The Hunt For Cures: Cancer

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Glivec is just one of several new therapies that work by cutting a cancer cell's lines of communication, either preventing it from reproducing or forcing it to self-destruct. Other signal-jamming treatments use monoclonal antibodies, tiny proteins that resemble the human immune system's own antibodies but that bind to the surface of cancer cells. New York City- based ImClone Systems has an antibody called IMC-C225, now in the final phases of testing in colorectal and head and neck cancer, that acts like bubble gum stuffed in a keyhole. It prevents a specialized protein known as a growth factor from fitting into a slot on the surface of the cancer cell and signaling it to reproduce.

Other antibodies carry tiny payloads of radioactive isotopes or poisons, which kill the tumor cell without affecting surrounding tissue. IDEC Pharmaceuticals in San Diego has just completed final rounds of testing on Zevalin, an antibody that is hooked to the radioactive isotope yttrium-90. Last month IDEC reported that the tumors in about one-third of 73 late-stage non-Hodgkins lymphoma patients were undetectable after being treated with Zevalin.

Antibodies are also being drafted to prod the immune system into attacking cancer cells. Clinicians have long dreamed of marshaling the body's own defenses to fight cancer, if only they could get the immune system to recognize cancer cells as easily as it spots foreign invaders such as bacteria and viruses. Researchers at Dendreon Corp. in Seattle have found a way to do just that by enlisting dendritic cells, some of the body's most potent immune stimulators.

Two years ago, Mohammad Omidian, 58, a general contractor from Orinda, Calif., had failed to respond to chemotherapy treatments for multiple myeloma that was eating away at his bones. He had shrunk 3 in. and was so weak, he says, "I could not sneeze without holding on to something." His doctors put him on Dendreon's experimental treatment Mylovenge, which required extracting dendritic cells from Omidian's blood, mixing them with molecules from myeloma cells and then returning them to the patient so they could deliver a swift kick to his immune system. Within two weeks, Omidian felt strong enough to return to work. Within two months, his cancer was in a remission that lasted until late last year, when he resumed treatment with Mylovenge.

Other companies are focused on boosting the immune system with vaccines that can direct it to target cancer cells. A new vaccine developed at Memorial Sloan-Kettering binds a protein from a mollusk called a limpet to seven different types of sugars and a protein fragment found only on cancer cells. The vaccine is then mixed with saponin, a soaplike derivative from a South American tree. This witch's brew serves to annoy the immune system, revving it up enough to attack cancer cells that are carrying the same sugars and protein fragment.