Neutralization Activity of Anti-drug Antibodies Against a Biotherapeutic Can Be Predicted from a Comprehensive Pharmacokinetics, Pharmacodynamics, and Anti-drug Antibody Data Analysis.

Historically, a neutralization antibody (NAb) assay is considered critical in immunogenicity assessment of biologic therapeutics, even with low anti-drug antibody (ADA) positive rates. In 2019, FDA new guidelines issued on immunogenicity testing acknowledged the possibility of using "a highly sensitive PD marker or an appropriately designed PK assay or both that generate data that inform clinical activity" to replace a NAb assay. In the current manuscript, we present data for PK, PD, and ADA assays which collectively succeed to replace the standalone NAb assay. The data include a total LC/MS-based PK assay, a serum neutralization antibody (SNA) assay that essentially measures pharmacodynamically functional PK and can detect NAb activity in the presence of 1:1 ratio of drug, and a highly drug-tolerant ADA assay. In addition, a model-based meta-analysis (MBMA) demonstrated that the ability of SNA assay to detect NAb at 1:1 ratio of drug is sensitive enough to monitor clinically meaningful efficacy change, which is 50% reduction of SNA titer. Our strategy of preparing a holistic data package discussed here may provide a roadmap to the community for alternatives in assaying neutralizing activity of ADA.

The Preservation of Bone Cell Viability in a Human Femoral Head through a Perfusion Bioreactor.

Current methods for drug development and discovery involve pre-clinical analyses that are extremely expensive and time consuming. Animal models are not the best precedent to use, when comparing to human models as they are not synonymous with the human response, thus, alternative methods for drug development are needed. One of which could be the use of an ex vivo human organ where drugs could be tested and the effects of those drugs could be observed. Finding a viable human organ to use in these preliminary ex vivo studies is difficult due to the availability, cost, and viability. Bone tissue and marrow contain a plethora of both bone and stem cells, however, these cells need constant perfusion to be viable over a longer time range. Here we maintain bone cell sustainability in an ex vivo model, through the use of human femoral heads in a novel bioreactor. This bioreactor was designed to directly perfuse cell culture media (DMEM) through the vasculature of a femoral head, providing ideal nutrients and conditions required for maintaining organ viability. We show, for the first time, that cells within a femoral head can stay alive up to 12 h. Further development could be used to determine the effects of drugs on a human organ system and could aid in the understanding of the progression of bone diseases and pathologies.