Cancer Vaccine Encouraging

A vaccine-like treatment wiped out or shrank tumors in patients whose kidney cancer had spread elsewhere in their bodies, according to a new study.

Experts called the results striking but cautioned that the preliminary study of only 17 patients would have to be confirmed by more work.

Tumors disappeared in four patients and shrank by more than half in two others, researchers from the University of Goettingen in Germany and elsewhere reported in the March issue of the journal Nature Medicine.

Cancer that has spread from the kidney is notoriously difficult to treat, and doctors often turn to experimental therapies. In the new study, tumors in the lung, bones, lymph nodes and elsewhere disappeared.

The work upon which the vaccine was based originated in the laboratory of Dr. Donald Kufe of the Dana-Farber Cancer Institute in Massachusetts.

"As a vaccine, it activates a 't' cell response, a response of the immune system against the patient's own tumor," he told CBS News Early Show co-anchor Jane Clayson.

The research was aimed at revving up the immune system to attack tumors, much as an ordinary vaccine primes the body to fight off germs. The study used blood cells called dendritic cells, which normally trigger an immune attack by presenting other blood cells with bits of a target germ.

The scientists fused millions of tumor cells from each patient to dendritic cells from donors, then injected the hybrid cells back into the patient. These hybrids could then alert the immune system by displaying bits of the patient's tumor.

Initially, patients were injected with the vaccine twice, six weeks apart. Those whose disease didn't progress continued to get boosters every three months. No serious side effects appeared.

In three of the four patients whose tumors disappeared, it happened within the first 12 weeks, the researchers reported.

"We were quite happy with how this worked," and further development may make the treatment work better, said one study author, Dr. Rolf-Hermann Ringert of the University of Goettingen. He said follow-up testing has already begun.

Kufe told CBS this is not your typical shot.

"When we think of vaccines, we think of prevention, for example, in smallpox and polio," he said, "but we can also use vaccines to treat disease. For decades, we thought vaccines could be used to activate the immune system in the treatment of cancer."

Dr. Samir Khleif, who conducts research on cancer vaccine treatments at the National Cancer Institute, called the report encouraging. But he stressed it must be confirmed by other researchers in studies that include more patients.

Few cancer vaccines so far have made tumors disappear in cases where the disease has spread in the body, he said.

Dr. Alan Houghton, chief of clinical immunology at the Memorial Sloan-Kettering Cancer Center in New York, said he is "cautiously optimistic."

One reason for cution is that cancers that spread from the kidney can sometimes shrink on their own, which can exaggerate the effect of therapy, he said. Another is that the strikingly high rate of tumor response in the study may not be matched in follow-up work, as has happened with other therapies, he said.

As for a vaccine to prevent cancer, first things first, said Kufe.

"First, our goal is to develop one to treat it, and once that's accomplished, then I think we can think towards developing a vaccine to prevent it," he said.

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