Approach to angiogenesis inhibition based on cyclooxygenase-2.

Two cyclooxygenase (COX) isoforms have been identified: COX-1 and COX-2. COX-1 is the constitutively expressed form of the enzyme and is ubiquitous in its distribution. COX-2 is inducible and is present in inflammatory foci, tumors, and neovasculature. Expression of COX-2 appears to be important in tumor promotion, growth, and metastasis. It is up-regulated in a variety of premalignant disorders and malignancies. COX inhibitors have a major role in the treatment of inflammation and pain. Epidemiologic evidence in patients who take nonsteroidal anti-inflammatory drugs links COX inhibition with decreases in malignant esophageal, stomach, colon, lung, and breast tumors. Nonselective COX inhibitors have demonstrated efficacy in control of familial adenomatous polyposis, a disorder associated with the development of thousands of benign intestinal polyps. The selective COX-2 inhibitor celecoxib (Celebrex, Pharmacia) has been shown to reduce the number of adenomatous colorectal polyps in familial adenomatous polyposis as an adjunct to usual care. Celecoxib has recently been approved for this indication and offers the potential for equivalent or greater efficacy than that seen with nonselective COX inhibitors but without the gastrointestinal mucosal toxicity and the inhibition of platelet function associated with those agents. Angiogenesis is a feature of both benign and malignant disease. Because COX-2 is up-regulated in the neovasculature of the rheumatoid pannus and in malignant tumors and their surrounding stroma, selective COX-2 inhibitors may be able to modify the progression of these disorders through the control of angiogenesis.