A new way to create a personalized vaccine can be an important tool in helping patients with colorectal cancer develop an immune response against their own tumors. A dendritic cell based vaccine developed at Dartmouth and described in an article published in the journal Clinical Cancer Research was used after resection of metastatic tumors to prevent the growth of subsequent metastases.

"In principle, we have developed a new way of using dendritic cells (DCs) that initiate an immune response to stimulate an antitumor reaction from the immune system of the patient's body," said Richard Barth Jr,. Dr. Bart leads the Department of General Surgery at the Dartmouth-Hitchcock Medical Center,.

Dendritic cells are essential for the immune system, helping to identify targets, or antigens, and stimulating its response to these antigens. In a new study, dendritic cells are grown from a patient's blood sample and mixed with the proteins of his tumor. Such a mixture is injected into the patient as a vaccine. The vaccine stimulates an antitumor response from the T cells, a kind of white blood cells that protect the body from disease.

During the study, Dr. Barth operated 26 patients for tumors that were metastases of colon tumors to the liver. Despite the fact that one could expect recovery of some of these patients as a result of surgical intervention alone, most of them would eventually die from the smallest metastases that can not be detected at the time of removal of a large tumor. A vaccine based on dendritic cells was administered to patients one month after surgery. As a result, the T cell mediated immune response against its own tumor developed in more than 60% of patients. Patients were observed not less than 5. 5 years. Five years after vaccine treatment, 63% of patients who developed an immune response to their own tumor were alive and had no tumor processes. In contrast, only 18% of patients whose immune response did not develop were alive and did not have tumors.

"We have shown that a DK vaccine based on a tumor lysate can induce an immune response against its own tumor in a large proportion of patients," states Dr. Barth, who researches DK vaccines in mice and humans for more than 10 years. "There were two main questions to which we wanted to receive an answer: first - can we call an immune response, and the second - will it work? Based on the results of the study, the answer to both questions is positive ".

Over the years, DK vaccines have been of great interest to many researchers, and previous studies have shown that they can not reduce or destroy measurable tumor metastases.

"It turned out that we require too much from the T-cells," says Bart. "A small number of T cells formed as a result of the action of the vaccine can not destroy a large tumor. However, what they can do is find and destroy the tumor cells existing as microscopic germs of future tumors. When, with the help of surgery, we relieve the patient of a measurable tumor, the antitumor T-cells formed as a result of the action of the DK vaccine can help suppress the development of precisely such cells ".

For a more complete understanding of the mechanism of action of the DK vaccine and its effect on survival, additional studies are needed, says Dr. Barth. He believes that such works will open the door to a significant change in the treatment of cancer in the near future. Unlike chemotherapy, the DK vaccine is non-toxic. "The struggle is led by your own immune system," he comments.. "I am optimistic and believe that this will give its result".

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