ACIs offer new hope for prostate cancer patients

Doctors hope that a new treatment using patients' own cells to treat prostrate cancer will be approved by the Food & Drug Administration-despite a recent decision by the agency to delay its approval. Described as active cellular immunotherapy (ACI), it uses a patient's cells that have been treated to trigger a specific and long-lasting immune response that enables the body to fight cancer cells.

According to Daniel P. Petrylak, M.D., associate professor of medicine at Columbia University Medical Center, "It is intended to train the immune system to recognize cancer cells as dangerous in order to ignite the natural cascade of immune system events that would allow the body to destroy cancer cells." The new findings were disclosed at the Prostate Cancer Symposium in February.

Last year, there were 234,460 new cases of prostrate cancer and an estimated 27,350 deaths from the disease, and researchers say ACI may be one of the new cures for the deadly disease. Neal D. Shore, M.D., director of the Carolina Urologic Research Center in Myrtle Beach, S.C., said several of his patients are participating in clinical trials of the ACI product, Provenge (sipuleucel-T), a vaccine made by Dendreon Corp.

"After approximately 40 hours, the antigen-presenting cells are ready to be used," said Monique Greer, a spokeswoman for Dendreon. "We subject each dose to quality-control testing." This process usually takes three days. Over 30 days, patients typically get three infusions, each lasting between 30 and 60 minutes.

According to researchers, Provenge activates T cells, which attack cancer cells. When a person is healthy, the immune system will treat cancer cells as foreign invaders and fight to remove them from the body.

Jim Kiefert, board chairman of Us TOO Prostate Cancer Education & Support Network, lauded the new treatment technique, because patients are unhappy with chemotherapy and radiation treatments. "A cure is what we need," he said. "But before we have a cure, we need medicines that delay the spread of cancer and increase survival."

"We desperately need better therapies for advanced prostate cancer than are currently available," said Thomas A. Farrington, president of the Prostate Health Education Network. "ACIs could be an answer."

"It helps the man's immune cells recognize cells that carry an antigen called prostatic acid phosphatase [PAP] as a foreign antigen and attack those cells," Shore said.

In a study involving 82 prostate cancer patients who received Provenge, the survival rate was 34% over a 36-month period. The study, published last year in the Journal of Clinical Oncology, found that there was an improvement in survival in patients who had not received chemotherapy.

There were limited side effects from the treatments administered in physicians' offices. There are no hematological toxicity, diarrhea, nausea, or other conditions that usually occur from drugs or chemotherapy, according to Shore.

Petrylak said docetaxel (Taxotere, Sanofi-Aventis) is probably the most promising prostate cancer drug treatment currently because the survival rate is higher and the side effects are only fluid retention, fatigue, and neutropenia. "Docetaxel combined with prednisone is the standard of care for androgen-independent prostate cancer [AIPC]," he said. "There remains a need for new treatments and regimens with improved efficacy and tolerability in AIPC. Immunotherapy-more imminently ACIs-may provide viable options in the AIPC treatment continuum."

Other drugs cited by Petrylak have a serious effect on patients. Zoledronic acid injection (Zometa, Novartis) causes renal impairment and osteonecrosis of the jaw. Mitoxantrone results in cardiac toxicity. And estramustine (Emcyt, Pfizer) results in fluid retention and thromboses, he said.

THE AUTHOR is a freelance writer based in Florida.