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. The gene discussed is CDKN2A; the disease is acute lymphoblastic leukemia.