Pharmaceutical giant Pfizer cite the use of HemaCare starting materials in the development of a new immune cell validation assay. 
The new assay is designed to measure dendritic cell activation as a predictor of immunogenicity, so that scientists can assess risk early in the development of new pharmaceuticals. Low immunogenicity points toward a better overall safety profile.
Dendritic cells (DC) are antigen-presenting cells, involved in the initiation and regulation of the immune response. Since DC are tumor-infiltrating cells central to the initiation of antigen-specific immunity, they have long been investigated as a means of improving cancer immunotherapy.
Immunotherapy development is a complicated process. Scientists must promote strong immune activity against cancer cells, while at the same time assuring that the immunogenicity of the therapeutic proteins themselves do not cause dangerous side effects in the patient.
The authors of the Pfizer study set out to validate their new dendritic cell activation assay using what is known as a “fit-for-purpose” (FFP) test. To achieve this, the scientists used HemaCare sourced PBMCs from 21 healthy human donors. CD14+ monocytes were isolated from the PBMCs by positive selection. Following isolation, CD14+ cells from each donor were individually cultured under conditions known to promote differentiation into dendritic cells.
One of the strongest gauges of an effective validation assay is robust reliability in the face of multiple variable factors. Inter-donor variability is one of the largest contributors to overall assay variability, but other factors such as testing day, number of replicates, and multiple analysts all contribute to the risk of an inaccurate result.
Inter-donor variability of the author’s 21-donor experiment was assessed through the measurement of 3 known dendritic cell activation markers. As expected, each donor showed varying degrees of immune response to foreign antigens, yet in total, the authors logged less than 30% variability for all 3 markers across the 21 donors.
In addition to variability, the researchers studied sensitivity, reproducibility, and the reliability of positive response thresholds. These parameters inform scientists of the lowest concentration of foreign antigen at which they can expect a positive immune response, as well as the reproducible limit of detection of the assay. The FFP test showed that dendritic cell activation results were highly reproducible, with biologically valid sensitivity. The donor cohort size and in-study donor acceptance criteria gave the authors additional confidence that the responses they were seeing were real and representative of the risk of dendritic cell activation. In summary, the Pfizer group were satisfied that the new assay will provide reliable and valid measurements of dendritic cell activation.
Assays that evaluate the immunogenicity of cell therapy treatments are used to determine responses in clinical trials, and to assess the risk immunotherapy candidates carry of triggering an unwanted immune response. They provide a critical method of evaluating immunotherapy candidate safety early in development. At HemaCare, we are proud to support immunotherapy risk management through the supply of consistent high-quality materials.
- Wickramarachchi D., et al. Fit-for-Purpose Validation and Establishment of Assay Acceptance and Reporting Criteria of Dendritic Cell Activation Assay Contributing to the Assessment of Immunogenicity Risk. The AAPS Journal. 22: 114. 2020.