Metabolic Imaging as a Biomarker of Early Radiation Response in Tumors

Abstract

(13)C-pyruvate hyperpolarized magnetic resonance imaging (HP-MRI) is emerging as a viable quantitative biomarker for solid tumor response and normal tissue toxicity after radiotherapy. This technology effectively predicts response related to metabolic agents or alterations in the tumor microenvironment, but challenges remain to be addressed to ensure successful translational implementation. See related article by Saito et al., p. 5073.

Figure 1. A model of therapeutic optimization using metabolic interrogation

Reactive oxygen species (ROS) have important roles in tumor growth and metastasis. Although low levels of ROS can have oncogenic effects, high levels of ROS, such as those resulting from ionizing radiation or chemotherapy are cytotoxic, and thus are crucial role for treatment effectiveness. Treatment-related ROS are also responsible for some of the toxicity to normal tissue associated with treatment of solid tumors. Metabolic interrogation, whether invasive (biochemical analysis) or noninvasive (metabolic imaging) could be used to devise treatment regimens that generate tumoricidal levels of ROS while maximally sparing normal tissues.