CHICAGO — The polymer injection treatment for gastroesophageal reflux disease, known as Enteryx, outperformed sham surgery and lasted up to 3 years, investigators said in presenting two studies at the annual Digestive Disease Week.
Enteryx, a liquid that solidifies into a spongy implant, is injected into the deep muscle layer at or below the esophagogastric junction to increase the competence of the lower esophageal sphincter.
In one of the two studies, investigators led by Jacques Deviere, M.D., compared Enteryx treatment with sham surgery; all patients were dependent on proton-pump inhibitor (PPI) therapy prior to the start of the study. At 3 months, 68% of 32 patients given the polymer injection treatment were completely off PPI drugs, and another 13% had reduced their use by at least 50%.
In contrast, in the sham surgery group of 32 patients, 41% discontinued PPI use and another 12% reduced PPI use by at least 50%, said Dr. Deviere, chief of the department of gastroenterology at Erasme Hospital of the Free University of Brussels.
In the second uncontrolled study, which involved a 3-year follow-up of 60 patients, the percentage of patients who benefited peaked at 1 year, when 71% were completely off PPI therapy, and another 13% had reduced their PPI use by 50%. At 3 years, 48% were off PPIs, and another 17% had reduced PPI use by 50%, said Glen A. Lehman, M.D., professor of medicine at Indiana University, Indianapolis.
These two studies are major steps forward toward the adoption of Enteryx treatment—approved by the Food and Drug Administration in 2003—into routine practice, commented Gary W. Falk, M.D., a professor of medicine at the Cleveland Clinic Foundation.
But the specific indications for this treatment are still not clear, because the subjects in the trials conducted to date have not been defined except that they have been chronic, PPI-dependent patients.
Moreover, caution needs to be exercised in evaluating the treatment because the material that is implanted appears to be permanent, and head-to-head trials with other therapies still need to be performed, Dr. Falk added.
At least 3,000 patients have received Enteryx treatment so far, according to available estimates.
But it is also not exactly clear how the treatment works, Dr. Falk noted. In all the trials reported so far, including the two new trials, the treatment has not appreciably changed the esophageal pH of most patients it has helped.
It may be that the pH is not changed, but the treatment is reducing the amount of acid escaping from the stomach into the esophagus, he suggested.
Regarding the fall-off in efficacy over time seen in the 3-year follow-up, Dr. Lehman said he could not predict whether that trend would continue. The study measured esophageal pH at 12 months, but there were no pH measurements after that. Moreover, none of the patients was examined endoscopically at 3 years to see if the implant was still present and how it was faring.
Dr. Lehman suggested that the fall-off could be due to patients' becoming unwilling to tolerate discomfort that they initially considered an improvement.
In his study, quality-of-life heartburn scores improved by a median of 76% relative to scores at baseline during a washout period when patients were withdrawn from PPI treatment. That percentage improvement continued throughout the 3 years, he noted.
The majority of patients treated with Enteryx experience a transient retrosternal, burning chest pain and/or dysphagia at first, the investigators noted. However, there were no serious, device-related adverse events in Dr. Lehman's follow-up trial. In the controlled trial, one patient treated with Enteryx needed an esophageal dilatation procedure because of continuing dysphagia.
The two trials were sponsored by Boston Scientific Corp., Natick, Mass., the manufacturer of the Enteryx procedure kit.