In vivo evaluation of [F-18]-labeled 3,5-bis(2-fluorobenzylidene)-4-piperidone as an imageable antiproliferative agent

Objectives We report a novel imageable curcuminoid derivative 2-[3,5-bis-(2-fluorobenzylidene)-4-piperidon-1-yl]-N-(4-fluorobenzyl)-acetamide (NFLOBA) as an antiproliferative agent.

Methods We synthesized 4-fluoro(18F)benzonitrile by a Kryptofix-mediated nucleophilic (F-18) displacement of nitro group in 4-nitrobenzonitrile in dimethylsulfoxide (130oC, 15 min). The benzonitrile was reduced to benzylamine which upon reaction with EF24 at 85oC, yielded 2-[3,5-bis(2-fluorobenzylidene-4-piperidonyl)-N-4-fluoro(18F)benzyl] acetamide] (RCY 40-45%). The anti-proliferative activity of cold NFLOBA was tested in H441 (lung adenocarcinoma) cells by hexosaminidase assay. For imaging we injected 50 µCi of 18F-NFLOBA in normal rats. The dynamic PET imaging for 1 h, followed by organ biodistribution at necropsy, was performed. In a separate group of nude rats we investigated efficacy of cold NFLOBA to control xenograft H441 lung tumor (100 µg/injection on alternate days for 15 d).

Results We found that 10 µM NFLOBA suppressed growth of culture H441 cells by 40% within 24 h. The PET imaging of 18F-NFLOBA in normal rats demonstrated that it was widely distributed in the body. Approximately, 70% of injected dose was cleared from blood within 10 min of injection. Evidently, liver (0.88 % ID/g) and kidney (1.16% ID/g) were responsible for the rapid clearance. About 12% of radiolabeled compound remained in blood up to 4 h. As a therapeutic compound, cold NFLOBA suppressed tumor growth in the xenograft lung cancer model by 83%.

Conclusions The imaging studies demonstrate a visual biodisposition of NFLOBA in a live animal model. Such knowledge about therapeutics from non-invasive methods could be of benefit in development of curcuminoids as potential anticancer agents.

Research Support NCI grant RO3-CA143614-01 and OUHSC-College of Pharmacy' seed grant progra