In the phase-I study, SAHA which is the synthetic HDACI removes HDAC activity in peripheral blood mononuclear cells (PBMCs), and has also antitumor activity in hematological and solid tumors.42In a patient with chronic lymphocytic leukemia (CLL) and acute lymphocytic leukemia (AML), depsipeptide is used as a natural HDACI effectively which inhibits HDAC as in vivo.44 Here, HDAC9 is linked to acute lymphoblastic leukemia.