Illness perceptions, symptom severity and psychosocial outcomes in adults with dysfunctional breathing

BACKGROUND

People with dysfunctional breathing (DB) experience symptoms such as air hunger and breathing pattern irregularities. The condition is often comorbid with other respiratory conditions, as well as anxiety and depression. Illness perceptions, the beliefs an individual has of an illness may explain health and wellbeing outcomes.

METHODS

In this cross-sectional study we examined the illness perceptions of those diagnosed with DB, symptom severity, and psychosocial outcomes of depression, anxiety, and impact on daily living. Data were analyzed using tests of comparison and regression analysis.

RESULTS

82 people diagnosed with DB completed the brief illness perception questionnaire, the Nijmegen symptoms questionnaire, and questionnaires measuring mood and impact on daily living. The illness perceptions of those with DB were overall negative. There was a positive correlation between illness perceptions and mood, indicating that the stronger the beliefs that individuals had that DB is a serious condition, the more negative their mood. Illness perceptions significantly predicted psychosocial outcomes, even when controlling for demographic factors and symptom severity (depression: adj. R2=.352, F(10,51)=4.32, p<.001; anxiety: adj. R2=.40, F(11,47)=4.55, p<.001; impact on daily living: adj. R2= .33, F(8,53)=4.79, p<.001).

CONCLUSIONS

This is the first study to examine illness perceptions held by those diagnosed with DB. Our study found significant relationships between illness perceptions and psychosocial outcomes. It is possible that psychological interventions that target illness perceptions may also improve outcomes.

Biomarker Predictors of Clinical Efficacy of the Anti-IgE Biologic Omalizumab in Severe Asthma in Adults: Results of the SoMOSA Study

Background: The anti-IgE monoclonal antibody omalizumab is widely used for severe asthma. This study aimed to identify biomarkers that predict clinical improvement during 1 year of omalizumab treatment. Methods: One-year open-label Study of Mechanisms of action of Omalizumab in Severe Asthma (SoMOSA) involving 216 patients with severe (Global Initiative for Asthma step 4/5) uncontrolled atopic asthma (at least two severe exacerbations in the previous year) taking high-dose inhaled corticosteroids and long-acting β-agonists with or without maintenance oral corticosteroids. It had two phases: 0-16 weeks, to assess early clinical improvement by Global Evaluation of Therapeutic Effectiveness (GETE); and 16-52 weeks, to assess late responses based on ⩾50% reduction in exacerbations or mOCS dose. All participants provided samples (exhaled breath, blood, sputum, urine) before and after 16 weeks of omalizumab treatment. Measurements and Main Results: A total of 191 patients completed phase 1; 63% had early improvement. Of 173 who completed phase 2, 69% had reduced exacerbations by ⩾50% and 57% (37 of 65) taking mOCSs had reduced their dose by ⩾50%. The primary outcomes 2,3-dinor-11-β-PGF2α, GETE score, and standard clinical biomarkers (blood and sputum eosinophils, exhaled nitric oxide, serum IgE) did not predict either clinical response. Five volatile organic compounds and five plasma lipid biomarkers strongly predicted the ⩾50% reduction in exacerbations (receiver operating characteristic areas under the curve of 0.780 and 0.922, respectively) and early responses (areas under the curve of 0.835 and 0.949, respectively). In an independent cohort, gas chromatography/mass spectrometry biomarkers differentiated between severe and mild asthma. Conclusions: This is the first discovery of omics biomarkers that predict improvement in asthma with biologic agent treatment. Prospective validation and development for clinical use is justified.

Comparison of Asthma Phenotypes in Severe Asthma Cohorts (SARP, U-BIOPRED, ProAR and COREA) From 4 Continents

PURPOSE

Asthma is a clinical syndrome with various underlying pathomechanisms and clinical phenotypes. Genetic, ethnic, and geographic factors may influence the differences in clinical presentation, severity, and prognosis. We compared the characteristics of asthma based on the geographical background by analyzing representative cohorts from the United States, Europe, South America, and Asia using the Severe Asthma Research Program (SARP), Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes (U-BIOPRED), Program for Control of Asthma in Bahia (ProAR), and Cohort for Reality and Evolution of Adult Asthma in Korea (COREA), respectively.

METHODS

The clinical characteristics and medications for the SARP (n = 669), U-BIOPRED (n = 509), ProAR (n = 996), and COREA (n = 3,748) were analyzed. Subgroup analysis was performed for severe asthma.

