Acute myeloid leukemia (AML) is an aggressive hematopoietic disease characterized by
glutamine-dependent metabolism. A novel
glutaminase (GLS) inhibitor,
CB-839, is currently under evaluation for treatment of
hematopoietic malignancies and solid
tumors. Our purpose was to measure cellular changes in AML associated with
CB-839 treatment and to test the ability of hyperpolarized
pyruvate for interrogating these changes to OCI-AML3 cells. Our results show that treatment with
CB-839 interfered with the citric acid cycle, reduced the
NADH/NAD+ ratio and
ATP levels, reduced cell proliferation and viability, and reduced the basal and maximal respiratory capacities [oxygen consumption rate (OCR)]. We observed a reduction of the conversion of hyperpolarized
pyruvate to
lactate in cell lines and in a mouse AML model after
CB-839 treatment. Our in vitro and in vivo results support the hypothesis that, in AML,
glutamine is utilized to generate reducing equivalents (
NADH,
FADH2) through the citric acid cycle and that reduction in redox state by GLS inhibition decreases the rate of
pyruvate to
lactate conversion catalyzed by
lactate dehydrogenase. We propose hyperpolarized
pyruvate/
lactate measurement as a method for direct monitoring of metabolic changes occurring in AML patients receiving
CB-839. With further optimization, this method may provide a noninvasive imaging tool to assess the early efficacy of therapeutic intervention with GLS inhibitors.