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January 11, 2002


FDA Panel Recommends Approval of Bone Growth Protein as Alternative to Bone Grafts in Spinal Fusion

rhBMP-2 Would Be Less Painful, With Speedier Recovery and Lower Cost, Emory Researcher Says

An advisory panel of the U.S. Food and Drug Administration (FDA) has unanimously recommended approval, with conditions, of a genetically engineered protein that stimulates the growth of bone cells and could provide a viable alternative to the painful bone grafts often used in spinal fusion surgery. If approved, the protein, called rhBMP-2 (recombinant human bone morphogenetic protein), would allow orthopaedic surgeons to use the body's own growth system to generate new bone following traumatic injury or disease.

The rhBMP-2 protein is a recombinant version of the naturally occurring BMP protein, which causes new bone to grow in cells capable of developing into bone cells. Scott D. Boden, M.D., an orthopaedic surgeon at Emory University School of Medicine, has been studying rhBMP-2 since 1993 as a potential alternative to spinal bone grafts. The Emory Spine Center has been a key contributor to reaching this important milestone of the first bone growth factor to be deemed approvable by an FDA panel.

The protein was developed and discovered by its manufacturer, Wyeth-Ayerst Laboratories, and will be distributed by Medtronic Sofamor Danek, a leader in spinal implants. The FDA Orthopaedic and Rehabilitation Devices Panel's conditions for approval include three post-approval studies.

When a person's lower back is painfully injured, or when a patient suffers from chronic back pain due to spinal deformity or instability caused by degeneration, cancer or infection, surgeons can fuse two or more vertebrae in the spine to relieve pressure. About half a million patients each year in the United States undergo this operation. Spinal fusion surgery requires that the surgeon take bone from the pelvis and apply it, or graft it, to the compromised area of the skeleton. The harvesting procedure is painful, and patients usually are immobilized for months while the graft fuses with the host bone.

Emory has been the leader of a pilot clinical trial of patients with degenerative disks and chronic back pain conducted over the past five years at Emory, the University of Wisconsin and UCLA. Dr. Boden and his colleagues found that 11/11 patients made solid bone with the rhBMP-2 protein.

Emory also has participated in the pivotal randomized clinical trial involving 279 patients, which has shown similar promising results. Approximately half the patients received bone grafts and the other half were treated with rhBMP-2. All the bone graft patients experienced pain at the donor graft site, whereas the rhBMP-2 patients experienced no hip pain. Fusion rates for both treatment groups were high, and patients in both groups were experiencing similar relief from their low back pain at two years. The experimental group experienced shorter operative times and less blood loss than did the control group.

"Whereas in many instances the body does not come through on its own, by using rhBMP-2 we can harness the body's own power to generate bone, " says Dr. Boden. "The exciting thing about rhBMP-2 is not only does it eliminate all the problems associated with taking the patient's own bone, it also has the potential to do it better."

When using the alternative treatment, Dr. Boden and his colleagues fill a cylindrical cage of titanium with a sponge soaked with BMP, then implant the cage in the spine where new bone is needed. The BMP attracts bone to grow and eventually the new bone surrounds the implanted titanium cage. If the FDA approves the BMP-2 product, which could happen in the next few months, it will be classified as a biological device.

The product's name will be InFUSE Bone Graft, and it will be available in select centers, including Emory, for very specific indication of anterior spine fusion with a tapered titanium fusion cage.

"This new technology will allow us to make bone safely and consistently," Dr. Boden said. "This means the potential for faster recovery, better results, less hospitalization and lower costs for eligible patients with low back pain."

Under the directorship of Dr. Boden, the Emory Spine center is internationally recognized for its award-winning research and excellence in clinical care and as one of the largest university-based multidisciplinary spine centers in the U.S.

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