Tumors that maintain the same distinct carbohydrate signature may be most susceptible to treatment with this new vaccine, according to the authors. Potential candidates include cancers such as colorectal, ovarian, breast, pancreatic, and some others. Co-senior author Geert-Jan Boons wrote, “This vaccine elicits a very strong immune response. It activates all three components of the immune system to reduce tumor size by an average 80 percent.”
The authors explain that sugars present of the surface proteins of cancerous cells differ from those in healthy cells. For several years, researchers have pursued means of triggering the immune system to identify the differences and target only the cancer cells, leaving normal cells alone. However, this task is not easy since cancer cells originate within the patient’s own body, and the immune system does not recognize them as foreign or pathogenic, and leaves them alone.
For the study, co-author-Sandra Gendler developed special mice for use in this experiment. Tumors in mice overexpress MUC1, a type of protein, on the surface of their cells. The surface of MUC1 in tumors has a unique, shorter set of carbohydrates compared to carbohydrates found on the surface of healthy cells.
According to Gendler, “This is the first time that a vaccine has been developed that trains the immune system to distinguish and kill cancer cells based on different sugar structures on proteins such as MUC1.” Gendler explains that MUC1 was found to exist in over 70% of all lethal cancer. In ovarian, pancreatic, and breast cancers, as well as multiple myeloma, in 90% of these cases MUC1 is expressed with the shorter carbohydrate.
When a cell develops cancerous properties, its structure becomes altered and MUC1 is overproduced – this promotes tumor formation. As a result, there is potential for a vaccine to target MUC1, either as a preventive measure in the case of high risk patients, or to lower the risk of cancer recurrence. The vaccine could also serve a purpose in cancer cases where surgery is not possible, such as pancreatic cancer, to be combined with chemotherapy.
Boons adds, “In the U.S. alone, there are 35,000 patients diagnosed every year whose tumors are triple negative. So we might have a therapy for a large group of patients for which there is currently no drug therapy aside from chemotherapy. We are beginning to have therapies that can teach our immune system to fight what is uniquely found in cancer cells.”