Nanomedicine for tumor microenvironment modulation and cancer treatment enhancement

Cancer, one of major threats to the human health, possesses intricate structure and constituents distinctive from normal organs and tissues. It has been well recognized that the unique tumor microenvironment (TME) would promote tumor progression and metastases, and in the meanwhile result in resistance of tumors to different types of therapies. Therefore, modulation of TME, instead of directly killing tumor cells, has been proposed as an alternative approach to improve the therapeutic outcomes of current cancer therapies. In this regard, nanomedicine strategies have shown significant potential as intensively reported in recent years. In this review, we would like to summarize the latest efforts utilizing nanomedicine to modulate various features within the microenvironment of solid tumors, including tumor hypoxia, tumor pH, the extracellular matrix, as well as the immune microenvironment within the tumor. The therapeutic benefits after such treatments, especially in combination with many existing cancer therapies, will be introduced. On the other hand, how the modulation of TME would in turn favor the therapeutic efficacy of nanomedicine, will also be discussed. The future perspectives of those strategies, especially towards clinical translation, will be addressed in the end.