Toxicologic Pathology最新文献

Test article (TA)-induced seizures represent a major safety concern in drug development. Seizures (altered brain wave [electrophysiological] patterns) present clinically as abnormal consciousness with or without tonic/clonic convulsions (where "tonic" = stiffening and "clonic" = involuntary rhythmical movements). Neuropathological findings following seizures may be detected using many methods. Neuro-imaging may show a structural abnormality underlying seizures, such as focal cortical dysplasia or hippocampal sclerosis in patients with chronic epilepsy. Neural cell type-specific biomarkers in blood or cerebrospinal fluid may highlight neuronal damage and/or glial reactions but are not specific indicators of seizures while serum electrolyte and glucose imbalances may induce seizures. Gross observations and brain weights generally are unaffected by TAs with seizurogenic potential, but microscopic evaluation may reveal seizure-related neuron death in some brain regions (especially neocortex, hippocampus, and/or cerebellum). Current globally accepted best practices for neural sampling in nonclinical general toxicity studies provide a suitable screen for brain regions that are known sites of electrical disruption and/or display seizure-induced neural damage. Conventional nonclinical studies can afford an indication that a TA has a potential seizure liability (via in-life signs and/or microscopic evidence of neuron necrosis), but confirmation requires measuring brain electrical (electroencephalographic) activity in a nonclinical study.

The 2024 annual Division of Translational Toxicology (DTT) Satellite Symposium, entitled "Pathology Potpourri," was held in Baltimore, Maryland, at the Society of Toxicologic Pathology's 42nd annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers' talks along with select images that were used by the audience for voting and discussion. Various lesions and topics covered during the symposium included induced nonneoplastic lesions in the mouse kidney, induced and spontaneous neoplastic lesions in the mouse lung, infectious and proliferative lesions in nonhuman primates, an interesting inflammatory lesion in a transgenic mouse strain, and a lesson on artifact recognition.

Through two decades of research and development, adoptive cell therapies (ACTs) have revolutionized treatment for hematologic malignancies. Many of the seven US Food and Drug Administration (FDA)-approved products are proven to be a curative last line of defense against said malignancies. The ACTs, known more commonly as chimeric antigen receptor (CAR) T-cells, utilize engineered lymphocytes to target and destroy cancer cells in a patient-specific, major histocompatibility complex (MHC)-independent manner, acting as "living drugs" that adapt to and surveil the body post-treatment. Despite their efficacy, CAR T-cell therapies present unique challenges in preclinical safety assessment. The safety and pharmacokinetics of CAR T-cells are influenced by numerous factors including donor and recipient characteristics, product design, and manufacturing processes that are not well-predicted by existing in vitro and in vivo preclinical safety models. The CAR therapy-mediated toxicities in clinical settings primarily arise from unintended targeting of non-tumor cells, potential tumorigenicity, and severe immune activation syndromes like cytokine release syndrome and immune effector cell-associated neurotoxicity. Addressing these issues necessitates a deep understanding of CAR target expression in normal tissues, inclusive of the spatial microanatomical distribution, off-target screening, and a deep understanding CAR cell manufacturing practices and immunopathology.

Adeno-associated virus (AAV)-based vectors are the most frequently used platform for retinal gene therapy. Initially explored for the treatment of loss-of-function mutations underpinning many inherited retinal diseases, AAV-based ocular gene therapies are increasingly used to transduce endogenous cells to produce therapeutic proteins, thus producing site-specific biofactories. Relatively invasive ocular routes of administration (ROA) mean prominent procedure-related in-life, and histopathological findings may be observed with some regularity. Test article-related findings may vary with the ROA and cell populations transduced, with retinal pigmented epithelium (RPE) changes prominent (ranging from pigment alteration through degeneration, with or without associated degeneration of the overlying retina) with subretinal ROA, and more anterior changes (iris, ciliary body) generally observed with the intravitreal ROA. Ocular inflammation is the most frequent finding that occurs nonclinically and in patients, and is particularly pronounced with intravitreal administration. Extraocular findings may be observed in extraocular muscles, regional ganglia, or central visual pathways with multiple ocular ROA. Work is still needed to understand the mechanisms underpinning many of these ocular and extraocular findings. Emerging patient data is helping to clarify both the potential for translating nonclinical findings to predict possible human responses and the applicability of nonclinical biomonitoring methods to the clinical setting.

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions) Project (www.toxpath.org/ inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in ocular tissues (eyes and glands and ocular adnexa) from laboratory nonrodent species (rabbits, dogs, minipigs, and nonhuman primates) used in nonclinical safety studies with an emphasis on ocular-targeted dosing. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes descriptions and visual depictions of spontaneous lesions and lesions induced by exposure to various test materials. A widely accepted and utilized internationally harmonized nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.

Minipigs are valued alternatives to dogs and non-human primates in non-clinical safety and toxicity studies, and Göttingen minipigs are bred specifically for experimental purposes. They are bred under barrier conditions and monitored regularly for many pathogens and opportunistic agents, and spontaneous disease is rare when compared to what is seen in production pigs. Knowledge of spontaneous background lesions is important when toxicological pathologists evaluate microscopic findings in pre-clinical toxicity studies to avoid interference with study data interpretation. In this brief communication, intra-abdominal granulomas/abscesses were seen in Göttingen minipigs. The minipigs did not show any clinical signs, but nodules were present in the abdominal peritoneum at necropsy. Microscopic evaluation revealed chronic inflammation, with abscess or granuloma formation. Areas of inflammation, occasionally associated with the presence of the Splendore-Hoeppli material, were surrounded by a fibrotic capsule. Special stains were applied to investigate for the presence of microorganisms.

Abnormal findings in the biliary tree are frequently encountered in response to acute and chronic exposures to various compounds. The more common findings are described here in an overview of previous publications such as the INHAND Proliferative and Nonproliferative Lesions of the Rodent Liver and the Liver-Nonneoplastic Lesion Atlas NTP with comments regarding current considerations. This was presented at the 2023 Annual Meeting of the Society of Toxicologic Pathology. Histologic descriptions and some discussions regarding the pathogenesis of the various categories of non-neoplastic lesions in the biliary tree are presented. Discussions regarding the use of the term oval cell versus ductular reaction and the potentially neoplastic nature of cholangiofibrosis are presented in some detail.

Digitalization of pathology workflows has undergone a rapid evolution and has been widely established in the diagnostic field but remains a challenge in the nonclinical safety context due to lack of regulatory guidance and validation experience for good laboratory practice (GLP) use. One means to demonstrate that digital slides are fit for purpose, that is, provide sufficient quality for pathologists to reach a diagnosis, is conduction of comparison studies, which have been published both, for veterinary and human diagnostic pathology, but not for toxicologic pathology. Here, we present an approach that uses study material from nonclinical safety studies and that allows for the statistical comparison of concordance rates for glass and digital slide evaluation while minimizing time and effort for the involved personnel. Using a benchmark study design, we demonstrate that evaluation of digital slides fits the purpose of nonclinical safety evaluation. These results add to reports of successful workflow validations and support the full adaptation of digital pathology in the regulatory field.