High molecular weight polyethylene glycol cellular distribution and PEG-associated cytoplasmic vacuolation is molecular weight dependent and does not require conjugation to proteins.

Conjugation of therapeutic proteins with high molecular weight polyethylene glycols (HMW PEGs) is used to extend the half-life of biologics. To evaluate the effects of HMW PEGs in animals, we used an immunohistochemical procedure to study the tissue distribution and toxicity of unconjugated HMW PEGs in rats given 100 mg/kg (10K)PEG, (20K)PEG, or (40K)PEG intravenously. Both the PEG cellular distribution and the histology were different between groups. In (10K)PEG and (20K)PEG groups, PEG immunoreactivity was most prominent in the renal tubule epithelium and in alveolar macrophages and hepatic Kupffer cells and cellular vacuolation was absent. In contrast, rats given (40K)PEG had strong PEG immunoreactivity in splenic subcapsular red pulp macrophages, renal interstitial macrophages, and choroid plexus epithelial cells that was frequently associated with cytoplasmic vacuolation. While the vacuolation appeared to be an adaptive response, there was focal renal tubular epithelial degeneration associated with strong PEG immunoreactivity in one rat given (40K)PEG. These data indicate that both the tissue distribution and the vacuolation observed with unconjugated HMW PEGs are markedly influenced by the molecular weight of the PEG and that when vacuolation is observed it is likely an adaptive change that is associated with PEG cytoplasmic immunoreactivity.

Carcinogenicity assessments of biotechnology-derived pharmaceuticals: a review of approved molecules and best practice recommendations.

An important safety consideration for developing new therapeutics is assessing the potential that the therapy will increase the risk of cancer. For biotherapeutics, traditional two-year rodent bioassays are often not scientifically applicable or feasible. This paper is a collaborative effort of industry toxicologists to review past and current practice regarding carcinogenicity assessments of biotherapeutics and to provide recommendations. Publicly available information on eighty marketed protein biotherapeutics was reviewed. In this review, no assessments related to carcinogenicity or tumor growth promotion were identified for fifty-one of the eighty molecules. For the twenty-nine biotherapeutics in which assessments related to carcinogenicity were identified, various experimental approaches were employed. This review also discusses several key principles to aid in the assessment of carcinogenic potential, including (1) careful consideration of mechanism of action to identify theoretical risks, (2) careful investigation of existing data for indications of proliferative or immunosuppressive potential, and (3) characterization of any proliferative or immunosuppressive signals detected. Traditional two-year carcinogenicity assays should not be considered as the default method for assessing the carcinogenicity potential of biotherapeutics. If experimentation is considered warranted, it should be hypothesis driven and may include a variety of experimental models. Ultimately, it is important that preclinical data provide useful guidance in product labeling.

A 6-month inhalation study to characterize the toxicity, pharmacokinetics, and pharmacodynamics of human insulin inhalation powder (HIIP) in beagle dogs.

The purpose of this study was to characterize the toxicity, pharmacokinetics, and pharmacodynamics of human insulin inhalation powder (HIIP) in beagle dogs when administered daily as an aerosolized dry powder formulation for 26 weeks via head-only inhalation. Conscious beagle dogs were exposed for 15 mins/day to an air control, placebo, maximal placebo (approximately three-fold the placebo dose), or one of three doses of HIIP (mean inhaled doses of 80, 240, or 701 microg/kg/day for the HIIP-low, HIIP-mid, and HIIP-high dose, respectively), The mass median aerodynamic diameters (MMAD) were between 2 and 3 microm and geometric standard deviation (GSD) values were approximately 2 across the groups, which is the ideal size range for favorable lung deposition. All groups were comprised of four dogs/sex, with the air control, HIIP-high, and maximal placebo groups having an additional two dogs/sex as recovery subgroups. Concentrations of serum insulin and glucose were determined from blood samples obtained following the first and last exposure for evaluation of the pharmacokinetics and pharmacodynamics of HIIP. Dose-related exposure (C(max), AUC) to inhaled insulin was observed with rapid absorption and no apparent gender differences or accumulation after repeated inhalation exposures for 26 weeks. The expected pharmacological effect of insulin was observed with dose-related decreases in serum glucose levels following HIIP administration. There were no toxic effects observed including no HIIP or placebo treatment-related effects on mean body weights, absolute body weight changes, clinical observations, food consumption, respiratory function parameters, ophthalmic examinations, electrocardiograms, heart rates, clinical pathology, or urinalysis. Similarly, there were no HIIP or placebo treatment-related effects on pulmonary assessments that included respiratory function parameters, bronchial alveolar lavage assessments, organ weights, or macroscopic and microscopic evaluations, including lung cell proliferation indices. HIIP was considered to have either low or no immunogenic potential in dogs. The no-observed-adverse-effect level (NOAEL) and maximum tolerated dose were the average inhaled dose of 701 microg insulin/kg/day.

Challenges and opportunities for the future of monoclonal antibody development: Improving safety assessment and reducing animal use.

