Using the immune system to fight cancer cells is one potential strategy to eradicate cancer. T cells, the most dominant cell in the immune system by number, are capable of killing cancer cells if they can recognize abnormal signals on the cancer cell, such as mutated DNA. However, in the current unmodified disease-state, T cells from cancer patients are generally only able to recognize a small proportion of these mutated DNA signals. Researchers from the Oslo University Hospital, University of Oslo, Netherlands Cancer Institute, and University of Copenhagen teamed up to discover that immune cells from healthy donors can actually recognize and respond to a significant number of these mutated signals. By inserting the component of the donor cells that allows for the recognition into patient T cells through genetic modifications, they were able to make the patient T cells recognize their own cancer cells that they were not responsive to before. This work makes personalized cancer immunotherapy a promising treatment modality for cancer patients. Future work will focus on developing high-throughput strategies to identify the mutated signals on cancer cells that T cells can see and to isolate the corresponding cells from healthy donors that can respond.