Lipid Nanosystems Enhance the Bioavailability and the Therapeutic Efficacy of FTY720 in Acute Myeloid Leukemia.

Protein phosphatase 2A (PP2A) is a serin-threonin phosphatase that regulates many proteins critical for malignant cell behavior; therefore, PP2A is considered to be a human tumor suppressor. In this study, we assessed the pharmacokinetic profile and the antileukemic effects of the PP2A activator FTY720, free or encapsulated in lipid nanoparticles, in in vitro and in vivo models of acute myeloid leukemia. FTY720 lipid nanoparticles presented diameters around 210 nm, with an encapsulation efficiency up to 75% and significantly increased FTY720 oral bioavailability. In addition, FTY720 restores PP2A phosphatase activity and decreases phosphorylation of PP2A and its targets Akt, ERK1/2 and STAT5, all implicated in the pathogenesis of acute myeloid leukemia. Moreover, FTY720 exerts an additive anti-leukemic effect in combination with drugs used in standard induction therapy. Importantly, FTY720 lipid nanoparticles were more efficient at inducing cell growth arrest and apoptosis than FTY720 solution. Finally, oral administration of FTY720 lipid nanoparticles to mice every three days was as effective in reducing acute myeloid leukemia xenograft tumor growth as daily oral administration of FTY720. These results provide the first evidence for the potential use of FTY720 lipid nanoparticles as an oral therapeutic agent in acute myeloid leukemia.