Abstract P3-08-58: Ratio of CD8 +/ FOXP3, number of FOXP3 + cells and the presence of PTEN labeling in tumor cells and association with survival in triple negative breast cancer

Abstract

Introduction: Triple-negative mammary carcinomas (CMTN) correspond to about 15 to 20%, the subtype being more aggressive when compared to the others. The interaction between immune system cells and cancer plays a crucial role in tumor development and progression. However, it is still unclear whether the presence of CD8 cytotoxic lymphocytes provides any prognostic information in breast cancer. Objective: To evaluate the prognostic significance of tumor-associated FOXP3 regulatory T cells (Tregs) and CD8 cytotoxic T lymphocytes (CTLs) in invasive breast carcinomas Method: This is an observational, descriptive retrospective cohort study were evaluated 76 patients diagnosed with non metastatic (stages I, II and III) TNBC. A tissue microarray (TMA) was constructed containing two cores from each tumor block. The expression of CD4, CD8, FOXP3, CD20, CD68, CD163, PD-1, PD-L1, PTEN and phosphoSTAT1 was determined by immunohistochemistry in the TMA. Results: We observed that the inflammatory infiltrate in TNBC is enriched for M2 macrophages and T lymphocytes (CD4+, CD8+ and FOXP3+). In our sample, we observed better survival associated with a higher CD8 + (p = 0.054) and CD4 + (p = 0.082) cell counts, but with no statistical significance in both situations. However, when we analyzed the association of overal survival (OS) with the ratio between the number of CD8 + cells and FOXP3 + (p = 0.007) and CD4 + and FOXP3 + (p = 0.034) and CD4 (p = 0.058) cells, we found that a higher relative proportion of CD8 + or CD4 + lymphocytes in relation to lymphocytes FOXP3 + was associated with an increase in OS. Together, these data suggest that infiltration by T lymphocytes into the tumor microenvironment should exhibit antirumor activity and promote growth control and tumor progression, as opposed to events favoring immunosuppression (regulatory lymphocyte infiltration). The number of FOXP3+ cells and the presence of PTEN staining in tumor cells were associated with OS. Conclusion: We did not observe improvement in survival, with an increase in CD8 and CD4 alone, so we found an improvement in survival, the higher the ratio between CD8 / FOXP3 being statistically significant. The number of FOXP3+ cells and the presence of PTEN staining in tumor cells were associated with OS. Citation Format: Monique C Tavares, Geraldine E Lima, Cristina D Sampaio, Victor P Andrande, Daniel G Gonçalves, Mariana P Macedo, Vladmir C Lima. Ratio of CD8 +/ FOXP3, number of FOXP3 + cells and the presence of PTEN labeling in tumor cells and association with survival in triple negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-58.