Cell Partnership Exploited by Cancer to Turn Off Immune Response

Blocking the partnership between regulatory T cells (Tregs) and dendritic cells may increase the efficacy of immunotherapy for pancreatic cancer, a new study suggests.

In the study, published in Cell Reports, investigators examined pancreatic ductal adenocarcinoma (PDA). Prior studies have shown a link between the early buildup of Tregs in tumors and a reduction in survival.

T cells create a partnership with dendritic cells to choose which protein pieces of viruses or cancer cells would be harnessed to set off an immune response. When in contact with a cancer cell protein, a dendritic cell breaks up the pieces and displays them on its surface for T cells in the nearest lymph node.

Based on the findings, the investigators hypothesize that the partnership between the 2 cell types is exploited by cancer cells via mutually reinforcing cross-talk to shut off the immune response. This means that killer T cells and Tregs may compete for dendritic cells near tumors, the authors noted.

“Our results argue that blocking the partnership between Tregs and dendritic cells might be needed to achieve effective immunotherapy for pancreatic cancer,” said lead author Dafna Bar-Sagi, PhD. “Upcoming studies in our lab will be looking to confirm that this relationship can become the foundation of new treatment strategies.”

The investigators used antibodies and other methods to dramatically deplete the supply of Tregs in mouse models. The results of the study showed a dramatic jump in the numbers of activated dendritic cells and CD8+ T cells in pancreatic tumor tissue, as well as a slowing of tumor growth.

In the United States, an estimated 53,670 individuals will be diagnosed with pancreatic cancer in 2017 and approximately 43,090 individuals will die of the disease.