Neurons, in Vitro Color!

VBLOC Eeks Out a Win at FDA

VBLOC therapy for obesity won a mixed but positive verdict from an FDA advisory panel after a long day of deliberations Tuesday. FDA’s expert panel for gastroenterology devices gave a split — but on balance positive — vote in favor of approval for the EnteroMedics Maestro VBLOC therapy system.

EnteroMedics Maestro VBLOC DeviceVBLOC therapy works to block the vagus nerve from transmitting sensations of hunger from the gut to the brain. The Maestro device is a nerve regulator implanted surgically and attached to the nerve. The surgery is minimally invasive, typically done on an outpatient basis.

Asked if effectiveness had been proven, the panel voted no by a margin of 5-4. On the question of safety, the vote was strongly positive, 8-1. And on the ultimate question, does the system provide benefits that are worth the risk, the panel voted yes by 6-2. One member abstained on that vote.

If you didn’t sit through the whole day of presentations and debates, you might wonder, “how could this panel say effectiveness wasn’t proven and then say it has benefits that are worth the risks?” The answer is that EnteroMedics got snagged in a statistical dilemma.

In negotiating the design of their pivotal trial with FDA, the company agreed to conduct the first ever sham-controlled study of such a device. One out of three patients in the trial had surgery to implant an inactive version of this vagal blocking system. And they agreed to a super-superiority standard of 10% better efficacy for their device versus the sham. They knew that their device would help people lose about 25% of their excess weight and they thought that the sham group would lose about 5%. Wrong on the last point. The sham group did very well, losing 16% at 12 months. So even though the 24% excess weight loss with VBLOC was superior to the sham (p<0.002), the results did not meet the super-superiority standard.

Statisticians argued that you can’t change the standard after the fact. But panel member Karen Woods summarized what appears to have emerged as the consensus:

There are two ways to look at this. The device didn’t meet the standard of super superiority. But it did beat the sham control. Considering need for treatment options, this device has value.

And, indeed, that view is reflected in the final vote.

With help from the Obesity Action Coalition, four patients — Patiricia Neece, Bernard Tessier, Pamela O’Hara, and Mike Magnant — testified before the panel during a public comment session. Their comments, along with comments from physicians and organizations concerned about obesity, brought attention to the need for innovation and more treatment options.

FDA will still have to render a final decision. But the panel vote can certainly justify an approval.

“Beginnings are always messy.” — John Galsworthy

Click here to read more from HealthDay, here for the complete FDA briefing materials for the meeting, and here for the slides presented by ConscienHealth Founder Ted Kyle.

Neurons, In Vitro Color! Photograph © / flickr

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