In addition, we find that the drug target of idarubicin (TOP2A) and Cytarabine (POLB) form a significant protein-protein interaction network (P < 1.0 × 10−16) (Szklarczyk et al., 2019), indicating that the predictive biomarkers work as the direct interactive proteins of cancer drug targets (Figure 7B). This evidence concerns the gene POLB and cancer.