British researchers have developed a vaccine that stimulates colorectal cancer patients' immune systems to fight cancerous cells. In a clinical trial of 67 patients, investigators at the University of Nottingham observed that when the vaccines were administered before and after surgery to remove cancerous tumors, they helped stimulated immune cell production in up to 70% of patients. These results were published in a recent issue of Clinical Cancer Research.
"This is the first vaccine shown to stimulate TNF-alphaan immune-system protein that is very effective at killing cancer cells," said Lindy Durrant, senior author of the study and professor of cancer immunotherapy at the university. The vaccine works by stimulating the patients' immune response to generate T cells, which in turn produce cytokines that destroy cancer cells. The antibody contained in the vaccine, called 105AD7, was cloned from a patient who survived 7 years with liver metastases from colorectal cancer, Durrant explained.
"This is very unusual as most patients die within 1 year of getting liver metastases," she said. "I thought if this antibody had helped this patient, if we could clone it, it might help others."
105AD7 is structurally similar to CD55, a protein that attaches to sugar molecules and is overexpressed in colorectal cancer cells, protecting them from attack by the body's immune system. While low levels of CD55 occur in all cells exposed to the immune system, increased expression of the protein has been observed in multiple types of tumors, including up to 80% of colorectal cancers.
A T-cell response against the vaccine was recorded in the majority of study patients. About 70% of patients produced both TNF-alpha and granulocyte-macrophage colony-stimulating factor in response to both the vaccine and to CD55. "The immune responses to both the vaccine and CD55 were measurable, adding support to the use of CD55 as a target in cancer treatment," Durrant said.