Protein Aggregates in Inhaled Biologics: Challenges and Considerations.

Pulmonary delivery is the main route of administration for treatment of local lung diseases. Recently, the interest in delivery of proteins through the pulmonary route for treatment of lung diseases has significantly increased, especially after Covid-19 pandemic. The development of an inhalable protein combines the challenges of inhaled as well as biologic products since protein stability may be compromised during manufacture or delivery. For instance, spray drying is the most common technology for manufacture of inhalable biological particles, however, it imposes shear and thermal stresses which may cause protein unfolding and aggregation post drying. Therefore, protein aggregation should be evaluated for inhaled biologics as it could impact the safety and/or efficacy of the product. While there is extensive knowledge and regulatory guidance on acceptable limits of particles, which inherently include insoluble protein aggregates, in injectable proteins, there is no comparable knowledge for inhaled ones. Moreover, the poor correlation between in vitro setup for analytical testing and the in vivo lung environment limits the predictability of protein aggregation post inhalation. Thus, the purpose of this article is to highlight the major challenges facing the development of inhaled proteins compared to parenteral ones, and to share future thoughts to resolve them.

Review of the Technical, Toxicological, and PKPD Considerations for Conducting Inhalation Toxicity Studies on Biologic Pharmaceuticals-The Outcome of a Cross-Industry Working Group Survey.

The inhaled route is still a relatively novel route for delivering biologics and poses additional challenges to those encountered with inhaled small molecules, further complicating the design and interpretation of toxicology studies. A working group formed to summarize the current knowledge of inhaled biologics across industry and to analyze data collated from an anonymized cross-industry survey comprising 12 inhaled biologic case studies (18 individual inhalation toxicity studies on monoclonal antibodies, fragment antibodies, domain antibodies, oligonucleotides, and proteins/peptides). The output of this working group provides valuable insights into the issues faced when conducting toxicology studies with inhaled biologics, including common technical considerations on aerosol generation, use of young and sexually mature nonhuman primates, pharmacokinetic/pharmacodynamic modeling, exposure and immunogenicity assessment, maximum dose setting, and no observed adverse effect levels determination. Although the current data set is too small to allow firm conclusions, testing of novel biologics remains an active area and is likely to remain so for molecules where delivery via the inhaled route is beneficial. In the future, it is hoped others will continue to share their experiences and build on the conclusions of this review to further improve our understanding of these complex issues and, ultimately, facilitate the safe introduction of inhaled biologics into clinical use.

BSTP Review of 12 Case Studies Discussing the Challenges, Pathology, Immunogenicity, and Mechanisms of Inhaled Biologics.

The inhalation route is a relatively novel drug delivery route for biotherapeutics and, as a result, there is a paucity of published data and experience within the toxicology/pathology community. In recent years, findings arising in toxicology studies with inhaled biologics have provoked concern and regulatory challenges due, in part, to the lack of understanding of the expected pathology, mechanisms, and adversity induced by this mode of delivery. In this manuscript, the authors describe 12 case studies, comprising 18 toxicology studies, using a range of inhaled biotherapeutics (monoclonal antibodies, fragment antigen-binding antibodies, domain antibodies, therapeutic proteins/peptides, and an oligonucleotide) in rodents, nonhuman primates (NHPs), and the rabbit in subacute (1 week) to chronic (26 weeks) toxicology studies. Analysis of the data revealed that many of these molecules were associated with a characteristic pattern of toxicity with high levels of immunogenicity. Microscopic changes in the airways consisted of a predominantly lymphoid perivascular/peribronchiolar (PV/PB) mononuclear inflammatory cell (MIC) infiltrate, whereas changes in the terminal airways/alveoli were characterized by simple ("uncomplicated") increases in macrophages or inflammatory cell infiltrates ranging from mixed inflammatory cell infiltration to inflammation. The PV/PB MIC changes were considered most likely secondary to immunogenicity, whereas simple increases in alveolar macrophages were most likely secondary to clearance mechanisms. Alveolar inflammatory cell infiltrates and inflammation were likely induced by immune modulation or stimulation through pharmacologic effects on target biology or type III hypersensitivity (immune complex disease). Finally, a group of experts provide introductory thoughts regarding the adversity of inhaled biotherapeutics and the basis for reasonable differences of opinion that might arise between toxicologists, pathologists, and regulators.

Periostin and Dipeptidyl Peptidase-4: Potential Biomarkers of Interleukin 13 Pathway Activation in Asthma and Allergy.

Periostin and dipeptidyl peptidase-4 (DPP-4) are proteins induced by type 2 cytokines interleukin (IL)-4 and IL-13 and show increased expression in asthma and diseases with type 2 inflammation, including atopic dermatitis and chronic rhinosinusitis. Both proteins can also be induced by other stimuli, such as profibrotic factors, which may confound their specificity as biomarkers of IL-13 pathway activation and type 2-driven disease. DPP-4 is important in glucose metabolism; therefore, serum concentrations may be confounded by the presence of concomitant metabolic disease. This review evaluates the potential of these biomarkers for anti-IL-13-directed therapy in asthma and diseases with type 2 inflammation.

Preclinical safety and biodistribution of Sindbis virus measles DNA vaccines administered as a single dose or followed by live attenuated measles vaccine in a heterologous prime-boost regimen.

Measles still causes considerable morbidity and mortality among infants and young children in developing countries. To develop a new public health tool to reduce this burden, we designed two Sindbis virus replicon vaccines encoding measles virus (MV) hemagglutinin (H) and fusion (F) proteins (pMSIN-H and pMSINHFdU). Our goal is to administer the vaccines to young infants at 6 and 10 weeks of age to prime the immune system to safely and effectively respond to subsequent immunization at age approximately 14 weeks with the licensed attenuated measles vaccine. In preparation for a phase 1 clinical trial, studies of plasmid distribution, integration, and toxicology were performed in rabbits. Biodistribution was assessed after a single DNA immunization delivered intradermally by needle-free injection. Toxicity was assessed using a heterologous prime-boost regimen consisting of a repeat-dose DNA prime followed by a live-attenuated measles vaccine boost. The only vaccine-related adverse effects observed were minimal transient erythema, edema, and inflammation confined to the injection site. Plasmids were detected in the subcutis and muscle at the site of inoculation. A small proportion of animals exhibited plasmids in the regional lymph nodes. There was no evidence of plasmid integration into the host genome. Both Sindbis-based vaccine plasmids were immunogenic in rabbits; pMSIN-H elicited higher virus-neutralizing antibody levels. Both vaccines were shown to be well tolerated and suitable for clinical trials and they are currently being tested in phase 1 studies in young adults.