The market for biotherapeutic monoclonal antibodies (mAbs) is large and is growing rapidly. However, attrition poses a significant challenge for the development of mAbs, and for biopharmaceuticals in general, with large associated costs in resource and animal use. Termination of candidate mAbs may occur due to poor translation from preclinical models to human safety. It is critical that the industry addresses this problem to maintain productivity. Though attrition poses a significant challenge for pharmaceuticals in general, there are specific challenges related to the development of antibody-based products. Due to species specificity, non-human primates (NHP) are frequently the only pharmacologically relevant species for nonclinical safety and toxicology testing for the majority of antibody-based products, and therefore, as more mAbs are developed, increased NHP use is anticipated. The integration of new and emerging in vitro and in silico technologies, e.g., cell- and tissue-based approaches, systems pharmacology and modeling, have the potential to improve the human safety prediction and the therapeutic mAb development process, while reducing and refining animal use simultaneously. In 2014, to engage in open discussion about the challenges and opportunities for the future of mAb development, a workshop was held with over 60 regulators and experts in drug development, mechanistic toxicology and emerging technologies to discuss this issue. The workshop used industry case-studies to discuss the value of the in vivo studies and identify opportunities for in vitro technologies in human safety assessment. From these and continuing discussions it is clear that there are opportunities to improve safety assessment in mAb development using non-animal technologies, potentially reducing future attrition, and there is a shared desire to reduce animal use through minimised study design and reduced numbers of studies.

Immunomodulation and lymphoma in humans.

Observational and clinical studies have associated increased cancer risks with primary or acquired immunodeficiencies, autoimmunity, and use of immunotherapies to treat chronic inflammation (e.g. autoimmunity) or support organ engraftment. Understanding of the relationship between immune status and cancer risk is generally grounded in two juxtaposing paradigms: that the immune system protects the host via surveillance of tumors and oncogenic viruses (e.g. immunosurveillance model) and that chronic inflammation can augment tumor growth and metastasis (inflammation model). Whereas these models support a role of immune status in many cancers, they are insufficient to explain the disproportionate increase in B-cell lymphoma risk observed across patient populations with either chronic immunosuppression or inflammation. Evaluation for the presence of Epstein-Barr virus (EBV) in lymphomas obtained from various populations demonstrates a variable role for the virus in lymphomagenesis across patient populations. An evaluation of the DNA alterations found in lymphomas and an understanding of B-cell ontogeny help to provide insight into the unique susceptibility of lymphocytes, primarily B-cells, to oncogenic transformation. EBV-independent B-cell oncogenic transformation is driven by chronic antigenic stimulation due to either inflammation (as seen in patients with autoimmune disease or a tissue allograft) or to unresolved infection (as seen in immunosuppressed patients), and the transformation arises as a result of DNA damage from genomic recombination and mutation during class switching and somatic hypermutation. This model explains the increased background rate of lymphoma in some patients with autoimmunity, and highlights the challenge of resolving the confounding that occurs between disease severity and use of targeted immunotherapies to treat chronic inflammation. The ability to distinguish between disease- and treatment-related risk of lymphoma and an appreciation of the etiology of B-cell transformation is central to an improved risk assessment by scientists, clinicians and regulators, including the approval, labeling, and chronic use of immunotherapies.

Duration of chronic toxicity studies for biotechnology-derived pharmaceuticals: is 6 months still appropriate?

For chronic use biotechnology-derived pharmaceuticals, toxicity studies of 6 months have generally been accepted for regulatory approval. This review assessed the data for 23 approved biotechnology-derived pharmaceuticals to determine whether the studies conducted were predictive of human safety and whether there is new data from approved products indicating that longer than 6 months is necessary. This assessment involved three approaches; whether new toxicities were identified at >6 months, similarity of findings between 6 months and shorter studies and predictivity of clinical adverse events. In two cases there were apparently new findings in studies >6 months. On examination however, one of these cases was a well established risk with foreign protein administration to animals (adalimumab). For insulin aspart, the 12 month study identified tumors not seen in shorter term studies, however, determination of carcinogenic potential is not a goal of chronic toxicity studies and is addressed by separate studies. In most cases the toxicology studies were predictive of common clinical adverse reactions, but were poorly predictive of rare clinical events or some serious adverse reactions. Although specific circumstances may require a longer study, this review indicates no new data is available to refute the utility of 6 month studies to support chronic clinical dosing with biotechnology-derived pharmaceuticals.

Safety assessment of biopharmaceuticals: Japanese perspective on ICH S6 guideline maintenance.

Safety assessment of biopharmaceuticals in preclinical studies is guided by the ICH S6 guideline issued in 1997. Along with enormous experiences and knowledge on safety assessment of some classes of biopharmaceuticals over the last decade, the necessity and feasibility of updating the guideline has been discussed. According to a recommendation by safety experts at the ICH meeting in Chicago in 2006, regional discussions of ICH S6 were held in the USA, EU and Japan. The meeting to clarify the values, challenges and recommendations for ICH S6 from Japanese perspective was held as a part of the first Drug Evaluation Forum in Tokyo on August 10, 2007. Of utmost importance, the "case-by-case" approach must be preserved as the basic principle of the ICH S6 guideline. It is our opinion that oligonucleotides, siRNA, aptamers and related molecules should be excluded from ICH S6 and may be more appropriate for separate guidance. However, based on experiences and accumulated knowledge, there are a number of issues that can be updated including new types of biopharmaceuticals such as bioconjugates, use of homologous proteins and transgenic animals, reproductive/developmental toxicity studies in non-human primates, in vitro cardiac ion channel assay and alternative approaches for carcinogenicity assessment. Preliminary recommendations for some of these topics were outlined at the meeting. The overall Japanese recommendation is that the ICH S6 guideline should be updated to address these topics.