'Breakthrough' Cancer Treatment Heads for U.S. Approval

Mar 30, 05:02 AM

Current Headlines: By Delthia Ricks

MELVILLE, N.Y. -- A therapy that recruits the body's own cells to destroy tumors could become a new way to treat men with advanced prostate cancer -- if federal health authorities ultimately approve the highly individualized treatment.

The first step toward approval by the U.S. Food and Drug Administration is to occur today when an advisory panel meets to weigh the fate of what some experts are calling the first vaccine for any form of cancer.

The drug's maker prefers to call the treatment "an active cellular immunotherapy," which company officials say involves using a patient's immune system to control cancer that has migrated to bone and other sites.

Called Provenge, the therapy was developed by Dendreon Corp., in Seattle. The therapy would be an important addition to the treatment of advanced prostate cancer, doctors say, because so few medications exist to control the disease once it spreads out of the prostate gland.

Dr. E. Roy Berger, a prostate cancer specialist at John T. Mather Memorial Hospital in Port Jefferson, N.Y., said FDA advisory committee recommendations are not cast in stone, but the agency rarely votes against its expert panelists. He is involved in the therapy's clinical research, having brought 25 Long Island men into the study. Neither Berger nor his patients know who has received the genuine treatment and who got a placebo.

"I think this is a breakthrough," Berger said of the therapy, which is custom-made for each patient. Immune system cells are extracted from participants and sent to a laboratory in New Jersey, where they are "loaded" with a highly specific protein called prostatic acid phosphatase. The loaded cells are then reinfused into patients. Flowing through the bloodstream, these cells seek out the immune system components called T-cells and prompt them to become cancer killers.

"Once they're in the patient they turn on," Berger said of the laboratory-manipulated cells. "It's actually the T cells that kill the cancer." T cells are known as orchestrators of the body's immune response.

Dr. Simon Hall, director of the Dean Prostate Health and Research Center at Mount Sinai Hospital in Manhattan, said Provenge differs from other cancer vaccines that have been studied. It centers on the body's dendritic cells, he said, which are the ones loaded with the activated protein in the laboratory. These cells are on a specific mission when they are returned to the body, Hall said.

"This is not a drug, it's a biologic agent," he added Tuesday. "It has very limited toxicity. Half of patients get a chill and fever, a feeling as if they're about to get the flu. That's really the only major toxicity."

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