NOTCH1 and/or FBXW7 mutations are present in three lines; CDKN2A biallelic loss is present in three lines; and all lines are wildtype for TP53. Two lines are ETP-ALL with wildtype NOTCH1, FBXW7, and TP53. For all five PDX lines tested, in vitro dual treatment led to robust cell death within 48 h. This evidence concerns the gene NOTCH1 and acute lymphoblastic leukemia.