Fully human anti-BAFF inhibitory monoclonal antibody tabalumab does not adversely affect T-dependent antibody responses in cynomolgus monkey (Macaca fasicularis): A summary of three pre-clinical immunotoxicology evaluations.

The potential immunotoxicity of tabalumab was assessed as a component of standard pre-clinical toxicology studies in cynomolgus monkeys. To evaluate potential tabalumab-associated immunosuppression after antigen challenge, cynomolgus monkeys were administered placebo control or tabalumab in three immunotoxicological safety studies. Study 1, a 4-week pilot study, evaluated biweekly intravenous (IV) control, and 0.3, 1.0, 5.0, and 15.0 mg/kg tabalumab doses. Study 2 evaluated IV control, and 0.1, 1.0, and 30.0 mg/kg tabalumab doses biweekly for 6 weeks. Study 3 evaluated IV control and 0.1, 1.0, 30.0 mg/kg, and subcutaneous (SC) 30.0 mg/kg tabalumab biweekly for 6 months, with recovery (16 weeks) to monitor standard immunotoxicity endpoints. T-cell dependent primary and secondary antibody responses to tetanus toxoid antigen challenge (4-week and 6-week studies) or keyhole limpet hemocyanin (KLH; 6-week and 6-month studies) were evaluated as a measure of immunocompetence, together with quantitation of T- and B-cell subsets. In addition, anti-tabalumab antibody formation (6-week and 6-month studies) was assessed. The results indicated that, despite expected decreases in circulating B-cell populations, no changes in follicle histopathology or organ weights, except decreases in spleen weight (after 6-months of 30 mg/kg IV/SC treatment only), were attributed to tabalumab. Non-adverse microscopic decreases in size or number of germinal centers in spleen, mesenteric, and mandibular lymph nodes occurred, but without an effect on antibody responses to KLH or tetanus. At 16-weeks recovery, microscopic compound-related changes observed after 6 months of treatment were completely reversed (0.1 mg/kg group) and partially reversed (1.0 and 30.0 mg/kg groups), while peripheral blood B cells remained 66-72% reduced from baseline. Despite reduced germinal centres in lymphoid organs, and reductions in circulating B cells, T-cell-dependent humoral immunity was maintained following tabalumab administration in three safety studies in cynomolgus monkeys.

Recommendations for the design and optimization of immunoassays used in the detection of host antibodies against biotechnology products.

Most biopharmaceutical therapeutics elicit some level of antibody response against the product. This antibody response can, in some cases, lead to potentially serious side effects and/or loss of efficacy. Therefore, the immunogenicity of therapeutic proteins is a concern for clinicians, manufacturers and regulatory agencies. In order to assess immunogenicity of these molecules, appropriate detection, quantitation and characterization of antibody responses are necessary. Inadequately designed antibody assays have led to the hampering of product development or, during licensure, post-marketing commitments. This document provides scientific recommendations based on the experience of the authors for the development of anti-product antibody immunoassays intended for preclinical or clinical studies. While the main focus of this document is assay design considerations, we provide scientific focus and background to the various assay performance parameters necessary for developing a valid assay. Sections on assay performance parameters, including those that appear in regulatory guidances, are contained in this manuscript.

A predictive F344 rat immunotoxicology model: cellular parameters combined with humoral response to NP-CgammaG and KLH.

The purpose of this study was to examine the predictive value of humoral and cellular immune parameters in determining the immunotoxic effects of the oral administration of azathioprine (AZA), cyclophosphamide (CY), or cyclosporin A (CsA) at doses of 25/17, 10, or 25 mg/kg per day, respectively, for 30 days in F344 female rats. The effect of these known immunosuppressive compounds on the immune response was assessed in a humoral model that consisted of the administration of nitrophenyl-chicken gamma globulin (NP-CgammaG) and keyhole limpet hemocyanin (KLH) antigens during immunosuppressive treatment and the measurement of resulting rat antigen-specific IgG and IgM, as well as total IgG, levels. Cellular assessment parameters were collected from the same groups of animals as the humoral parameters and included organ weights and cellularity, hematology, lymphocyte phenotype characteristics, spleen cell mitogen stimulation (T and B cell-dependent), splenic natural killer (NK) cell cytotoxicity, and bone marrow cellularity and lymphocyte phenotype differential. Although decreases in several of the cellular assay parameters were observed, the only functional assays to demonstrate a statistically significant immunosuppressive effect by all three immunosuppressive agents were the antigen-specific serum IgG levels. The primary (day 10; 15 days post-immunization) and secondary (day 25; 5 days post-rechallenge) nitrophenyl (NP) responses were significantly suppressed by > or =60%. The use of NP hapten provided consistent responses when analyzed with a sensitive, well developed, ELISA methodology. Absolute lymphocyte phenotyping and lymphocyte hematology were also predictive of T cell immunosuppression for all three compounds. The data presented herein suggests that these two parameters, NP-IgG humoral response and lymphocyte phenotyping, are sufficient for identifying immunosuppressive compounds.

