MDM4 and neoplasm: At present, a variety of tissue-based biomarkers have been proven to be effective in predicting the efficacy of NSCLC immunotherapy, mainly including the PD-L1 expression level, tumor mutational burden (TMB), microsatellite instability (MSI), mismatch repair (MMR) gene defects, CD8+ tumor-infiltrating lymphocytes (TILs), T cell inflammatory gene expression profile and driver genes (such as epidermal growth factor receptor (EGFR)), anaplastic lymphoma kinase (ALK), STK11/LKB1 mutation, K-RAS/TP53 co-mutation, murine double minute 2, MDM2/MDM4 amplification, and EGFR amplification [84].