Moreover, since tumour cells with decreased antigenicity could evade immune-mediated elimination and promote tumour outgrowth, resulting in tumour clonal heterogeneity,24 we examined the expression levels of PLK1 protein, surface MHC-I, and surface PD-L1 on freshly isolated CD90.1+C1498 cells from liver tissue (referred to as C1498Liver) of mice that exhibited progressive tumour growth after receiving PLK1122DC_TriVax with PD-L1 blockade post 52-days of tumour infusion. This evidence concerns the gene PLK1 and neoplasm.