Tumor-Killing 101: Vaccine Trains Immune Cells to Keep Skin Cancer at Bay

Cancer researchers have developed a therapeutic vaccine for melanoma, a deadly form of skin cancer. Instead of protecting against an infectious agent, such as with the flu vaccine, this cancer vaccine uses the patient’s own cancer cells to train the immune system to attack and destroy cancer.

“This is a new strategy for immunotherapy,” said University of Chicago professor and study lead Melody Swartz. “It has the potential to be more efficacious, less expensive, and much safer than many other immunotherapies. It is truly personalized medicine that has the potential to overcome many issues that arise with other treatments.” The research was published in Science Advances.

Skin cancer is the most common of all cancers, and melanomas make up just 1 percent of these. Melanomas affect melanocytes—pigment-producing cells in the upper layers of skin.

During melanoma development, tumors can start to fuse with lymphatic vessels during metastasis, allowing them to spread deeper into the skin and other parts of the body. However, Swartz and colleagues identified that tumors associated with lymphatic vessels become sensitized to immune attack, either by resident T cells or by immunotherapies. A molecule called vascular endothelial growth factor C, or VEGF-C, facilitates this interaction between melanomas and the lymphatic system.

The researchers used an animal model of melanoma, in which they genetically engineered the tumor cells to overexpress VEGF-C. Next, they irradiated the melanomas and reintroduced the dying cancer cells back into mice. They found that this step activated immune cells, which burst into action and began to target living tumor cells in the body. 

This process of “training” the immune system yielded a robust and long-lasting immune response targeted against cancer. Importantly, it also led to immunological memory: Tumor cells reintroduced into the animals nearly a year later were promptly destroyed.

“This shows that the therapy may provide long-term efficacy against metastasis and relapse,” said Swartz.

The scientists are expanding the horizons of their new vaccine, currently testing a similar strategy to treat breast and colon cancers with the aim of testing these therapies in a clinical trial setting one day.

“We think this has huge promise for the future of personalized cancer immunotherapy,” Swartz commented.

Sources: Science Advances, University of Chicago.