Small bowel interventions
There are several small bowel interventions, with different mechanisms of action, available internationally. Many of these are under investigation in the United States; however, none are currently FDA approved.
Duodenal-jejunal bypass liner
Duodenal-jejunal bypass liner (DJBL; GI Dynamics, Boston, Mass.) is a 60-cm fluoropolymer liner that is endoscopically placed and removed at 12 months. It is anchored at the duodenal bulb and ends at the jejunum. By excluding direct contact between chyme and the proximal small bowel, DJBL is thought to work via foregut mechanism where there is less inhibition of the incretin effect (greater increase in insulin secretion following oral glucose administration compared to intravenous glucose administration due to gut-derived factors that enhance insulin secretion) leading to improved insulin resistance. In addition, the enteral transit of chyme and bile is altered suggesting the possible role of the hindgut mechanism. The previous U.S. pivotal trial (ENDO trial) met efficacy endpoints. However, the study was stopped early by the company because of a hepatic abscess rate of 3.5%, all of which were treated conservatively.42 A new U.S. pivotal study is currently planned. A meta-analysis of 17 published studies, all of which were from outside the United States, demonstrated a significant decrease in hemoglobin A1c of 1.3% and 18.9% TWL at 1 year following implantation in patients with obesity with concomitant diabetes.43
Duodenal mucosal resurfacing
Duodenal mucosal resurfacing (Fractyl, Lexington, Mass.) involves saline lifting of the duodenal mucosa circumferentially prior to thermal ablation using an inflated balloon filled with heated water. It is hypothesized that this may reset the diseased duodenal enteroendocrine cells leading to restoration of the incretin effect. A pilot study including 39 patients with poorly controlled diabetes demonstrated a decrease in hemoglobin A1c of 1.2%. The SAE rate was 7.7% including duodenal stenosis, all of which were treated with balloon dilation.44 The U.S. pivotal trial is currently planned.
Gastroduodenal-jejunal bypass
Gastroduodenal-jejunal bypass (ValenTx., Hopkins, Minn.) is a 120-cm sleeve that is anchored at the gastroesophageal junction to create the anatomic changes of RYGB. It is placed and removed endoscopically with laparoscopic assistance. A pilot study including 12 patients demonstrated 35.9% excess weight loss at 12 months. Two out of 12 patients had early device removal due to intolerance and they were not included in the weight loss analysis.45
Incisionless magnetic anastomosis system
The incisionless magnetic anastomosis system (GI Windows, West Bridgewater, Mass.) consists of self-assembling magnets that are deployed under fluoroscopic guidance through the working channel of colonoscopes to form magnetic octagons in the jejunum and ileum. After a week, a compression anastomosis is formed and the coupled magnets pass spontaneously. A pilot study including 10 patients showed 14.6% TWL and a decrease in hemoglobin A1c of 1.9% (for patients with diabetes) at 1 year.46 A randomized study outside the United States is currently underway.
Summary
Endoscopic bariatric and metabolic therapies are emerging as first-line treatments for obesity in many populations. They can serve as a gap therapy for patients who do not qualify for surgery, but also may have a specific role in the treatment of metabolic comorbidities. This field will continue to develop and improve with the introduction of personalized medicine leading to better patient selection, and newer combination therapies. It is time for gastroenterologists to become more involved in the management of this challenging condition.
Dr. Jirapinyo is an advanced and bariatric endoscopy fellow, Brigham and Women’s Hospital, Harvard Medical School, Boston; Dr. Thompson is director of therapeutic endoscopy, Brigham and Women’s Hospital, and associate professor of medicine, Harvard Medical School. Dr. Jirapinyo has served as a consultant for GI Dynamics and holds royalties for Endosim. Dr. Thompson has contracted research for Aspire Bariatrics, USGI Medical, Spatz, and Apollo Endosurgery; has served as a consultant for Boston Scientific, Covidien, USGI Medical, Olympus, and Fractyl; holds stocks and royalties for GI Windows and Endosim, and has served as an expert reviewer for GI Dynamics.
