Biodegradable nanoparticles exposing a short anti-FLT1 peptide as antiangiogenic platform to complement docetaxel...

Inhibition of tumor angiogenesis is considered as a valuable clinical strategy to treat some tumors, although benefits in term of progression-free and overall survival have been modest. Recent findings have pushed toward the use of antiangiogenic drugs in combination with chemotherapy regimens to potentiate therapeutic outcome. Herein, we propose a novel type of biodegradable antiangiogenic core-shell polymeric nanoparticles (NPs) for the delivery of poorly water-soluble chemotherapeutics. An amphiphilic diblock copolymer of poly(ethyleneglycol)-poly(ε-caprolactone) (PEG-PCL) was conjugated with an anti-FLT1 hexapeptide (aFLT1) at -OH PEG end, mixed in appropriate ratios with a monomethoxy-PEG-PCL and nanoprecipitated to form core-shell aFLT1-bearing NPs (DBL_aFLT1). DBL_aFLT1 were <100 nm, exposed aFLT1 on the surface and showed a higher thickness of the external hydrophilic shell as compared to NPs that do not bear aFLT1 (DBL). Very interestingly, DBL_aFLT1 showed an antiangiogenic activity in the human umbilical endothelial cells (HUVEC) tube formation assay three-fold higher than an equivalent dose of free aFLT1. To provide a proof-of-concept of DBL_aFLT1 potential in the delivery of conventional chemotherapeutics, docetaxel (DTX) was selected as model drug. DBL_aFLT1 entrapped DTX with high efficiency and sustained its release along time in simulated biological conditions. At a non-cytotoxic dose, DTX-loaded DBL_aFLT1 almost completely abolished tube formation in HUVEC while inhibition of DTX loaded DBL was significantly lower. The cytotoxicity of DTX-loaded NPs in HUVEC and triple negative breast cancer cells (MDA-MB-231) was not significantly different from that of the free drug in a wide range of concentrations and up to 72 h. Studies carried out in MDA-MB-231 cells implanted in chicken embryo chorioallantoic membranes (CAMs) evidenced an antiangiogenic activity of DTX-loaded DBL_aFLT1 higher as compared with that of both DTX-loaded DBL and free DTX. While cancer cell migration from the tumor site was unaffected, the anticancer activity of DTX-loaded NPs was higher than that of free DTX and maximized for DTX-DBL_aFLT1. In perspective, these results suggest that the delivery approach proposed here can be applied to other lipophilic chemotherapeutics devoid of relevant antiangiogenic properties to improve the final therapeutic response.