Ultra pH-sensitive polymeric nanovesicles co-deliver doxorubicin and navitoclax for synergetic therapy of endometrial carcinoma

Endometrial carcinoma is a kind of epithelial malignant tumor occurring in the endometrium with high incidence (nearly 200 000 people are diagnosed every year). At present, surgery is the main strategy for the treatment of endometrial carcinoma. However, in special cases such as serous, clear cell carcinoma and postoperative recurrences, chemotherapy is still essential and indispensable. The combined chemotherapy schemes of cisplatin, paclitaxel and doxorubicin (DOX) in clinical applications are unfortunately complicated and easily cause severe side effects. In recent years, with the development of nanotechnology, the targeted delivery of multi-chemotherapeutic drugs shows great advantages in reducing side effects and improving anticancer efficacy. Here, an ultra pH-sensitive nanovesicle based on polyethylene glycol-poly(diisopropylamino)ethyl methacrylate (PEG-PDPA) was fabricated. A chemotherapeutic drug (doxorubicin) and an anti-apoptotic Bcl-2 inhibitor (navitoclax) were co-encapsulated in the hydrophilic cavity and hydrophobic membrane of the vesicle, respectively. After accumulating in the tumor tissue via the enhanced permeability and retention (EPR) effect, the nanovesicles could be efficiently diffused in tumor cells by endocytosis and then rapidly release drugs in response to the lysosomal acidic environment, leading to an enhanced tumor-killing effect based on the combination therapy between DOX and the Bcl-2 inhibitor. The drug co-delivery system and microenvironment-triggered drug release may provide an efficient strategy for endometrial carcinoma therapy.