Soon, vaccine that can shrink tumours

Scientists have developed a vaccine that promises a new strategy for treating ovarian, colorectal and pancreatic cancer. Researchers from the University of Georgia and the Mayo Clinic in Arizona have developed a vaccine that dramatically reduces tumours in a mouse model that mimics 90 percent of human breast and pancreatic cancer cases-including those that are resistant to common treatments. "This vaccine elicits a very strong immune response," said study co-senior author Geert-Jan Boons. "It activates all three components of the immune system to reduce tumor size by an average of 80 per cent." When cells become cancerous, the sugars on their surface proteins undergo distinct changes that set them apart from healthy cells. For decades, scientists have tried to enable the immune system to recognize those differences to destroy cancer cells rather than normal cells. But since cancer cells originate within the body, the immune system generally does not recognize them as foreign and therefore does not mount an attack. The researchers used unique mice developed by Sandra Gendler, Grohne Professor of Therapeutics for Cancer Research at the Mayo Clinic in Arizona and co-senior author on the study. Like humans, the mice develop tumours that over express a protein known as MUC1 on the surface of their cells. The tumour-associated MUC1 protein is adorned with a distinctive, shorter, set of carbohydrates that set it apart from healthy cells. "This is the first time that a vaccine has been developed that trains the immune system to distinguish and kill cancer cells based on their different sugar structures on proteins such as MUC1," Gendler said. "We are especially excited about the fact that MUC1 was recently recognized by the National Cancer Institute as one of the three most important tumor proteins for vaccine development." Gendler pointed out that MUC1 is found on more than 70 per cent of all cancers that kill. Many cancers, such as breast, pancreatic, ovarian and multiple myeloma, express MUC1 with the shorter carbohydrate in more than 90 per cent of cases. She explained that when cancer occurs, the architecture of the cell changes and MUC1 is produced at high levels, promoting tumour formation and also said that a vaccine directed against MUC1 has tremendous potential as a preventative for recurrence or as a prophylactic in patients at high risk for particular cancers. A vaccine also can be used together with standard therapy such as chemotherapy in cancers that cannot be cured by surgery, such as pancreatic cancer. Although promising results in mice often don't translate to humans, Boons claimed he is confident that vaccines that target the specific carbohydrate signatures of cancer cells will ultimately play an important role in the treatment of the disease. "We are beginning to have therapies that can teach our immune system to fight what is uniquely found in cancer cells," Boons said. "When combined with early diagnosis, the hope is that one day cancer will become a manageable disease," Boons added.