Vaccine Fights Melanoma
Experimental Vaccine Shrinks
Tumors in People With Deadly Skin Cancer
By Charlene Laino
WebMD Health News
Reviewed by Louise Chang, MD
June 1, 2009 (Orlando) -- For the first time, a vaccine that trains the
immune system to seek out and attack cancer cells has been shown to shrink
tumors in people with melanoma.
In a study of 185 melanoma patients, the experimental vaccine also extended
the time that people remained free of cancer.
There are even indications that people given the vaccine live longer, but
patients need to be followed longer before researchers can be sure, says Patrick
Hwu, MD, head of melanoma medical oncology at the
University of Texas M.D.
Anderson Cancer Center in Houston.
Hwu presented the results at the annual meeting of the American Society of
Clinical Oncology.
Melanoma Vaccine: How It Works
Unlike the vaccine that helps prevent cervical cancer in healthy women, the
melanoma vaccine is designed to help people who already have cancer.
The vaccine is given along with interleukin-2, or IL-2,
the standard treatment for melanoma. IL-2 stimulates the immune system to attack and kill
cancer cells. Tumors shrink in one in four patients with advanced melanoma who
get this treatment.
The vaccine contains a substance, called gp100, that is on the surface of
melanoma cells. The idea is that the immune system will see this as a threat and
incite an even stronger attack against cancer cells.
"The vaccine is capable of taking immune system soldiers to boot camp. Then,
interleukin-2 multiplies them into an army," Hwu tells WebMD.
Melanoma is the deadliest form of
skin cancer. This year
in the U.S., there will be an estimated 68,720 new cases and 8,650 deaths from
the disease, according to the American Cancer Society.
Melanoma Vaccine Shrinks Tumors
In the study, people with advanced melanoma were given the vaccine or a
placebo injection,
followed by four days of intravenous interleukin-2 treatment.
This was repeated every three weeks until the tumor shrank or the cancer
progressed.
Tumors shrank in 22% of patients given the vaccine plus interleukin-2,
compared with 10% of those given interleukin-2 alone. The vaccine also extended
the time until the cancer started growing, from about one-and-a-half months for
interleukin-2 alone to nearly three months for the one-two punch.
That may not sound like much, but cancer advances are made in baby steps,
says Len Lichtenfeld, MD, deputy medical director of the American Cancer
Society.
Lichtenfeld tells WebMD that there's reason for "cautious optimism." A lot of
cancer vaccines that seemed promising in early studies haven't panned out, he
says.
Louis M. Weiner, MD, head of the Lombardi Comprehensive Cancer Center in
Washington, D.C., says the vaccine study is the latest in a series showing that
the immune system can be mobilized to attack cancer.
"Many of us believe that a combined approach that includes an immune system
attack on cancer cells will ultimately prove to be most useful in controlling
cancers such as melanoma," he tells WebMD.
Hwu says the next step is to try to reproduce the findings in a longer,
larger study. Also, his team hopes to add yet another punch -- in the form of an
agent that takes the brakes off the immune system.
Then, the immune system soldiers can proliferate with impunity, hopefully
killing even more cancer cells, he explains.
SOURCES:
American Society of Clinical Oncology Annual Meeting 2009, Orlando, May 29-June
2, 2009.
Patrick Hwu, MD, head of melanoma medical oncology, University of Texas M.D.
Anderson Cancer Center, Houston.
Len Lichtenfeld, MD, deputy medical director, American Cancer Society.
Louis M. Weiner, MD, head of Lombardi Comprehensive Cancer Center, Washington,
D.C.
© 2009 WebMD, LLC. All rights reserved.
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