TP53 and undifferentiated carcinoma: Finally, our data also demonstrate that tumors engrafted in vivo may present features that can differ from the original tumor biopsy, as demonstrated by the detection of increased histological grade (e.g., PDOX3), or the progression into more aggressive histological types (such as TP53‐positive serous carcinoma in the case of PDOX13, or undifferentiated carcinoma as seen in PDOX7).