Assessment of Tumoricidal Efficacy and Response to Treatment with F-18-FDG PET/CT After Intraarterial Infusion with the Antiglycolytic Agent 3-Bromopyruvate in the VX2 Model of Liver Tumor
The purpose of this study was to determine the effects of 3-bromopyruvate (3-BrPA) on tumor glucose metabolism as imaged with (18)F-FDG PET/CT at multiple time points after treatment and compare them with those after intraarterial control injections of saline. Twenty-three New Zealand White rabbits implanted intrahepatically with VX2 tumors were assigned to 1 of 2 groups: 14 rabbits were assigned to the treatment group (TG) and 9 to the saline control group (SG). All animals were infused with 25 mL of either 1.75 mM 3-BrPA or saline over 1 h via a 2-French catheter, which was secured in the hepatic artery. For PET/CT, the animals were injected with 37 MBq of (18)F-FDG at 1 d before treatment and 2 h, 24 h, and 1 wk after treatment. Tumor size, tumor and liver maximal standardized uptake value (SUV(max)), and tumor-to-background ratios were calculated for all studies. Seven TG and 5 SG animals were sacrificed at 1 wk after treatment for histopathologic analysis. Intense (18)F-FDG uptake was seen in untreated tumors. A significant reduction in tumor SUV(max) was noted in TG animals, when compared with SG animals, at 1 wk after treatment (P = 0.006). The tumor-to-liver background ratio in the TG animals, compared with the SG animals, was significantly reduced as early as 24 h after treatment (P = 0.01) and remained reduced at 1 wk (P = 0.003). Tumor SUV(max) increased from the baseline levels at 7 d in controls (P = 0.05). The histopathologic analysis of explanted livers revealed increased tumor necrosis in all TG samples. There was a significant inverse correlation (r(2) = 0.538, P = 0.005) between the percentage of tumor necrosis on histopathology and tumor SUV(max) on (18)F-FDG PET at 7 d after treatment with 3-BrPA. Intraarterial injection of 3-BrPA resulted in markedly decreased (18)F-FDG uptake as imaged by PET/CT and increased tumor necrosis on histopathology at 1 wk after treatment in the VX2 rabbit liver tumor. PET/CT appears to be a useful means to follow antiglycolytic therapy with 3-BrPA.