Scientists from the Cancer Vaccine Collaborative (CVC) have discovered that the cancer-specific protein, SSX-2, induces a spontaneous immunological reaction against cancer cells in melanoma patients, offering a new target for the development of a therapeutic melanoma vaccine. SSX-2 is the prototype of the SSX family, and is part of a larger group of proteins known as cancer/testis (CT) antigens. CT proteins are expressed in cancer cells and on normal testes, but the immune system recognizes CT antigens only when they are present on cancer cells. This exquisite immunological specificity for cancer, but not normal, cells has drawn many scientists and clinicians to investigate vaccines against CT antigens as cancer therapies.
“SSX-2 is a particularly good target for a cancer vaccine,” says Dr. Danila Valmori, an Assistant Member of the Ludwig Institute for Cancer Research (LICR), and the senior author of the study. “We found that patients are mounting their own immunological responses against cancer cells expressing SSX-2, and although these spontaneously occurring immunological responses are apparently not sufficient for stopping tumor growth, possibly because they develop late in the disease progression, we think that a vaccine that stimulates and amplifies this naturally-occurring attack will have a good chance of giving a clinical response.”