Researchers have developed a new vaccine that sharply reduces tumors in a mouse model that mimics 90 percent of human breast and pancreatic cancer cases, including resistant cancers to common treatments.

The vaccine could lead to a new strategy for treating cancers that share the same distinct carbohydrate signature, including ovarian and colorectal cancers said researchers from the University of Georgia and the Mayo Clinic in Arizona said. The results of the study were published in the journal Proceedings of the National Academy of Sciences.

"This vaccine elicits a very strong immune response," said study co-senior author Geert-Jan Boons, Franklin Professor of Chemistry and a researcher in the UGA Cancer Center and its Complex Carbohydrate Research Center.

"It activates all three components of the immune system to reduce tumor size by an average of 80 percent."

Using 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, the researchers were able for the first time to create a vaccine that determines the good cells from the bad cells.

The researchers explained that when cells become cancerous, the sugars on their surface proteins undergo distinct changes that set them apart from healthy cells.

But for decades, scientist haven’t been able to determine the difference from the two, therefore they couldn’t destroy the bad cells without destroying the good cells as well.

Researchers have now developed a vaccine that does this in mice.

The mice developed tumors that overexpress a protein known as MUC1 on the surface of their cells. The tumor-associated MUC1 protein is adorned with a distinctive, shorter, set of carbohydrates that set it apart from healthy cells, the authors explained.

"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 said.

Gendler said that MUC1 is found on more than 70 percent 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 percent of cases.

Boons said that while many patients are diagnosed with cancer each year and such tumors are difficult to treat, a new treatment option is urgently needed.

"In the U.S. alone, there are 35,000 patients diagnosed every year whose tumors are triple-negative," Boons said. "So we might have a therapy for a large group of patients for which there is currently no drug therapy aside from chemotherapy."

Researchers are currently doing further research of the vaccine’s effectiveness against human cancer cells.

"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."