Cancer Vaccine Quest

Some day, the worst thing about cancer may be the shot you get to prevent it.

Even before this somewhat over-optimistic statement appeared in an American Cancer Society ad, researchers were working to bring that day closer. In 1969 scientists succeeded in immunizing chickens against an avian-cancer virus. Now, two German researchers have gone even further by immunizing monkeys--which are several evolutionary steps closer to man --against a virus that causes cancer in primates. Their work raises hope that eventually similar vaccines can be developed for use in humans.

Professor Rainer Laufs and Dr.

Hans Steinke conducted their experiments with cotton-topped marmosets, South American monkeys that are known to develop lymphoma, a cancer of the lymphatic system, when they are exposed to two viruses of the herpes family. The researchers reported in the British journal Nature that they inoculated 42 of the animals with a vaccine made from killed herpes saimiri viruses, then exposed some of the immunized animals and controls to live, cell-free viruses. Most of the non-immunized monkeys developed malignant lymphoma and died of the disease. The immunized animals remained healthy.

The work of the German researchers is also significant because it shows that killed viruses (which are far safer to use in a vaccine than live agents) apparently can be used to stimulate the monkeys' immune system into manufacturing antibodies against cancer viruses.

Doctors have long suspected that viruses, submicroscopic packets of nucleic acids similar to the DNA found in chromosomes, play a role in human as well as animal cancers. Dr. Sol Spiegelman, director of the Institute of Cancer Research at New York Columbia-Presbyterian Medical Center and one of the world's leading cancer virologists, points out that virus-like particles can be found in just about every human cancer. But proving that these particles cause the cancers has been more difficult. The cases against several suspect viruses have had to be dismissed for lack of scientific proof. There is largely statistical evidence against others--most notably herpes simplex Type I, responsible for cold sores, and herpes simplex Type II, which causes genital infections. Both have been tenuously linked to a variety of cancers. Although the case against a virus isolated recently by Drs. Robert Gallo and Robert Gallagher of the National Cancer Institute is even stronger, further proof that it is in fact a human-cancer virus is still being sought.

Even if it is proved that viruses cause human cancer, cautions Spiegelman, it may be years before science can develop a safe, successful vaccine against them. But identification of cancer viruses is likely to produce a payoff long before vaccines become practical. Spiegelman believes that the presence of viral particles, which are unique to each type of cancer, may provide doctors with effective methods of detecting cancer in its earliest stages--well before it can be diagnosed by X rays and more conventional methods. That development by itself could save many of the Americans who die of cancer every year.

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