Posted by Kate Murphy on April 15th, 2008
UPDATES FROM THE AACR ANNUAL MEETING
Combining a very low dose of oral difluoromethylornithine (DFMO) and the NSAID sulindac (Clinoril) once a day signficantly decreased new colon polyps (adenomas) for patients with a history of polyps. After three years the two drugs reduced all new polyps by 70 percent, advanced adenomas by 92 percent, and multiple adenomas by 95 percent.
The results were so striking that the study was closed early so that all participants could benefit from the new intervention.
In the study, 375 patients who had at least one polyps removed within the past five years, were randomly assigned to the two-drug chemoprevention treatment or a placebo. After three years, they had repeat colonoscopies to look for new polyps.
Researchers found many fewer new polyps in treated patients compared to those who received placebos:
- 41.1% of placebo patients had new polyps compared to 12.3% of the treated group.
- 8.5% placebo group had advanced adenomas compared to less than 1 percent of those receiving DFMO and sulindac.
- For patients who previously had more than one polyp, treatment reduced new adenomas from 13.2 percent to less than 1 percent.
Side effects, including gastrointestinal problems, hearing loss, cardiovascular problems, or need for hospitalization, were not different between the two groups.
Frank Meyskens, MD, director of the Cancer Center at the University of California at Irvine who headed the study team said,
There is a great hope that we will be able to prevent colon cancer effectively using this method. We had not been able to do this before due to the high toxicity of available therapies. Difluoromethylornithine is a targeted agent that represents a new treatment paradigm,
DFMO inhibits the development of polyamines in the lining of the colon, chemicals that trigger cell division and growth. At high doses it can cause hearing problems, but there was no hearing loss noticed during the trial.
Originally developed as a potential cancer treatment, DFMO is now used to treat one form of African sleeping sickness.
Sulindac is a non-steroidal anti-inflammatory drug that is used to treat arthritis pain and to prevent colon polyps in patients with familial adenomatous polyposis (FAP). It is thought to prevent polyps by reducing inflammation in the colon.
Dr. Meyskens pointed out that people recovering from colon cancer might also benefit from treatment with DFMO and sulindac to prevent new polyps that could lead to a second cancer.
Patients who have been shown to have advanced adenomas are probably the largest group that will be helped. Another group consists of those who have been cured of colon cancer, because about 35% will go on to have another colon cancer, so they are a good target.
SOURCE: AACR 2008 Annual Meeting Abstract: Marked efficacy of difluoromethylornithine plus sulindac in reducing recurrent colorectal adenomas in patients with prior adenomas: results of a randomized, placebo-controlled double-blind phase III trial: Abstract LB-142
Dr. Meysken’s audio presentations with slides at the 2008 annual meeting of the American Association for Cancer Research.