A little GEM

BioMimetic Therapeutics has recently initiated three clinical trials to evaluate GEM OS1 Bone Graft for use in foot and ankle fusion procedures and the treatment of unstable distal radius fractures.

GEM OS1 is a bioactive drug-device combination product that combines a tissue growth factor, recombinant human Platelet-Derived Growth Factor (rhPDGF), one of the principal wound healing stimulators in the body, with a synthetic bone matrix, Beta-tricalcium phosphate (Beta-TCP).

BioMimetic is leveraging the same combination drug-device technology for orthopaedic applications as it utilised in its FDA approved product, GEM 21S Growth-factor Enhanced Matrix for the treatment of periodontally related defects and gingival recession.

‘As a foot and ankle surgeon, I see a significant number of lower extremity fusion procedures that either do not heal or heal slowly, often leading to prolonged recovery times, increased patient morbidity, and greater cost to the patient and health care system,’ said lead US investigator, Dr. Christopher W. DiGiovanni, chief of foot and ankle in the department of orthopaedic surgery at Rhode Island Hospital and associate professor at Brown Medical School in Providence, RI.

‘Based on pre-clinical studies demonstrating the ability of GEM OS1 to stimulate a broad range of cellular events critical for the initiation and progression of new bone formation, this product candidate appears well suited for bone regeneration procedures,” he added.

GEM OS1 BioMimetic is developing GEM OS1 for use in open surgical treatment of fractures and bone fusions where the use of bone graft, a material used to augment bone healing, is indicated.

GEM OS1 is designed to be placed directly into an open surgical site to stimulate bone regeneration. The combination of the two GEM OS1 components, rhPDGF and Beta-TCP, is said to be key to the product’s overall effectiveness. rhPDGF is intended to provide the biological stimulus for tissue regeneration by stimulating the in-growth and proliferation of osteoblasts, cells responsible for the formation of bone, while Beta-TCP provides a framework or scaffold for new bone growth to occur.

Three centres

A three centre US feasibility study is being conducted at Rhode Island Hospital in conjunction with Brown Medical School, The University of Rochester Medical Center and the University of Medicine and Dentistry of New Jersey (UMDNJ).

The study’s objective is to determine the preliminary safety and effectiveness of GEM OS1 as a bone regeneration device in foot and ankle fusion procedures requiring open surgery. The Company expects that preliminary study results, which will include up to 20 volunteer patients, will be available in late 2006.

In addition to the US study, the company also has initiated a three centre pilot clinical study in Canada to evaluate GEM OS1 in foot and ankle fusion procedures and a single centre clinical study in Sweden to evaluate GEM OS1 in distal radius fractures. Distal radius fractures, or fractures of the wrist, are one of the world’s most common fractures, especially in elderly individuals with osteoporosis. The company anticipates completing enrolment for both the Canadian and Swedish studies by mid 2006.

Foot and ankle procedures

There are more than one million procedures performed annually in the United States involving fusions and corrective surgeries of the foot and ankle. The indications included as part of the GEM OS1 clinical study program represent approximately 70,000 of this annual number.

Foot and ankle fusion procedures are performed primarily in patients with severe osteoarthritis, who do not respond to more conservative treatments.

In a fusion procedure, the joint space between adjacent bones is surgically prepared and rigidly fixed with hardware to stimulate a fusion, or permanent connection of the two bone ends. This fusion eliminates the pain associated with the movement of the joint.

Typically, foot and ankle fusions are augmented with bone graft harvested from the patient, which is obtained as the result of a second surgical procedure.

Harvesting bone graft material has significant drawbacks, which include the associated pain and potential complications of this second surgery and inconsistent volume and quality of the harvested bone material.

GEM OS1 is a fully synthetic bone graft substitute that eliminates the need for this second surgery. The Beta-TCP component of GEM OS1 fills the gap between the bone surfaces and acts as a scaffold for the formation of new bone, while the rhPDGF, as shown in pre-clinical studies, is designed to stimulate the healing response by attracting new bone cells and enhancing the formation of blood vessels to facilitate the tissue regeneration process.