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Sunday, December 5, 2010

Individualized dendritic cell cancer vaccines

Richard Barth and his colleagues from Dartmouth have taken a crucial step in developing an anti-cancer vaccine. They’ve successfully tested a dendritic cell (DC) vaccine created from patients’ own cells against their own colorectal tumors.

Dendritic cells form part of the mammalian immune system. Their key function is to gather foreign material and present it on their surfaces so that the other immune cells can find those antigens and react to them. For their purposes, the researchers grew dendritic cells from 26 patients suffering from metastatic colorectal cancer. These patients had previously undergone surgery to remove the tumors from their colons, but unfortunately, the cancer had already spread to their livers. The subjects’ dendritic cells were mixed with samples of their own tumors, and then the concoction was injected back into the patients.

Five years after this treatment, 63% of the patients who had developed an immune response against their own tumors were still alive and tumor-free, compared with only 18% of those who had not developed such an immune response.

Previous tests with DC vaccines have been less successful. In most of those cases, the patients had not previously undergone surgery to remove the bulk of their tumors. Barth speculates that the DC vaccine may be most useful in eliminating the microscopic deposits of metastatic cancer that are inadvertently left behind after surgery, rather than in fighting entire tumors.

Further studies are needed to understand and improve the mechanism of DC vaccines. For one thing, only about 60% of patients developed an immune response against their own tumors. Still, considering the expected death rate from this type of cancer, that’s a significant achievement.