Disruption of vitamin A homeostasis by the biocide tetrakis(hydroxymethyl) phosphonium sulphate in pregnant rabbits.

The biocide tetrakis(hydroxymethyl)phosphonium sulphate (THPS) and other members of the tetrakis(hydroxymethyl) phosphonium salts (THPX) family are associated with liver toxicity in several mammalian species and teratogenicity in rabbits. Malformations include skeletal changes and abnormalities in eye development and are very similar to those seen with vitamin A deficiency or excess. For this reason, it was hypothesized that teratogenicity of THPS(X) might be attributed to disturbances in retinol availability and/or metabolism as a result of maternal toxicity, for example, either due to insufficient dietary intake by the mothers or due to liver toxicity. Therefore, in the present study, liver toxicity and vitamin A homeostasis were studied in pregnant rabbits that were exposed to 13.8 or 46.0 mg/kg THPS during organogenesis and in precision-cut liver slices of rats and rabbits exposed to 0-70 µM THPS. Results show that in vivo exposure to THPS leads to a marked reduction of food intake, increased plasma concentrations of γ-glutamytransferase, degenerative changes in the liver and to changes in retinoid content in liver and plasma in the rabbits during organogenesis. In addition, THPS, both in vivo and ex vivo, caused a change in expression of proteins related to vitamin A metabolism and transport. Together, these observations could explain the birth defects observed in earlier teratogenicity studies.

Maintenance of drug metabolism and transport functions in human precision-cut liver slices during prolonged incubation for 5 days.

Human precision-cut liver slices (hPCLS) are a valuable ex vivo model that can be used in acute toxicity studies. However, a rapid decline in metabolic enzyme activity limits their use in studies that require a prolonged xenobiotic exposure. The aim of the study was to extend the viability and function of hPCLS to 5 days of incubation. hPCLS were incubated in two media developed for long-term culture of hepatocytes, RegeneMed®, and Cellartis®, and in the standard medium WME. Maintenance of phase I and II metabolism was studied both on gene expression as well as functional level using a mixture of CYP isoform-specific substrates. Albumin synthesis, morphological integrity, and glycogen storage was assessed, and gene expression was studied by transcriptomic analysis using microarrays with a focus on genes involved in drug metabolism, transport and toxicity. The data show that hPCLS retain their viability and functionality during 5 days of incubation in Cellartis® medium. Albumin synthesis as well as the activity and gene expression of phase I and II metabolic enzymes did not decline during 120-h incubation in Cellartis® medium, with CYP2C9 activity as the only exception. Glycogen storage and morphological integrity were maintained. Moreover, gene expression changes in hPCLS during incubation were limited and mostly related to cytoskeleton remodeling, fibrosis, and moderate oxidative stress. The expression of genes involved in drug transport, which is an important factor in determining the intracellular xenobiotic exposure, was also unchanged. Therefore, we conclude that hPCLS cultured in Cellartis® medium are a valuable human ex vivo model for toxicological and pharmacological studies that require prolonged xenobiotic exposure.

Rat precision-cut liver slices predict drug-induced cholestatic injury.

Drug-induced cholestasis (DIC) is one of the leading manifestations of drug-induced liver injury (DILI). As the underlying mechanisms for DIC are not fully known and specific and predictive biomarkers and pre-clinical models are lacking, the occurrence of DIC is often only reported when the drug has been approved for registration. Therefore, appropriate models that predict the cholestatic potential of drug candidates and/or provide insight into the mechanism of DIC are highly needed. We investigated the application of rat precision-cut liver slices (PCLS) to predict DIC, using several biomarkers of cholestasis: hepatocyte viability, intracellular accumulation of total as well as individual bile acids and changes in the expression of genes known to play a role in cholestasis. Rat PCLS exposed to the cholestatic drugs chlorpromazine, cyclosporine A and glibenclamide for 48 h in the presence of a 60 µM physiological bile acid (BA) mix reflected various changes associated with cholestasis, such as decrease in hepatocyte viability, accumulation and changes in the composition of BA and changes in the gene expression of Fxr, Bsep and Ntcp. The toxicity of the drugs was correlated with the accumulation of BA, and especially DCA and CDCA and their conjugates, but to a different extent for different drugs, indicating that BA toxicity is not the only cause for the toxicity of cholestatic drugs. Moreover, our study supports the use of several biomarkers to test drugs for DIC. In conclusion, our results indicate that PCLS may represent a physiological and valuable model to identify cholestatic drugs and provide insight into the mechanisms underlying DIC.

