Vaccine May Help Treat Advanced Melanoma
Study Shows Experimental Vaccine May Shrink Tumors in Patients With Late-Stage Melanoma
How the Vaccine Works continued...
And the vaccine can't be used in everyone. The inoculation only works in people with a certain type of protein signature on the surface of their cells, called an HLA type, though researchers said the vaccine could be tailored, in the future, to work with different HLA types.
Patients also have to be healthy enough to withstand the toxic effects of treatment, which can be significant.
But for patients who are battling advanced melanoma, which is one of the deadliest kinds of cancer, any options, even limited ones, are likely to be welcome news.
"Cancer patients want to do something to fight their cancer, but if you have stage II or stage III disease, the standard of care is observation," says Tim Turnham, PhD, executive director of the Melanoma Research Foundation in Washington, D.C. "That's really tough for patients."
Using Vaccines to Fight Cancer
For the study, researchers recruited 185 patients at 21 centers across the U.S.
To be eligible for the study, patients had to have metastatic melanoma, either stage IV or locally advanced stage III, and they had to be HLA-type A0201, a tissue type carried by about half of people in the U.S.
All patients received high-dose IL-2 therapy. IL-2 was approved by the FDA in 1998 for the treatment of metastatic melanoma.
About half of patients, 91, were randomly assigned to also receive the experimental gp100 vaccine. That vaccine uses a protein found on the surface of cancer cells to flag those cells so they can be destroyed by the immune system.
Radiologists who weren't told which group was getting the vaccine reviewed scans to determine tumor progression.
Just 6% of patients who got IL-2 alone saw their tumors shrink by at least 50%. In the vaccine group, however, 16% saw that much improvement.
The midpoint for progression-free survival was 1.6 months in the IL-2 only group, compared to 2.2 months in the vaccine group.
The median for overall survival was 11.1 months in the group that only received IL-2 compared to 17.8 months in the vaccine group. This indicates a trend in increased in overall survival in the vaccine group.
"The numbers are small, if you look at the absolute numbers in terms of the benefit," says study researcher Douglas J. Schartzentruber, MD, a surgical oncologist who is medical director of the Indiana University Health Goshen Center for Cancer Care.
But he points out that the first drug ever to demonstrate a survival benefit for patients with melanoma, Yervoy, was just approved last month by the FDA.
"We're just beginning to develop some effective treatment strategies for metastatic melanoma and, in this case, the vaccine is proof of principle that vaccines have a role," he says.