Inhibition of the Adenosine Pathway to Potentiate Cancer Immunotherapy: Potential for Combinatorial Approaches.

Cancer immunotherapy has revolutionized the way that we think about treating cancer. Although checkpoint blockade therapy, including anti-PD-1/PD-L1 and anti-CTLA-4, has shown remarkable success, the responses are limited to only a subset of patients. This discrepancy highlights the many overlapping avenues for immune evasion or suppression that can be employed by a tumor. One such mechanism of immunosuppression is adenosinergic signaling within the tumor microenvironment. We provide an overview of the current status of clinical trials targeting the adenosine pathway, including CD73, CD39, and adenosine receptors. Additionally, we highlight several avenues that may be explored to further potentiate responses in the clinic by combining adenosine-targeting agents to target multiple arms of the pathway or by using conventional immunotherapy agents.