Human precision-cut liver slices as an ex vivo model to study idiosyncratic drug-induced liver injury.

Idiosyncratic drug-induced liver injury (IDILI) is a major problem during drug development and has caused drug withdrawal and black-box warnings. Because of the low concordance of the hepatotoxicity of drugs in animals and humans, robust screening methods using human tissue are needed to predict IDILI in humans. According to the inflammatory stress hypothesis, the effects of inflammation interact with the effects of a drug or its reactive metabolite, precipitating toxic reactions in the liver. As a follow-up to our recently published mouse precision-cut liver slices model, an ex vivo model involving human precision-cut liver slices (hPCLS), co-incubated for 24 h with IDILI-related drugs and lipopolysaccharide (LPS), was developed to study IDILI mechanisms related to inflammatory stress in humans and to detect potential biomarkers. LPS exacerbated the effects of ketoconazole and clozapine toxicity but not those of their non-IDILI-related comparators, voriconazole and olanzapine. However, the IDILI-related drugs diclofenac, carbamazepine, and troglitazone did not show synergistic toxicity with LPS after incubation for 24 h. Co-incubation of ketoconazole and clozapine with LPS decreased the levels of glutathione in hPCLS, but this was not seen for the other drugs. All drugs affected LPS-induced cytokine release, but interestingly, only ketoconazole and clozapine increased the level of LPS-induced TNF release. Decreased levels of glutathione and cysteine conjugates of clozapine were detected in IDILI-responding livers following cotreatment with LPS. In conclusion, we identified ketoconazole and clozapine as drugs that exhibited synergistic toxicity with LPS, while glutathione and TNF were found to be potential biomarkers for IDILI-inducing drugs mediated by inflammatory stress. hPCLS appear to be suitable for further unraveling the mechanisms of inflammatory stress-associated IDILI.

Safety-Related Drug Label Changes Following Large Post-Marketing Cardiometabolic Trials: A Review of European Public Assessment Reports.

Selective safety data collection may simplify late-stage clinical trials and improve their feasibility. However, the impact on increasing overall drug safety knowledge is unknown. The aim of this study is to evaluate how much safety information is added to the drug label based on large trials after initial authorization. Changes made to the "undesirable effects" section of the drug label of cardiometabolic agents approved between 2000 and 2020 based on the results of large (> 1,000 patient) clinical trials submitted to the European Medicines Agency (EMA) were evaluated. The study focused on glucose lowering, antithrombotic, and lipid-modifying agents. The primary outcome was the number of changes in adverse drug reactions in the drug label. The EMA reviewed 55 large trials concerning 25 cardiometabolic agents after the initial marketing authorization, which included 402,444 patients. Ultimately, 38 trials (69%) resulted in a safety section update, whereas 17 trials (31%) did not. Changes in listed adverse drug reactions were made following 19 trials (35%) for 12 agents: 77 adverse drug reactions were added, 11 were deleted, and the frequencies of 43 were changed. Most changes in adverse drug reactions arose from trials with antithrombotic agents (88%) and trials performed in a new population (92%). Large trials for cardiometabolic agents reported after authorization add limited new safety information on adverse drug reactions, especially when performed in the population studied prior to approval. This suggests that selective safety data collection does not reduce learnings from late stage cardiometabolic trials in populations comprehensively studied before.

Contribution of Real-World Evidence in European Medicines Agency's Regulatory Decision Making.

Real-world data/evidence (RWD/RWE) may provide insightful information on medicines' clinical effects to guide regulatory decisions. While its contribution has been recognized for safety monitoring and disease epidemiology across medicines' life cycles, using RWD/RWE to demonstrate efficacy requires further evaluation. This study aimed to (i) characterize RWD/RWE presented by applicants to support claims on medicines' efficacy within initial marketing authorization applications (MAAs) and extension of indication applications (EoIs), and (ii) analyze the contribution of RWD/RWE to regulatory decisions on medicines' benefit-risk profile. RWD/RWE was included to support efficacy in 32 MAAs and 14 EoIs submitted 2018-2019. Of these, RWD/RWE was part of the preauthorization package of 16 MAAs and 10 EoIs, and was (i) considered supporting the regulatory decision in 10 applications (five MAAs, five EoIs), (ii) considered not supporting the regulatory decision in 11 (seven MAAs, four EoIs), and (iii) not addressed at all in the evaluation of 5 applications (four MAAs, one EoI). Common limitations of submitted RWD/RWE included missing data, lack of representativeness of populations, small sample size, absence of an adequate or prespecified analysis plan, and risk of several types of bias. The suitability of RWD/RWE in a given application still requires a case-by-case analysis considering its purpose of use, implying reflection on the data source, together with its assets and limitations, study objectives and designs, and the overall data package issued. Early interactions and continuous dialogues with regulators and relevant stakeholders is key to optimize fit-for-purpose RWE generation, enabling its broader use in medicines development.

