Polymer-lipid hybrid nanoparticles of exemestane for improved oral bioavailability and anti-tumor efficacy: An extensive preclinical investigation

Exemestane (EXE), an irreversible aromatase inhibitor, is primarily used as a first-line therapy for estrogen receptor-positive breast cancer patients. However, complex physicochemical characteristics of EXE limit its oral bioavailability (<10%) and anti-breast cancer efficacy. The present study aimed to develop a novel nanocarrier system to improve the oral bioavailability and anti-breast cancer efficacy of EXE. In this perspective, EXE-loaded TPGS-based polymer lipid hybrid nanoparticles (EXE-TPGS-PLHNPs) were prepared by the nanoprecipitation method and evaluated for their potential in improving oral bioavailability, safety, and therapeutic efficacy in the animal model. EXE-TPGS-PLHNPs showed significantly higher intestinal permeation in comparison to EXE-PLHNPs (without TPGS) and free EXE. After oral administration, EXE-TPGS-PLHNPs and EXE-PLHNPs revealed 3.58 and 4.69 times higher oral bioavailability in Wistar rats compared to the conventional EXE suspension. The results of the acute toxicity experiment suggested that the developed nanocarrier was safe for oral administration. Furthermore, EXE-TPGS-PLHNPs and EXE-PLHNPs represented much better anti-breast cancer activity in Balb/c mice bearing MCF-7 tumor xenograft with tumor inhibition rate of 72.72% and 61.94% respectively in comparison with the conventional EXE suspension (30.79%) after 21 days of oral chemotherapy. In addition, insignificant changes in the histopathological examination of vital organs and hematological analysis further confirm the safety of the developed PLHNPs. Therefore, the findings of the present investigation advocated that the encapsulation of EXE in PLHNPs can be a promising approach for oral chemotherapy of breast cancer.