Supplemental Figure S7. Dose-dependent effect of BAY 87-243 (1 and 9 mg/kg) on (A) 18F-FAZA uptake and (B) tumor volume for H460 xenografts of nude, murine models. For (A), *- p<0.001 for 2-way ANOVA of vehicle vs. BAY 87-2243, n=6 tumors and for (B) *-P<0.01 for 2-way ANOVA of vehicle vs. BAY 87-2243, n=6 tumors.
ARTICLE ABSTRACT
Purpose: We describe a noninvasive PET imaging method that monitors early therapeutic efficacy of BAY 87-2243, a novel small-molecule inhibitor of mitochondrial complex I as a function of hypoxia-inducible factor-1α (HIF1α) activity.Experimental Design: Four PET tracers [18F-FDG, 18F-Fpp(RGD)2, 18F-FLT, and 18F-FAZA] were assessed for uptake into tumor xenografts of drug-responsive (H460, PC3) or drug-resistant (786-0) carcinoma cells. Mice were treated with BAY 87-2243 or vehicle. At each point, RNA from treated and vehicle H460 tumor xenografts (n = 3 each) was isolated and analyzed for target genes.Results: Significant changes in uptake of 18F-FAZA, 18F-FLT, and 18F-Fpp(RGD)2 (P < 0.01) occurred with BAY 87-2243 treatment with 18F-FAZA being the most prominent. 18F-FDG uptake was unaffected. 18F-FAZA tumor uptake declined by 55% to 70% (1.21% ± 0.10%ID/g to 0.35 ± 0.1%ID/g; n = 6, vehicle vs. treatment) in both H460 (P < 0.001) and PC3 (P < 0.05) xenografts 1 to 3 days after drug administration. 18F-FAZA uptake in 786-0 xenografts was unaffected. Decline occurred before significant differences in tumor volume, thus suggesting 18F-FAZA decrease reflected early changes in tumor metabolism. BAY 87-2243 reduced expression of hypoxia-regulated genes CA IX, ANGPTL4, and EGLN-3 by 99%, 93%, and 83%, respectively (P < 0.001 for all), which corresponds with reduced 18F-FAZA uptake upon drug treatment. Heterogeneous expression of genes associated with glucose metabolism, vessel density, and proliferation was observed.Conclusions: Our studies suggest suitability of 18F-FAZA-PET as an early pharmacodynamic monitor on the efficacy of anticancer agents that target the mitochondrial complex I and intratumor oxygen levels (e.g., BAY 87-2243). Clin Cancer Res; 21(2); 335–46. ©2014 AACR.
