CD274 and neoplasm: The above observations suggest that the tumour recognition of T-cells and the efficacy of anti–PD-L1 Abs depend on the expression levels of MHC-I and PD-L1 molecules, and down-regulation of MHC-I and PD-L1 expression could be result of in vivo immune-escaping caused by heterogeneous antigenic expression of C1498 leukaemic cells.