Table 9.

Summary of recent published studies of PD-L1 expression in breast cancer using FDA-approved clones

Reference	No., type of breast tumors	Clones	Pathologic material	Cutoffs for positive/high staining	Correlation with prognosis
He et al. [16]	68, IBC, post NACT	28–8	TMA	TC > 1%	Worse prognosis
Humphries et al. [17]	≥ 109, various types	SP142	TMA	> 1%, epithelial and lymphoid cells	Better prognosis
Karnik et al. [18]	136, ductal (primary and metastasis)	22C3, SP263	WSS (biopsies and resections)	TC ≥ 1%	Not performed
Li et al. [19]	191, HER2 positive, no NACT	22C3, 28–8	TMA	TC ≥ 1%; IC, cutoff not defined	Better prognosis
Pelekanou et al. [20]	163, HER2 negative, locally advanced, or IBC (120, pretreatment; 43, post NACT)	22C3	WSS	Either tumor or stromal cells ≥ 1%	Not associated (but better pCR)
Downes et al. [21]	30, not specified	22C3, SP142, SP263	TMA	22C3: CPS ≥ 1; SP142: IC ≥ 1%; SP263: cutoff not defined	Not performed
Noske et al. [22]	1318, various types, all node-positive	SP263	TMA	TC ≥ 1%; IC ≥ 1%	Not associated
Van Berckelaer et al. [23]	349 (207, pretreatment IBC; 142, non-IBC)	SP142	WSS (biopsies)	TC, IC (categorized based on %)	Not associated (but better pCR)

IBC inflammatory carcinoma, NACT neoadjuvant chemotherapy, TC tumor cell, IC immune cell, CPS combined positive score, TMA tissue microarray, WSS whole slide section, pCR pathologic complete response