RESUMO
BACKGROUND: Locally advanced triple-negative breast cancer (TNBC) represents a public health problem in Brazil. Its standard treatment consists of neoadjuvant chemotherapy (NAC). METHODS: This was a longitudinal study with follow-up performed between the years 2015 and 2017. Thirty women with locally advanced TNBC submitted to NAC, and 30 healthy were included. Peripheral blood samples were collected before NAC (Pre-NAC) and after NAC (Post-NAC). RESULTS: Patients with TNBC had elevated levels of CD28+ T, FAS+ T, CTLA4+ T, PD1+ T, CD28+CD4+ T, PD1+CD4+ T and CD8+ T and PD1+ CD8+ T cells compared to controls (p < 0.05). Patients with pathological complete response (pCR) had low FAS+ T cells, FAS+CD4+ T cells, and PD1+CD8+ T cells compared to the non-pCR (p < 0.05). Significant differences were observed in the levels of CD28+ T cells, FAS+ T and PD1+ T, CD4+ T, CD28+CD4+ T, FAS+CD4+ T, PD1+CD4+ T, CD8+ T, and PD1+CD8+ T cells between Pre-NAC and Post-NAC groups (p < 0.05). CONCLUSION: Alterations in the circulating FAS+CD4+ T and PD1+CD8+ T cell levels Pre-NAC are associated with pCR, suggesting potential predictive biomarkers of NAC response in TNBC. The largest changes in the cellular immune response profile Post-NAC showed that chemotherapy treatment can modulate the immune response and that it is associated with prognosis in TNBC.