Strategies to target drugs to gliomas and CNS metastases of solid tumors

The treatment for central nervous system metastases of solid tumors and gliomas is limited as the blood-brain barrier (BBB) is an obstacle to systemic therapy. Here, we review the physiochemical properties of the BBB and both current and new drug strategies to penetrate brain tumors. We focus on targeting receptor- or carrier-mediated transport mechanisms over the BBB used by drug conjugates, nanoparticles, polymer-based nanocarriers, siRNA, and antibodies.