Novel bone graft substitute shows potential in interim Canadian trial analysis

BioMimetic Therapeutics' GEM OS1 appears as effective as autologous bone graft in foot and ankle fusions.

Interim results of a Canadian pilot study suggest GEM OS1, an investigational bone graft substitute, is "at least as effective as autograft" for stimulating bone regeneration in foot and ankle fusion patients, according to a press release from BioMimetic Therapeutics Inc., the device's developer.

GEM OS1 combines recombinant human platelet-derived growth factor, which is intended to stimulate ingrowth and proliferation of osteoblasts, and beta-tricalcium phosphate, which provides a scaffold for the new bone growth. BioMimetic Therapeutics is evaluating the safety and utility of the device for orthopedic foot and ankle applications in a multicenter, open label trial. Initially, 20 patients were to be included, but investigators expanded enrollment to include 60 patients following Canadian government authorization.

Timothy R. Daniels, MD, the lead investigator for the study, presented the interim results for 32 patients at the Dewar Orthopaedic Society meeting. The results show that GEM OS1 is at least as effective as autograft, according to the press release.

Of the 32 patients, over 70% have at least one risk factor for delayed union or nonunion. Specifically, 44% were obese, 25% had a history of smoking within the last 5 years, 13% had diabetes, 41% had failed previous surgical treatment and 44% had multiple risk factors.

Among 29 patients evaluated at 12 weeks follow-up, 85% of patients showed some degree of fusion on radiographs and 67% achieved more than 50% osseous bridging as measured on CT scans. Also, 67% of 30 patients evaluated clinically at 12 weeks achieved full weight-bearing, according to the release.

Investigators found no evidence of ectopic or otherwise abnormal bone formation, according to the release.

These results are similar to recently published data using autograft, where 48% of patients demonstrated greater than 50% fusion mass at 12 weeks on CT scans, company officials noted in the release.

"The results observed to date show that GEM OS1 is a safe alternative to autograft — I haven't seen any complications related to the product, and the results are at least comparable to autogenous bone graft," Daniels, associate professor at St. Michael's Hospital, University of Toronto, and co-founder of the Canadian Foot and Ankle Society, said in the release.

"We look forward to completion of patient enrollment and being able to fully analyze all the data from the larger trial involving 60 patients," he said.

For more information:
BioMimetic Therapeutics Inc. Web site: www.biomimetics.com.