Precision medicine in regulatory decision making: Biomarkers used for patient selection in European Public Assessment Reports from 2018 to 2020.

Biomarkers can guide precision medicine in clinical trials and practice. They can increase clinical trials' efficiency through selection of study populations more likely to benefit from treatment, thus increasing statistical power and reducing sample size requirements or study duration. We performed a narrative synthesis to explore biomarker utilization for patient selection to guide precision medicine trials in marketing authorization dossiers of centrally approved medicines in Europe between 2018 and 2020 and analyzed in-depth those that eventually included biomarkers in the medicines' indications. From 119 eligible products, 26 included a biomarker in the indication, of which most were oncology products (n = 15). Included biomarkers were often known from literature or from previously approved products in the European Union or the United States. Additionally, 52 dossiers mentioned one or more biomarkers for patient selection in their clinical efficacy and safety information. Although these were not always included in the medicines' indication, they were often implicitly embedded in condition definitions adopted from clinical guidelines or practice. In 15 out of the 26 medicines with a biomarker-guided indication, only biomarker-positive populations were included in the main clinical studies supporting the marketing authorization. These studies were mostly randomized controlled trials or single-arm trials; only two products were studied for multiple indications in an innovative basket trial. Definitions of biomarkers could be subject of debate and needed adaptation after post hoc analyses requested by the assessment committee in four cases, stressing the importance of thorough justification of these definitions to include the right population for an optimal benefit-risk balance, enabling precise medicine.

Translating Academic Drug Discovery Into Clinical Development: A Survey of the Awareness of Regulatory Support and Requirements Among Stakeholders in Europe.

Important discoveries by academic drug developers hold the promise of bringing innovative treatments that address unmet medical needs to the market. However, the drug development process has proved to be challenging and demanding for academic researchers, and regulatory challenges are an important barrier to implementing academic findings in clinical practice. European regulators offer varying degrees of support services to help drug developers meet regulatory standards and requirements. "Strengthening Training of Academia in Regulatory Sciences and Supporting Regulatory Scientific Advice" (STARS) is a European Commission-funded consortium aiming to strengthen the training of academics in regulatory science and requirements. Here, we report the results of four surveys that investigated the awareness and utilization of support tools offered by European regulators and identified the regulatory challenges and support needs of researchers. The surveys targeted four main European stakeholders in academic medicines research: academic research groups (706 respondents), academic research centers (99), funding organizations (49), and regulators (22). The results show that while European regulators provide various regulatory support tools, less than half of the responding academic researchers were aware of these tools and many experienced challenges in reaching a sufficient level of regulatory knowledge. There was a general lack of understanding of the regulatory environment that was aggravated by poor communication between stakeholders. The results of this study form a foundation for an improved European medicines regulatory network, in which regulatory challenges faced by academia are tackled.

Mouse precision-cut liver slices as an ex vivo model to study idiosyncratic drug-induced liver injury.

