Lack of cytoplasmic expression of a new marker programmed cell death ligand-1 in tumor cells is significant

Table 10 Results of the studies of the prognostic and predictive significance of programmed cell death ligand 1 expression in immune cells

Ref.	No. of patients BC subtype	Clone of anti-PD-L1 antibody	Staining type, cutoff point, n (%)	Association of PD-L1 expression in ICs with BC characteristics
Oner et al[17], 2021	50, TNBC	Clone SP263 (rabbit monoclonal antibody, Ventana)	NS; ≥ 1%; four scoring intervals: ≥ 1%; ≥ 5%; ≥ 10% and ≥ 20%; 23 (46)	ICs+ score ≥ 1% was associated with tumor G3 (Р = 0.0001) and pCR (Р = 0.064). ICs+ score ≥ 20% was associated with better DFS (Р = 0.041) and OS (Р = 0.049)
Shang et al[18], 2022	155, HER2+	Clone SP142 (rabbit monoclonal antibody, Ventana, Shanghai Roche Diagnostic Products Limited Company, Shanghai, China)	Membrane or cytoplasmic; ≥ 1%; continuous scale with 5% step; 108 (69.7)	With ER-negative status (Р < 0.05), PR-negative status (Р < 0.05), and pCR
Çetin et al[19], 2024	85, HER2+	Clone 73–10 (monoclonal antibody, Leica Biosystems, Newcastle, United Kingdom)	Membrane or cytoplasmic; ≥ 1%; 32 (37.6)	With tumor G3 (Р = 0.002), a high Ki67, a high TILs and pCR
Stanowska et al[32], 2022	93, TNBC, G3	Clone SP142 (rabbit monoclonal antibody, Roche Diagnostics, Basel, Switzerland)	NS; ≥ 1%; 53 (57)	With a high TILs (Р < 0.001) and pCR (Р < 0.01)
Hoffmann et al[20], 2022	127, all	Clone ZR3 (rabbit monoclonal antibody, Cell Marque – Sigma-Aldrich, MO, United States)	Membrane or cytoplasmic; ≥ 1%; All 70 (55.1); HR+HER2- (46.2); HR+HER2+ (61.5); HR-HER2+ (50.0); TNBC (87.5)	With a high TILs (Р = 0.01)
Bae et al[33], 2016	465, all	Clone E1 L3 (rabbit monoclonal antibody, Cell Signaling Technology, Beverly, United States)	Membrane or cytoplasmic; H-score 0-300 (0–99 - negative/Low expression, and 100–300 - positive expression); All 63 (13.5); Luminal A (2.5); HR+HER2- (17.1); HR+HER2+ (18.9); HR-HER2+ (28.9); TNBC (29.6)	With tumor G3 (Р < 0.001), N0 stage (Р = 0.011), early stages (Р = 0.025), ER-negative status (Р < 0.001) and PR-negative status (Р = 0.002), HER2-positive status (Р = 0.003), a high Ki67, a high TILs (Р < 0.001), with better DFS and OS in patients with HR+HER2+, HR-HER2+ and TNBC (Р < 0.05)
Mori et al[16], 2017	248, all	Clone E1 L3N (monoclonal rabbit antibody, Cell Signaling Technology, Beverly, MA, United States)	NS; ≥ 5%; 129 (52.0)	Correlations with RFS and OS were absent
Hoda et al[34], 2020	156, TNBC	Clone SP142 (Ventana Medical Systems, United States)	NS; ≥ 1%; 74 (47.4)	With a high TILs (Р < 0.001); PD-L1 expression in ICs was more frequently detected in primary tumors than in metastatic tumors
Sigurjonsdottir et al[31], 2024	237, early-stage TNBC	Clone SP142 (Ventana Medical Systems, Inc., AZ, United States)	NS; ≥ 1%; 120 (50.6)	With better DFS (Р = 0.017), OS (Р = 0.032) and distant relapse-free interval (Р = 0.027) but only in patients who received neo-A-ChT
Cha et al[35], 2021	316, all	Clone SP142 (Ventana Medical System)	Membrane and cytoplasmic; ≥ 1%; All 43 (14.3); HR+HER2- (1.4); HR+HER2+ (11.9); HR-HER2+ (11.9); TNBC (20.7)	With tumor G3 (Р < 0.001), early stages (Р = 0.042), ER-negative status (Р < 0.001) and PR-negative status (Р < 0.001), a high Ki67 (Р < 0.001) and TNBC (Р < 0.001). Correlations of markers with RFS and OS were absent (Р > 0.05)
Cha et al[35], 2021	316, all	Clone SP263 (Ventana Medical System)	Membrane and cytoplasmic; ≥ 1%; All 115 (38.5); HR+HER2- (9.9); HR+HER2+ (37.3); HR-HER2+ (37.3); TNBC (54.8)	With tumor G3 (Р < 0.001), ER-negative status (Р = 0.008) and PR-negative status (Р = 0.003), a high Ki67 (Р = 0.002) and TNBC (Р < 0.001). Correlations of markers with RFS and OS were absent (Р > 0.05)
Guo et al[27], 2020	341, all	Clone 22C3 (Dako North America Inc., Carpinteria, CA, United States)	Membrane and cytoplasmic; ≥ 1%; All 58 (17.1); HR+ (13); HER2+ (29); TNBC (31)	With tumor G3 (Р < 0.0001), ER-negative status (Р = 0.0011), PR-negative status (Р < 0.0001), TNBC (P = 0.0069), a high TILs (Р < 0.0001) and decreased OS in patients with HAChT (Р = 0.021)
Chu et al[28], 2022	132, TNBC	Clone SP142 (Ventana Medical Systems)	Membrane and cytoplasmic; ≥ 1%; All 46 (34.8); ≥ 10% (20.5)	ICs+ score ≥ 10% with pT1 (Р = 0.03), fewer lymph node metastases (Р = 0.002), the absence of LVI (Р = 0.024) and better DFS (Р = 0.038)
Ni et al[29], 2022	1752, all	Clone SP142 (rabbit monoclonal primary antibody, Ventana Medical Systems Inc.)	Membrane and cytoplasmic; ≥ 1%; 600 (34.2)	With ER-negative status, PR-negative status, HER-positive status, TNBC, a high Ki67, a high TILs and PD-L1-positive TCs. Correlations with DSS, RFS and OS were absent

BC: Breast cancer; DSS: Disease-specific survival; ER: Estrogen receptor; HER2: Human epidermal growth factor receptor 2; HR: Hormone receptor; H-score: Histo-score; ICs: Immune cells; LVI: Lymphovascular invasion; NS: Not specified; OS: Overall survival; pCR: Pathologic complete response; PD-L1: Programmed cell death ligand 1; PR: Progesterone receptor; RFS: Relapse-free survival; TCs: Tumor calls; TILs: Tumor infiltrating lymphocytes; TNBC: Triple negative breast cancer.