CD274 and breast cancer: As the primary marker currently utilized to stratify patients for immune checkpoint treatment in BC is PD-L1, their findings imply that PD-1, CXCL13, and MHC-I, possibly in combination with previously identified T cell exhaustion markers like LAG-3 and TIM-329, are more effective at differentiating immunological TME that may show to be differentially receptive to this treatment.