Innovative Nanocarriers of Sorafenib in the Optimisation of Therapeutic Outcome: Challenges and Applications in Breast Cancer.

Sorafenib is an oral tyrosine kinase inhibitor which inhibits the growth of cancer cells by inhibiting several tyrosine kinase receptors taking part in the perpetuation and pathogenesis of breast tumours. Sorafenib was approved in 2005 for the treatment of liver and prostate cancers. In recent years, focused studies have explored the drugs clinical potential in breast cancer. There are several clinical trials (ongoing and completed) of sorafenib to treat metastatic breast cancer patients. Interestingly, these have shown encouraging results in particular in combination with other clinically-used drugs. However, effective clinical use has been somewhat hampered due to the drug's hydrophobicity, rapid first pass metabolism, short half-life, low oral bioavailability and side effects including hand and foot reaction as well as hypersensitivity. In attempts to overcome some of these drawbacks, nanotechnology-based delivery systems have been explored including nanocarriers like liposomes, niosomes, lipid-polymer hybrid nanoparticles, solid lipid nanocarriers, microemulsions, nanovectors and gel matrices. We will describe current state-of-the-art nanocarrier-based strategies, and discuss how such approaches can be harnessed to enhance the clinical efficacy of sorafenib for breast cancer treatment.