulted in a significant elevation in trough concentration (>2.0 mg/L) in 83% of the study participants. Furthermore, increased LZD drug exposure may be partly because of decreased clearance and elimination. Overall, the PK data underscore the need for dose adjustment when LZDs are intended for long-term treatment.

Circulating factors following doxorubicin treatment in a tumor-bearing model induce endothelial dysfunction

Chemotherapy (CTx) is essential to prevent the growth of tumors and has increased patient survival significantly. However, CTx agents have cardiotoxic side effects that can ultimately lead to heart failure. As a result, cardiovascular (CV) death is now the second leading cause of death in cancer patients. It has been accepted that adverse CV events are driven by a dysfunctional microcirculation, therefore CTx-induced endothelial dysfunction may play a key role in development of myocardial pathologies.Many CTx agents induce mitochondrial DNA (mtDNA) damage as many drugs intercalate into double stranded DNA, promoting the release of cell-free mtDNA (cf-mtDNA) into the circulation. Toll-like receptor 9 (TLR9) on the vascular endothelium detects cf-mtDNA and results in an inflammatory response. Prolonged exposure to CTx agents may enhance the mtDNA damage and stimulate the release of additional cf-mtDNA. To determine whether increased drug exposure exacerbates mtDNA damage, two forms of clinically used CTx were utilized: doxorubicin (Dox) and a lysosomal-derived nanoparticle with encapsulated Dox (Dox-NP), which targets tumor cells more specifically. With the ability of tumor-targeted delivery via Dox-NP, we hypothesize that Dox-NP augments mtDNA damage and the inflammatory response.Male Sprague Dawley rats received rat hepatoma-derived tumor cells into the liver twelve days prior to treatment start. Rats were treated with one weekly Dox or Dox-NP injection (7.5mg/kg·BW) for two weeks (cumulative dose 15mg/kg·BW). Cardiac function was evaluated before and six weeks after the initial dose of CTx. Vessel function was evaluated following euthaniasia six weeks after the initial dose. Plasma was obtained upon euthanasia, and cf-mtDNA levels were quantified via qPCR. NF-kB expression, downstream of TLR9 was determined via western blot.Rat microvessels from both treatment groups showed reduced endothelial-mediated vasodilation. Quantification of cf-mtDNA showed a trend toward increased cf-mtDNA levels in response to both Dox and Dox-NP. Likewise, NF-kB expression was elevated three-fold in comparison to Dox. To confirm whether endothelial dysfunction was the result of the inflammatory TLR9 signaling in vivo, isolated human microvessels were treated with 100nM Dox-NP. Vasodilation was not impaired, suggesting that Dox-NP is not directly harmful to the endothelium.Together, these data indicate that tumor-targeted Dox-NP have little to non-direct impact on the endothelium. Thus, endothelial dysfunction in animals treated with Dox-NP is secondary to its effects on a tumor and may be mediated by tumor-derived cf-mtDNA and TLR9 signaling. Moreover, the present data shows that direct effects of standard Dox on ECs may be only partially responsible for impaired dilator function. Conclusively, this work supports the concepts of a new mechanism of Dox-induced endothelial dysfunction. This work was supported by the NIH, 5 R01 HL133029-0 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Pharmacokinetic Boosting of Kinase Inhibitors.

(1) Introduction: Pharmacokinetic boosting of kinase inhibitors can be a strategy to enhance drug exposure and to reduce dose and associated treatment costs. Most kinase inhibitors are predominantly metabolized by CYP3A4, enabling boosting using CYP3A4 inhibition. Kinase inhibitors with food enhanced absorption can be boosted using food optimized intake schedules. The aim of this narrative review is to provide answers to the following questions: Which different boosting strategies can be useful in boosting kinase inhibitors? Which kinase inhibitors are potential candidates for either CYP3A4 or food boosting? Which clinical studies on CYP3A4 or food boosting have been published or are ongoing? (2) Methods: PubMed was searched for boosting studies of kinase inhibitors. (3) Results/Discussion: This review describes 13 studies on exposure boosting of kinase inhibitors. Boosting strategies included cobicistat, ritonavir, itraconazole, ketoconazole, posaconazole, grapefruit juice and food. Clinical trial design for conducting pharmacokinetic boosting trials and risk management is discussed. (4) Conclusion: Pharmacokinetic boosting of kinase inhibitors is a promising, rapidly evolving and already partly proven strategy to increase drug exposure and to potentially reduce treatment costs. Therapeutic drug monitoring can be of added value in guiding boosted regimens.