RESULTS

The mean age was highest and lowest in the COREA and SARP, respectively. The asthma onset age was lowest in the ProAR. The mean body mass index was highest and lowest in the SARP and COREA, respectively. Baseline pulmonary function was lowest and highest in the U-BIOPRED and COREA, respectively. The number of patients with acute exacerbation in the previous year was highest in U-BIOPRED. The mean blood eosinophil count was highest in COREA. The total immunoglobulin E was highest in the ProAR. The frequency of atopy was highest in the SARP. The principal component analysis plot revealed differences among all cohorts.

CONCLUSIONS

The cohorts from 4 different continents exhibited different clinical and physiological characteristics, probably resulting from the interplay between genetic susceptibility and geographical factors.

Physiologically Based Pharmacokinetic Modeling to Predict the Impact of Liver Cirrhosis on Glucuronidation via UGT1A4 and UGT2B7/2B4-A Case Study with Midazolam

Hepatic impairment, due to liver cirrhosis, decreases the activity of cytochrome P450 enzymes (CYPs). The use of physiologically based pharmacokinetic (PBPK) modeling to predict this effect for CYP substrates has been well-established, but the effect of cirrhosis on uridine-glucuronosyltransferase (UGT) activities is less studied and few PBPK models have been reported. UGT enzymes are involved in primary N-glucuronidation of midazolam and glucuronidation of 1'-OH-midazolam following CYP3A hydroxylation. In this study, Simcyp was used to establish PBPK models for midazolam, its primary metabolites midazolam-N-glucuronide (UGT1A4) and 1'-OH midazolam (CYP3A4/3A5), and the secondary metabolite 1'-OH-midazolam-O-glucuronide (UGT2B7/2B4), allowing to simulate the impact of liver cirrhosis on the primary and secondary glucuronidation of midazolam. The model was verified in noncirrhotic subjects before extrapolation to cirrhotic patients of Child-Pugh (CP) classes A, B, and C. Our model successfully predicted the exposures of midazolam and its metabolites in noncirrhotic and cirrhotic patients, with 86% of observed plasma concentrations within 5th-95th percentiles of predictions and observed geometrical mean of area under the plasma concentration curve between 0 hours to infinity and maximal plasma concentration within 0.7- to 1.43-fold of predictions. The simulated metabolic ratio defined as the ratio of the glucuronide metabolite AUC over the parent compound AUC (AUCglucuronide/AUCparent, metabolic ratio [MR]), was calculated for midazolam-N-glucuronide to midazolam (indicative of UGT1A4 activity) and decreased by 40% (CP A), 48% (CP B), and 75% (CP C). For 1'-OH-midazolam-O-glucuronide to 1'-OH-midazolam, the MR (indicative of UGT2B7/2B4 activity) dropped by 35% (CP A), 51% (CP B), and 64% (CP C). These predicted MRs were corroborated by the observed data. This work thus increases confidence in Simcyp predictions of the effect of liver cirrhosis on the pharmacokinetics of UGT1A4 and UGT2B7/UGT2B4 substrates. SIGNIFICANCE STATEMENT: This article presents a physiologically based pharmacokinetic model for midazolam and its metabolites and verifies the accurate simulation of pharmacokinetic profiles when using the Simcyp hepatic impairment population models. Exposure changes of midazolam-N-glucuronide and 1'-OH-midazolam-O-glucuronide reflect the impact of decreases in UGT1A4 and UGT2B7/2B4 glucuronidation activity in cirrhotic patients. The approach used in this study may be extended to verify the modeling of other uridine glucuronosyltransferase enzymes affected by liver cirrhosis.

