Tuesday, December 27, 2011

Canadian researchers believe they are near to developing a vaccine for ovarian cancer

Canadian researchers close in on vaccine for ovarian cancer montrealgazette.com Brad Nelson, a molecular and cellular biologist and project leader of the research at the B.C. Cancer Agency's Deeley Research Centre, said the team believes it is three to five years away from clinical trials of a vaccine. Nelson said this has been made possible by breakthroughs in recent years in DNA sequencing. "It's a whole new approach to cancer vaccines that's never been used before," he said. According to Ovarian Cancer Canada, more than 2,600 Canadian women are diagnosed with the disease every year and it kills 1,750 annually. If it is detected early, survival rates can reach 90 per cent. But no screening tools exist to test for it, and symptoms can be vague and easily missed. Most diagnoses occur when the cancer has reached an advanced stage. Ovarian cancer cells can be shed into surrounding bodily fluid. They can then implant on other structures, including the uterus, bladder or bowel, forming new tumours. He said the course of treatment for ovarian cancer is normally surgery followed by chemotherapy. Patients usually respond well at first, but within two to three years, the cancer often reappears. By that time, the cancer cells often have become resistant to chemotherapy drugs, and survival rates start to drop off. Nelson said his research is geared toward a therapeutic vaccine that would be administered after surgery and chemotherapy have beaten down the cancer cells. The vaccine would work by educating the body's immune system to recognize cancerous cells and attack them. Nelson said the planned vaccine would be personalized by creating a DNA profile of the patient's tumours. With ovarian cancer, cells with mutations begin to arise and together band into tumours. By performing a DNA analysis of the tumour, a more targeted vaccine can be developed. It would alert the immune system of a particular patient to recognize and attack the mutated cells of tumours. Also, if the cancer should reappear, another personalized vaccine can be created. This new version could target cells of the second cancer, which likely would have mutated from the first. "There really is no limit to how long you can play this strategy," Nelson said. Furthermore, because cancer cells tend to mutate into hundreds of DNA sequences, the vaccine would target five of the mutations, giving the patient's immune system a good chance of winning. "The chance a tumour will be able to bypass all five is very low," he said. It's an approach similar to modern drug cocktail treatments for HIV. A variety of drugs are used to beat back the AIDS virus as it mutates into various forms. "Viruses are like tumours รข they are dumb," Nelson said. "They aren't really trying to kill you, they just keep on blindly evolving." Researchers in the U.S. are taking a similar approach to developing personalized vaccines for different cancers. But Nelson said the B.C. Cancer Centre in Victoria offers him a unique, "front-line" scientific environment. Nelson bumps shoulders every day with clinical doctors and patients. "You start to think differently," he said. "What can I do in three to five years that is going to make a difference?" Meanwhile, Lorraine Dixon of Saltspring Island, a survivor of ovarian cancer and one of the nearly 100 women who have agreed to donate tissue and blood samples to help out, is glad to hear the work is going well. Dixon reports every year to have blood drawn for research. Since she was diagnosed in 2008, Dixon has had two bouts of surgery, one round of chemotherapy and one round of radiation therapy. The tests show she has responded well. But Dixon said she has a vested interest beyond her own body. She also has a grown daughter, two granddaughters and five nieces. "I agreed (to the research) before my first surgery," she said. Nelson's work has been funded by Genome B.C., an organization supported by government partnering with private industry to act as a catalyst in life-sciences research, including medicine. - Posted from my iPad2

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