A PET Glutamate Analogue to Measure Cancer Cell Redox State and Oxidative Stress: Promise and Paradox.

[18F]FSPG was shown to provide an indirect measure of the cellular redox state and may be used as an early indicator of therapy response to cancer therapies that cause oxidative stress. A somewhat paradoxical finding was that reduced [18F]FSPG cellular uptake was associated with either lower cellular concentrations of cystine or glutamate, despite opposing the transport of these substances in the Xc- antiporter, for which [18F]FSPG is also a substrate. Further studies of the kinetics of [18F]FSPG will help elucidate the factors mediating a decline in [18F]FSPG with oxidative stress.See related article by McCormick et al, p. 853.