Tumor-specific HSP90 inhibition as a therapeutic approach in JAK-mutant acute lymphoblastic leukemias

The development of the dual Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib for the treatment of myeloproliferativeneoplasms (MPNs)has led to studies of ruxolitinib in other clinical contexts, including JAK-mutated acute lymphoblastic leukemia (ALL). However, the limited ability of JAK inhibition to induce molecular or clinicopathological responses in MPNs suggests a need for development of better therapies for JAK kinase-dependent malignancies. Here,we demonstrate that heat shock protein 90 (HSP90) inhibition using a purine-scaffold HSP90 inhibitor in early clinical development is an effective therapeutic approach in JAK-dependent ALL and can overcome persistence to JAK-inhibitor therapy in ALL cells.