FDA Panel Approves Drug for Rare Colorectal Cancer
Dec. 14, 1999 (Washington) -- A new approach for treating a deadly, inherited form of colorectal cancer took a major step toward approval Tuesday following a recommendation by an advisory committee to the FDA. The drug, Celebrex (celecoxib), got the OK from the Oncologic Drugs Advisory Committee as an additional therapy to control familial adenomatous polyposis (FAP), a disease in which there is a growth of precancerous polyps in the colon. The vote was 14 in favor and 1 against approval.
Manufactured by G.D. Searle and Co., Celebrex is widely used as a painkiller. "It's a step. This is an agent that clearly reduces polyps, and the postmarketing studies are going to be the really significant ones [and] will tell patients how much benefit they're likely to get," acting panel chair Derek Raghavan, MD, of the University of Southern California, tells WebMD.
In a trial on 83 patients, 400 mg of Celebrex was compared to placebo among those with FAP. After six months, gastroenterologists looked at videotapes and pictures of the colons of the treatment groups to determine if the drug inhibited the growth of hundreds or thousands of precancerous growths in the colon, which characterize the condition.
A count of polyps marked by "tattoos" at the beginning of the study shows that Celebrex was about 25% more effective than the placebo in keeping polyps in check. Currently, there are no FDA-approved drugs for FAP.
Speaking for the drug, Ernest Hawk, MD, of the Division of Cancer Prevention at the National Cancer Institute (NCI), says patients in the study also experienced reductions in polyp size ranging from about 30% to 80% while taking the drug. NCI is collaborating with Searle in researching Celebrex for a variety of tumors including cancers of the esophagus, skin, and throat, says Gary Gordon, MD, director of cancer prevention and treatment at Searle.
Celebrex was generally well tolerated. However, one patient had a severe allergic reaction to the drug.
The hope is that since Celebrex appears to inhibit polyp growth, the drug would delay the need for polyp removal or, ultimately, surgery to treat colorectal cancer. Although only one in 10,000 people will get FAP, it has a devastating effect. Left untreated, almost 90% of those with the genetic error go on to develop cancer by age 45.
The FDA reviewers agreed that Celebrex works as an addition to other treatment, but raised questions about the drug's long-term effectiveness, specifically whether the treatment would ultimately reduce the development of colorectal cancers or the need for corrective surgeries. The company is conducting follow-up studies to find out if Celebrex actually works against cancer.
The agency is also concerned some doctors might delay life-saving surgeries for patients taking Celebrex. "I think the FDA has a good track record in making information clear. If doctors read the information, they won't be confused," says Raghavan.
Earlier studies with non-steroidal anti-inflammatory drugs indicate they may help FAP patients in their battle to delay cancer progression, but they can also cause intestinal bleeding. Approved a year ago for the treatment of arthritis and osteoarthris, Celebrex sales have already exceeded a billion dollars. The so-called "super aspirin" works by inhibiting cyclooxygenase-2 (Cox-2), an enzyme linked to pain, while sparing a related body chemical that protects the gastrointestinal tract.
Celebrex is getting a priority review by the FDA for FAP, and action on the drug is expected by the end of the year. The agency generally, but not always, follows the recommendations of its advisory panels.