A T-cell-dependent antibody response study using a murine surrogate anti-PD-1 monoclonal antibody as an alternative to a non-human primate model.

The programmed cell death 1 (PD-1) pathway represents a major immune checkpoint which may be engaged by cells in a tumor microenvironment to overcome active T-cell immune surveillance. Pembrolizumab (Keytruda) is a potent and highly selective humanized monoclonal antibody (mAb) of the IgG/κ isotype designed to directly block the interaction between PD-1 and its ligands, PD-L1 and PD-L2. The current work was focused on developing a mouse T-Dependent Antibody Response (TDAR) model using a murinized rat anti-mouse PD-1 antibody (muDX400; a rodent surrogate for pembrolizumab) to evaluate the potential impact of treatment with a PD-1 inhibitor on immune responses to an antigen challenge (e.

Cancer Immunotherapy: Factors Important for the Evaluation of Safety in Nonclinical Studies.

The development of novel therapies that can harnass the immune system to eradicate cancer is an area of intensive research. Several new biopharmaceuticals that target the immune system rather than the tumor itself have recently been approved and fundamentally transformed treatment of many cancer diseases. This success has intensified the search for new targets and modalities that could be developed as even more effective therapeutic agents either as monotherapy or in combination.

An Evaluation of the Impact of PD-1 Pathway Blockade on Reproductive Safety of Therapeutic PD-1 Inhibitors.

This report discusses the principles of reproductive toxicity risk assessment for biopharmaceuticals blocking the PD-1/programmed cell death ligand 1 (PD-L1) pathway, which have been developed for the treatment of patients with advanced malignancies. The PD-1/PD-L1 pathway is a T-cell co-inhibitory pathway that normally maintains immune tolerance to self. Its role in pregnancy is to maintain immune tolerance to the fetal allograft.

The T-dependent antibody response to keyhole limpet hemocyanin in rodents.

Central to the evaluation of potential immunotoxicants is the concept that measurement of multiple parameters is required for the determination of toxicity toward the immune system. A carefully considered integration of endpoints involved in the immune response should be used to determine an immunotoxic effect. A functional evaluation, specifically the rodent T-cell-dependent antibody response (TDAR) model developed for regulated immunotoxicity evaluations, has been established to detect potential immunotoxicity, especially immunosuppression, caused by chemicals and novel pharmaceuticals in development.

Summary of a workshop on nonclinical and clinical immunotoxicity assessment of immunomodulatory drugs.

The number of anti-inflammatory and immunomodulatory drugs being developed in the pharmaceutical industry has increased considerably in the past decade. This increase in research and development has been paralleled by questions from both regulatory agencies and industry on how best to assess decreased host resistance to infections or adverse immunostimulation caused by immunomodulatory agents such as anti-cytokine antibodies (e.g.

Immunotoxicity evaluation by immune function tests: focus on the T-dependent antibody response (TDAR) [Overview of a Workshop Session at the 45th Annual Meeting of the Society of Toxicology (SOT) March 5-9, 2006 San Diego, CA].

Increased expectations from a number of regulatory agencies, e.g., Environmental Protection Agency (EPA), Food and Drug Administration (FDA), European Medicines Agency (EMEA), and the Ministry of Health, Labour and Welfare (MHLW) of Japan, call for the evaluation of potential adverse effects on the immune system.

Adequate immunotoxicity testing in drug development.

Modulation of the immune system can lead to either immunostimulation or immunosuppression and can be either intended or unintended. While many effects on the immune system's components can be found as a result of a drug treatment or chemical exposure, true immunotoxicity occurs when such treatment results in adverse effects or defects in the immune response. Regulatory expectations to evaluate potential adverse effects of pharmaceuticals warrants a need for reliable and readily standardized methods.

Primary antibody response to keyhole limpet hemocyanin in rat as a model for immunotoxicity evaluation.

To address current regulatory expectations on immunotoxicity testing of new chemicals, we describe an animal model that measures the primary antibody response to the T-cell dependent antigen, keyhole limpet hemocyanin (KLH). Single immunization with KLH by either footpad (300microg/rat) or intravenous (300microg/kg) route in Sprague Dawley rats resulted in increased germinal center formation in the spleen and a robust anti-KLH IgM (70-388microg/ml) and IgG (230-470microg/ml) antibody response with peak detection on Days 5 and 14 post-immunization, respectively. Subcutaneous immunization with KLH (300microg/kg) resulted in a much weaker anti-KLH IgM and IgG (< or =20microg/ml) antibody response with no detectable increase in splenic germinal center formation.

Preclinical safety of recombinant human interleukin-18.

Recombinant human interleukin-18 (rHuIL-18) is currently in clinical trials for treatment of cancer. This report presents results of preclinical toxicity studies with rHuIL-18 in cynomolgus monkeys and recombinant murine IL-18 (rMuIL-18) in mice. The rHuIL-18 was administered intravenously in 1 or 2 different 5-day cycles at doses 0.

Identification of natural antibodies to interleukin-18 in the sera of normal humans and three nonhuman primate species.

Natural antibodies to cytokines can be found in the sera of normal healthy individuals in the absence of specific immunostimulation. However, the function, impact, and purpose of natural antibody development have yet to be fully elucidated. Interleukin (IL)-18 is a cytokine that exerts proinflammatory activities and induces natural killer (NK) cell activity.

The immunogenicity of therapeutic cytokines.

Therapeutic cytokines that modulate immune responses are designed to enhance host defense to combat tumors and chronic infections. In general, cytokines are pleiotropic molecules and mediate both systemic and local immune activities. Therapeutic recombinant human cytokines currently in clinical use include interferons (IFN alpha, IFN beta and IFN gamma), interleukins (IL-2 and IL-12) and hematopoietic factors such as granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, erythropoietin and thrombopoietin.

Immunopharmacology of recombinant human interleukin-18 in non-human primates.

Recombinant human interleukin (IL)-18 (rHuIL-18) has a potential as a therapeutic agent in cancer and is currently in drug development. Since human IL-18 displays 96% and 100% amino acid sequence homology with cynomolgus monkey and chimpanzee IL-18, respectively, the biological responses to rHuIL-18 were evaluated in these species. A single intravenous dose of rHuIL-18 at 1 or 10mg/kg in cymonolgus monkeys caused a transient reduction in lymphocyte counts, induction of IL-1alpha and tumour necrosis factor alpha (TNF-alpha) mRNA in whole blood cells and a marked increase in plasma neopterin.