Evaluation of in vivo MRI for detecting midodrine-induced arteritis in rats

There are no specific and sensitive biomarkers for arteritis, and the occurrence of arteritis in nonclinical toxicological studies of a candidate drug makes development of the drug very difficult. However, we showed in a previous study that the high signal intensity region around the artery on magnetic resonance imaging (MRI) could be a candidate biomarker for detection of arteritis. The present study was conducted to clarify the details of midodrine hydrochloride (MH)-induced arteritis lesions and whether arteritis induced by a mechanism other than the vasodilatory effect, which was evaluated in a previous study, could be detected by MRI. MH is a selective peripherally acting alpha-1 adrenergic receptor agonist, known to induce arteritis due to its vasoconstrictor action, but there is not enough information about MH-induced arteritis. Based on the data obtained under multiple dosing conditions, MH was administered subcutaneously to each rat once daily for 2 days at a dose level of 40 mg/kg/day for MRI assessment. The mesenteric arteries were examined using in vivo MRI at 1 day or 7 days after administration of the final dose and examined histopathologically. On the day after the final dose, high signal intensity region around the artery was observed in animals with minimal perivascular lesions confirmed by histopathology and not observed in an animal without histological changes. On the 7th day after the final dose, no abnormality was observed in histopathological examinations and no high signal intensity regions were observed by MRI in any animal. In conclusion, although further investigation is needed to confirm that high signal intensity is a reliable biomarker for humans, it is suggested that high signal intensity around the artery could be a versatile candidate biomarker with high specificity and sensitivity.

Scientific and Regulatory Policy Committee Points to Consider: Integration of Clinical Pathology Data With Anatomic Pathology Data in Nonclinical Toxicology Studies

Integrating clinical pathology data with anatomic pathology data is a common practice when reporting findings in the context of nonclinical toxicity studies and aids in understanding and communicating the nonclinical safety profile of test articles in development. Appropriate pathology data integration requires knowledge of analyte and tissue biology, species differences, methods of specimen acquisition and analysis, study procedures, and an understanding of the potential causes and effects of a variety of pathophysiologic processes. Neglecting these factors can lead to inappropriate data integration or a missed opportunity to enhance understanding and communication of observed changes. In such cases, nonclinical safety information relevant to human safety risk assessment may be misrepresented or misunderstood. This "Points to Consider" manuscript presents general concepts regarding pathology data integration in nonclinical studies, considerations for avoiding potential oversights and errors in data integration, and focused discussion on topics relevant to data integration for several key organ systems, including liver, kidney, and cardiovascular systems.

Scientific and Regulatory Policy Committee Points to Consider: Integration of Clinical Pathology Data With Anatomic Pathology Data in Nonclinical Toxicology Studies

This article is temporarily under embargo.

Human Vascular Wall Microfluidic Model for Preclinical Evaluation of Drug-Induced Vascular Injury

Drug-induced vascular injury (DIVI) in preclinical animal models often leads to candidate compound termination during drug development. DIVI has not been documented in human clinical trials with drugs that cause DIVI in preclinical animals. A robust human preclinical assay for DIVI is needed as an early vascular injury screen. A human vascular wall microfluidic tissue chip was developed with a human umbilical vein endothelial cell (HUVEC)-umbilical artery smooth muscle cell (vascular smooth muscle cell, VSMC) bilayer matured under physiological shear stress. Optimized temporal flow profiles produced HUVEC-VSMC bilayers with quiescent endothelial cell (EC) monolayers, EC tight junctions, and contractile VSMC morphology. Dose-response testing (3-30 μM concentration) was conducted with minoxidil and tadalafil vasodilators. Both drugs have demonstrated preclinical DIVI but lack clinical evidence. The permeability of severely damaged engineered bilayers (30 μM tadalafil) was 4.1 times that of the untreated controls. Immunohistochemical protein assays revealed contrasting perspectives on tadalafil and minoxidil-induced damage. Tadalafil impacted the endothelial monolayer with minor injury to the contractile VSMCs, whereas minoxidil demonstrated minor EC barrier injury but damaged VSMCs and activated ECs in a dose-response manner. This proof-of-concept human vascular wall bilayer model of DIVI is a critical step toward developing a preclinical human screening assay for drug development. Impact statement More than 90% of drug candidates fail during clinical trials due to human efficacy and toxicity concerns. Preclinical studies rely heavily on animal models, although animal toxicity and drug metabolism responses often differ from humans. During the drug development process, perfused in vitro human tissue chips could model the clinical drug response and potential toxicity of candidate compounds. Our long-term objective is to develop a human vascular wall tissue chip to screen for drug-induced vascular injury. Its application could ultimately reduce drug development delays and costs, and improve patient safety.

