Evaluation of LDH-A and glutaminase inhibition in vivo by hyperpolarized 13C-pyruvate magnetic resonance spectroscopy of tumors.

Hyperpolarized (13)C magnetic resonance spectroscopy provides a unique opportunity to detect real-time metabolic fluxes as a means to measure metabolic treatment responses in vivo. Here, we show that pharmacologic inhibition of lactate dehydrogenase-A suppressed the conversion of hyperpolarized (13)C-pyruvate to lactate in murine xenografts of P493 human lymphoma. In contrast, a glutaminase inhibitor reduced conversion of (13)C-pyruvate to alanine without affecting conversion of pyruvate to lactate. These results illustrate the ability to monitor biomarkers for responses to antimetabolic therapy in real-time, paving the way for clinical development of imaging biomarkers to monitor metabolic pharmacodynamics.