In silico modeling and simulation of organ-on-a-chip systems to support data analysis and a priori experimental design

Organ-on-a-chip (OoC) systems are a promising new class of in vitro devices that can combine various tissues, cultured in different compartments, linked by media flow. The properties of these novel in vitro systems linked to increased physiological relevance of culture conditions may lead to more in vivo-relevant cell phenotypes, enabling better in vitro pharmacology and toxicology assessment. Improved cell activities combined with longer lasting cultures offer opportunities to improve the characterization of absorption, distribution, metabolism, and excretion (ADME) processes, potentially leading to more accurate prediction of human pharmacokinetics (PKs). The inclusion of barrier tissue elements and metabolically competent tissue types results in complex concentration-time profiles (in vitro PK) for test drugs and their metabolites that require appropriate mathematical modeling of in vitro data for parameter estimation. In particular, modeling is critical to estimate in vitro ADME parameters when multiple different tissues are combined in a single device. Therefore, sophisticated in silico data analysis and a priori experimental design are highly recommended for OoC experiments in a manner not needed with standard ADME screening. The design of the experiment should be optimized based on an investigation of the structural characteristics of the in vitro system, the ADME features of the test compound and any available knowledge of cell phenotypes. This tutorial aims to provide such a modeling framework to inform experimental design and refine parameter estimation in a Gut-Liver OoC (the most studied multi-organ systems to predict the oral drug PKs) to improve translatability of data generated in such complex cellular systems.

Phase 1, first-in-human study of TYRP1-TCB (RO7293583), a novel TYRP1-targeting CD3 T-cell engager, in metastatic melanoma: active drug monitoring to assess the impact of immune response on drug exposure

Introduction

Although checkpoint inhibitors (CPIs) have improved outcomes for patients with metastatic melanoma, those progressing on CPIs have limited therapeutic options. To address this unmet need and overcome CPI resistance mechanisms, novel immunotherapies, such as T-cell engaging agents, are being developed. The use of these agents has sometimes been limited by the immune response mounted against them in the form of anti-drug antibodies (ADAs), which is challenging to predict preclinically and can lead to neutralization of the drug and loss of efficacy.

Methods

TYRP1-TCB (RO7293583; RG6232) is a T-cell engaging bispecific (TCB) antibody that targets tyrosinase-related protein 1 (TYRP1), which is expressed in many melanomas, thereby directing T cells to kill TYRP1-expressing tumor cells. Preclinical studies show TYRP1-TCB to have potent anti-tumor activity. This first-in-human (FIH) phase 1 dose-escalation study characterized the safety, tolerability, maximum tolerated dose/optimal biological dose, and pharmacokinetics (PK) of TYRP1-TCB in patients with metastatic melanoma (NCT04551352).

Results

Twenty participants with cutaneous, uveal, or mucosal TYRP1-positive melanoma received TYRP1-TCB in escalating doses (0.045 to 0.4 mg). All participants experienced ≥1 treatment-related adverse event (TRAE); two participants experienced grade 3 TRAEs. The most common toxicities were grade 1-2 cytokine release syndrome (CRS) and rash. Fractionated dosing mitigated CRS and was associated with lower levels of interleukin-6 and tumor necrosis factor-alpha. Measurement of active drug (dual TYPR1- and CD3-binding) PK rapidly identified loss of active drug exposure in all participants treated with 0.4 mg in a flat dosing schedule for ≥3 cycles. Loss of exposure was associated with development of ADAs towards both the TYRP1 and CD3 domains. A total drug PK assay, measuring free and ADA-bound forms, demonstrated that TYRP1-TCB-ADA immune complexes were present in participant samples, but showed no drug activity in vitro.

Discussion

This study provides important insights into how the use of active drug PK assays, coupled with mechanistic follow-up, can inform and enable ongoing benefit/risk assessment for individuals participating in FIH dose-escalation trials. Translational studies that lead to a better understanding of the underlying biology of cognate T- and B-cell interactions, ultimately resulting in ADA development to novel biotherapeutics, are needed.

PBPK Modelling for Drugs Cleared by Non-CYP Enzymes: State-of-the-Art and Future Perspectives

