NEWS

Cuban Vaccine Tested in Canadian Trial

Judith Randal

Mark Vincent, M.B., Ch.B., a fellow of the Royal College of Physicians, Canada, is an oncologist at the London Regional Cancer Center, Ontario. There he is running a trial of the Cuban vaccine in advanced non-small cell lung cancer patients who haven’t been helped by chemotherapy. It is the vaccine’s first trial outside its homeland and Vincent would clearly like that soft-pedaled. In talking to a reporter, he made a point of telling her that he would not "want to be associated with any particular political viewpoint."



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Dr. Mark Vincent

 
The conversation then turned to the rationale for the vaccine, starting with Vincent’s reminder that circulating estrogen—the estrogen that floats in the blood as a matter of course—can drive breast cancer growth.

Similarly, he said, certain other cancers—non-small cell lung and many head and neck cancers, for instance—can be fueled by epidermal growth factor (EGF), which also circulates in the blood. The vaccine, accordingly, is meant to cause a patient’s immune system to form antibodies to EGF that will prevent its doing that.

In a pilot study in Cuba, all patients given the vaccine have had advanced non-small cell lung cancer. The study is ongoing. In a follow-up study, the 80 patients in the Canadian trial, which opened last September, are being randomized to get or not get the vaccine. Vincent is not sure of definitive results. "We may find," he said, "that our end-stage people with non-small cell lung cancer do not mount an immune response to anything because they are too immuno-depressed. If so, we may need to move to a randomized study of the vaccine in patients with slightly less advanced disease."

In the current trial, however, detecting survival differences between the treated patients and the controls is secondary to assessing the vaccine’s safety and immunogenicity. It is not, Vincent indicated, that the Cuban findings on these scores are invalid; they are not. In fact, after a trip to Havana with a Canadian Medical Research Council group, he came away thinking that many of the scientists he met there "seemed quite good and could probably find employment anywhere in the western world."

The difficulty, he said, was that "our [Canadian] patients are somewhat different from those in Cuba in that they have had chemotherapy of a different sort and may be at a different point in their natural history [of non-small cell lung cancer]."

Besides, he added, the randomized design of the Canadian trial allows you to learn to what degree the vaccine is immunogenic. Otherwise, you might never know because it so happens that "there is a natural antibody level to EGF in everyone and it may fluctuate."

For all that, Vincent thinks the vaccine was soundly conceived. "It deserves a proper scientific test," he said. "That’s where I am coming from."



             
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