Human Induced Pluripotent Stem Cells as a Screening Platform for Drug-Induced Vascular Toxicity

Evaluation of potential vascular injury is an essential part of the safety study during pharmaceutical development. Vascular liability issues are important causes of drug termination during preclinical investigations. Currently, preclinical assessment of vascular toxicity primarily relies on the use of animal models. However, accumulating evidence indicates a significant discrepancy between animal toxicity and human toxicity, casting doubt on the clinical relevance of animal models for such safety studies. While the causes of this discrepancy are expected to be multifactorial, species differences are likely a key factor. Consequently, a human-based model is a desirable solution to this problem, which has been made possible by the advent of human induced pluripotent stem cells (iPSCs). In particular, recent advances in the field now allow the efficient generation of a variety of vascular cells (e.g., endothelial cells, smooth muscle cells, and pericytes) from iPSCs. Using these cells, different vascular models have been established, ranging from simple 2D cultures to highly sophisticated vascular organoids and microfluidic devices. Toxicity testing using these models can recapitulate key aspects of vascular pathology on molecular (e.g., secretion of proinflammatory cytokines), cellular (e.g., cell apoptosis), and in some cases, tissue (e.g., endothelium barrier dysfunction) levels. These encouraging data provide the rationale for continuing efforts in the exploration, optimization, and validation of the iPSC technology in vascular toxicology.

Cardiovascular microphysiological systems (CVMPS) for safety studies - a pharma perspective

The integrative responses of the cardiovascular (CV) system are essential for maintaining blood flow to provide oxygenation, nutrients, and waste removal for the entire body. Progress has been made in independently developing simple in vitro models of two primary components of the CV system, namely the heart (using induced pluripotent stem-cell derived cardiomyocytes) and the vasculature (using endothelial cells and smooth muscle cells). These two in vitro biomimics are often described as immature and simplistic, and typically lack the structural complexity of native tissues. Despite these limitations, they have proven useful for specific "fit for purpose" applications, including early safety screening. More complex in vitro models offer the tantalizing prospect of greater refinement in risk assessments. To this end, efforts to physically link cardiac and vascular components to mimic a true CV microphysiological system (CVMPS) are ongoing, with the goal of providing a more holistic and integrated CV response model. The challenges of building and implementing CVMPS in future pharmacological safety studies are many, and include a) the need for more complex (and hence mature) cell types and tissues, b) the need for more realistic vasculature (within and across co-modeled tissues), and c) the need to meaningfully couple these two components to allow for integrated CV responses. Initial success will likely come with simple, bioengineered tissue models coupled with fluidics intended to mirror a vascular component. While the development of more complex integrated CVMPS models that are capable of differentiating safe compounds and providing mechanistic evaluations of CV liabilities may be feasible, adoption by pharma will ultimately hinge on model efficiency, experimental reproducibility, and added value above current strategies.

