Relationship between PD-L1 expression and tumor-infiltrating lymphocytes in canine mammary tumor
Lopes-Neto, Belarmino EugênioNunes-Pinheiro, Diana Célia SousaCarvalheira, Júlio Gil ValeSchmitt, FernandoGärtner, Maria de Fátima
Background: Studies pointed out that the tumor-infiltrating lymphocytes (TILs) have considerable importance in caninemammary tumor (CMT). On the other hand, cancer cells sometimes find ways to use immune checkpoint proteins as ashield to avoid being identified and attacked by the immune system as programmed death 1 ligand 1 (PD-L1). In this study,it was investigated the relationship between PD-L1 expression, stromal tumor-infiltrating lymphocytes (TILs) in caninemammary tumor (CMT), and the association with clinical and pathological characteristics of the tumors.Materials, Methods & Results: PD-L1 expression and TILs were assessed in 23 female dogs with CMT. The tumors weregrouped into simple carcinoma (CA, n = 8) and complex carcinoma (CC, n = 15). Stromal TILs were assessed using twothresholds as TILs-Low representing < 50% of infiltrate within stromal area and TILs-High representing ≥ 50% of stromalarea. Clinicopathological data of CMT was characterized according to key parameters, as well as survival rates. TILs evaluation within tumor stroma revealed that 65.2% (n = 15) of tumors had TILs-Low. PD-L1 expression and stromal TILs weresignificantly associated (P = 0.009). PD-L1 expression was observed in 39% (n = 9) of all tumors of which 17.4% (n = 4)were from CA group and 21.7% (n = 5) were from CC group. PD-L1 expression within TILs was observed in 39% (n =9) of the tumors. PD-L1 in malignant epithelium was present in all lymph node metastasis (n = 5). PD-L1 was associatedwith involvement of regional lymph nodes (P = 0.034). Survival curves demonstrated TILs-Low had higher (P = 0.010)overall survival (OS) compared with TILs-High, and PD-L1+ and PD-L1 (P = 0.06) did not differed. The clinicopathological variables significantly correlated with OS by univariate analysis were the histological grade (P = 0.009), lymphnode involvement (P = 0.004), stromal...(AU)
Texto completo