To Assess the Predictive and Prognostic Role of PD-L1 and CD8 Following Neoadjuvant Chemotherapy in Breast Cancer

Neoadjuvant chemotherapy (NACT), introduced in 1970 for inoperable tumors, has become the standard treatment approach in locally advanced breast cancer (LABC). Pathological complete response (pCR) following NACT is an important indicator for disease-free survival. An increased number of CD8-positive tumor-infiltrating lymphocytes (TILs) in the tumor center is thought to indicate an effective antitumor-immune response. Aberrant expression of programmed death ligand-1 (PD-L1) allows tumor cells to escape the host immune system. Change in PD-L1 expression may serve as an indirect indicator to assess the response to NACT. The residual cancer burden (RCB) category defined by routine histopathological evaluation represents the extent of residual disease and may predict disease-free survival. In this study, we assessed the expression of PD-L1 and CD8 in pre- and post-NACT specimens and their role in predicting pathological response to NACT. This study was conducted for a period of 3 years at Uttar Pradesh University of Medical Sciences, Saifai. PD-L1 and CD8 expression was compared on pre- and post-NACT tissue specimens. Pathological response to NACT was assessed by the RCB system. A total of 62 cases were evaluated. The mean age of patients was 47.58 ± 11.16 years. Six (9.7%) patients achieved pCR (RCB-0). PD-L1 and CD8 expression was found to be positively associated with pathological response (P < 0.001 for both). Tumors with negative PD-L1 (OR = 0.02) and pre-NACT intermediate/low expression of CD8 in TILs (OR = 0.11) are less likely to show a response to NACT. Prognostic role of PD-L1 and CD8 was also assessed by the Nottingham prognostic index (NPI). The expression of PD-L1 and CD8-positive TILs correlate with response to chemotherapy. High PD-L1 and CD8-positive TILs may predict better response to neoadjuvant chemotherapy.