CD103 and Intratumoral Immune Response in Breast Cancer.

Abstract

CD103 is expressed in several immune cell types but in the context of the intratumoral immune response may be most important as a marker of antigen-activated CD8 T cells. We have examined the prognostic significance of CD103 TILs in breast cancer by IHC in a cohort of 424 breast cancer patients. CD103 TILs were present in all subtypes but were more abundant in ER-negative tumors where CD103 TILs were preferentially localized to the intraepithelial compartment. CD103 was associated with tumor size, tumor grade, and ER/PR status (P < 0.05). CD103 TIL density and the epithelial to stromal ratio was highest in the basal-like tumors. Intraepithelial CD103 but not intrastromal CD103 was associated with better relapse-free and overall survival in basal-like subtype tumors [HR = 0.28; 95% confidence interval (CI), 0.17-0.72; P = 0.0047 and HR = 0.25; 95% CI, 0.17-0.66; P = 0.0017, respectively). CD8 status showed similar but less significant associations, but the combination of dual CD103⁺CD8⁺ TIL status was the most strongly prognostic combination for relapse-free and overall survival (HR = 0.10; 95% CI, 0.07-0.62; P = 0.006 and HR = 0.09; 95% CI, 0.07-0.57; P = 0.003, respectively). CD103 TILs are indicative of a good prognosis specifically within the basal-like subtype of breast cancer. Clin Cancer Res; 22(24); 6290-7. ©2016 AACR.