PURPOSE: New therapies are urgently needed for patients with acute myelogenous 
leukemia (AML). The novel NEDDylation inhibitor MLN4924 (pevonedistat) has 
demonstrated significant preclinical antileukemic activity and preliminary 
efficacy in patients with AML in a phase I trial. On the basis of its 
antimyeloid and DNA-damaging properties, we investigated the ability of MLN4924 
to augment conventional cytarabine (ara-C) therapy.
EXPERIMENTAL DESIGN: The effects of MLN4924/ara-C on viability, clonogenic 
survival, apoptosis, DNA damage, and relevant pharmacodynamic targets were 
determined. The efficacy and pharmacodynamics of MLN4924/ara-C were assessed in 
an AML xenograft model.
RESULTS: Cotreatment of AML cell lines and primary patient specimens with 
MLN4924 and ara-C led to diminished clonogenic survival, increased apoptosis, 
and synergistic levels of DNA damage. RNAi demonstrated that stabilization of 
CDT-1, an event previously shown to mediate the DNA-damaging effects of MLN4924, 
was not a key regulator of sensitivity to the MLN4924/ara-C combination. Global 
metabolic profiling revealed that MLN4924 disrupts nucleotide metabolism and 
depletes intracellular nucleotide pools in AML cells. Subsequent experiments 
showed that MLN4924 promoted increased incorporation of ara-C into the DNA of 
AML cells. This effect as well as the therapeutic benefit of the MLN4924/ara-C 
combination was antagonized by supplementation with the nucleotide building 
block ribose. Coadministration of MLN4924 and ara-C to mice bearing FLT3-ITD(+) 
AML xenografts stably inhibited disease progression and increased DNA damage in 
vivo.
CONCLUSIONS: Our findings provide strong rationale for clinical investigation of 
the MLN4924/ara-C combination and establish a new link between therapeutic 
inhibition of NEDDylation and alterations in nucleotide metabolism. Clin Cancer 
Res; 21(2); 439-47. ©2014 AACR.