Abstract 1739: Detection of regulatory T cells, a comparison of flow cytometry and epigenetic qPCR immunophenotyping using healthy donor and oncology patient whole blood

Abstract

Abstract Human regulatory T cells (Tregs) are part of the adaptive immune response and play a pivotal role in suppressing both the immune and anti-tumor responses. Infiltration of Tregs into the tumor microenvironment has been associated with poor clinical prognosis. In addition, increased peripheral Treg frequency is associated with disease progression. Monitoring Tregs in both the blood and in the tumor of patients is being used to evaluate clinical prognosis and response to treatment in immuno-oncology studies. The key challenge is the ability to detect Tregs with high accuracy and precision. Here, we have used epigenetic qPCR (Epiontis ID®) as a method to detect and quantify Tregs in peripheral whole blood and compared it with flow cytometry. Flow cytometry is the current gold standard for immunophenotyping. For method comparison, we analyzed 113 whole blood samples from healthy donors. We have demonstrated equivalence and shown a strong correlation between epigenetic qPCR and flow cytometry-based data, indicating that Epiontis ID® is a robust and sensitive DNA-based method for Treg quantification. This epigenetic qPCR method does not require fresh samples or intact cells, since DNA can be extracted from frozen blood. We then evaluated Treg levels in blood samples from solid tumor cancer patients by epigenetic qPCR to demonstrate the clinical application and relevance for immune monitoring. Here, Treg frequencies were reported as relative (%) and absolute counts (cells/µL) values. Epigenetic qPCR for immune monitoring mitigates the operational and technical challenges of monitoring Tregs in the periphery for immuno-oncology studies which traditionally been performed by flow cytometry. This Epiontis ID® method provides the sensitivity and accuracy needed for determining patient response in progressive disease. Citation Format: Udo Baron, Laura Lozza, Angelina Bisconte, Eva Raschke, Deborah Phippard, Sven Olek. Detection of regulatory T cells, a comparison of flow cytometry and epigenetic qPCR immunophenotyping using healthy donor and oncology patient whole blood [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 1739.