The Use of Nanocarriers for Drug Delivery in Cancer Therapy

Cancer treatment involving chemotherapy is typically accompanied by toxic side effects, thereby limiting the amount of the drug that can be given to a patient. As a result, all of the tumor tissue may not be exposed to a lethal dose of the drug. The use of nanocarriers such as liposomes and micelles can improve the pharmacological properties of traditional chemotherapeutics. Their small size (~100nm or less) allows them to readily extravasate from circulation through vascular defects typically present at tumor sites due to ongoing angiogenesis (Maeda et al., 2000), where they can then deliver encapsulated cytotoxic agents to tumor tissue. This, coupled with the fact that there is generally poor lymphatic drainage at tumor sites, results in a phenomenon known as the enhanced permeability and retention (EPR) effect (Gabizon, 2001a; Matsumura et al., 2004), which in part explains their clinical success. For example, both DaunoXome and Doxil are examples of clinically-approved liposomal-based drugs that are currently used to treat either Kaposi’s Sarcoma (Torchilin, 2007; Wang et al., 2008), or both ovarian and recurrent breast cancer (Allen and Cullis, 2004; Wang et al., 2008) (Table 1). Alternatively, micellarbased drugs containing doxorubicin, paclitaxel, or cisplatin are in various stages of clinical trials (Hamaguchi et al., 2007; Wilson et al., 2008; Valle et al., 2010) (Table 1).