An immune stratification reveals a subset of PD-1/LAG-3 double-positive triple-negative breast cancers

Abstract

BackgroundStromal tumor-infiltrating lymphocytes (TILs) are a robust prognostic factor in triple-negative breast cancer (TNBC). However, the clinical significance of TILs may be influenced by the complex landscape of the tumor immune microenvironment. In this study, we aimed to evaluate the composition and the functionality of lymphocytic infiltration and checkpoint receptors in TNBC.MethodsFormalin-fixed, paraffin-embedded tissues were retrospectively collected from a cohort of patients with early-stage TNBC treated with adjuvant anthracycline-based chemotherapy (n = 259). Results were validated in an independent cohort of patients with TNBC (n = 104). Stromal TILs were evaluated on hematoxylin-and-eosin-stained sections. The density of CD4+, CD8+, and FOXP3+ lymphocytes, and the expression of the immune checkpoints PD-1 and LAG-3, were assessed by immunohistochemical analysis.ResultsThe presence of elevated TILs positively correlated with the density of all T cell subtypes, especially cytotoxic CD8+ lymphocytes. We showed that increasing stromal TILs assessed as a continuous variable is an independent prognostic marker of prolonged relapse-free survival and overall survival in TNBC. Among immune subpopulations, CD8+ lymphocytes are the main effectors of anti-tumor immune responses. In two independent cohorts, we found that PD-1 and LAG-3 were concurrently expressed in approximately 15% of patients with TNBC. The expression of both checkpoint receptors positively correlated with the presence of TILs, but was not significantly associated with patient outcome.ConclusionsOverall, our data indicate that the evaluation of stromal TILs remains the most reliable immune prognostic marker in TNBC, and support the clinical evaluation of anti-PD-1/PD-L1 and anti-LAG-3 in a subset of patients with TNBC who have concurrent expression of both checkpoint receptors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-016-0783-4) contains supplementary material, which is available to authorized users.

TIM-3 expression in breast cancer

“…Studies from our group and from others have been consistent in finding that the presence of immune checkpoint markers on intra-epithelial TILs in breast tumors is an uncommon event, and mostly restricted to ER- breast cancers 33,36,37 . However, TILs positive for immune checkpoint markers are able to discriminate breast cancer patients with favorable survival, consistent with an active anticancer immune microenvironment.…”

T cell exhaustion in cancer: Mechanisms and clinical implications

“…Recent data shows that in some tumors such as NSCLC, breast cancer and squamous cell carcinoma (SCC), the expression of LAG‐3 is higher and positively correlated with PD‐1/PD‐L1 expression . LAG‐3 as well as PD‐L1 could partially represent poor prognostic in early postoperative patients .…”

“…26 Recent data shows that in some tumors such as NSCLC, breast cancer and squamous cell carcinoma (SCC), the expression of LAG-3 is higher and positively correlated with PD-1/PD-L1 expression. [27][28][29] LAG-3 as well as PD-L1 infection, naive T cells are activated by antigen and they proliferate to form effector T cells. During acute infection where antigen is cleared, effector CD8 + T cells differentiate into memory CD8 + T cells that can produce cytokines and cause punchy recall responses upon secondary infection.…”

LAG3: The Biological Processes That Motivate Targeting This Immune Checkpoint Molecule in Human Cancer

“…PD-1 and LAG3 were shown to be concomitantly expressed in approximately 15% of TNBC patients and positively correlated with a TIL presence in another study [71]. However, PD-1 and LAG3 expression was not significantly associated with patient outcome in this dataset, potentially because authors did not perform spatial analysis of LAG3 + cells in the TME [72]. Their data identified an increased probability of achieving a pathologic complete response following neoadjuvant treatment if pre-treatment biopsies highly expressed LAG3, finding it was correlated with PD-1 and PD-L1 expression.…”