Questions and Answers
NIH Halts Use of COX-2 Inhibitor in Large Cancer Prevention Trial
The National Institutes of Health (NIH) announced today that it
has suspended the use of COX-2 inhibitor celecoxib (Celebrex™
Pfizer, Inc.) for all participants in a large colorectal cancer
prevention clinical trial conducted by the National Cancer Institute
(NCI). The study, called the Adenoma Prevention with Celecoxib (APC)
trial, was stopped because analysis by an independent Data Safety
and Monitoring Board (DSMB) showed a 2.5-fold increased risk of
major fatal and non-fatal cardiovascular events for participants
taking the drug compared to those on a placebo. (Press release:
http://www.nih.gov/news/pr/dec2004/od-17.htm)
Q: What is NIH doing in response to these findings?
NIH has halted the use of COX-2 inhibitor celecoxib (Celebrex™
Pfizer, Inc.) for all participants in a large colorectal cancer
prevention clinical trial. Additionally, Elias A. Zerhouni, M.D.,
Director, NIH, has called for an immediate review of the entire
grant portfolio for studies using COX-2 inhibitor drugs. NIH is
also notifying all principal investigators of the NCI study findings
and will ask investigators to inform the agency of their plan to
analyze their data in light of this information. In addition, NIH
is asking the Institutional Review Boards (IRBs) for all related
trials to assess the new information and to conduct a safety review.
Q: Are other NIH studies using COX-2 inhibitors?
NIH sponsors more than 40 studies using celecoxib for the prevention
and treatment of cancer, rheumatoid and osteoarthritis, dementia
and other diseases. NIH’s commitment is to advance the health
and to protect the safety of participants in clinical trials. The
agency is examining the use of these agents in all NIH-sponsored
clinical studies. In addition, NIH is working closely with colleagues
at FDA to ensure that the public has the information they need to
make informed decisions about the use of this class of drug.
Q: Why has NCI been using COX-2 inhibitors in clinical trials?
Numerous compounds are examined by the National Cancer Institute
(NCI) for their potential to prevent or treat cancer. One class
of compounds, cyclooxygenase (COX) inhibitors, is currently being
tested in both prevention and treatment clinical trials. Epidemiologic
studies have shown that people who regularly take non-steroidal
anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen
to treat conditions like arthritis, have lower rates of colorectal
polyps, colorectal cancer, and death due to colorectal cancer. NSAIDs
block cyclooxygenase enzymes, which are produced by the body when
there is inflammation and are also produced by precancerous tissues.
Inhibition of COX-2 may help treat and prevent cancer, while inhibition
of COX-1 may induce certain medical problems, like stomach bleeding,
that occur when NSAIDS are taken regularly for long periods of time.
Q: What is Celebrex and why has NCI used this drug in their trials?
Pharmaceutical companies have created NSAIDs that block only COX-2;
one of them, celecoxib (Celebrex™), manufactured by Pfizer, Inc.,
New York, was approved by the U.S. Food and Drug Administration
(FDA) for the treatment of both osteoarthritis and adult rheumatoid
arthritis (diseases in which the joints are inflamed) in December
1998. Because over a decade of scientific work has suggested the
potential of COX-2 inhibitors to prevent and treat cancer, the National
Cancer Institute (NCI) has clinical trials under way to look at
the efficacy and safety of these drugs.
Q: What specific trials has NCI been conducting with Celebrex?
NCI's Division of Cancer Prevention (DCP) began its studies with
celecoxib with a trial in people with Familial Adenomatous Polyposis
(FAP). Patients with FAP develop hundreds to thousands of precancerous
polyps (adenomas) throughout the colon and rectum. Left untreated,
nearly all FAP patients develop colorectal cancer by their 40s and
50s. The primary treatment for FAP is surgical removal of most or
all of the colon and rectum with subsequent surveillance of any
remaining colorectal segment. In an NCI-sponsored trial, celecoxib
helped reduce the number of colon polyps in patients with FAP. The
results of this study were published in the New England Journal
of Medicine on June 29, 2000, and led to FDA-approval of celecoxib
as an adjunctive drug (an accessory or auxiliary agent) that could
be added to the standard of care in people with FAP.
As of October 2004, DCP sponsored 23 trials of varying sizes to
test the potential of celecoxib to prevent cancer in a number of
organ sites. These trials range in size from under 10 participants
to more than 2,000 and aim to prevent bladder, breast, cervical,
colorectal, esophageal, head and neck, skin, lung, oral, and prostate
cancers, as well as multiple myeloma. The majority of these trials
are in collaboration with Pfizer, Inc.
Additionally, to examine potential benefits of COX-2 inhibitors
for the treatment of patients with cancer, NCI's Division of Cancer
Treatment and Diagnosis (DCTD) is sponsoring approximately 20 trials
of varying sizes with celecoxib. The majority of these studies are
small phase I or II clinical trials in cancers such as pancreatic,
breast, ovarian, non-small cell lung, and solid tumors. DCTD also
is sponsoring two ongoing randomized phase III clinical trials:
the first trial compares two chemotherapy agents, exemestane vs
anastrozole, in postmenopausal women with estrogen receptor-positive
primary breast cancer; the second trial compares several chemotherapy
agents in node-negative breast cancer patients. Both phase III trials
randomized women to either those taking celecoxib or not taking
celecoxib, in addition to the agents mentioned above.
Q: What is the status of the APC (Adenoma Prevention with Celecoxib)
Trial?
The National Cancer Institute suspended the use of COX-2 inhibitor
celecoxib (Celebrex™; Pfizer) on December 17, 2004, for all
participants in a large colorectal cancer prevention clinical trial,
the Adenoma Prevention with Celecoxib (APC) trial, because analysis
by an independent Data Safety Monitoring Board (DSMB) showed a 2.5-fold
increased risk of major fatal and non-fatal cardiovascular events
for participants taking the drug compared to those on a placebo.
Safety monitoring of a similar study that was sponsored by Pfizer,
called the PreSAP cancer trial, did not find an increased risk of
cardiovascular events.
Additional cardiovascular expertise was added to the safety monitoring
committees at the request of the steering committees for these trials
after a September 2004 report that the COX-2 inhibitor rofecoxib
(Vioxx™) caused a two-fold increased risk of cardiovascular
toxicities in a trial to prevent adenomas. The APC trial is a study
of more than 2,000 people who have had a precancerous growth (adenomatous
polyp) removed. They were randomized to take either 200 mg of celecoxib
twice a day, 400 mg of celecoxib twice a day, or a placebo for three
years. The trial began in early 2000 and is scheduled to be completed
by spring 2005.
Investigators at the 100 sites in the APC trial, located primarily
in the United States, with a few additional sites in the United
Kingdom, Australia, and Canada, have been instructed to immediately
suspend study drug use for all participants on the trial, although
the participants will remain under observation for the planned remainder
of the study.
Q: What actions is NCI planning to take to notify patients on
other COX-2 inhibitor clinical trials?
NCI will notify all of the principal investigators of its sponsored
trials involving COX-2 inhibitors. They will be instructed to notify
their institutional review boards, data safety monitoring boards,
and participants about this new information. NCI will also require
that the informed consent for these trials be revised to reflect
this new information and that individuals in the trials be re-consented
(asked to sign new consent forms with updated information about
risks and benefits of the trials).
For more information about cancer, please visit the NCI Web site
at http://www.cancer.gov or
call NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
For more information about regulation of COX-2 inhibitors by the
FDA, please visit the FDA Web site at http://www.fda.gov/cder/drug/default.htm.
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Halts Use of COX-2 Inhibitor in Large Cancer Prevention Trial
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