Clinical Trial to Test Whether Antibiotic Slows Growth of Abdominal Aortic Aneurysms

Clinical Trial to Test Whether Antibiotic Slows Growth of Abdominal Aortic Aneurysms

Mar 23, 2016 10:34 AM

(SALT LAKE CITY)—Abdominal aortic aneurysms (AAA) affect about 2 million people in the United States. Most AAAs are small when diagnosed and typically are monitored until they grow large enough to require surgery to prevent a potentially fatal rupture.

In a new nationwide clinical trial, medical researchers are testing whether doxycycline, a commonly used antibiotic, can slow the growth of AAAs to delay or even prevent the need for surgery to repair them. The University of Utah (U OF U) School of Medicine’s Division of Vascular Surgery has been selected to take part in the trial and is looking for participants with smaller AAAs –3.5 to 5 centimeters in diameter – who have not had a surgical repair. Participants must be 55 or older and not acutely ill or in renal failure to take part, according to Larry W. Kraiss, M.D., U of U professor and chief of vascular surgery and lead Utah investigator in the trial.

“We’re looking for patients who are interested in closely tracking their AAA treatment,” Kraiss said. “If this investigational therapy works, it may provide the first non-surgical treatment for AAA.”

AAAs, so called because they form a bulge in the wall of the aorta in the abdomen, are typically asymptomatic and often undetected until the weakened aortic wall ruptures. Spontaneous rupture of an aortic aneurysm is usually fatal and is conservatively estimated to cause at least 15,000 deaths each year in the United States.

When an abdominal aortic aneurysm grows too large and poses a risk to patients, doctors typically recommend fixing the bulge in the aorta, which is the body’s largest artery and runs from the heart through the abdomen. Doxycycline may block an enzyme that weakens the aorta by taking apart proteins in the bulge wall.  This trial is assessing whether patient use of this drug may slow the growth rate of the aneurysm and perhaps make surgery unnecessary.

Small bulges can stay the same size for varying lengths of time; most grow slowly, but some grow quickly. No one knows the exact reason for these differences. When a small bulge is present, the usual course is to check its size every six months to see if it grows to the point that it should be fixed.  The time it might take for a bulge to reach this large size ranges from a few months to years. Because bulge growth rate varies, it can be hard to tell if a new medicine really works. To find out if doxycycline can slow the growth of aneurysms, it must be tested in a trial against an inactive “look-alike” capsule or placebo for two to three years.

The nationwide trial, approved by the U.S. Food and Drug Administration, will enroll a total of 265 participants. The name of the study is N-TA3CT. Participants will take 100 milligrams (mg) of doxycycline twice a day for a total of 200 mg per day or a placebo twice a day. Patients are randomly selected to receive either the active medication or the placebo and won’t know which one they receive.

“We hope that if taking doxycycline slows the growth of an AAA, then patients may delay or even avoid a surgery to fix the bulge,” Kraiss said.

Participants will be examined with computed tomography (CT) scans and blood draws every six months, with a total of seven required face-to-face follow-up visits. Although this type of treatment for AAA has not been tested thoroughly in people, it has worked in laboratory mice, according to Kraiss.

“The University of Utah already is a state-of-the-art referral center for AAA management,” Kraiss said. “Now we’re offering trials for those in whom a ‘watchful waiting’ approach feels unsettling because it seems like nothing is being done to try to avoid surgery in the first place.”

Research studies are good opportunities to help doctors to learn more about AAA and to discover new ways to treat this condition. 

People interested in participating in the trial can contact:

Study Coordinator, Maria Maloney: (801)585-3663, email: maria.maloney@hsc.utah.edu

Or

Research Assistant, Sarah Rogers: (801) 581-1494, email: sarah.rogers@hsc.utah.edu

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