ABL1 and acute lymphoblastic leukemia: Indeed, the combination of PU-H71 (HSP90i) along with Mitoxantrone (TOP2i) displayed a significant (ZIP Synergy score ≥ 20) synergistic interaction against two BCR-ABL1 + BCP-ALL (relapsed) patient derived xenograft (PDX) cells and BCR-ABL1 + CML leukemia cell lines (K562 and KCL22) (Fig. 3C, Supplemental Fig. 3C).