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Kidney Cancer Vaccine Shows Promise

A new study shows experimental therapy appears to cut risk of recurrence

FRIDAY, Feb. 20, 2004 (HealthDayNews) -- An experimental vaccine for kidney cancer appears to reduce the risk of recurrence and increase survival odds for people with the disease.

The findings, appearing in the Feb. 21 issue of The Lancet, have led the study authors to conclude the vaccine can be considered for patients who have tumors larger than 2.5 centimeters, the group that benefited the most from the vaccine in the study.

Outside experts, however, state that while researchers may be closer to a vaccine for kidney cancer, they still are not there.

"The findings are suggestive, but not conclusive," says Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society in Atlanta.

While surgery to remove all or part of the kidney is standard practice for this type of cancer, additional treatments such as chemotherapy or radiation have not met with much success. As a result, half of patients will have a recurrence within five years.

On the other hand, there has been a great interest in developing a vaccine for this particular type of cancer because some people have had unexplained response in their tumors even without treatment.

"Kidney cancer has been recognized as a possible target for a vaccine therapy because of the way the cancer itself behaves," Lichtenfeld says. "Some people have had unexplained changes in their tumor, suggesting that the body may in fact be able to recognize kidney cancer." This unexplained behavior has long represented a hopeful window of opportunity for researchers in this field.

Although many studies are ongoing, no cancer vaccines have yet been approved for use. The idea is to take cancer cells (often from the actual patients) and process them in such a way that they can be given back to the patients to help foster an immune response.

The current trial, which used cells from the patients' own tumors, is one of the largest and furthest along of its kind. "As far as I can tell, this is the largest vaccine phase III [final stage] trial for kidney cancer that's been finished and come out," says Dr. Mayer Fishman, an assistant professor of interdisciplinary oncology at the Moffitt Cancer Center of the University of South Florida in Tampa and author of an accompanying commentary.

The study authors analyzed information on 379 patients from 55 medical centers in Germany who had had surgery for cancer of the kidney. Before surgery was performed, all of the participants were randomized to receive a vaccine (six injections in all) or no additional treatment.

More than three-quarters (77 percent) of the vaccine group and 68 percent of the control group survived without a recurrence for five years.

Patients who were at a high risk for recurrence (that is, they had a large tumor size and high tumor grade) had an even greater therapy, although this data was not outlined in the report.

The trial was sponsored by a company, LipoNova of Hannover, Germany, a factor Fishman says may have affected how the data was presented.

The paper did not include overall survival comparisons between the two groups, Fishman points out. "The primary endpoint of the study was not about survival, and the purpose of the paper was not to be the final word about data," he says. "This is an industry-sponsored trial, and every page of that they consider to be proprietary information."

At this point, the findings are specific and limited, experts say.

"We're dealing with a study that has been published that suggests tumor vaccines may work in this situation, but we still have a long way to go in knowing how really effective these vaccines may be in this type of cancer," Lichtenfeld says. "It's similar to other studies that suggest a possible effect, but more research is needed before we can incorporate it into therapy for all kidney cancer."

According to Fishman, the company has already started approval proceedings in Germany, but it's unclear if that will succeed and, even if it does, how the U.S. Food and Drug Administration will respond.

"I don't think they have enough from this study to get this product approved for this indication," Fishman adds. On the other hand, the company may be using the study to find out what additional specific information the regulatory authorities need before approving the product. "In that sense, that's a reasonable commercial endeavor."

More information

For more on kidney cancer, visit the National Cancer Institute. The American Cancer Society has more on cancer vaccines.

SOURCES: Mayer Fishman, M.D., Ph.D., assistant professor, interdisciplinary oncology, Moffitt Cancer Center, University of South Florida, Tampa; Len Lichtenfeld, M.D., deputy chief medical officer, American Cancer Society, Atlanta; Feb. 21, 2004, The Lancet
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