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

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 (DBLaFLT1). DBLaFLT1 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, DBLaFLT1 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 DBLaFLT1 potential in the delivery of conventional chemotherapeutics, docetaxel (DTX) was selected as model drug. DBLaFLT1 entrapped DTX with high efficiency and sustained its release along time in simulated biological conditions. At a non-cytotoxic dose, DTX-loaded DBLaFLT1 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 DBLaFLT1 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-DBLaFLT1. 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.