Physiologically-based pharmacokinetic (PBPK) modeling has become the established method for predicting human pharmacokinetics (PK) and drug-drug interactions (DDI). The number of drugs cleared by non-CYP enzyme metabolism has increased steadily and to date, there is no consolidated overview of PBPK modeling for drugs cleared by non-CYP enzymes. This review aims to describe the state-of-the-art for PBPK modeling for drugs cleared via non-CYP enzymes, to identify successful strategies, to describe gaps and to provide suggestion to overcome them. To this end, we conducted a detailed literature search and found 58 articles published before the 1st of January 2023 containing 95 examples of clinical PBPK models for 62 non-CYP enzyme substrates. Reviewed articles covered the drug clearance by uridine 5'-diphospho-glucuronosyltransferases (UGTs), aldehyde oxidase (AO), flavin-containing monooxygenases (FMOs), sulfotransferases (SULTs) and carboxylesterases (CES), with UGT2B7, UGT1A9, CES1, FMO3 and AO being the enzymes most frequently involved. In vitro-in vivo extrapolation (IVIVE) of intrinsic clearance and the bottom-up PBPK modeling involving non-CYP enzymes remains challenging. We observed that the middle-out modeling approach was applied in 80% of the cases, with metabolism parameters optimized in 73% of the models. Our review could not identify a standardized approach used for model optimization based on clinical data, with manual optimization employed most frequently. Successful development of models for UGT2B7, UGT1A9, CES1, and FMO3 substrates provides a foundation for other drugs metabolized by these enzymes and guides the way forward in creating PBPK models for other enzymes in these families. Significance Statement Our review charts the rise of PBPK modeling for drugs cleared by non-CYP enzymes. Analyzing 58 articles and 62 non-CYP enzyme substrates, we found that UGTs, AO, FMOs, SULTs, and CES were the main enzyme families involved and that UGT2B7, UGT1A9, CES1, FMO3 and AO are the individual enzymes with the strongest PBPK modeling precedents. Approaches established for these enzymes can now be extended to additional substrates and to drugs metabolized by enzymes that are similarly well characterized.

The Activity of Members of the UDP-Glucuronosyltransferase Subfamilies UGT1A and UGT2B is Impaired in Patients with Liver Cirrhosis

BACKGROUND AND OBJECTIVE

The impact of liver cirrhosis on the activity of UDP-glucuronosyltransferases (UGTs) is currently not well characterized. We investigated the glucuronidation capacity and glucuronide accumulation in patients with liver cirrhosis.

METHODS

We administered the Basel phenotyping cocktail (caffeine, efavirenz, flurbiprofen, omeprazole, metoprolol, midazolam) to patients with liver cirrhosis (n = 16 Child A, n = 15 Child B, n = 5 Child C) and n = 12 control subjects and obtained pharmacokinetic profiles of substrates and primary metabolites and their glucuronides.

RESULTS

Caffeine and its metabolite paraxanthine were only slightly glucuronidated. The metabolic ratio (AUCglucuronide/AUCparent, MR) was not affected for caffeine but decreased by 60% for paraxanthine glucuronide formation in Child C patients. Efavirenz was not glucuronidated whereas 8-hydroxyefavirenz was efficiently glucuronidated. The MR of 8-hydroxyefavirenz-glucuronide formation increased three-fold in Child C patients and was negatively correlated with the glomerular filtration rate. Flurbiprofen and omeprazole were not glucuronidated. 4-Hydroxyflurbiprofen and 5-hydroxyomeprazole were both glucuronidated but the corresponding MRs for glucuronide formation were not affected by liver cirrhosis. Metoprolol, but not α-hydroxymetoprolol, was glucuronidated, and the MR for metoprolol-glucuronide formation dropped by 60% in Child C patients. Both midazolam and its metabolite 1'-hydroxymidazolam underwent glucuronidation, and the corresponding MRs for glucuronide formation dropped by approximately 80% in Child C patients. No relevant glucuronide accumulation occurred in patients with liver cirrhosis.

CONCLUSIONS

Detailed analysis revealed that liver cirrhosis may affect the activity of UGTs of the UGT1A and UGT2B subfamilies according to liver function. Clinically significant glucuronide accumulation did not occur in the population investigated.

CLINICAL TRIAL REGISTRATION

NCT03337945.

Dose adjustment in patients with liver cirrhosis - comparison of two different modeling approaches

Failure to perform adequate dose adjustment in patients with liver cirrhosis may be associated with increased toxicity. We compared the prediction of AUC and clearance for the six compounds of the Basel phenotyping cocktail (caffeine, efavirenz, flurbiprofen, omeprazole, metoprolol, midazolam) using a well-known physiology-based pharmacokinetic approach ("PBPK approach", Simcyp®) and a novel top-down method based on the systemic clearance in healthy volunteers adjusted for markers of liver and renal dysfunction ("top-down approach"). With few exceptions, plasma concentration-time curves were accurately predicted by the PBPK approach. In comparison to the measured AUC and clearance of these drugs in patients with liver cirrhosis and healthy controls, except for efavirenz, the estimates of both approaches were within 2 standard deviations of the mean for total and free drug concentrations. For both approaches, a correction factor for dose adjustment in patients with liver cirrhosis could be calculated for the drugs administered. AUCs calculated using the adjusted doses were comparable to the AUCs measured in control subjects, with slightly more accurate predictions generated by the PBPK approach. For drugs with a free fraction <50%, predictions using free drug concentrations were more accurate than with total drug concentrations. In conclusion, both methods provided good qualitative predictions of the changes by liver cirrhosis in the pharmacokinetics of the six compounds investigated. The top-down approach is easier to implement but the PBPK approach predicted changes in drug exposure more accurately than the top-down approach and provided reliable estimates for plasma concentrations.

