Nick Pullen

Preclinical safety testing of monoclonal antibodies: the significance of species relevance

Selecting a pharmacologically relevant animal species for testing the safety and toxicity of novel monoclonal antibody (mAb) therapies to support clinical testing can be challenging. Frequently, the species of choice is the primate. With the increased number of mAbs in the pharmaceutical pipeline, this has significant implications for primate use, and so raises several important scientific, ethical and economic issues. Here, following a recent international workshop held to debate this topic, we discuss issues in the preclinical testing of mAbs, with a particular focus on species relevance and primate use, and provide suggestions for how these issues might be addressed.

Regulation of mucosal addressin cell adhesion molecule 1 expression in human and mice by vascular adhesion protein 1 amine oxidase activity

Primary sclerosing cholangitis (PSC) and autoimmune hepatitis are hepatic complications associated with inflammatory bowel disease (IBD). The expression of mucosal addressin cell adhesion molecule 1 (MAdCAM‐1) on mucosal endothelium is a prerequisite for the development of IBD, and it is also detected on the hepatic vessels of patients with liver diseases associated with IBD. This aberrant hepatic expression of MAdCAM‐1 results in the recruitment of effector cells initially activated in the gut to the liver, in which they drive liver injury. However, the factors responsible for the aberrant hepatic expression of MAdCAM‐1 are not known. In this study, we show that deamination of methylamine (MA) by vascular adhesion protein 1 (VAP‐1) [a semicarbazide‐sensitive amine oxidase (SSAO) expressed in the human liver] in the presence of tumor necrosis factor α induces the expression of functional MAdCAM‐1 in hepatic endothelial cells and in intact human liver tissue ex vivo. This is associated with increased adhesion of lymphocytes from patients with PSC to hepatic vessels. Feeding mice MA, a constituent of food and cigarette smoke found in portal blood, led to VAP‐1/SSAO–dependent MAdCAM‐1 expression in mucosal vessels in vivo. Conclusion: Activation of VAP‐1/SSAO enzymatic activity by MA, a constituent of food and cigarette smoke, induces the expression of MAdCAM‐1 in hepatic vessels and results in the enhanced recruitment of mucosal effector lymphocytes to the liver. This could be an important mechanism underlying the hepatic complications of IBD. (HEPATOLOGY 2011;53:661‐672)

In vitro and in vivo characterization of PF-04418948, a novel, potent and selective prostaglandin EP2 receptor antagonist

BACKGROUND AND PURPOSE Studies of the role of the prostaglandin EP2 receptor) have been limited by the availability of potent and selective antagonist tools. Here we describe the in vitro/in vivo pharmacological characterization of a novel EP2 receptor antagonist, PF‐04418948 (1‐(4‐fluorobenzoyl)‐3‐{[(6‐methoxy‐2‐naphthyl)oxy]methyl} azetidine‐3‐carboxylic acid).

Preclinical development of monoclonal antibodies: considerations for the use of non-human primates.

The development of mAbs remains high on the therapeutic agenda for the majority of pharmaceutical and biotechnology companies. Often, the only relevant species for preclinical safety assessment of mAbs are non-human primates (NHPs), and this raises important scientific, ethical and economic issues. To investigate evidence-based opportunities to minimize the use of NHPs, an expert working group with representatives from leading pharmaceutical and biotechnology companies, contract research organizations and institutes from Europe and the USA, has shared and analyzed data on mAbs for a range of therapeutic areas. This information has been applied to hypothetical examples to recommend scientifically appropriate development pathways and study designs for a variety of potential mAbs. The addendum of ICHS6 provides a timely opportunity for the scientific and regulatory community to embrace strategies which minimize primate use and increase efficiency of mAb development.

Pharmacological characterization of PF-00547659, an anti-human MAdCAM monoclonal antibody

Background and purpose:  The adhesion molecule mucosal addressin cell adhesion molecule (MAdCAM) plays an essential role in the recruitment of lymphocytes to specialized high endothelial venules of the gastrointestinal tract and in their excessive tissue extravasation observed in inflammatory conditions, such as Crohns disease. We have characterized the in vitro pharmacological properties of two monoclonal antibodies blocking MAdCAM, MECA‐367 and PF‐00547659, and determined their pharmacokinetic/pharmacodynamic profiles in vivo.

The design of chronic toxicology studies of monoclonal antibodies: implications for the reduction in use of non-human primates.

