In the current data set, subsets of cancer with MDM2 amplification also were associated with less-frequent high TMB status compared with MDM2 wild type (sarcoma, not otherwise specified, 0% [zero of 103] v 4.2% [36 of 852], respectively [P = .03]; urothelial carcinoma, 3.5% [seven of 198] v 11.8% [200 of 1,700], respectively [P < .001]; glioblastoma, 0.4% [one of 244] v 4.4% [120 of 2,725], respectively [P < .001]; Fig 2; Data Supplement). Here, MDM2 is linked to urothelial carcinoma.