A84 FACTORS ASSOCIATED WITH HIGH LEVELS OF TELEPHONE CARE SATISFACTION AMONG INDIVIDUALS WITH INFLAMMATORY BOWEL DISEASE

Background

Individuals with inflammatory bowel disease (IBD) require regular medical follow-up with gastroenterology care providers. Individuals in rural areas face barriers in assessing specialized IBD care. Virtual care (VC) may act as a solution. The coronavirus disease 2019 pandemic increased the use of VC, particularly telephone care (TC) appointments in Saskatchewan, Canada. There is limited evidence around the levels and factors associated with satisfaction with TC among individuals with IBD.

Purpose

This study aims to measure satisfaction with TC in individuals with IBD who live in Saskatchewan, Canada, and evaluate the factors associated with TC satisfaction.

Method

A cross-sectional study was conducted among individuals with IBD through an online survey between December 2021 and April 2022 in Saskatchewan. The Telephone Care Satisfaction Questionnaire for individuals with IBD (TCSQ-patient) was a 16-item questionnaire used to measure TC satisfaction on a scale from 1 (very dissatisfied) to 7 (very satisfied). The online survey also included the Quality of Care Through the Patient’s Eyes-IBD (QUOTE-IBD) questionnaire, Short Inflammatory bowel disease questionnaire (SIBDQ), and demographic questions. Factors associated with TC satisfaction were explored using linear regression models. A backward model building strategy was used, and 95% confidence intervals (95%CI) were reported.

Result(s)

In total, 87 individuals with IBD participated in the study. Among the study participants, 54 (64.3%) had Crohn's disease, 53 (61.6%) were female, 60 (69.8%) lived in urban centres, and 37 (43.5%) were between 41-59 years old. The mean satisfaction with TC was 5.70 (SD=0.94). In addition, the means of the QUOTE-IBD and SIBDQ were, respectively, 8.96 (SD=1.70) and 48.14 (SD=13.02). In the bivariate analysis, area of residence (rural vs. urban) and health related quality of life quality (SIBDQ>50 vs SIBDQ<50) were associated with satisfaction with TC, respectively, 0.47 (95%CI 0.02-0.91) and 0.48 (95%CI 0.08-0.88). Adjusting by gender, age group, type of disease, and health care provider managing IBD, we identified that the satisfaction with TC was 0.48 (95%CI 0.02-0.94) higher among individuals with IBD living in rural Saskatchewan in comparison to their urban counterparts.

Conclusion(s)

Individuals living with IBD in Saskatchewan reported high levels of satisfaction with TC. Rural residence is associated with higher levels of TC satisfaction. These results could help in the promotion of TC utilization and improve access to specialized IBD care, especially among those living in rural areas.

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Saskatchewan Health Research Foundation (SHRF)

Disclosure of Interest

None Declared

A83 ADAPTATION AND VALIDATION OF QUESTIONNAIRES TO MEASURE SATISFACTION WITH TELEPHONE CARE AMONG IBD PATIENTS AND GASTROENTEROLOGY CARE PROVIDERS

Background

People living with inflammatory bowel disease (IBD) require regular medical follow-up, which could be challenging for individuals living in rural areas and those who have limited access to specialized care. Telephone care (TC) could improve health care by increasing access to specialized care. The Covid-19 pandemic resulted in increased use of virtual care, which was predominantly TC in Saskatchewan (SK) , Canada. There are no validated questionnaires to measure satisfaction with TC among IBD patients and gastrointestinal care providers (GCPs).

Purpose

This study aimed to adapt and validate a questionnaire to evaluate the satisfaction of IBD individuals and GCPs with TC in SK, Canada.