Evaluating Associations Between Nonclinical Cardiovascular Functional Endpoints and Repeat-dose Cardiovascular Toxicity in the Beagle Dog: A Cross-company Initiative

Integrating nonclinical in vitro, in silico, and in vivo datasets holistically can improve hazard characterization and risk assessment. In pharmaceutical development, cardiovascular liabilities are a leading cause of compound attrition. Prior to clinical studies, functional cardiovascular data are generated in single-dose safety pharmacology telemetry studies, with structural pathology data obtained from repeat-dose toxicology studies with limited concurrent functional endpoints, eg, electrocardiogram via jacketed telemetry. Relationships between datasets remain largely undetermined. To address this gap, a cross-pharma collaboration collated functional and structural data from 135 compounds. Retrospective functional data were collected from good laboratory practice conscious dog safety pharmacology studies: effects defined as hemodynamic blood pressure or heart rate changes. Morphologic pathology findings (mainly degeneration, vacuolation, inflammation) from related toxicology studies in the dog (3–91 days repeat-dosing) were reviewed, harmonized, and location categorized: cardiac muscle (myocardium, epicardium, endocardium, unspecified), atrioventricular/aortic valves, blood vessels. The prevalence of cardiovascular histopathology changes was 11.1% of compounds, with 53% recording a functional blood pressure or heart rate change. Correlations were assessed using the Mantel-Haenszel Chi-square trend test, identifying statistically significant associations between cardiac muscle pathology and (1) decreased blood pressure, (2) increased heart rate, and between cardiovascular vessel pathology and increased heart rate. Negative predictive values were high, suggesting few compounds cause repeat-dose cardiovascular structural change in the absence of functional effects in single-dose safety pharmacology studies. Therefore, observed functional changes could prompt moving (sub)chronic toxicology studies forward, to identify cardiovascular liabilities earlier in development, and reduce late-stage attrition.

Vascular Cells and Tissue Constructs Derived from Human Pluripotent Stem Cells for Toxicological Screening

The ability of human stem cells to generate somatic cell lineages makes them ideal candidates for use in toxicological testing and eventually, preclinical drug development. Such resources would support an evolution away from human primary cells or research animal models, which suffer from variability and poor predictability, toward off-the-shelf assays of chemical toxicity and drug efficacy using human cells and tissues. To this end, we generated vascular cell populations (smooth muscle cells and endothelial cells) from human pluripotent stem cells (hPSCs), arranged them into 3D co-cultures within supportive gel matrices, and directed their propensity for self-organization resembling microvasculature. The resulting vascular cell populations and co-cultured constructs were then arrayed in high throughput and used for screening a library of environmental and clinical chemical agents for immunological and toxicological responses. The screen effectively stratified the chemicals into various levels of toxicity, with both cell type-specific and co-culture-dependent responses observed. Thus, hPSC-derived vascular cells and constructs could be progressed further toward use in toxicant and drug screening.

Biomarkers of translational medicine

The development of new medicines is one of the priority areas of translational medicine. A significant role for biomarkers (BM) that assess the safety and efficacy of new drugs. The right choice of BM reduces the time and costs necessary for the development of drugs and transfer them to the clinic. The review is devoted to the analysis of modern scientific literature on the role of previously known and newly discovered BM in translational research. Translational BM (TBM) established during preclinical studies and are applicable at all stages of the study. TBM should have a high sensitivity and specificity, be easily measured in real time in an easily accessible biological fluids, to evaluate the same process in different species of animals (including humans), make it possible to compare the results of clinical trials with preclinical. The main role of the TBM toxicity to predict, identify and monitor the toxicity of drugs at all stages of their study. The international consortium (Predictive Safety Testing Consortium, PSTC) whose main task is the qualification of new TBM toxicity and the search for new, more advanced than existing methods for testing markers, was established. Under PSTC formed 6 working groups, each of which coordinates research for the study and selection of TBM toxicity caused by the administration of drugs in the liver, kidney, heart and blood vessels, skeletal muscle, testes. The first qualified consortium markers were 7 contained in the urine markers for preclinical studies on rats with the goal of establishing early lesions in the kidney induced by drugs. Only a small number of BM used in the study of new drugs, can be translational.

