In a novel approach to treating cancer, Johns Hopkins researchers plan to begin using prostate cancer patients' own tumor cells -- and gene therapy -- to enable the men's immune systems to kill the cancer.
The treatment, involving a complicated gene manipulation, has been proven to work in animals with prostate and kidney cancers.
Researchers believe it could be effective against other malignancies, such as colon cancer and melanoma.
The treatment might offer the patient a kind of vaccination to ward off future attacks by a specific type of cancer.
The U.S. Food and Drug Administration recently approved human trials of the therapy for prostate cancer, and Hopkins researchers plan to enroll eight patients in the next several weeks, a Johns Hopkins spokeswoman said yesterday. Approval of the prostate cancer trial became public this weekend at a New Orleans conference for science writers.
About 40,400 men are expected to die this year from prostate cancer, the second most common cause of cancer death in men.
Hopkins researchers are already testing the method with a group of kidney cancer patients. Those results will not be made public until later this spring.
Experts say the therapy offers promise, particularly in cases where pieces of a tumor break off and travel through the body, spreading the cancer. Essentially, the therapy would train a person's immune system to seek out and destroy those small pieces -- possibly for a lifetime.
To do that, doctors remove cancer cells from the patient's tumor and then insert into those cells a copy of a gene that stimulates the immune system.
The cells are next irradiated, so they won't multiply, and injected back into the patient. Theoretically, the introduction of the genetically altered cells activates the patient's immune system to kill the cancer. The process takes several weeks.
"This is one of those things that is very exciting. It has the potential of being very significant, and it's something that I really think we have to try," said Dr. Otis Brawley, a prostate cancer specialist at the National Cancer Institute.
Even so, researchers warned that the treatment is experimental and the studies are in preliminary stages. The therapy is not available to the general public.
To be involved in the prostate trial, patients must be newly diagnosed with an advanced stage of the cancer and previously untreated. If all goes well with the first eight patients, the trial will be expanded, the spokeswoman said.
The lead researcher, Dr. Jonathan Simons, assistant professor of oncology and urology at the Johns Hopkins School of Medicine, was not available for comment yesterday.
"The idea is to make a vaccine that will stimulate the body to generate immune cells that go on a search-and-destroy mission to eradicate any prostate cancer cells that remain in the patient's body," he told the Associated Press Sunday.
Dr. Harmon Eyre, the American Cancer Society's chief medical officer, who discussed the therapy with Dr. Simons, is very optimistic.
"It represents a new approach to the treatment of cancer that has yet to be tried and that works very well in animals," Dr. Eyre said. "This is the first type of therapy that's ever been found to cure prostate cancer in mice."
New therapies are urgently needed for prostate cancer, Dr. Simons said. Roughly 100,000 men each year have their prostate glands removed because of cancer. But in 30 percent to 40 percent of these men, pieces of the tumor break off and spread, frequently to the lungs. The pieces are often so small they can't be detected by imaging techniques or X-rays. Even if detected, no chemotherapy, radiation or hormone therapy has been successful in stopping the cancer, and the men die.
In the new therapy, scientists believe they may be able to turn that around by inserting one of the human body's most powerful immune system boosters -- the gene known as GM-CSF, the Granulocyte-Macrophage Colony Stimulating Factor.
Researchers don't know how long the immune system might retain the "memory" of how to fight the cancer, and the long-term outcome of participants in the Hopkins trials won't be known for years.
The prostate cancer treatment would be very expensive, possibly as much as $30,000 per patient, because it would be tailored to the individual. For instance, one person's cancer cells couldn't be used to make the therapy for another patient.