Abstract B87: CXCL13-producing follicular helper CD4+ T cells infiltrating human breast cancer signal an organized immune response and predict a favorable clinical outcome.

Abstract

Abstract CD4+ T cells are critical regulators of immune responses but their functional role in human breast cancer is relatively unknown. The goal of this study was to produce a comprehensive image of CD4+ T cells infiltrating breast tumors (TIL) using limited ex vivo manipulation to better understand the in vivo differences associated with patient prognosis. Toward this goal we employed gene expression arrays, qRT-PCR, flow cytometry and immunohistochemistry to produce molecular profiles of CD4+ T cells freshly isolated from untreated invasive primary breast tumors (n=70) compared with non-adjacent breast tissue and CD4+ T cells isolated from the lymph nodes and blood. Gene expression profiling of the TIL discovered a CD4+ follicular helper T (Tfh) cell presence along with Th1, Th2 and Th17 effector memory and Treg subpopulations. TIL expression patterns revealed alterations in T cell signaling pathways that reflect a mixture of activation and suppression characterized by restricted cytokine/chemokine production, which inversely parallel lymphoid infiltration levels and can be reproduced in activated donor CD4+ T cells treated with primary tumor supernatant. Comparison of extensive versus minimally-infiltrated tumors led to a key finding that extensive immune infiltrates are distinguished by CD4+ Tfh cells principally located in the germinal centers of organized tertiary lymphoid structures (TLS). Similar to secondary lymphoid organs, the TLS are composed of a T cell zone containing a majority of CD4+ T cells and a B cell follicle that includes Tfh and follicular dendritic cells along with the B cells. The CD4+ Tfh cells (and not tumor cells) were identified as the major producer of the potent B cell chemoattractant CXCL13, known for its role in promoting lymphoid neogenesis. An increased peri-tumoral TLS presence parallels an elevated level of intra-tumoral leukocytes (principally CD8+ T cells). Our data suggest that the level of tumor-mediated T cell suppression reflects not just the intrinsic suppressive quality of the tumor itself but also the presence (or not) of TLS, which successfully sequester lymphocytes for activation in a protected microenvironment adjacent to the tumor. An eight gene Tfh signature derived from the expression data powerfully predicted long-term survival in a patient cohort with >10-year survival (n=794) or pathological complete response in patients treated with preoperative chemotherapy (n=996). Our identification of CD4+ Tfh cells as a new key immune element in breast cancer, linked with organized immunity and associated with a higher response rate to chemotherapy and/or excellent long-term clinical outcome, suggests that their detectable presence is an important prognostic factor. Citation Format: Chunyan Gu-Trantien, Karen Willard-Gallo. CXCL13-producing follicular helper CD4+ T cells infiltrating human breast cancer signal an organized immune response and predict a favorable clinical outcome. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B87.