Flow cytometry in cancer immunotherapy: Applications, quality assurance, and future

Abstract

Cancer immunotherapy seeks to elicit or augment the antitumor immune response in a patient in order to enlist the help of the patient’s own immune system for tumor control. In this context, immune monitoring provides evidence of immunogenicity, guides the choice and dosage of antigens, assesses the effects of immune modulators and therapy combinations, and has the potential to reveal early biomarkers of clinical efficacy. In view of their role in the anticancer immune response, the quantity and quality of tumor antigen-specific effector CD4+ and CD8+ T cells are of particular interest, and characterization of regulatory T cells and myeloid-derived suppressor cells is increasingly relevant. The canonical multiparameter assay for the characterization of immune cells is polychromatic flow cytometry, and it is ubiquitously used for immune monitoring in preclinical tumor immunology and in cancer immunotherapy trials. This chapter describes the main flow cytometry methods being applied in cancer immunotherapy, with an emphasis on recent progress in the field, challenges associated with quality control, its promise to reveal biomarkers of clinical efficacy, and further developments that are likely to be rapidly implemented in routine cancer immunology.