ABCB1 and cancer: In this regard, exosomes offer several advantages over liposomes and nanoparticles, including low clearance rates, higher bioavailability (they can easily pass through biological barriers including the blood–brain barrier, placental barrier, and intestinal barrier), minimal immunogenicity, low cumulative toxicity in normal tissues, and the capacity to specifically deliver anti-cancer drugs to cancer cells by utilizing ligand–receptor interaction or endocytosis, thereby addressing drug resistance caused by P-glycoprotein or other multidrug resistance-associated problems [15,16].