Cancer Cells Selectively Load and Secrete Exosomes to Prevent T Cells from Infiltrating Tumors; Implications for More Targeted and Effective Use of Checkpoint Inhibitor Drugs in Cancer Treatment

Checkpoint inhibitor drugs have been a game-changer for many cancer patients. Yet approximately 70% don’t respond to these medications, which work by removing the “brakes” on the immune system’s response to a tumor. Researchers have found that in some of these non-responders, the immune system’s killer T cells, which normally act to eliminate cancerous cells, cannot penetrate tumor boundaries. In a new study, biologist Wei Guo, PhD, of the University of Pennsylvania's School of Arts & Sciences, and colleagues identify a mechanism responsible for keeping killer T cells from infiltrating a tumor. The work, which was published on July 14, 2022 in Nature Communications, offers a new tool to predict how a patient might respond to checkpoint inhibitor drugs. The open-access article is titled “HRS Phosphorylation Drives Immunosuppressive Exosome Secretion and Restricts CD8⁺ T-Cell Infiltration into Tumors.”