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In Brief
Prevention Study Halted Amid Concerns About Celebrex
The National Cancer Institute has halted a large colorectal cancer prevention trial after an analysis by the trial's data safety and monitoring board found that participants taking the drug celecoxib (Celebrex) had an increased risk of major cardiovascular events compared with those taking a placebo.
Celecoxib is a COX-2 inhibitor that is approved by the U.S. Food and Drug Administration for the treatment of osteoarthritis, rheumatoid arthritis, and familial adenomatous polyposis. The drug is also being tested in several cancer prevention trials.
The Adenoma Prevention with Celecoxib (APC) trial had been testing two dosage levels of celecoxib—200 mg and 400 mg twice daily—against placebo for 3 years in more than 2,000 people who had had an adenomatous polyp removed. Patients taking the 400 mg dose were 3.4 times as likely to have cardiovascular events as those on placebo, and patients taking the 200 mg dose had a 2.5-fold increased risk. However, in a second prevention trial using celecoxib, the Prevention of Spontaneous Adenomatopus Polyps (PreSAP), there has been no increased risk of cardiovascular events.
A third trial, the Alzheimer's Disease Anti-Inflammatory Prevention Trial (ADAPT), which has been testing the potential long-term benefits of celecoxib and naproxen (Aleve) in the prevention of Alzheimer's disease, did not find a statistically significant increased risk of cardiovascular events associated with celecoxib use compared with placebo. However, patients taking naproxen had a 50% higher incidence of cardiovascular events compared with those taking placebo, and this trial has now been halted by its sponsor, the National Institute on Aging.
At this time, neither celecoxib nor naproxen is being taken off the market. However, Pfizer, the manufacturer of Celebrex, has agreed to suspend marketing celecoxib to the public but will continue marketing the drug to doctors.
See also News, Vol. 96, no. 23, p. 1734, "Vioxx Withdrawal Alarms Cancer Prevention Researchers."
Colonoscopy the Most Accurate Method for Colon Cancer Detection, Study Finds
A new study has found that colonoscopy had better sensitivity (more true positive results) and specificity (more true negative results) than either air contrast barium enema (ACBE) or computed tomographic colonography (CTC), also known as virtual colonoscopy.
Current guidelines recommend colorectal cancer screening for people age 50 and older with one of four methods: fecal occult blood test (FOBT), barium enema, flexible sigmoidoscopy, or colonoscopy. CTC has been introduced as a possible option, but studies comparing it to the other methods have had mixed results.
In a study published online December 17 by the Lancet, Don C. Rockey, M.D., of the Duke University Medical Center in Durham, N.C., and colleagues screened 614 individuals with an increased likelihood of having colorectal abnormalities with ACBE followed by CTC and colonoscopy 1 to 2 weeks later. For lesions 10 mm or larger in size and those 6 to 9 mm, sensitivity was higher with colonoscopy (98% and 99%, respectively) compared with either ACBE (48% and 35%) or CTC (59% and 51%). For the larger lesions, specificity was also highest with colonoscopy.
The authors note that a study published earlier this year that found CTC to be superior to colonoscopy used primary 3D reading, and that it is not known if CTC using 3D reading is superior to the 2D reading method that was used in this most recent study.
Iressa Fails to Show Survival Benefit in Lung Cancer Trial
Gefitinib (Iressa) failed to prolong survival compared with placebo in a trial of patients with non-small-cell lung cancer (NSCLC) who had failed other courses of therapy, according to a statement from AstraZeneca.
Gefitinib was approved by the U.S. Food and Drug Administration under its accelerated approval program in May 2003 for the treatment of NSCLC patients who had failed two or more courses of therapy. The approval was based on a surrogate endpoint—data that showed the drug caused tumor shrinkage in about 10% of patients—but AstraZeneca was expected to study the drug further and study whether there is a benefit for a primary endpoint, survival.
This trial of nearly 1,700 NSCLC patients found that there was no statistically significant survival benefit among all patients (5.6 months median survivial for those on active treatment versus 5.1 months for those on placebo) or only among patients with adenocarcinomas (6.3 months versus 5.4 months).
The FDA has said it will review the new study results and determine whether gefitinib should be withdrawn from the market or if other actions are appropriate.
See also News, Vol. 96, No. 18, p. 1352, "Research Unveils the `Who' and `Why' of Gefitinib."
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