Vaccine offers hope for cancer patients

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An experimental cancer vaccine being tested for its safety and toxicity has produced startling results, appearing to provide immunity from the disease and leaving most patients cancer-free after more than two years.

Patients at two Melbourne hospitals given a protein found in many cancers and a drug to boost immunity developed strong immune responses, producing antibodies to the protein as well as helper T-cells and killer T-cells.

Patients given just the protein or a placebo had a weaker immune response. Many have developed secondary cancers.

The results of the trial on post-operative cancer patients by doctors at the Ludwig Institute for Cancer Research at the Austin Hospital, and the Peter MacCallum Cancer Centre, are published today in the Proceedings of the National Academy of Sciences.

Lead investigator Jonathan Cebon said the results were a surprise because the trial was designed to test whether the drug produced adverse reactions in the first tests on humans.

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"We didn't know we were going to get these results," he said. "This was never intended as an end point of the study."

Of 23 melanoma patients given a placebo or part-treatment, 14 have since developed cancer, compared with only two of 19 melanoma patients given the combination treatment.

While the sample size was small, no other factors, such as the patient's age or the stage of their cancer, appeared to significantly influence the results.

Associate Professor Cebon said patients given the combination treatment developed a strong immunity to the protein.

"We found if we increased the dose of the vaccine, the immune response got stronger," he said. "We don't know how long the immunity persists for."

Researchers have begun recruiting melanoma patients for further studies, one part-funded by a $US600,000 ($A820,000) grant from the Cancer Research Institute in the United States.

One will be a randomised study, to see whether the trial results can be repeated.

A second will test the vaccine on patients with an inoperable disease.

"It has the potential to be applied broadly to a range of cancers, but not to all cancers," he said.