MDM4 and neoplasm: Several biomarkers, including tumor mutational burden (TMB) (11), blood tumor mutational burden (bTMB) (22), human leukocyte antigens (HLA) loss-of-heterozygosity (LOH) status (20), and murine double minute 2/4 (MDM2/MDM4) amplification (23), which could affect the adaptive immune response to the tumors, have been widely studied to be associated with the efficacy of ICI therapy in LUAD patients.