Saturday, January 21, 2012

Good News In The Advancement of A Breast Cancer Vaccine

Over the past few years scientists have worked on a vaccine to help breast cancer patients. This new E75 vaccine that is in the final phases of clinical trials. Through the testing it has shown that women injected with E75, who have experienced the trauma of breast cancer, prevented recurrence in 50% of the patients. U.S. Army Col. George Peoples, chief of surgical oncology, at San Antonio Military Medical Center is the developer of this vaccine.
This is what Peoples has said in a recent interview:
"What I have been the most interested in doing in how to engage the engage the patients immune response, to help the patient's immune system to fight off the cancer,” said Col. George Peoples, a cancer surgeon and director of SAMMC's cancer vaccine development program, who's leading the study.
Like any vaccine, E75 primes the immune system to recognize a target — in this case a substance called human epidermal growth factor receptor 2, or HER2. Most breast cancers produce some level of HER2, which fuels their growth.
And most breast cancer patients are tested for HER2, because those with the highest levels — about 20 percent of patients — can be helped by a drug called Herceptin.
But E75 seems to work best in patients who produce low to medium levels of HER2 — a group that makes up maybe 60 percent of breast cancer patients, and who usually aren't eligible for Herceptin.
Peoples has been studying different parts of the HER2 protein as potential vaccine targets since 1995, first as a civilian and then after a return to Army medicine at Walter Reed Army Medical Center and SAMMC.

“Within the first year or two of starting that trial, we could tell there was a benefit because the control arm (the comparison group that didn't get the real vaccine) started having recurrences, and the vaccine group was not,” Peoples said.
“The promise of cancer vaccines for many years has been solely a promise,” said Dr. Kim Lyerly, director of the Duke Comprehensive Cancer Center in Durham, N.C., and a scientific adviser to Susan G. Komen for the Cure. “Our understanding of what it takes to mount an immune-system response and to create a vaccine is getting better and better. So that's why this (E75) study, based on really solid Phase 2 data, is very exciting.”
Most experimental drugs and vaccines are first tested in very sick people. Peoples focused instead on healthy women — those successfully treated but at high risk of seeing their cancers return.
“The whole point of the vaccine is to engage the host immune system to get an immune response against a cancer,” Peoples said. “Well, an end-stage patient's immune system is not healthy.”
Early studies also showed the vaccine's protection waned over time. It was a group of Peoples' own patient volunteers who insisted he include a booster shot in the trial. He agreed, adding booster shots at six-month intervals that have kept immunity strong.
“It was breast cancer advocacy at its best,” Peoples said. “They came to me as a group and said, with every other vaccine we know of you have to get a booster inoculation. Why aren't we? I said, it's not part of the trial. They said, make a part.”
If the current study confirms the vaccine is effective in preventing a recurrence of cancer, the next question would be if it can prevent the disease in the first place.
“Eventually if we can prove that a vaccine can work in that situation, then hopefully during my lifetime we will go and do a true prevention trial,” he said.
And HER2 isn't only found in breast cancer. Other tumors, including prostate, ovarian and colon also produce medium amounts."

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