A Phase I Trial of the Epigenetic Modulators Vorinostat, in Combination with Azacitidine (azaC) in Patients with the Myelodysplastic Syndrome (MDS) and Acute Myeloid Leukemia (AML): A Study of the New York Cancer Consortium

Background:The hypomethylating agent azacitidine (azaC) which can reverse epigenetic silencing, is the first agent demonstrated to alter the natural history of MDS and improve survival in higher-risk patients (Silverman JCO 2002, Fenaux Blood 2007). AzaC also produces comparable rates of response in patients with non-proliferative AML and appears to affect survival (Silverman JCO 2006). Time to response is slow with single agent azaC, requiring a median of 3 to 4 cycles to initial response and the CR + PR rates ranges from 7 to 27%. Vorinostat, a histone deacetylase inhibitor (HDACI) which inhibits class I and II HDAC, has demonstrated single agent activity in patients with MDS and AML with responses of 25% (Garcia-Manero Blood 2006). In vitro the 2 agents are synergistic in reactivating epigenetically silenced genes. The effect is sequence dependent requiring exposure to the hypomethylating agent first followed by the HDACI. This study was designed to test the safety of the combination and to determine the response rate and effects on the MDS/AML clone.