Clinicopathological Correlates of γδ T Cell Infiltration in Triple-Negative Breast Cancer.

The prognostic impact of the different tumor-infiltrating lymphocyte (TIL) subpopulations in solid cancers is still debated. Here, we investigated the clinicopathological correlates and prognostic impact of TILs, particularly of γδ T cells, in 162 patients with triple-negative breast cancer (TNBC). A high γδ T cell density (>6.625 γδ T cells/mm) was associated with younger age ( = 0.008), higher tumor histological grade ( = 0.002), adjuvant chemotherapy ( = 0.010), promoter methylation ( = 0.010), TIL density ( < 0.001), and PD-L1 ( < 0.001) and PD-1 expression ( = 0.040). In multivariate analyses, γδ T cell infiltration (cutoff = 6.625 γδ T cells/mm) was an independent prognostic factor (5-year relapse-free survival: 63.3% vs. 89.8%, = 0.027; 5-year overall survival: 73.8% vs. 89.9%, = 0.031, for low vs. high infiltration). This prognostic impact varied according to the tumor mutational status. High γδ T cell infiltration was associated with better survival in patients with wild-type tumors, but the difference was not significant in the subgroup with -mutated tumors. Altogether, these data suggest that high γδ T cell infiltrate is correlated with immune infiltration and might represent a candidate prognostic tool in patients with TNBC.