Abstract 1544: MBK-103, a potent novel conjugation platform-based antibody-drug conjugate, changing therapeutic options in folate receptor alpha positive cancer patients

Abstract Folate receptor alpha (FOLR1) is a clinically validated target, that is overexpressed extracellularly in numerous solid malignancies with a high unmet medical need. Ovarian, non-small cell lung and breast adenocarcinomas are among indications with the highest frequency of FOLR1-positive patients with one out of two patients showing upregulated topoisomerase I expression. MBK-103, an antibody-drug conjugate targeting FOLR1, is based on Mablink’s novel proprietary hydrophilic drug-linker platform. It is comprised of: (i) an Fc-attenuated humanized IgG1 monoclonal antibody, that selectively binds to FOLR1; (ii) a polysarcosine hydrophobicity masking entity allowing for a high drug-to-antibody ratio (DAR) of 8, while improving the pharmacokinetics and tolerability of the drug; (iii) a proprietary dipeptide cleavable unit and iv) exatecan, a potent topoisomerase I inhibitor. MBK-103 showed excellent ex vivo stability in human plasma enabling a prolonged half-life, similar to that of the unconjugated monoclonal antibody. This led to an increased drug exposure, resulting in a potent antitumor efficacy observed in a collection of more than ten in vivo mouse tumor models with a diverse FOLR1 expression, already at doses as low as 1-3 mg/kg. In addition, the distinct mode of action of exatecan along with the unique characteristics of the proprietary drug-linker platform resulted in the in vivo antitumor potency obtained also in colorectal cancer models, in which tubulin-inhibiting agents exhibit only limited therapeutic effects. The compound was also very well tolerated in cynomolgus monkeys with HNSTD at 50 mg/kg and even when administered repeatedly. High conjugation yields along with 100% homogeneity are major drivers of the successful ongoing manufacturing process with planned IND submission in Q4/2023. Citation Format: Warren Viricel, Louise Conilh, Edouard Leroy, Jean-Guillaume Lafay, Frederique Brune, Lenka Kyrych Sadilkova, Charles Dumontet. MBK-103, a potent novel conjugation platform-based antibody-drug conjugate, changing therapeutic options in folate receptor alpha positive cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1544.

A phase I/II study of ASKB589 (anti-claudin 18.2 [CLDN18.2] monoclonal antibody) in patients with solid tumors.

397 Background: ASKB589 is a humanized IgG1 monoclonal antibody against Claudin 18.2 (CLDN18.2) with high affinity and enhanced antibody-dependent cellular cytotoxicity activity. We report preliminary safety and efficacy data from an ongoing Phase I/II, first-in-human, dose-escalation and expansion study of ASKB589 in patients (pts) with advanced solid tumors (NCT04632108). Methods: A two-part study was initiated to determine the maximum tolerated dose (MTD), safety and tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of ASKB589 as monotherapy (Part A) and in combination with chemotherapy (Part B). Each part used a modified 3 + 3 dose escalation design. Responses were assessed per RECIST 1.1 every 2 cycles (6 weeks). Adverse events (AEs) were graded using CTCAE v5.0. In Part A, pts with heavily pre-treated solid tumors received ASKB589 intravenously (IV) at doses of 0.3, 1, 3, 6, 10,15 or 20mg/kg every 3 weeks (Q3W). In Part B, pts with gastric/gastro-esophageal junction (G/GEJ) cancers received ASKB589 IV at doses of 3, 6, 10 or 15 mg/kg Q3W in combination with capecitabine plus oxaliplatin. Results: As of September 9, 2022, 51 pts received ASKB589 and no drug limiting toxicity (DLT) was observed. In expansion, pts have been enrolled into 6, 10, 15 mg/kg doses. In Part A, 17 pts were enrolled in escalation and 13 in expansion. All pts had metastatic disease, and most (90%) had ≥2 lines of prior therapy. 24 (80%) pts had treatment-related adverse events (TRAEs), the most common being nausea (53%), vomiting (43%), hypoalbuminemia (40%) and loss of appetite (30%). While the majority of TRAEs were grade 1 or 2, 3 pts (10%) had grade 3 events. For the 9 evaluable pts (G/GEJ cancer who received ≥10 mg/kg ASKB589 with at least one post-baseline tumor assessment), 5 pts (45%) had decreases in tumor size (range 1-38% from baseline). 2 pts achieved a partial response (PR) for an objective response rate (ORR) of 22%. In addition, 6 pts had stable disease (SD) for a disease control rate (DCR) of 89%. In Part B, 13 pts were enrolled in escalation and 8 in expansion. These pts were with advanced disease (95% stage IV) and had no prior systemic treatment in this setting. 17 (81%) pts had TRAEs, the most common being nausea (76%), vomiting (66%), hypoalbuminemia (52%), granulocytopenia (38%) and hypoleukemia (33%). While the majority of TRAEs were grade 1 or 2, 8 pts (38%) had grade 3 events. For the 12 evaluable pts (G/GEJ cancer who received ≥6 mg/kg ASKB589 with at least one post-baseline tumor assessment), all had decreases in tumor size (range 6-66% from baseline). 9 pts achieved PR for an ORR of 75%. In addition, 3 pts had SD for a DCR of 100%. The PK profile showed dose-related increases in drug exposure across study doses. Conclusions: ASKB589 showed a manageable safety profile up to doses of 20 mg/kg and promising antitumor activity, both as monotherapy and in combination with chemotherapy. Clinical trial information: NCT04632108 .