The ligand nanoparticle conjugation approach for targeted cancer therapy.

Cancer therapy often requires frequent and high drug dosing. Yet, despite the significant progress in cancer research and the wide versatility of potent available drugs, treatment efficacy is still hurdled and often failed by the lack of pharmaco-selectivity to diseased cells, indiscriminate drug toxicities and poor patient compliance. Thus, innovative pharmaceutical solutions are needed to effectively deliver the cytotoxic drugs specifically to the tumor site while minimizing systemic exposure to frequent and high drug doses. Polymeric nanocarriers, particularly nanoparticles, have been extensively studied for improved oncological use. Such nanocarriers hold great potential in cancer treatment as they can be biocompatible, adapted to specific needs, tolerated and deliver high drug payloads while targeting tumors. Active targeting, as opposed to passive targeting, should add value to selective and site specific treatment. Active targeting of nanosized drug delivery systems is firmly rooted in the Magic Bullet Concept as was envisioned by Paul Ehrlich over 100 years ago. This targeting strategy is based on the molecular recognition of tumor biomarkers which are over-expressed on cancer cells, via specific vector molecules conjugated to the surface of the drug carrier. These vector molecules dictate the carrier's biodistribution and its biological affinity to the desired site of action. Many recent publications have shown encouraging results suggesting that targeting nanocarriers represent a highly-promising strategy for improved cancer treatment. This chapter will focus mainly on polymeric nanoparticles as the main drug carriers to be conjugated to various ligands able to deliver the drug to the specific desired pathological tissue.