One agent, a short component of DNA, boosts the expression of a receptor on the surface of the T cells. The second agent is an antibody that attaches itself to this surface receptor, which activates the T cells and triggers them to attack the tumor.
As these agents are directly emplaced within the tumor, only T cells inside it are activated in this way. That way, they’re trained to recognize what the threat is immediately, and – after destroying the tumor – they swim through the body and obliterate its remnants elsewhere.
Clearly, the trial has been remarkably successful. In 90 mice infected with lymphoma – a cancer of the immune system – 87 of them were completely cured. The cancer did return in three of the cured mice, but a second round of treatment put that insurrection to an end.
Additional work on treating other cancers in mice, including breast cancer and colon cancer, has had somewhat more mixed results. Although the breast cancer mice responded well and often remained in remission, colon cancer seemed to be unaffected in experiments.
“The results of this study are very exciting, although there are some caveats,” Aimee Eckert, a doctoral research student focusing on cancer biology at University of Sussex – and who wasn’t involved in the study – told IFLScience.
“Studies that work well in mice do not guarantee success in human patients, though the fact that each of the two individual treatments used in this study are currently in clinical trials – and that they are now recruiting for the first human trials – is encouraging.”
Additionally, “not all tumors will be accessible for injection – many tumors require surgery first,” Eckert added. However, she suggests that “if this treatment is used alongside surgery and this can prevent secondary tumors or metastases from forming, then we could greatly improve life expectancy and/or cure rates for patients.”
Update: The use of the word "vaccine" in the study stems from the injection's ability to use the immune system to prevent the occurrence of future tumors.