RX-3117(TV-1360; Fluorocyclopentenylcytosine) is novel a cytidine analog; shows anticancer activity in several cancer cell lines, including gemcitabine-resistant variants.IC50 value: 0.4- >30 nM (15 cancer cell lines) [1]Target: cytidine analogin vitro: RX-3117 showed a different sensitivity profile compared to cyclopentenyl-cytosine (CPEC) and azacytidine, substrates for uridine-cytidine-kinase (UCK).RX-3117 was a very poor substrate for cytidine deaminase (66,000-fold less than gemcitabine). In sensitive U937 cells 1 μM RX-3117 resulted in 90% inhibition of RNA synthesis but 100 μM RX-3117 was required in A2780 and CCRF-CEM cells. RX-3117 at IC50 values did not affect the integrity of RNA [1].in vivo: Orally-administered RX-3117 was examined in 9 different human tumor xenograft models (colon, non-small cell lung, small cell lung, pancreatic, renal and cervical), grown subcutaneously in athymic nude mice. In the Colo 205, H460, H69 and CaSki models, gemcitabine treatment resulted in 28%, 30%, 25% and 0% tumor growth inhibition (TGI), respectively, whereas oral treatment with RX-3117 induced 100%, 78%, 62% and 66% TGI, respectively [2].

[1]. Peters GJ, et al. Metabolism, mechanism of action and sensitivity profile of fluorocyclopentenylcytosine (RX-3117; TV-1360). Invest New Drugs. 2013 Dec;31(6):1444-57. [2]. Yang MY, et al. A novel cytidine analog, RX-3117, shows potent efficacy in xenograft models, even in tumors that are resistant to gemcitabine. Anticancer Res. 2014 Dec;34(12):6951-9.