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FDA Approves First-of-Kind Device to Treat Obesity

Electrical stimulation blocks nerve activity between brain and stomach

The FDA has approved the Maestro Rechargeable System (EnteroMedics) for certain obese adults –– the first weight-loss treatment device that targets the nerve pathway between the brain and the stomach that controls feelings of hunger and fullness.

The system, the first FDA-approved obesity device since 2007, is approved to treat patients 18 years of age and older who have not been able to lose weight with a weight-loss program, and who have a body mass index (BMI) of 35 to 45, with at least one other obesity-related condition, such as type-2 diabetes.

BMI, which measures body fat based on an individual’s weight and height, is used to define obesity categories. According to the Centers for Disease Control and Prevention, more than one-third of all U.S. adults are obese, and people with obesity are at increased risk of heart disease, stroke, type-2 diabetes, and certain kinds of cancer.

“Obesity and its related medical conditions are major public health problems,” said William Maisel, MD, MPH, deputy director for science and chief scientist at the FDA’s Center for Devices and Radiological Health. “Medical devices can help physicians and patients to develop comprehensive obesity treatment plans.”

The Maestro Rechargeable System consists of a rechargeable electrical pulse generator, wire leads, and electrodes implanted surgically into the abdomen. The system works by sending intermittent electrical pulses to the trunks in the abdominal vagus nerve, which is involved in regulating stomach emptying and in signaling to the brain that the stomach feels empty or full. Although it is known that the electrical stimulation blocks nerve activity between the brain and the stomach, the specific mechanisms for weight loss due to use of the device are unknown.

External controllers allow patients to charge the device and let health care professionals adjust the device’s settings to provide optimal therapy with minimal adverse effects.

The safety and effectiveness of the Maestro Rechargeable System were evaluated in a clinical trial that included 233 patients with a BMI of 35 or greater. The weight loss and adverse events (AEs) in 157 patients who received an activated Maestro electrical pulse generator (the experimental group) were compared with those of 76 patients in the control group, which received a Maestro device that was not activated. The study found that, after 12 months, subjects in the experimental group lost 8.5% more of their excess weight compared with those in the control group. Approximately half (52.5%) of the subjects in the experimental group lost at least 20% of their excess weight, and 38.3% lost at least 25% of their excess weight.

This study did not meet its original efficacy endpoint, which was that subjects in the experimental group lose at least 10% more excess weight than those in the control group. However, the FDA’s Gastroenterology–Urology Devices Panel found that the 18-month data supported sustained weight loss and agreed that the benefits of the device outweighed its risks for use in patients who met the device’s proposed indication.

In reviewing the benefits and risks of the Maestro Rechargeable System, the FDA considered the pivotal study results and the panel’s recommendations. In addition, the agency looked at a survey related to patients’ preferences for obesity devices, which showed that they would accept risks associated with a surgically implanted device for the amounts of weight loss expected to be provided by the Maestro Rechargeable System.

As part of the FDA’s approval, the device’s manufacturer must conduct a 5-year post- approval study that will collect additional safety and efficacy data from at least 100 patients, including weight loss, AEs, surgical revisions and explants, and changes in obesity-related conditions.

Serious AEs reported in the pivotal clinical study included nausea, pain at the neuroregulator site, vomiting, and surgical complications. Other AEs included pain, heartburn, problems swallowing, belching, mild nausea, and chest pain.

Source: FDA; January 14, 2015.

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