Recent advances in brain tumor-targeted nano-drug delivery systems

INTRODUCTION: Brain tumors represent one of the most challenging and difficult areas in unmet medical needs. Fortunately, the past decade has seen momentous developments in brain tumor research in terms of brain tumor-targeted novel nano-drug delivery systems with significant important superiority over conventional formulations with respect to decreased toxicity and improved pharmacokinetics/pharmacodynamics. AREA COVERED: This review first introduces the characteristics of the two major obstacles in brain-tumor targeted delivery, blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB), and then reviews recent advances in brain tumor-targeted novel nano-drug delivery systems according to their targeting strategies aimed at different stages of brain tumor development and growth. EXPERT OPINION: Based on continuously changing vascular characteristics of brain tumors at different development and growth stages, we propose the concept of 'whole-process targeting' for brain tumor for nano-drug delivery systems, referring to a series of overall targeted drug delivery strategies aimed at key points during the whole development of brain tumors.