Figure 2.

Therapy resistance mechanisms driven by the tumor microenvironment in pancreatic cancer. Role of the TME in chemoresistance are extensively studied, while its function in regulating tumor response to novel therapeutics needs further investigation. For chemoresistance mechanisms, the TME mainly provides growth factors to promote tumor cell survival and decreases the uptake or inactivate chemo drugs. For targeted therapy resistance, the TME usually nourishes tumor cells by activating parallel or alternative pathways. For immunotherapy resistance, the TME not only forms physical barriers to prevent the cytotoxic immune cell infiltration, but also produces immune suppressive factors to inactivate them. CDA, cytidine deaminase; dCK, deoxycytidine kinase; deoxyC, deoxycytidine.