Method

The Telehealth Usability Questionnaire was adapted to the IBD TC context by a committee of experts, comprised of three IBD GCPs, two IBD-patient partners, and two health care researchers. Two questionnaires were generated -: the Telephone Care Satisfaction Questionnaire (TCSQ) for patients (IBD-TCSQ-patient) and GCPs (IBD-TCSQ-provider). The committee evaluated the content validity of the adapted questionnaires. A pilot assessed the readability and usability of the questionnaire items. Subsequently, individuals living with IBD in SK and GCPs completed an online survey with the TCSQ-patient and IBD-TCSQ-provider questionnaires in the winter of 2022. Data were analysed using descriptive and correlational techniques. Psychometric analyses were conducted to examine the reliability and validity of the TCSQ-patient, but not for the TCSQ-provider due to small sample size.

Result(s)

The IBD-TCSQ-patient and IBD-TCSQ-provider questionnaires were developed, each with 16 individual items and one question on global TC satisfaction. The pilot demonstrated good readability and usability of the questionnaires. Then, 87 IBD individuals completed the IBD-TCSQ-patient and six GCPs the IBD-TCSQ-provider. The standardized level of TC satisfaction for the 16-item IBD-TCSQ-patient was 5.70 (SD=0.94) on a scale from 1.00-7.00. All items of the IBD-TCSQ-patient were significantly correlated (p<0.001). A strong correlation was observed between the 16-item standardized TC satisfaction and its overall item r=0.85 (p<0.001). The IBD-TCSQ-patient had optimal internal reliability (α=0.96). Two factors were identified in the exploratory factor analysis. Factor 1 focused on TC convenience while factor 2 addressed TC usability. Regarding the IBD-TCSQ-provider questionnaire, the standardized level of TC satisfaction was 5.76 (SD=0.68) on a scale from 1.00 to 7.00.

Conclusion(s)

We generated questionnaires to measure satisfaction with TC among individuals living with IBD and GCPs. The study results confirmed good validity and reliability of the IBD-TCSQ-patient questionnaire. The IBD-TCSQ-provider questionnaire was adapted; subsequent studies could assess its validity and reliability among GCPs nationally. These questionnaires could help identify opportunities for improvement and utilization of TC among IBD patients and GCPs.

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Other, None

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Saskatchewan Health Research Foundation (SHRF)

Disclosure of Interest

None Declared

Contribution of UGT Enzymes to Human Drug Metabolism Stereoselectivity: A Case Study of Medetomidine, RO5263397, Propranolol, and Testosterone

The enantiomeric forms of chiral compounds have identical physical properties but may vary greatly in their metabolism by individual enzymes. Enantioselectivity in UDP-glucuronosyl transferase (UGT) metabolism has been reported for a number of compounds and with different UGT isoforms involved. However, the impact of such individual enzyme results on overall clearance stereoselectivity is often not clear. The enantiomers of medetomidine, RO5263397, and propranolol and the epimers testosterone and epitestosterone exhibit more than a 10-fold difference in glucuronidation rates by individual UGT enzymes. In this study, we examined the translation of human UGT stereoselectivity to hepatic drug clearance considering the combination of multiple UGTs to overall glucuronidation, the contribution of other metabolic enzymes such as cytochrome P450s (P450s), and the potential for differences in protein binding and blood/plasma partitioning. For medetomidine and RO5263397, the high individual enzyme (UGT2B10) enantioselectivity translated into ∼3- to >10-fold differences in predicted human hepatic in vivo clearance. For propranolol, the UGT enantioselectivity was irrelevant in the context of high P450 metabolism. For testosterone, a complex picture emerged due to differential epimeric selectivity of various contributing enzymes and potential for extrahepatic metabolism. Quite different patterns of P450- and UGT-mediated metabolism were observed across species, as well as differences in stereoselectivity, indicating that extrapolation from human enzyme and tissue data are essential when predicting human clearance enantioselectivity. SIGNIFICANCE STATEMENT: Individual enzyme stereoselectivity illustrates the importance of three-dimensional drug-metabolizing enzyme-substrate interactions and is essential when considering the clearance of racemic drugs. However, translation from in vitro to in vivo can be challenging as contributions from multiple enzymes and enzyme classes must be combined with protein binding and blood/plasma partitioning data to estimate the net intrinsic clearance for each enantiomer. Preclinical species may be misleading as enzyme involvement and metabolism stereoselectivity can differ substantially.