Developmental immunotoxicity (DIT) testing of pharmaceuticals: current practices, state of the science, knowledge gaps, and recommendations.

The development and regulatory approval of immunomodulatory pharmaceuticals to treat many human diseases has increased significantly over the last two decades. As discussed by FDA and ICH guidelines, all human pharmaceuticals in development should be evaluated for potential adverse effects on the immune system. Developmental immunotoxicology (DIT) focuses on the concern that early-life (during pre-/post-natal development) exposure to agents which target the immune system may result in enhanced susceptibility to immune-related disease (e.g., infection, autoimmunity, and cancer, particularly leukemia) compared to adults, unique effects not observed in adults, or more persistent effects in comparison to those following adult exposure. This article provides a substantive review of the literature and presents detailed considerations for DIT testing strategies with a specific focus on pharmaceuticals and biopharmaceuticals. In this regard, differences between small molecule and large molecule therapeutics will be considered, along with recommendations for best practices in the assessment of DIT during drug development. In addition, gaps in the DIT knowledge base and current testing strategies are identified. Finally, a summary of an ILSI-HESI-ITC sponsored Workshop conducted in 2010, entitled 'Developmental Immunotoxicity Testing of Pharmaceuticals' will be presented. This Workshop consisted of participants from the pharmaceutical, biotechnology, academic, and regulatory sectors, where many of the issues relating to DIT outlined in this review were discussed, key points of consensus reached, and current gaps in the science identified.

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., the tumor necrosis factor-alpha inhibitors), anti-adhesion molecule antibodies (e.g., anti-alpha-4 integrin inhibitors) and immunostimulatory molecules (e.g., anti-CD28 antibodies). Although several methods have been developed for nonclinical assessment of immunotoxicity, highly publicized adverse events have brought to light significant gaps in the application of nonclinical immunotoxicity testing in assessing potential risk in humans. Confounding this problem is inconsistent application of immunotoxicology methods for risk assessment within the scientific community, limited understanding of appropriate immunotoxicity testing strategy for immunomodulators and inconsistent testing requests by regulatory agencies. To address these concerns, The Immunotoxicology Technical Committee (ITC) of the International Life Science Institute (ILSI) Health and Environmental Sciences Institute (HESI) organized a workshop on Immunomodulators and Clinical Immunotoxicology in May 2007. The Workshop was convened to identify key gaps in nonclinical and clinical immunotoxicity testing of anti-inflammatory and immunomodulatory agents and to begin to develop consistent approaches for immunotoxicity testing and risk assessment. This paper summarizes the outcome of the HESI ITC Immunomodulators and Clinical Immunotoxicology Workshop. Topics not discussed at the Workshop were outside the scope of this report. Although more work is needed to develop consistent approaches for immunotoxicity assessment of immunomodulators, this Workshop provided the foundation for future discussion.

Preclinical immunogenicity testing for recombinant therapeutic proteins.

The assessment of the immunogenicity of recombinant therapeutic proteins (RTPs) has received more attention in the past 4 years than in the previous 20 years. The induction of clinically adverse events in RTP-treated patients and the subsequent measurement of antibodies to those RTPs has challenged the scientific community to re evaluate the methods and techniques used for determining the immunogenic potential of therapeutic proteins. One preclinical strategy for determining the relative immunogenicity of RTPs is the use of a comparative hyperimmunization technique in animals that optimizes an immunological response. This approach has utility for analyzing the immunogenic potential of different formulations as well as for potential adverse effects. The hyperimmunization model may also provide a source of antisera specific to the RTP that can be used during selection of the appropriate assay technique(s) and conditions for measuring the immune response. Solid- or liquid-phase, affinities and the frequency of washes, isotypes, and sensitivities are key parameters that have become the focus of assay development techniques. The techniques that will be discussed include enzyme-linked immunoassays, surface plasmon resonance (Biacore), and capillary electrophoresis.

Task force report: future research needs for the prevention and management of immune-mediated drug hypersensitivity reactions.

Immune-mediated drug hypersensitivity reactions (IDHR) have a significant impact on clinical practice, drug development, and public health. However, research to understand IDHR mechanisms and to develop diagnostic and predictive tests has been limited. To stimulate more research, a task force with representatives from the key stakeholders (research clinicians, regulatory scientists, and immunotoxicologists from the pharmaceutical industry) was assembled to identify critical data gaps and opportunities and to make recommendations on how to overcome some of the barriers to IDHR research and address research needs. It is hoped that this report will act as a springboard for future discussions and progress toward increased funding and development of organizational structures for IDHR research.