Contrary to market expectations, on Thursday an FDA panel narrowly voted in favour of approving BioMimetic’s Augment bone graft device for use in the United States.
Two days before the panel meeting, shares in BioMimetic Therapeutics Inc. lost a third of their value as investors assumed that a negative review of Augment by the FDA’s own staff would cause the panel to vote against FDA approval.
Augment is a synthetic product designed to stimulate bone healing in certain foot and ankle surgeries that fuse bones together. It has two active ingredients, a bone growth factor to stimulate osteoblasts, the cells that form bone, and a calcium compound that acts as a “scaffolding” for new bone growth. The two ingredients are called recombinant human Platelet-Derived Growth Factor (rhPDGF) and Beta-tricalcium phosphate (Beta-TCP).
The product is intended as an alternative to autograft where tissue from another part of the patient’s body is transplanted into the surgical site to promote bone regeneration.
The FDA’s own review expressed concern that the synthetic growth factor might encourage the development of certain cancers, but the company said there was “absolutely no data” to support such an effect, reports the Wall Street Journal.
The FDA panel reviewed safety and effectiveness data from a randomized, controlled study that compared 414 Augment-treated patients to about half as many treated with autograft. BioMimetic point out that Augment was shown to be statistically non-inferior to autograft in the main measure of success (50% osseous bridging on CT scans six months after surgery), and that “15 of 16 secondary endpoints were statistically significant at 12 months”.
But in information posted on the agency website, the FDA own staff’s review said the study seemed too small and the results from the intent-to-treat patients was not statistically significant. Also, while the Augment results appear to be as good as autograft after two years, after three years, the difference is no longer statistically significant, according to an Associated Press report.
However, the Orthopedic and Rehabilitation Devices Panel of the Medical Devices Advisory Committee of the US Food and Drug Administration (FDA), voted to recommend market approval of the product. The FDA does not have to follow the advice of its advisory committees, but it usually does.
The panel voted three times: 12-6 in support of the safety of Augment as an alternative to autograft in hindfoot and ankle fusion surgery; 10-8 in support of the product’s efficacy as an alternative to autograft, and 10-8 that the product’s benefits outweigh the risks.
In a statement, BioMimetic noted that there was “unanimous support on all three recommendations from the foot and ankle specialists serving on the panel”. They noted that:
“If approved by the FDA, Augment Bone Graft would be the first, new recombinant protein technology for orthopedics introduced to the market in nearly a decade and the first and only cost effective fully synthetic bone growth factor replacement for autograft with Level 1 data supporting its safety and efficacy.”
Dr Christopher W. DiGiovanni, professor and program director of the department of orthopaedic surgery at the Warren Alpert School of Medicine at Brown University, in Providence, Rhode Island, told the press:
“As a clinician who is constantly faced with having to consider fusion surgery as a potential therapeutic modality for my patients, I am very excited about this product.”
DiGiovanni was the lead investigator for an Augment Bone Graft trial that looked at arthrodesis rates (how well bones fused together) in foot and ankle surgery that used either Augment or autograft. He said he was sure that all his colleagues from the American Orthopaedic Foot and Ankle Society who took part in the trial were confident that the data shows Augment is safe and effective and offers an attractive risk-benefit ratio.
“The product, if approved, would provide our specialty an alternative means of enhancing ossteointegration while simultaneously eliminating the potential risk and morbidity associated with autogenous bone graft harvest,” he added.
Should the FDA give the product the go-ahead, the company expects it to be on the market no more than six months later.
Canada approved the use of BioMimetic’s Augment Bone Graft in November 2009.
The market for bone grafting in the US is worth around $2.5 billion.
Sources: BioMimetic Therapeutics via BusinessWire; FDA; Wall Street Journal; Associated Press.
Written by: Catharine Paddock, PhD