The cyclooxygenase-2 inhibitor celecoxib is a potent preventive and therapeutic agent in the min mouse model of adenomatous polyposis.
Epidemiological and animal studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce colon cancer risk. NSAIDs nonselectively inhibit both the constitutive cyclooxygenase (COX) 1 associated with side effects and the desired therapeutic target COX-2, which is induced in inflammation and neoplasia. We used the adenomatous polyposis coli (Apc) mutant Min mouse model to determine whether the selective COX-2 inhibitor celecoxib is effective for adenoma prevention and/or regression, and whether it might be safer than the nonselective NSAID previously shown to be most effective in this model, piroxicam. Min mice (n = 120) were randomized to treatment with celecoxib (0, 150, 500, or 1500 ppm celecoxib mixed in the diet) or piroxicam. To distinguish prevention from regression effects, groups were treated either "early" (before adenomas develop) or "late" (after most adenomas are established). Celecoxib caused dramatic reductions in both the multiplicity and size of tumors in a dose-dependent manner (P < 0.01). Early treatment with 1500 ppm of celecoxib was effective for prevention, decreasing tumor multiplicity to 29% and tumor size to only 17% of controls (P < 0.01). Late treatment demonstrated regression effects, reducing tumor multiplicity and size by about half. In contrast to the significant toxicity of piroxicam, which caused ulcers complicated by perforation and bleeding, celecoxib caused no gastrointestinal side effects and did not inhibit platelet thromboxane B2 at plasma drug levels similar to those obtained in early clinical trials in humans. These results provide the first evidence that selective inhibitors of COX-2 are safe and effective for the prevention and regression of adenomas in a mouse model of adenomatous polyposis and strongly support ongoing clinical trials in humans with the same syndrome. The broader population of patients with common sporadic adenomas that have somatic mutations of the same gene (APC) may also benefit from this treatment approach.