(July 31, 2007) CRI/LICR Cancer Vaccine Collaborative Clinical Investigator Dr. Kunle Odunsi at the Roswell Park Cancer Institute in Buffalo, NY, and collaborators announced that results from a phase I study of an ovarian cancer vaccine show the vaccine stimulated a durable, integrated immune response and delayed cancer recurrence in women who are at high risk for their cancers coming back. The vaccine targets the NY-ESO-1 protein antigen, an immunogenic molecular marker found in ovarian and other forms of cancer. Data from the study was published in the July 31 issue of Proceedings of the National Academy of Sciences.

The vaccine was administered to 18 women who had already received standard treatment for epithelial ovarian cancer, the most common form of the disease. According to Dr. Odunsi, the relapse rate for these patients is extremely high, up to 70 percent. Often, the disease can return within six to eight months of therapy. Dr. Odunsi's patients, however, remained cancer free well beyond this point, with a median of nineteen months of relapse-free survival. One of the patients with measurable disease at the start of vaccination underwent complete regression after ten vaccinations, though her cancer returned when vaccination was stopped. Laboratory monitoring studies of patient sera showed that levels of cancer-specific CD4+ and CD8+ T cells increased following vaccination, and that these levels were maintained from six to twelve months after the last injection.

Dr. Odunsi's trial lays the foundation for future studies, including a currently ongoing phase II study of a NY-ESO-1 ovarian cancer vaccine administered in a prime-boost setting with recombinant smallpox and vaccinia. Meanwhile, the Cancer Vaccine Collaborative, under whose auspices Dr. Odunsi's trials are being conducted, is exploring other vaccine combinations targeting the NY-ESO-1 antigen in various types of cancer. Data from Dr. Odunsi's trial is being compared to results from other trials within the Collaborative. Thus, Cancer Vaccine Collaborative researchers are rapidly learning which vaccination approaches produce the strongest, most durable, most effective immune responses against cancer.

"It is very gratifying to see that the cancer vaccines being tested in the Cancer Vaccine Collaborative are beginning to show real clinical benefit for patients," CRI Executive Director Dr. Jill O'Donnell-Tormey said. "Momentum in this field is picking up, and the Collaborative model ensures the shortest route from laboratory discovery to clinical application. As part of a broader international research effort, Dr. Odunsi's ovarian cancer vaccine studies are helping to accelerate the optimization of vaccines for other types of cancer, as well." The PNAS article can be viewed here.