MDM4 and neoplasm: The data shows that the incidence of HPD in tumor immunotherapy is about 10% (Champiat et al., 2017; Ferrara et al., 2018), and the gene amplification of MDM2, MDM4, EGFR and 11q13 (including CCND1, FGF3, FGF4, FGF19) may be related to tumor immunotherapy HPD (Kato et al., 2017), the molecular mechanisms of HPD and the relative predictive biomarkers, etc., need further research.