CD123 mRNA and protein expression was significantly higher in B‐lineage (n = 65) compared with T‐lineage (n = 25) ALL PDXs (p < 0.0001), and mice engrafted with B‐lineage PDXs achieved significantly longer EFS than those engrafted with T‐lineage PDXs (p < 0.0001). Here, IL3RA is linked to acute lymphoblastic leukemia.