[Immune response and cancer]

Cellular transformation is initiated by genetic and epigenetic mutations that activate oncogenes and inactivate tumor suppressor pathways. Cancers thus arise when somatic cells escape intrinsic and extrinsic tumor suppressor mechanisms in the context of their cellular microenvironment. Given the well established importance of the immune system at controlling and shaping developing tumors, pointing the different strategies of tumor escape may provide important insights for the development of effective cancer therapies. In respect, a better understanding of the molecular interactions between tumors and the host immune system may thus allow the development of novel integrated approaches based on the simultaneous control of tumor escape pathways and the activation of anti-cancer immune responses. We hereafter review the currently known escape strategies developed by tumors and discuss the very limited success of trials using active immunization with vaccines or adoptive immunotherapy conducted to date, with a focus on potential therapeutic avenues. We believe that the induction of clinically relevant anti-cancer immunity and tumor rejection require an orchestrated set of events that are thus far impossible to activate by a single approach. Therefore, combining immunotherapy with conventional therapies may help in breaking down the existing barriers.