Vaccine May Enlist Body’s Immune System to Kill Mesothelioma Cancer Cells

• Nancy Meredith
• Asbestos Exposure, Mesothelioma, Research

Researchers at the Mayo Clinic and the University of Georgia have developed a vaccine that may offer a promising new strategy for treating various cancers including mesothelioma. An aggressive cancer associated with breathing asbsestos, mesothelioma originates most often in the lining of the lung and abdominal cavity.

The vaccine, which has shown dramatic results at reducing tumors in mice in laboratory experiments, helps a cancer patient’s immune system identify cancer cells and kill them, according to an article this week in the Proceedings of the National Academy of Sciences. Treatments that employ the body’s own defenses are known as immunotherapy. The research was funded by the National Cancer Institute.

Scientists have long sought to direct the immune system to distinguish when cells become cancerous by the distinct changes that sugars on the cell’s surface undergo. But since cancer cells originate within the body, the immune system generally doesn’t recognize them as foreign.

The vaccine identifies a special protein that is  a signature of certain cancer cells. When malignant tumors occur, they produce the protein MUC1 at high levels, promoting the growth of tumors. Mesothelioma is among the types of cancer in which MUC1 is overexpressed, previous studies such as a 2008 study have shown.

“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,” Sandra Gendler, a cancer researcher at the Mayo Clinic in Arizona and co-author of the study said in a press release.

The National Cancer Institute recently recognized MUC1 as one of the three most important tumor proteins for vaccine development, Dr. Gendler noted. MUC1 is found in more than 70 percent of lethal cancers including breast cancer, pancreatic cancer, ovarian, multiple myeloma, lung cancer and mesothelioma.

Geert-Jans Boons, a cancer researcher at the University of Georgia Cancer Center and developer of the vaccine, said the treatment, called MUC1 tripartite immunotherapy, produces a very strong immune response. The vaccine was shown to reduce tumors in mice by 80 percent or more, the researcher said.

The researchers are currently testing the vaccine’s effectiveness  against cultured human cancer cells in the laboratory to assess toxicity. Phase I clinical trials involving cancer patients to assess the safety of the vaccine could begin in 2013.

Approximately 3,000 people are diagnosed with mesothelioma each year in the United States. Most are older workers, retired workers and veterans who were exposed to asbestos decades ago in the workplace.

Mesothelioma has a long incubation period, typically taking 30 to 50 years for symptoms to appear. When it does appear, the cancer is stubbornly resistant to conventional treatments such as chemotherapy and radiation and has a high fatality rate. So more effective treatments are urgently needed.