Novel Parathyroid Hormone-Based Bone Graft, KUR-113, in Treatment of Acute Open Tibial Shaft Fracture: A Phase-2 Randomized Controlled Trial.

Background: Treatment of an open tibial shaft fracture (TSF) is complex, and many cases are associated with delayed bone union or malunion. Parathyroid hormone (PTH) plays a key role in bone metabolism. A peptide fragment of PTH (PTH1-34) has been shown to promote bone healing. The objective of this study was to evaluate the safety and efficacy of a novel PTH-based bone graft (KUR-113) in the treatment of subjects with an open TSF.

Methods: The study was a randomized, controlled, open-label (dose-blinded), dose-finding study of 200 subjects who had an open TSF secondary to trauma. Subjects were randomized into 1 of 4 groups to receive the standard of care (SoC) alone (control) or the SoC plus a single application of 4 mL of KUR-113 containing TGplPTH1-34 in fibrin at a concentration of 0.133 mg/mL (KUR-113-low), 0.4 mg/mL (KUR-113-mid), or 1.0 mg/mL (KUR-113-high). KUR-113 was administered at the fracture site after internal fracture fixation and before wound closure. Subjects were followed for up to 12 months after treatment. The primary outcome measure was fracture healing at 6 months assessed by the study investigator using radiographic and clinical measures. The primary end point was the proportion of subjects with fracture healing at 6 months.

Results: A total of 200 subjects were enrolled and randomized to 1 of the 4 treatments. The primary end point was met in the KUR-113-mid group, which showed a significantly higher prevalence of healing at 6 months than the control group (37 of 46; 80.4% versus 31 of 48; 64.6%). By 12 months, healing had occurred in the majority of subjects in all treatment groups, with the control group requiring more surgical interventions to achieve fracture healing. Adverse events occurred at similar frequencies between the KUR-113 groups and the SoC group. No ectopic bone formation or abnormal bone resorption at the fracture site was observed in any of the treatment groups.

Conclusions: KUR-113 has the potential to be a good adjunctive therapy in the treatment of open TSFs.

Level Of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.