Celecoxib and the drug research roller coaster
In clinical trials, the arthritis drug showed promise in preventing cancer, but then it fell into the Vioxx controversy's wake.
The drug celecoxib (also known by its commercial name Celebrex) is often cited as an example of the mistrust and skepticism that has stunted research on many medicines with the potential to drive down individuals' cancer risks.
In 2004, celecoxib, part of a class of drugs called Cox-2 inhibitors, was one of a group of arthritis drugs -- among them, the blockbuster drug Vioxx -- found to increase the risk of heart attacks and strokes, especially in patients who took them steadily over long periods of time.
In several trials, however, the drug has appeared to offer a real prospect of preventing cancer. In a study published in 2006, for example, celecoxib was found to suppress significantly the process by which colon polyps turn cancerous. In another large international trial, subjects who had precancerous polyps experienced a reduction of new ones by 33% to 45%. In a small UCLA trial published in 2004, those on celecoxib were found to have lower-than-expected levels of inflammation (inflammation is an indicator of elevated lung cancer risk).
And in May, researchers from M.D. Anderson Cancer Center in Houston announced that a larger study had found similar significant reduction in signs of precancerous lesions in the lungs of longtime smokers.
But after Vioxx was withdrawn from the market and Celebrex was found to carry similar risks, researchers and Pfizer, the maker of Celebrex, quickly called off a number of clinical trials in the works and abandoned efforts to have the drug's cancer-prevention qualities recognized by the Food and Drug Administration. Some, though not all, of the trials were restarted in 2005 with the FDA's blessing.
"After all the hype about the cardiovascular risk of the Cox-2 inhibitors, my personal opinion, after reviewing all the studies and looking at all the details, is that the cardiovascular risks have been blown out of proportion," says Dr. Jenny Mao, a UCLA researcher who is studying the use of celecoxib for lung-cancer prevention. "It certainly should be used with caution -- you don't want to use it for people at high risk for heart attacks or strokes. But it is a pretty safe drug."
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Melissa Healy
