CTLA4 and breast cancer: Among BC subtypes, the phenotype of PD-L1+CD45−CK+ was present in 41% (26 out 64) of TNBC vs. 29% (9 out of 31) of luminal patients, while the phenotype of CTLA-4+CD45−CK+ was present in 36% (23 out of 64) of TNBC and 23% (7 out of 31) of luminal patients (Figure 4A and Table S1).