Translating New Science Into the Drug Review Process: The US FDA's Division of Applied Regulatory Science

In 2011, the US Food and drug Administration (FDA) developed a strategic plan for regulatory science that focuses on developing new tools, standards, and approaches to assess the safety, efficacy, quality, and performance of FDA-regulated products. In line with this, the Division of Applied Regulatory Science was created to move new science into the Center for Drug Evaluation and Research (CDER) review process and close the gap between scientific innovation and drug review. The Division, located in the Office of Clinical Pharmacology, is unique in that it performs mission-critical applied research and review across the translational research spectrum including in vitro and in vivo laboratory research, in silico computational modeling and informatics, and integrated clinical research covering clinical pharmacology, experimental medicine, and postmarket analyses. The Division collaborates with Offices throughout CDER, across the FDA, other government agencies, academia, and industry. The Division is able to rapidly form interdisciplinary teams of pharmacologists, biologists, chemists, computational scientists, and clinicians to respond to challenging regulatory questions for specific review issues and for longer-range projects requiring the development of predictive models, tools, and biomarkers to speed the development and regulatory evaluation of safe and effective drugs. This article reviews the Division's recent work and future directions, highlighting development and validation of biomarkers; novel humanized animal models; translational predictive safety combining in vitro, in silico, and in vivo clinical biomarkers; chemical and biomedical informatics tools for safety predictions; novel approaches to speed the development of complex generic drugs, biosimilars, and antibiotics; and precision medicine.

Technological Advances in Cardiovascular Safety Assessment Decrease Preclinical Animal Use and Improve Clinical Relevance

Cardiovascular (CV) safety liabilities are significant concerns for drug developers and preclinical animal studies are predominately where those liabilities are characterized before patient exposures. Steady progress in technology and laboratory capabilities is enabling a more refined and informative use of animals in those studies. The application of surgically implantable and telemetered instrumentation in the acute assessment of drug effects on CV function has significantly improved historical approaches that involved anesthetized or restrained animals. More chronically instrumented animals and application of common clinical imaging assessments like echocardiography and MRI extend functional and in-life structural assessments into the repeat-dose setting. A growing portfolio of circulating CV biomarkers is allowing longitudinal and repeated measures of cardiac and vascular injury and dysfunction better informing an understanding of temporal pathogenesis and allowing earlier detection of undesirable effects. In vitro modeling systems of the past were limited by their lack of biological relevance to the in vivo human condition. Advances in stem cell technology and more complex in vitro modeling platforms are quickly creating more opportunity to supplant animals in our earliest assessments for liabilities. Continuing improvement in our capabilities in both animal and nonanimal modeling should support a steady decrease in animal use for primary liability identification and optimize the translational relevance of the animal studies we continue to do.

Use of Rat Primary Mesenteric Cells for the Prediction of PDE4 Inhibitor Drug-Induced Vascular Injury

Drug-induced vascular injury (DIVI) in preclinical studies can delay, if not terminate, a drug development program. Clinical detection of DIVI can be very difficult as there are no definitive biomarkers known to reliably detect this disorder in all instances. The preclinical identification of DIVI requires detailed microscopic examination of a wide range of tissues although one of the most commonly affected areas in rats is the mesenteric vasculature. The reason for this predisposition of mesenteric arteries in rats as well as the exact mechanism and cell types involved in the initial development of these lesions have not been fully elucidated. We hypothesized that by using a mixed culture of cells from rat mesenteric tissue, we would be able to identify an RNA expression signature that could predict the invivo development of DIVI. Five compounds designed to inhibit Phosphodiesterase 4 activity (PDE4i) were chosen as positive controls. PDE4i's are well known to induce DIVI in the mesenteric vasculature of rats and there is microscopic evidence that this is associated, at least in part, with a proinflammatory mechanism. We surveyed, by qRT-PCR, the expression of 96 genes known to be involved in inflammation and using a Random-Forest model, identified 12 genes predictive of invivo DIVI outcomes in rats. Using these genes, we were able to cross-validate the ability of the Random-Forest modeling to predict the concentration at which PDE4i caused DIVI invivo.

