Macrophages are important immune cells that help keep us safe from viruses, bacteria, and pre-cancerous cells. However, when a few pre-cancerous cells manage to evade macrophages and other immune cells, they can develop into a tumor. Once that happens, the tumor actually recruits those same immune cells to do the opposite job – namely, helping the tumor evade our immune system, grow, and spread. Therefore, identifying and targeting the tumor-supporting immune cells has become a promising new way of improving cancer treatment, called immunotherapy.

Tumor-supporting macrophages are the most abundant immune cells found in tumors, making them an important immunotherapy target. In people, there are many ways to distinguish the tumor-supporting macrophages from the tumor-destroying macrophages, and several clinical trials are looking at ways of re-teaching the tumor-supporting macrophages to instead destroy cancer cells.

While it is easy to identify macrophages in dogs, the ability to distinguish the different subsets is poor. This project has identified a novel marker of tumor-supporting macrophages, a protein called TRAF3. The researchers aim to validate TRAF3 as a marker of canine tumor-supporting macrophages, with the intent to better identify and target this subset of macrophages. The goal of the project is to help close the gap that currently exists in macrophage-targeted cancer therapy between people and dogs, as well as potentially identify new ways to target macrophages in human and canine cancer.