Idiosyncratic drug-induced liver injury (IDILI) has been the top reason for withdrawing drugs from the market or for black box warnings. IDILI may arise from the interaction of a drug's reactive metabolite with a mild inflammation that renders the liver more sensitive to injury resulting in increased toxicity (inflammatory stress hypothesis). Aiming to develop a robust ex vivo screening method to study inflammatory stress-related IDILI mechanisms and to find biomarkers that can detect or predict IDILI, mouse precision-cut liver slices (mPCLS) were coincubated for 24 h with IDILI-related drugs and lipopolysaccharide. Lipopolysaccharide exacerbated ketoconazole (15 µM) and clozapine (45 µM) toxicity but not their non-IDILI-related comparators, voriconazole (1500 µM) and olanzapine (45 µM). However, the other IDILI-related drugs tested [diclofenac (200 µM), carbamazepine (400 µM), and troglitazone (30 µM)] did not cause synergistic toxicity with lipopolysaccharide after 24 h of incubation. Lipopolysaccharide further decreased the reduced glutathione levels caused by ketoconazole or clozapine in mPCLS after 24 h of incubation, which was not the case for the other drugs. Lipopolysaccharide significantly increased nitric oxide (NO), cytokine, and chemokine release into the mPCLS media, while the treatment with the drugs alone did not cause any substantial change. All seven drugs drastically reduced lipopolysaccharide-induced NO production. Interestingly, only ketoconazole and clozapine increased the lipopolysaccharide-induced granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) release. Pilot experiments showed that diclofenac and troglitazone, but not carbamazepine, demonstrated synergistic toxicity with lipopolysaccharide after a longer incubation of 48 h in mPCLS. In conclusion, we have developed an ex vivo model to detect inflammatory stress-related liver toxicity and identified ketoconazole, clozapine, troglitazone, and diclofenac as drugs that showed synergistic toxicity with lipopolysaccharide. Reduced glutathione, G-CSF, and GM-CSF were identified to be potential biomarkers for IDILI-inducing drugs mediated by inflammatory stress, and mPCLS appear to be a promising screening tool to further unravel the mechanism of IDILI.

Biomarker Qualification at the European Medicines Agency: A Review of Biomarker Qualification Procedures From 2008 to 2020.

Regulatory qualification of biomarkers facilitates their harmonized use across drug developers, enabling more personalized medicine. This study reviews various aspects of the European Medicines Agency's (EMA's) biomarker qualification procedure, including frequency and outcome, common challenges, and biomarker characteristics. Our findings provide insights into the EMA's biomarker qualification process and will thereby support future applications. All biomarker-related "Qualification of Novel Methodologies for Medicine Development" procedures that started from 2008 to 2020 were included. Procedural data were extracted from relevant documents and analyzed descriptively. In total, 86 biomarker qualification procedures were identified, of which 13 resulted in qualified biomarkers. Whereas initially many biomarker qualification procedures were linked to a single company and specific drug development program, a shift was observed to qualification efforts by consortia. Most biomarkers were proposed (n = 45) and qualified (n = 9) for use in patient selection, stratification, and/or enrichment, followed by efficacy biomarkers (37 proposed, 4 qualified). Overall, many issues were raised during qualification procedures, mostly related to biomarker properties and assay validation (in 79% and 77% of all procedures, respectively). Issues related to the proposed context of use and rationale were least common yet were still raised in 54% of all procedures. While few qualified biomarkers are currently available, procedures focus increasingly on biomarkers for general use instead of those linked to specific drug compounds. The issues raised during qualification procedures illustrate the thorough discussions taking place between applicants and regulators-highlighting aspects that need careful consideration and underlining the importance of an appropriate validation strategy.

Attention for sex in COVID-19 trials: a review of regulatory dossiers.

An under-representation of women and a lack of sex-specific analyses in COVID-19 trials has been suggested. However, the higher number of men than women who are severely affected by COVID-19 and the restricted information in scientific publications may have biased these suggestions. Therefore, we evaluated sex proportionality and sex-specific efficacy and safety data in trials of COVID-19 treatments and vaccines using both publicly available regulatory documents and confidential documents used by regulators in their review of medicinal products. Included were two treatments (ie, remdesivir and dexamethasone) and four vaccines (ie, BNT162b2 mRNA (BioNTech/Pfizer), mRNA-1273 (Moderna), ChAdOx1-S (AstraZeneca) and Ad26.COV2-S (Janssen)) that received marketing authorisation by the European Commission at the time of the study conduct. An under-representation of women was shown in three of the nine data sets for one treatment (ie, remdesivir), but the proportion of women included was representative in each of the data sets for the other five products. This indicates that there is no structural under-representation of women in the COVID-19 trials. Currently, sex-specific efficacy data are available for five of the six assessed products and sex-specific safety data are available for half of the products only. It is important that this information will also be made available for the other products. There are only small differences in efficacy and safety between men and women which are likely to be of limited clinical relevance. Sex-specific efficacy information can generally be found in the publicly available regulatory documents other than the Summary of Product Characteristics, for which more awareness might be required.