Small structural changes of the imidazopyridine diacylglycerol acyltransferase 2 (DGAT2) inhibitors produce an improved safety profile

Small molecule DGAT2 inhibitors have shown promise for the treatment of metabolic diseases in preclinical models. Herein, we report the first toxicological evaluation of imidazopyridine-based DGAT2 inhibitors and show that the arteriopathy associated with imidazopyridine 1 can be mitigated with small structural modifications, and is thus not mechanism related.

Naphthoquine-induced Central Nervous System and Hepatic Vasculocentric Toxicity in the Beagle Dog

Naphthoquine phosphate (NP) was considered as a partner drug with a promising antimalarial drug candidate. Here we report unexpected adverse clinical signs and microscopic findings in a canine pilot toxicology study with NP. Male and female dogs were dosed daily by oral gavage with NP at 2, 10, or 50 mg/kg/day for a maximum of 14 days. NP was not tolerated at ≥10 mg/kg/day; several animals were sacrificed in moribund condition and marked neurological clinical signs were noted at 50 mg/kg/day. The main microscopic observation was central nervous system vasculocentric inflammation (mainly lymphocytes and macrophages) in the white and gray matter of various regions of the brain at ≥2 mg/kg/day and at lower incidence in the spinal cord at ≥10 mg/kg/day. Vasculocentric microscopic changes predominantly centered on the centrilobular vein were also observed in the liver at ≥2 mg/kg/day. Females were more sensitive than males with comparable NP plasma exposure. In conclusion, under the conditions of this study, the administration of NP to dogs via daily oral gavage for up to 2 weeks was not tolerated causing moribundity, marked neurological clinical signs, and vasculocentric microscopic changes in the central nervous system and the liver.

A bilayer small diameter in vitro vascular model for evaluation of drug induced vascular injury

In pre-clinical safety studies, drug-induced vascular injury (DIVI) is defined as an adverse response to a drug characterized by degenerative and hyperplastic changes of endothelial cells and vascular smooth muscle cells. Inflammation may also be seen, along with extravasation of red blood cells into the smooth muscle layer (i.e., hemorrhage). Drugs that cause DIVI are often discontinued from development after considerable cost has occurred. An in vitro vascular model has been developed using endothelial and smooth muscle cells in co-culture across a porous membrane mimicking the internal elastic lamina. Arterial flow rates of perfusion media within the endothelial chamber of the model induce physiologic endothelial cell alignment. Pilot testing with a drug known to cause DIVI induced extravasation of red blood cells into the smooth muscle layer in all devices with no extravasation seen in control devices. This engineered vascular model offers the potential to evaluate candidate drugs for DIVI early in the discovery process. The physiologic flow within the co-culture model also makes it candidate for a wide variety of vascular biology investigations.

Human Vascular Microphysiological System for in vitro Drug Screening

In vitro human tissue engineered human blood vessels (TEBV) that exhibit vasoactivity can be used to test human toxicity of pharmaceutical drug candidates prior to pre-clinical animal studies. TEBVs with 400–800 μM diameters were made by embedding human neonatal dermal fibroblasts or human bone marrow-derived mesenchymal stem cells in dense collagen gel. TEBVs were mechanically strong enough to allow endothelialization and perfusion at physiological shear stresses within 3 hours after fabrication. After 1 week of perfusion, TEBVs exhibited endothelial release of nitric oxide, phenylephrine-induced vasoconstriction, and acetylcholine-induced vasodilation, all of which were maintained up to 5 weeks in culture. Vasodilation was blocked with the addition of the nitric oxide synthase inhibitor L-N^G-Nitroarginine methyl ester (L-NAME). TEBVs elicited reversible activation to acute inflammatory stimulation by TNF-α which had a transient effect upon acetylcholine-induced relaxation, and exhibited dose-dependent vasodilation in response to caffeine and theophylline. Treatment of TEBVs with 1 μM lovastatin for three days prior to addition of Tumor necrosis factor – α (TNF-α) blocked the injury response and maintained vasodilation. These results indicate the potential to develop a rapidly-producible, endothelialized TEBV for microphysiological systems capable of producing physiological responses to both pharmaceutical and immunological stimuli.

