National Study Tests Potential Prostate Cancer Vaccine

Scientists across North America are testing a vaccine that stimulates the immune system to fight prostate cancer, a disease that affects 16 percent of American men.

Led locally by University of Cincinnati (UC) medical oncologist Leslie Oleksowicz, MD, the phase-3 clinical trial will determine whether the vaccine can 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, director of UC’s medical genitourinary oncology program. “Cells that don’t need androgen to grow will eventually take over and begin to spread.”

Researchers believe that the vaccine—called VITAL-1—may 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,” she adds, “he wouldn’t have cancer in the first place.”

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.

Researchers will obtain skeletal X-rays periodically throughout treatment to monitor bone-related complications—such as fractures—and progress of the disease.

According to the American Cancer Society, more than 230,000 new cases of prostate cancer were diagnosed in 2005. The disease annually results in about 30,000 deaths in the United States, making it the second leading cause of cancer-related death among men. When detected in an early stage, prostate cancer is one of the most curable types of the disease. 

For more information on the study, which is sponsored by Cell Genesys Inc., call Cheryl Sizemore, at (513) 584-7614. Dr. Oleksowicz has no financial interest in the company.