Keep an Eye on Cox-2 Inhibitors
In a presentation at the recent Science Writers Seminar sponsored by the American Cancer Society, Dr. Ernest Hawk of the National Cancer Institute reported on a new class of drugs called Cox-2 inhibitors that appear to have extraordinary potential for treating a wide range of cancers.
This is remarkable because Cox-2 (cyclooxygenase-2) inhibitors are basically aspirin derivates that were originally developed to ease pain in patients with chronic diseases such as arthritis.
For years, researchers have suspected that certain ingredients in aspirin might inhibit an enzyme called cyclooxygenase (COX), which has been associated with an increased risk of colorectal cancer. But they were hesitant to recommend aspirin to these patients because long-term aspirin use could result in stomach ulcers and intestinal bleeding.
However, scientists soon learned that there are actually two forms of the COX enzyme-COX-1, which is necessary to maintain overall health; and COX-2, which is linked to inflammation and tumor formation. Cancer researchers began searching for ways to "inhibit" COX-2 as a potential new treatment for colorectal cancer.
A landmark National Institute of Cancer study was then undertaken to see if a new COX-2 inhibitor, celecoxib, could reduce the number of precancerous polyps occurring the people with an inherited predisposition to colon cancer. In fact, the number of polyps was reduced by 28 percent in those patients taking celecoxib.
The success of that NCI study prompted a number of similar investigations to see if COX-2 inhibitors might have a similar impact on preventing-and treating-other cancers.
At the American Cancer Society seminar, Hawk noted that more than a half-dozen COX-2 inhibitors are currently being researched to treat a variety of cancers. He specifically pointed out studies that have linked COX-2 inhibitors with reductions in breast, prostate, head and neck, bladder, colon and pancreatic cancers.
Hawk further emphasized that COX-2 inhibitors may have a wide-ranging benefit throughout the cancer development process, from pre-invasive lesions to metastatic disease. In fact, The National Institute of Cancer is also expanding its initial research with celecoxib to see if it can thwart colon cancer at various stages of its development.
Researchers still don't know exactly how COX-2 inhibitors act to prevent cancer. But they do know that COX-2 inhibitors reduce the production of free radicals, which are involved in the uncontrolled cellular growth that is a characteristic of cancer.
There are some extremely promising clinical trials now underway which should help answer these and other questions about the mechanism of COX-2 inhibitors-and their extraordinary potential for treating a wide range of cancers. Stay tuned.
SOURCES:
American Cancer Society Science Writers Seminar, April 24, 2001, Dana Point, California
The National Cancer Institute (http://www.nci.nih.gov)
The American Cancer Society (http://www2.cancer.org)
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