Temporal Patterns of Novel Circulating Biomarkers in IL-2-mediated Vascular Injury in the Rat

Recombinant interleukin-2 (rIL-2) administration in oncology indications is hampered by vascular toxicity, which presents as a vascular leak syndrome. We used this aspect of the toxicity of rIL-2 to evaluate candidate biomarkers of drug-induced vascular injury (DIVI) in rats given 0.36 mg/kg rIL-2 daily. Groups of rats were given either 2 or 5 doses of rIL-2 or 5 doses of rIL-2 followed by a 7-day recovery. The histomorphologic lexicon and grading scheme developed by the Vascular Injury Working Group of the Predictive Safety Testing Consortium of the Critical Path Institute were utilized to enable semiquantitative integration with circulating biomarker levels. The administration of rIL-2 was associated with time-dependent endothelial cell hyperplasia and hypertrophy and perivascular inflammation that correlated with increases in circulating angiopoietin-2, lipocalin-2, monocyte chemotactic protein-1, tissue inhibitor of metalloproteinase-1, vascular endothelial growth factor A, E-selectin, and chemokine (C-X-C motif) ligand-1, and the microRNAs miR-21, miR-132, and miR-155. The dose groups were differentially identified by panels comprising novel candidate biomarkers and traditional hematologic parameters. These results identify biomarkers of the early stages of DIVI prior to the onset of vascular smooth muscle necrosis.

The Far Side of Vascular Injury

Substances historically thought to cause direct vascular injury in laboratory animals are a heterogeneous group of toxic agents with varied mechanisms of action. Morphologically, the reviewed agents can be broadly categorized into those targeting endothelial cell (ECs) and those targeting smooth muscle cells (SMCs). Anticancer drugs, immunosuppressants, and heavy metals are targeting primarily ECs while allylamine, β-aminopropionitrile, and mitogen-activated protein kinase kinase inhibitors affect mainly SMCs. It is now recognized that the pathogenicity of some of these agents is often mediated through intermediary events, particularly vasoconstriction. There are clear similarities in the clinical and microscopic findings associated with many of these agents in animals and man, allowing the use of animal models to investigate mechanisms and pathogenesis. The molecular pathogenic mechanisms and comparative morphology in animals and humans will be reviewed.

Cardiovascular safety risk assessment for new candidate drugs from functional and pathological data: Conference report

This is a report on a 2-day joint meeting between the British Society of Toxicological Pathology (BSTP) and the Safety Pharmacology Society (SPS) held in the UK in November 2013. Drug induced adverse effects on the cardiovascular system are associated with the attrition of more marketed and candidate drugs than any other safety issue. The objectives of this meeting were to foster inter-disciplinary approaches to address cardiovascular risk assessment, improve understanding of the respective disciplines, and increase awareness of new technologies. These aims were achieved. This well attended meeting covered both 'purely functional' cardiovascular adverse effects of drugs (e.g., electrophysiological and haemodynamic changes) as well as adverse effects encompassing both functional and pathological changes. Most of the presentations focused on nonclinical safety data, with information on translation to human where known. To reflect the content of the presentations we have cited key references and review articles.

