By using a vaccine patterned after a protein fragment found on some malignant cells, scientists have been able to direct an immune response against ovarian cancer.
The protein fragment, called NY-ESO-1, appears on the surface of tumor cells in about 40 percent of ovarian cancer cases, and also in some other cancers.
In the new study, scientists at the Roswell Park Cancer Institute in Buffalo, N.Y., selected 18 patients who had ovarian cancers that were positive for NY-ESO-1. In most of the volunteers, the cancer had spread beyond the ovaries. All the women had undergone chemotherapy, and their cancers were under control at the time they entered the study, says study coauthor Kunle Odunsi, a gynecologic oncologist at Roswell.
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The women received shots containing the NY-ESO-1 vaccine every 3 weeks for a period of 4 to 11 months between 2003 and 2005. After treatment, the women experienced no recurrence of ovarian cancer for an average of 19 months, Odunsi and his colleagues report in the July 31 Proceedings of the National Academy of Sciences.
Following vaccination, most of the women’s immune systems made cells primed to attack anything sporting NY-ESO-1. A few of the patients also developed antibodies against the protein fragment.
Blood samples obtained up to 18 months after the treatments showed that the immune response was durable. “If the cancer begins to grow, the immune system is still ready to attack,” Odunsi says. However, some patients relapsed when they formed tumors that didn’t display NY-ESO-1.
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Odunsi’s team reports that 15 of the 18 patients are still alive and that seven remain free of ovarian cancer.