Targeting adenosine in cancer immunotherapy: a review of recent progress.

INTRODUCTION: The adenosine pathway plays a key role in modulating immune responses in health and in disease. In health, anti-inflammatory effects of adenosine balance pro-inflammatory ATP, limiting tissue destruction by activated immune cells. In disease, this balance is disturbed. Areas covered: This review focuses on cancer and explains how in the microenvironment, the ATP-adenosine balance shifts towards an excess of extracellular adenosine Expert commentary: The CD73-adenosine axis plays a key role in the inhibition of anti-tumor functions of immune effector cells. Today, adenosine emerges as one of the immune checkpoints that are implicated in the tumor escape from the host immune system. The adenosine pathway is currently viewed as a significant barrier to the effectiveness of immune therapies and becomes an important therapeutic target in cancer. Pharmacologic inhibitors or antibodies specific for the components of the adenosine pathways or adenosine receptors show efficacy in pre-clinical studies and are entering the clinical arena.