Abstract 627: Custom Vectra® Polaris™ fluorescent multiplex IHC panel identifies mature tertiary lymphoid structures in colorectal cancer

Abstract

Abstract Introduction: Tertiary lymphoid structures (TLS) are promising prognostic indicators of positive outcomes for patients with solid tumors including colorectal cancer (CRC) [1]. Large-scale retrospective analysis shows patients with mature TLS in particular respond to PD-1/PD-L1 antibody treatment with improved objective response, progression-free and overall survival [2]. Since not all patients respond to PD-1/PD-L1 antibody treatment, identifying patients with mature TLS is clinically relevant as it enables selection of patients likely to respond to immune checkpoint blockade. Mature TLS are composed of T cells (CD3+), follicular B cells (CD20+), germinal center B cells (CD23+), and follicular dendritic cells (CD21+) [3]. The ability to identify and evaluate TLS is limited by detection methods which traditionally employ hematoxylin and eosin (H&E) staining for visual quantification of immune aggregates, potentially significantly underestimating their quantity [4]. Multiplexed fluorescent immunohistochemistry (IHC) detection assays have the capability to precisely quantify mature TLS within the TME. Colorectal cancer specimens expressing a dynamic range of TLS are stained with a novel custom Vectra® Polaris™ multiplex immunofluorescence panel detecting CD20, CD21, CD23, CD3 and pan-cytokeratin. Identification of mature TLS with CD3+CD20+CD21+ and CD3+CD20+CD23+ expression in the TME is reported. Results: Vectra® Polaris™ TLS multiplex immunofluorescence panel successfully identified mature TLS in the TME of colorectal cancer patient samples. TLS were quantified via custom analytics algorithms generated with Indica HALO software. Conclusion: Characteristics of TME immunity in colorectal cancer differentially impact an individual patient’s odds of survival [5]. The novel Vectra® Polaris™ multiplex assay in this study shows a detailed picture of mature TLS in patient cancer samples. Future applications of this panel include investigations of TLS associated with successful anti-tumor immune development and therapeutic response to treatment. [1] Oncoimmunology. 2020; 9(1): 1724763 [2] Nat Cancer. 2, 794-802 (2021) [3] Oncoimmunology. 2021; 10(1): 1900508. [4] Mod Pathol 2017 Sep;30(9):1204-1212. doi: 10.1038/modpathol.2017.43. [5] Cell. 2020 Sep 3;182(5):1341-1359.e19. doi: 10.1016/j.cell.2020.07.005 Citation Format: Sara G. Pollan, Arezoo Hanifi, James Hargrove, Erinn A. Parnell, Jessica Lin, Josette William Ragheb, Qingyan Au. Custom Vectra® Polaris™ fluorescent multiplex IHC panel identifies mature tertiary lymphoid structures in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 627.