POLYMYALGIA RHEUMATICA AFTER MRNA COVID-19 VACCINATION

Introduction

Polymyalgia rheumatica (PMR) is an inflammatory disorder characterized by muscle pain and stiffness. We present a 67-year-old man who developed PMR after immunization with the mRNA COVID-19 vaccine.

Case Description

A 67-year-old male with a history of viral pericarditis, non-ischemic cardiomyopathy, Raynaud's phenomenon, and prostate cancer presented for evaluation of acute-onset proximal muscle pain and weakness, extreme fatigue, malaise, and weight loss. Symptoms developed 10 days after the first dose of the mRNA COVID-19 vaccine. No associated fever or skin rashes. No history of natural COVID-19 infection. A workup for malignancy was negative. CRP and ESR were elevated. ANA was positive (1:80, speckled pattern). ENAs were negative. CK and aldolase were normal. He had low IgG at 328 mg/dL with normal IgA and IgM. However, repeat IgG levels a week later were normal (1130 mg/dL), raising the possibility of a laboratory error. Lymphocyte subsets in peripheral blood were normal. IgG titers to the SARS-COV2 spike and nucleocapsid proteins were consistent with COVID-19 immunity from prior immunization. He was treated with low-dose oral prednisone with resolution of his symptoms and has been slowly tapering prednisone as tolerated.

Discussion

This case report raises the possibility that PMR may be triggered by an immune response to the mRNA COVID-19 vaccine in susceptible individuals. However, further studies involving a larger population are required to assess whether this association is causative or rather coincidental.

Preclinical InVivo Data Integrated in a Modeling Network Informs a Refined Clinical Strategy for a CD3 T-Cell Bispecific in Combination with Anti-PD-L1

TYRP1-TCB is a CD3 T-cell bispecific (CD3-TCB) antibody for the treatment of advanced melanoma. A tumor growth inhibition (TGI) model was developed using mouse xenograft data with TYRP1-TCB monotherapy or TYRP1-TCB plus anti-PD-L1 combination. The model was translated to humans to inform a refined clinical strategy. From xenograft mouse data, we estimated an EC₅₀ of 0.345 mg/L for TYRP1-TCB, close to what was observed in vitro using the same tumor cell line. The model showed that, though increasing the dose of TYRP1-TCB in monotherapy delays the time to tumor regrowth and promotes higher tumor cell killing, it also induces a faster rate of tumor regrowth. Combination with anti-PD-L1 extended the time to tumor regrowth by 25% while also decreasing the tumor regrowth rate by 69% compared to the same dose of TYRP1-TCB alone. The model translation to humans predicts that if patients' tumors were scanned every 6 weeks, only 46% of the monotherapy responders would be detected even at a TYRP1-TCB dose resulting in exposures above the EC₉₀. However, combination of TYRP1-TCB and anti-PD-L1 in the clinic is predicted to more than double the overall response rate (ORR), duration of response (DoR) and progression-free survival (PFS) compared to TYRP1-TCB monotherapy. As a result, it is highly recommended to consider development of CD3-TCBs as part of a combination therapy from the outset, without the need to escalate the CD3-TCB up to the Maximum Tolerated Dose (MTD) in monotherapy and without gating the combination only on RECIST-derived efficacy metrics.

Application of a gut-liver-on-a-chip device and mechanistic modelling to the quantitative in vitro pharmacokinetic study of mycophenolate mofetil

Microphysiological systems (MPS) consisting of multiple linked organ-on-a-chip (OoC) components are highly promising tools with potential to provide more relevant in vitro to in vivo translation of drug disposition, efficacy and toxicity. A gut-liver OoC system was employed with Caco2 cells in co-culture with HT29 cells in the intestinal compartment and single donor primary hepatocytes in the hepatic compartment for the investigation of intestinal permeability, metabolism (intestinal and hepatic) and potential interplay of those processes. The prodrug mycophenolate mofetil was tested for quantitative evaluation of the gut-liver OoC due to the contribution of both gut and liver in its metabolism. Conversion of mycophenolate mofetil to active drug mycophenolic acid and further metabolism to a glucuronide metabolite was assessed over time in the gut apical, gut basolateral and liver compartments. Mechanistic modelling of experimental data was performed to estimate clearance and permeability parameters for the prodrug, active drug and glucuronide metabolite. Integration of gut-liver OoC data with in silico modelling allowed investigation of the complex combination of intestinal and hepatic processes, which is not possible with standard single tissue in vitro systems. A comprehensive evaluation of the mechanistic model, including structural model and parameter identifiability and global sensitivity analysis, enabled a robust experimental design and estimation of in vitro pharmacokinetic parameters. We propose that similar methodologies may be applied to other multi-organ microphysiological systems used for drug metabolism studies or wherever quantitative knowledge of changing drug concentration with time enables better understanding of biological effect.

