TP53 and cancer: We characterized genomic alterations for 571 cancer-related genes (Supplementary Table 1 and Supplementary Table 4) in all 31 PDXs using a targeted next-generation sequencing assay, allowing the detection of mutations, the estimation of copy number alterations (CNA), tumor mutational burden (TMB), and MSI status (Figure 1C). As anticipated, the most frequent genomic alterations were mutations in TERT (68%) and TP53 (61%) and the homozygous deletion of CDKN2A/B (~50%).