Scientific and Regulatory Policy Committee Points to Consider: Histopathologic Evaluation in Safety Assessment Studies for PEGylated Pharmaceutical Products.

Colorless, intracytoplasmic vacuoles occur in multiple tissues in animals following repeated administration of polyethylene glycol (PEG)-conjugated molecules. The extent of vacuolation depends on physical characteristics and molecular backbone of the PEG and the dose, product, drug target/pharmacology, and duration of exposure. The collective experience gathered from multiple nonclinical toxicology studies of PEGylated biopharmaceuticals indicates that in general, PEG-related vacuolation is not associated with demonstrable cell and tissue damage or dysfunction and is reversible with sufficient duration of drug-free periods. Existing data are insufficient to predict whether nonclinical animal species differ in their sensitivity to develop PEG-associated vacuoles; however, recent data suggest that there may be species differences. Recent comprehensive reviews have addressed the basic challenges in developing PEGylated pharmaceutical products, including general reference to and description of PEG-associated tissue findings. These manuscripts have identified gaps in our current understanding of PEG-associated vacuolation, including the lack of a widely accepted standardized histological terminology and criteria to record and grade the severity of vacuolation as well as insufficient knowledge regarding the nature of the contents of these vacuoles. The goal of this article is to help address some of the gaps identified above by providing points to consider, including a pictorial review of PEG-associated microscopic findings, when evaluating and reporting the extent, severity, and significance (adversity or lack of adversity) of PEG-associated cytoplasmic vacuolation in safety assessment studies. [Box: see text].

Naturally occurring infections in non-human primates (NHP) and immunotoxicity implications: discussion sessions.

Non-human primates (NHP) are used to best understand and address pharmacology and toxicology obligations for human patients with highest and/or unmet need. In order to ensure the most appropriate care and use of NHP, it is important to understand the normal micro flora and fauna of NHP and ensure their utmost health to generate the most valuable and applicable data. There are many infections, including viral, bacterial, parasitic, and fungal that may perturb physiologic endpoints relevant to human health, and are essential to monitor and/or eradicate for NHP health. This publication captures a discussion involving the experience, knowledge and opinion from academic, industry and government experts regarding emerging and normal infections in NHP as they relate to immunotoxicity, and treatment and consequences of known infections.

Opportunistic infections in non-human primates exposed to immunomodulatory biotherapeutics: considerations and case examples.

Immunomodulatory biotherapeutics are most often evaluated for safety preclinically by way of repeat dose toxicity studies in non-human primates. Since immunomodulation is expected with this class of therapeutics, and since non-human primates share many opportunistic or latent infectious agents with humans, non-human primates in these toxicity studies may present with opportunistic or recrudescent infections that would be of concern if they occurred clinically in humans. In such instances, it is suggested that non-clinical safety assessment scientists consider a series of key questions that aim to clarify the relationship of the findings to the biotherapeutic under study and the expected predictivity of the findings to the human clinical setting. In this review, relevant case examples are considered comprising (i) gammaherpesviruses-mediated B-lymphocyte proliferation associated with a T-lymphocyte depleting fusion protein; (ii) increased plasmodial hemoparasite burdens associated with a monoclonal antibody inhibitory to T-lymphocyte trafficking and macrophage function, and (iii) the expected predictivity of non-human primate models for the occurrence of encephalic polyomavirus infections.

Nutritional regulation of porcine bacterial-induced colitis by conjugated linoleic acid.

Excessive intake of saturated fatty acids and/or linoleic acid favors the induction of an array of lipid mediators and cytokines enhancing inflammatory responses. Conversely, dietary supplementation with (n-3) fatty acids or vitamin D ameliorates inflammation and autoimmune diseases. Although it was well accepted that conjugated linoleic acid (CLA) prevented diseases with a common inflammatory pathogenesis (i.e., cancer and atherosclerosis), no studies were available on the roles of CLA in mucosal inflammation. The present study was designed to investigate the anti-inflammatory actions and molecular mechanisms underlying the regulation of colonic health by CLA. We hypothesized that colonic inflammation can be ameliorated by dietary CLA supplementation. To test this hypothesis, inflammation of the colonic mucosa was triggered by challenging pigs fed either soybean oil-supplemented or CLA-supplemented diets with an enteric bacterial pathogen (i.e., Brachyspira hyodysenteriae). Immunoregulatory cytokines and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) mRNA expression were assayed in colonic lymph nodes and colon of pigs. Colonic mucosal lesions and lymphocyte subset distribution were evaluated by histology and immunohistochemistry. Supplementation of CLA in the diet before the induction of colitis decreased mucosal damage; maintained cytokine profiles (i.e., interferon-gamma and interleukin-10) and lymphocyte subset distributions (i.e., CD4+ and CD8+), resembling those of noninfected pigs; enhanced colonic expression of PPAR-gamma; and attenuated growth failure. Therefore, CLA fed preventively before the onset of enteric disease attenuated inflammatory lesion development and growth failure.