Exploration and application of a liver-on-a-chip device in combination with modelling and simulation for quantitative drug metabolism studies

Microphysiological systems (MPS) are complex and more physiologically realistic cellular in vitro tools that aim to provide more relevant human in vitro data for quantitative prediction of clinical pharmacokinetics while also reducing the need for animal testing. The PhysioMimix liver-on-a-chip integrates medium flow with hepatocyte culture and has the potential to be adopted for in vitro studies investigating the hepatic disposition characteristics of drug candidates. The current study focusses on liver-on-a-chip system exploration for multiple drug metabolism applications. Characterization of cytochrome P450 (CYP), UDP-glucuronosyl transferase (UGT) and aldehyde oxidase (AO) activities was performed using 15 drugs and in vitro to in vivo extrapolation (IVIVE) was assessed for 12 of them. Next, the utility of the liver-on-a-chip for estimation of the fraction metabolized (f_m) via specific biotransformation pathways of quinidine and diclofenac was established. Finally, the metabolite identification opportunities were also explored using efavirenz as an example drug with complex primary and secondary metabolism involving a combination of CYP, UGT and sulfotransferase enzymes. A key aspect of these investigations was the application of mathematical modelling for improved parameter calculation. Such approaches will be required for quantitative assessment of metabolism and/or transporter processes in systems where medium flow and system compartments result in non-homogeneous drug concentrations. In particular, modelling was used to explore the effect of evaporation from the medium and it was found that the intrinsic clearance (CL_int) might be underestimated by up to 40% for low clearance compounds if evaporation is not accounted for. Modelling of liver-on-a-chip in vitro data also enhanced the approach to f_m estimation allowing objective assessment of metabolism models of different complexity. The resultant diclofenac f_m,UGT of 0.64 was highly comparable with values reported previously in the literature. The current study demonstrates the integration of mathematical modelling with experimental liver-on-a-chip studies and illustrates how this approach supports generation of high quality of data from complex in vitro cellular systems.

HCV Infection Alters Salivary Gland Histology and Saliva Composition

Hepatitis C virus (HCV) infection is the most common blood-borne chronic infection in the United States. Chronic lymphocytic sialadenitis and sicca syndrome have been reported in chronic HCV infection. Up to 55% of these patients may have xerostomia; the mechanisms of the xerostomia and salivary gland (SG) hypofunction remain controversial. The objectives of this project are to establish if xerostomia associates with SG and HCV infection and to characterize the structural changes in SG and saliva composition. Eighteen HCV-infected patients with xerostomia were evaluated for SG dysfunction; 6 of these patients (patients 1–6) were further evaluated for SG histopathological changes and changes in saliva composition. The techniques used include clinical and laboratory assessment, SG ultrasonography, histological evaluation, sialochemical and proteomics analysis, and RNA in situ hybridization. All the HCV patients had low saliva flow, chronic sialadenitis, and SG fibrosis and lacked Sjögren syndrome (SS) characteristic autoantibodies. Further evaluation of a subgroup of 6 HCV patients (patients 1–6) demonstrated diffuse lymphocytic infiltrates that are predominantly CD8+ T cells with a significant increase in the number of inflammatory cells. Alcian Blue/periodic acid–Schiff staining showed significant changes in the ratio and intensity of the acinar secretory units of the HCV patients’ minor SG. The submandibular glands showed significant ultrasonographic abnormalities in the parenchyma relative to the parotid glands. Significant changes were also observed in the concentration of sodium and mucin 5b. Although no significant correlation was observed between the lymphocytic infiltrates and the years of HCV chronic infection, a positive correlation was observed between HCV RNA–positive epithelial cells and the years of HCV infection. Consistent with the low saliva flow and xerostomia, patients showed changes in several markers of SG acinar and ductal function. Changes in the composition of the saliva suggest that HCV infection can cause xerostomia by mechanisms distinct from SS.