The changing environment of monoclonal antibody (mAb) development is impacting on the cost of drug development and the use of experimental animals, particularly non-human primates (NHPs). The drive to reduce these costs is huge and involves rethinking and improving nonclinical studies to make them more efficient and more predictive of man. While NHP use might be unavoidable in many cases because of the exquisite specificity and consequent species selectivity of mAbs, our increasing knowledge base can be used to improve drug development and maximise the output of experimental data. Data on GLP regulatory toxicology studies for 58mAbs were obtained from 10 companies across a wide range of therapeutic indications. These data have been used to investigate current practice and identify study designs that minimise NHP use. Our analysis shows that there is variation in the number of animals used for similar studies. This information has been used to develop practical guidance and make recommendations on the use of science-based rationale to design studies using fewer animals taking into account the current regulatory guidance. There are eight recommendations intended to highlight areas for consideration. They include guidance on the main group size, the inclusion of recovery groups and the number of dose groups used in short and long term chronic toxicology studies.

The relationship between the nucleolus and cancer: Current evidence and emerging paradigms

The nucleolus is the most prominent nuclear substructure assigned to produce ribosomes; molecular machines that are responsible for carrying out protein synthesis. To meet the increased demand for proteins during cell growth and proliferation the cell must increase protein synthetic capacity by upregulating ribosome biogenesis. While larger nucleolar size and number have been recognized as hallmark features of many tumor types, recent evidence has suggested that, in addition to overproduction of ribosomes, decreased ribosome biogenesis as well as qualitative changes in this process could also contribute to tumor initiation and cancer progression. Furthermore, the nucleolus has become the focus of intense attention for its involvement in processes that are clearly unrelated to ribosome biogenesis such as sensing and responding to endogenous and exogenous stressors, maintenance of genome stability, regulation of cell-cycle progression, cellular senescence, telomere function, chromatin structure, establishment of nuclear architecture, global regulation of gene expression and biogenesis of multiple ribonucleoprotein particles. The fact that dysregulation of many of these fundamental cellular processes may contribute to the malignant phenotype suggests that normal functioning of the nucleolus safeguards against the development of cancer and indicates its potential as a therapeutic approach. Here we review the recent advances made toward understanding these newly-recognized nucleolar functions and their roles in normal and cancer cells, and discuss possible future research directions.

CNS elevation of vascular and not mucosal addressin cell adhesion molecules in patients with multiple sclerosis

The mucosal addressin cell adhesion molecule (MAdCAM) and vascular cell adhesion molecule (VCAM) appear to play roles in the recruitment of leukocytes to specialized endothelium lining the gastrointestinal tract. The purpose of this study was to clarify the role of MAdCAM and VCAM in the central nervous system by comparing protein expression in patients with multiple sclerosis (MS) and control subjects by immunohistochemistry. Specific antibodies to human VCAM and MAdCAM were used to confirm expression in control and MS nervous system specimens by immunohistochemistry. VCAM immunoreactivity was detected in endothelial cells, perivascular tissue, and in some cases, leukocytes within the meninges, gray, and white matter, of both controls and MS patients. VCAM immunoreactivity was maximal in a patient with acute active plaques, but of lower intensity and reduced distribution in controls and those with chronic active or inactive MS plaques. In contrast, MAdCAM immunoreactivity could not be detected in brain tissue from unaffected or MS patients. Taken together, these data support a role of VCAM, but not MAdCAM in the development of MS.

The future of non-human primate use in mAb development

It has been predicted that the use of non-human primates (NHPs) is going to increase considerably in the development of monoclonal antibodies (mAbs). Opportunities exist to focus on a rigorous, science-based approach to drug development, however, which will minimize this increase. In this article, the authors review current and future NHP use in mAb development based on surveys, experience and expert opinion and propose a framework that will minimize future NHP use and continue to support science and innovation.

Bridging Translation by Improving Preclinical Study Design in AKI

Despite extensive research, no therapeutic interventions have been shown to prevent AKI, accelerate recovery of AKI, or reduce progression of AKI to CKD in patients. This failure in translation has led investigators to speculate that the animal models being used do not predict therapeutic responses in humans. Although this issue continues to be debated, an important concern that has not been addressed is whether improvements in preclinical study design can be identified that might also increase the likelihood of translating basic AKI research into clinical practice using the current models. In this review, we have taken an evidence-based approach to identify common weaknesses in study design and reporting in preclinical AKI research that may contribute to the poor translatability of the findings. We focused on use of N-acetylcysteine or sodium bicarbonate for the prevention of contrast-induced AKI and use of erythropoietin for the prevention of AKI, two therapeutic approaches that have been extensively studied in clinical trials. On the basis of our findings, we identified five areas for improvement in preclinical study design and reporting. These suggested and preliminary guidelines may help improve the quality of preclinical research for AKI drug development.