Metabolites of 2′-fluoro-2′-deoxy-D-glucose detected by 19F magnetic resonance spectroscopy in vivo predict response of murine RIF-1 tumors to 5-fluorouracil

There is a clinical need fur early detection of tumor response to therapy. This study aimed to determine whether metabolites of fluorodeoxyglucose (FDG) detected in solid mouse tumors in situ by F-19 magnetic resonance spectroscopy (F-19 MRS) correlated with response to 5-fluorouracil chemotherapy, After injection of FDG (1.4 mmol/kg i.p.), uptake and metabolism was monitored for 2 h in RIF-1 tumors. FDG was detectable immediately. and after 10 min, a second broad peak was detected 5-6 ppm upfield, F-19 MRS analysis of cell and tumor extracts in vitro showed that the upfield peak (greater than or equal to 15% of the total detectable F-19 signal) consisted of the epimer alpha-fluorodeoxymannose (FDM) and various conjugates, Mice treated with 5-fluorouracil (130 mg/kg) received, 48 h later, a repeat dose of FDG. The change in the rate of FDM formation, but not the FDG or total F-19 signal, correlated significantly with the response to 5-fluorouracil (P = 0.032), suggesting that F-19 MRS of FDM metabolism in vivo may be a novel means of predicting tumor response.