Better science with human cell-based organ and tissue models

At present, animal-based models are the major test systems for assessing the tolerability and safety of chemical substances for regulatory purposes, and also for pivotal efficacy testing in pharmaceutical development. In spite of the high genetic similarity between many laboratory animals and humans, animal models are very poor predictors of human health effects and pathophysiological processes. Thus, models and testing strategies that are more relevant to human biology, are needed for these purposes. The best predictability is achieved with human organotypic models that mimic the microenvironment of human tissues. During their development, such models have to be characterised at the structural, genetic and functional levels, and compared to the respective human tissues. Their predictivity should be confirmed by using known reference chemicals with corresponding human data. The use of these methods in safety assessment and biomedical research, combined with the knowledge gained of the underlying biological processes on gene and protein expression, as well as on cellular signalling, will ultimately lead to better human science and animal welfare.

Regulatory Forum Opinion Piece*

Renal tubule lesions often prove troublesome for toxicologic pathologists because of the diverse nature and interrelated cell types within the kidney and the presence of spontaneous lesions with overlapping morphologies similar to those induced by renal toxicants. Although there are a number of guidance documents available citing straightforward diagnostic criteria of tubule lesions for the pathologist to refer to, most are presented without further advice on the when to or to the why and the why not of diagnosing one lesion over another. Documents presenting diagnostic perspectives and recommendations derived from an author’s experience are limited since guidance documents are generally based on descriptive observations. In this Regulatory Forum opinion piece, the authors attempt to dispel confusing renal tubule lesion terminology in laboratory animal species by suggesting histological advice on the recognition and interpretation of these complex entities.

Scientific and Regulatory Policy Committee Points-to-consider Paper*

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. Although DIVI in laboratory animal species has been well characterized for vasoactive small molecules, there is little available information regarding DIVI associated with biotherapeutics such as peptides/proteins or antibodies. Because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans and the lack of robust biomarkers of DIVI, preclinical DIVI findings can cause considerable delays in or even halt development of promising new drugs. This review discusses standard terminology, characteristics, and mechanisms of DIVI associated with biotherapeutics. Guidance and points to consider for the toxicologist and pathologist facing preclinical cases of biotherapeutic-related DIVI are outlined, and examples of regulatory feedback for each of the mechanistic types of DIVI are included to provide insight into risk assessment.

Scientific and Regulatory Policy Committee Points-to-consider Paper*: Drug-induced Vascular Injury Associated with Nonsmall Molecule Therapeutics in Preclinical Development: Part 2. Antisense Oligonucleotides

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. In recent years, DIVI has been occasionally observed in nonhuman primates given RNA-targeting therapeutics such as antisense oligonucleotide therapies (ASOs) during chronic toxicity studies. While DIVI in laboratory animal species has been well characterized for vasoactive small molecules, and immune-mediated responses against large molecule biotherapeutics have been well described, there is little published information regarding DIVI induced by ASOs to date. Preclinical DIVI findings in monkeys have caused considerable delays in development of promising new ASO therapies, because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans, and the lack of robust biomarkers of DIVI. This review of DIVI discusses clinical and microscopic features of vasculitis in monkeys, their pathogenic mechanisms, and points to consider for the toxicologist and pathologist when confronted with ASO-related DIVI. Relevant examples of regulatory feedback are included to provide insight into risk assessment of ASO therapies.

Recommendations for adaptation and validation of commercial kits for biomarker quantification in drug development

Increasingly, commercial immunoassay kits are used to support drug discovery and development. Longitudinally consistent kit performance is crucial, but the degree to which kits and reagents are characterized by manufacturers is not standardized, nor are the approaches by users to adapt them and evaluate their performance through validation prior to use. These factors can negatively impact data quality. This paper offers a systematic approach to assessment, method adaptation and validation of commercial immunoassay kits for quantification of biomarkers in drug development, expanding upon previous publications and guidance. These recommendations aim to standardize and harmonize user practices, contributing to reliable biomarker data from commercial immunoassays, thus, enabling properly informed decisions during drug development.