Strengthening regulatory science in academia: STARS, an EU initiative to bridge the translational gap.

Truly disruptive medicine innovation and new treatment paradigms tend to start in non-commercial research institutions. However, the lack of mutual understanding between medicine developers and regulators when it comes to medicine development significantly delays or even prevents the access of patients to these innovations. Here, we outline what regulatory-related barriers hamper the translational development of novel products or new treatment paradigms initiated in academia, and propose key steps towards improved regulatory dialogue among academia, funding bodies and regulatory authorities. Moreover, we briefly describe how the STARS (Strengthening Training of Academia in Regulatory Science) project aims to reach out to medicine innovators in academia to bridge the regulatory knowledge gap and enhance this dialogue to facilitate the implementation of academic research findings in clinical practice.

Challenges on the road to a multicellular bioartificial liver.

Over recent years, the progress in the development of a bioartificial liver (BAL) as an extracorporeal device or as a tissue engineered transplantable organ has been immense. However, many important BAL characteristics that are necessary to meet clinical demands have not been sufficiently addressed. This review describes the existing challenges in the development of a BAL for clinical applications, highlighting multicellularity and sinusoidal microarchitecture as crucial BAL characteristics to fulfil various liver functions. Currently available sources of nonparenchymal liver cells, such as endothelial cells, cholangiocytes and macrophages, used in BAL development are defined. Also, we discuss the recent studies on the reconstruction of the complex liver sinusoid microarchitecture using various liver cell types. Moreover, we highlight some other aspects of a BAL, such as liver zonation and formation of a vascular as well as biliary network for an adequate delivery, biotransformation and removal of substrates and waste products. Finally, the benefits of a multicellular BAL for the pharmaceutical industry are briefly described. Copyright © 2016 John Wiley & Sons, Ltd.

Differentiation of human-induced pluripotent stem cell under flow conditions to mature hepatocytes for liver tissue engineering.

Hepatic differentiation of human-induced pluripotent stem cells (hiPSCs) under flow conditions in a 3D scaffold is expected to be a major step forward for construction of bioartificial livers. The aims of this study were to induce hepatic differentiation of hiPSCs under perfusion conditions and to perform functional comparisons with fresh human precision-cut liver slices (hPCLS), an excellent benchmark for the human liver in vivo. The majority of the mRNA expression of CYP isoenzymes and transporters and the tested CYP activities, Phase II metabolism, and albumin, urea, and bile acid synthesis in the hiPSC-derived cells reached values that overlap those of hPCLS, which indicates a higher degree of hepatic differentiation than observed until now. Differentiation under flow compared with static conditions had a strong inducing effect on Phase II metabolism and suppressed AFP expression but resulted in slightly lower activity of some of the Phase I metabolism enzymes. Gene expression data indicate that hiPSCs differentiated into both hepatic and biliary directions. In conclusion, the hiPSC differentiated under flow conditions towards hepatocytes express a wide spectrum of liver functions at levels comparable with hPCLS indicating excellent future perspectives for the development of a bioartificial liver system for toxicity testing or as liver support device for patients.

Viability, function and morphological integrity of precision-cut liver slices during prolonged incubation: Effects of culture medium.

Precision-cut liver slices (PCLS) are an ex vivo model for metabolism and toxicity studies. However, data on the maintenance of the morphological integrity of the various cell types in the slices during prolonged incubation are lacking. Therefore, our aims were to characterize morphological and functional changes in rat PCLS during five days of incubation in a rich medium, RegeneMed®, and a standard medium, Williams' Medium E. Although cells of all types in the slices remain viable, profound changes in morphology were observed, which were more prominent in RegeneMed®. Slices underwent notable fibrosis, bile duct proliferation and fat deposition. Slice thickness increased, resulting in necrotic areas, while slice diameter decreased, possibly indicating cell migration. An increased proliferation of parenchymal and non-parenchymal cells (NPCs) was observed. Glycogen, albumin and Cyp3a1 were maintained albeit to a different level in two media. In conclusion, both hepatocytes and NPCs remain viable and functional, enabling five-day toxicity studies. Tissue remodeling and formation of a new capsule-like cell lining around the slices are evident after 3­4 days. The differences in effects between media emphasize the importance of media selection and of the recognition of morphological changes in PCLS, when interpreting results from toxicological or pharmacological studies.