The finding holds a lesson applicable to all new treatments for cancer and other diseases, such as AIDS and tuberculosis, according to Dr. Robert J. Mayer, a professor of medicine at Harvard Medical School and vice chairman for academic affairs at the Dana-Farber Cancer Institute, who wrote an editorial accompanying the study.
"The message is that the way you learn whether adding more drugs to the treatment you have is beneficial is by conducting a proper clinical study," Mayer said.
There is an established belief, he said, that adding new drugs that have different modes of action to therapy will be beneficial. "But these are new classes of molecules, molecularly targeted treatments," Mayer said. "There can be cross-talk between one element of a cell and another. Even though the side effects may not be overlapping, the notion that the overall effect always will be beneficial doesn't seem to be true."
Living cells are complex machines, Mayer said. "The simple notion is that, like driving a car, you can turn the key and start running seven or eight steps under the hood, and that the same thing happens in a cell," he said. "That doesn't fully appreciate all those steps that might be occurring."
It's just not possible to predict what will happen when a new agent is added to a cancer treatment, Mayer said. "We must do these large and admittedly very expensive clinical trials," he said. "These aren't trivial undertakings. But we certainly have the enthusiasm and encouragement that having these molecules can provide benefit."
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