ABSTRACT
Multi-drug resistance (MDR), or resistance of tumor cells to an anticancer agent, along with other structurally and functionally dissimilar chemotherapeutic drugs, creates an obstacle in the path of successful chemotherapy. Development of MDR is a complex phenomenon, which involves multiple mechanisms working together. Broadly, these can be categorized as pump-mediated and pump-independent mechanisms. Up-regulation of ATP-binding cassette (ABC) transporter proteins is one of the significant mechanisms involved in the development of MDR. ABC transporter proteins such as P-gp cause increased drug efflux, thereby decreasing the intracellular concentration of the drug, which in turn hampers drug efficacy. Several approaches have been employed so far for reversal of MDR, but each possesses certain limitations. Nanotechnology is a promising tool to overcome such limitations of conventional chemotherapy and to provide effective treatment to resistant tumors. Evidence from the available literature demonstrates that the continuous development of a diverse variety of engineered drug-loaded nanocargos improves tumor-targeted drug delivery of chemotherapeutics through passive and active targeting approaches. This chapter aims to focus on the detailed biology, MDR reversal strategies with limitations, different opportunities and challenges in the use of nanocargos in order to improve the effectiveness of anticancer agents against MDR in tumors.
