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March 2006 Issue

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Breakthrough Vaccine May Halt Prostate Cancer

By Amanda Harper
Published March 2006

For more than 16 percent of American men, prostate cancer is a fact of life. But Leslie Oleksowicz, MD, a UC medical oncologist, is part of a national team testing a breakthrough new treatment that may make dying from prostate cancer a thing of the past.

That treatment is a vaccine used to stimulate the immune system to fight off the cancer.

Dr. Oleksowicz, director of UC's medical genitourinary oncology program, is leading the local segment of a phase-3 clinical trial taking place across North America to determine whether the vaccine--called VITAL-1--can stop tumor growth without decreasing the patient's quality of life.

VITAL-1 uses modified tumor cells that secrete a powerful protein known as granulocyte-macrophage colony-stimulating factor (GM-CSF), which stimulates the immune system.

"Tumors invade the immune system by producing antigens that trick the body into tolerating them," explains Dr. Oleksowicz. "Our hope is that this vaccine will 'jump start' the immune system to fight off the tumor. If the patient's immune system were working properly, he wouldn't have cancer in the first place."

Researchers believe the vaccine may increase survival for patients whose disease has spread and stopped responding to hormone therapy.

Hormone therapy prevents the body from making or using androgen, a male hormone linked to the growth of certain prostate cancer cells. The treatment decreases hormone levels and slows cancer growth.

"We regularly use hormone therapy to treat men with advanced prostate cancer, but unfortunately it doesn't work forever," explains Dr. Oleksowicz. "Cells that don't need androgen to grow will eventually take over and begin to spread."

Previous clinical trials evaluating a similar prostate cancer vaccine suggested it could potentially provide a more beneficial--and less toxic--alternative to chemotherapy.

"The problem with chemotherapy is that it can harm otherwise healthy tissue," Dr. Oleksowicz explains. "We need targeted alternative treatments to hormone and chemotherapy that don't jeopardize the patient's overall health and safety."

Researchers from about 70 medical centers are recruiting 600 men with adenocarcinoma, a type of cancer that begins in the lining of certain internal organs and can spread through the body's glandular system. Patients who have been treated with chemotherapy, gene therapy or immunotherapy are not eligible.

Study participants will be randomized into one of two treatment groups. The first group will receive the investigational prostate cancer vaccine every two weeks for a total of 13 vaccinations. The second will get chemotherapy (docetaxel and prednisone) every three weeks.

"We're hopeful that when we administer the vaccine," says Dr. Oleksowicz, "we'll boost the immune system and eradicate the patient's tumor."

Dr. Oleksowicz is currently conducting several prostate cancer clinical trials, including a novel treatment using a medical "blockade"--combining chemotherapy, hormonal therapy, a new tumor-targeting agent and bone-strengthening treatments--to reduce the recurrence of prostate tumors and help prevent painful bone injuries associated with the disease.

According to the American Cancer Society, more than 230,000 new cases of prostate cancer were diagnosed in 2005. The disease is the second leading cause of cancer-related death among men. When detected early, it is one of the most curable types of cancer.

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