Results of two major long-term clinical trials presented today in Washington D.C. at a meeting of the American Association for Cancer Research showed that Pfizer's COX-2 inhibitor, Celebrex (celecoxib) helps stop the growth of pre-cancerous polyps (adenomas) that can lead to colon cancer.
The investigational trials -- the Adenoma Prevention with Celecoxib (APC) trial, co-sponsored by the National Cancer Institute and Pfizer, and the Prevention of Sporadic Adenomatous Polyps (PreSAP) trial, sponsored by Pfizer -- found that sustained, higher doses of Celebrex for almost three years reduce pre-cancerous polyps (adenomas) with the greatest benefit for those at highest risk of polyp recurrence.
Both trials enrolled patients who had already had precancerous colon polyps removed.
Patients were about 60 years old, on average, at the start of the trial. The majority had cardiovascular risk factors such as high blood pressure, diabetes, angina, previous heart attacks, strokes or were smokers.
In the PreSAP trial, 34 out of 100 patients on Celebrex (400 mg.) developed pre-cancerous polyps over the three-year study period, compared to 49 out of 100 receiving no medication (placebo). In the APC study, 42 out of 100 on the 400 mg. dose and 37 out of 100 on the 800 mg. dose of Celebrex developed pre-cancerous polyps, compared to 61 out of 100 patients receiving no medication. Overall this represents up to a 45 percent reduction in the development of pre-cancerous polyps, Pfizer said.
“Importantly, both trials showed the largest benefit in people who had the most advanced polyps --which have a higher risk of developing into cancer,” said Joseph Feczko, chief medical officer at Pfizer in a statement. “Colorectal cancer takes years to develop and frequently starts with an adenomatous polyp that transforms over many years into cancer. These trials reflect the growing focus on the use of pharmaceutical medicines in cancer prevention."
The final results of APC demonstrated a statistically significant increase in the Celebrex group compared to placebo for serious cardiovascular events, while PreSAP did not. A new, broader analysis of serious and other cardiovascular events, including angina, for both APC and PreSAP, found more cardiovascular events with Celebrex compared to placebo.
These results are consistent with the current warnings on cardiovascular risk in the Celebrex label, Pfizer said.