Abstract 3863: Flow cytometry using stabilized whole blood to assess innate and adaptive immune cells (Monocytes, NK, T, and B cells) in immunotherapies

Abstract

Abstract Flow cytometry assays using fresh whole blood which are interrogating either an extremely rare cell subset or a depleting immunotherapy, may require samples to be processed from global clinical sites over a wide geographical area, which can pose a major challenge for clinical operations. Precision for Medicine (PfM) has addressed these operational challenges using commercial stabilizers which are added to the blood allowing samples to be frozen at -80°C and subsequently batch processed for sample testing. We have performed a fit for purpose assay qualification of a multiparameter flow cytometry panel allowing the immunophenotypic analysis of monocyte, T cell, B cell and NK immune populations using Cytodelics™ fixed/stabilized healthy donor whole blood. Additionally, the assay was verified in whole blood samples from multiple solid tumor disease states including melanoma, colorectal cancer, head & neck, non-small cell lung cancer to demonstrate clinical application. In these oncology samples, we were able to assess both immune cell frequencies and their activation status in both fresh whole blood as well as fixed whole blood over a short-term sample stability study, where the samples had been stored at -80°C for several months. This data provides a representative example of the use of commercial stabilizing fixatives for clinical studies to extend the stability window of whole blood for subsequent assessment by flow cytometry. Fixed whole blood can be stored at -80°C, shipped on dry ice allowing multiple timepoints in a cohort to be assessed together, thus minimizing assay variability as compared to fresh whole blood analysis, and mitigating the impact of shipping delays and temperature excursions on the samples. With sufficient time for assay development there are several commercial stabilizers that can be tested to determine if the markers in the flow assay are compatible with these reagents, providing a valuable option to assess the impact of immunotherapies on the immune cells of interest and reducing operational challenges in global studies. Citation Format: Jackie Benko, Samantha Splitt, Angelina Bisconte, Laura Lozza, Rachel Owen, Deborah Phippard. Flow cytometry using stabilized whole blood to assess innate and adaptive immune cells (Monocytes, NK, T, and B cells) in immunotherapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3863.