Abaloparatide and Pelvic Fracture Healing

Overview

This is a prospective randomized, double-blinded, placebo-controlled, phase 2, three-month study of the efficacy of abaloparatide in postmenopausal women and men ≥ 50 years of age with acute fractures of the pelvis (n=78). The primary outcome is CT image based evidence of fracture healing. The secondary aims are pain and physical performance measures at 3 months. This study will be extended with 9 months of open label abaloparatide to determine if any potential differences between the placebo and abaloparatide groups during the 3 months of treatment are evident and persist over time, even in patients who use abaloparatide after the three-month placebo controlled intervention.

By 2030 over 25% of the entire US population will be older than 65 years of age. Pelvic fracture rates are higher in women. Over 90% of pelvic fractures in patients \>60 years are defined as osteoporosis related fractures. In a recent study in Germany, the rate of all first pelvic fractures in persons over 60 was 22.4 \[95% CI 22.0-22.9\] per 10,000 person-years. The incidence rate increases dramatically with age, from 5.4 and 3.8 per 10,000 person-years in women and men aged 65 to 69 years to 93.5 and 44.5 per 10,000 person-years in women and men aged 90 years and older, respectively. This is in agreement with studies in the US and Finland, also showing an increase in incidence of pelvic fractures with age. Pelvic fractures are most often a result of low-energy trauma, such as a fall from standing height. Pelvic fractures are the most relevant for this proposed randomized placebo-controlled study. This fracture is accompanied by severe pain, chronic immobility and loss of function and independence in the elderly. The current treatment strategy of pelvic fractures includes pain management, patient mobilization, and the prevention of complications associated with comorbid conditions. In a review of six studies with over 500 patients, the mean length of hospital stay was 13.4 days and the average 1-year mortality was 16.3%. Mortality rates in 1300 pelvic fracture patients were still elevated at 3 years. Pelvic fractures are associated with slow healing and a delayed return to full function and normal activity. Pelvic fractures consume substantial healthcare resources, and based on administrative claims data, they are one of the most costly osteoporosis related fractures. Un-healed fractures, occurring in one-third of pelvic fracture patients at 3 months, can cause continued pain and impact mobility. With aging of the population and expected concomitant increase in the incidence of pelvic fractures, there is a pressing need to find effective treatments that will accelerate healing. There are strong preclinical data, as well as clinical evidence, that administration of parathyroid hormone (PTH) receptor agonists may improve bone union, hasten fracture healing and improve physical function. In one nonrandomized, un-blinded study, 100% of pelvic fracture patients given 1-84PTH were healed within 12 weeks compared to 68% of the controls. However, there is not sufficient evidence at this time to recommend routine use of PTH receptor agonists for fracture healing. Pelvic fractures are ideal to study for the impact of abaloparatide on rate of fracture healing because there are no surgical repairs for the vast majority of the fractures. Prior studies of teriparatide on wrist fracture healing were limited and confounded by the increased prevalence of surgical fixation to treat these fractures. Strong evidence of pelvic fracture healing that may result from this study may not only have an impact on pelvic fractures but perhaps may indicate a potential use for other fractures as well. In the proposed randomized, double blind, placebo controlled clinical trial in patients \>50 years of age with acute pelvic fracture, the investigators plan to evaluate whether treatment with daily subcutaneous ABALOPARATIDE 80 mcg/day compared with placebo, in addition to standard treatment (pain management, bed rest and prevention of complications from comorbid conditions), is effective in accelerating fracture healing in women and men compared to standard treatment alone. The investigators hypothesize that development of a successful adjunctive therapy (ABALOPARATIDE) will accelerate radiographic evidence of fracture healing and speed functional recovery. If this hypothesis holds true, it would lead to a change in clinical practice and an improved quality of care for pelvic fracture patients. Evidence of an impact on the healing of pelvic fractures may also extend to a potential to improve healing of other osteoporosis-related fractures. In the planned trial the investigators will recruit women and men with acute pelvic fractures and address 3 specific aims over 3 months of treatment in a placebo controlled double blind study to determine if ABALOPARATIDE in addition to standard care versus placebo and standard care: 1. Results in evidence of more complete cortical bridging at 3 months using focus CT to reduce radiation exposure from CT scans (primary outcome). 2. Leads to a faster reduction in pain as assessed by both the Numeric Rating Scale and a reduction in the use of narcotics (secondary outcome). 3. Leads more to a more rapidly improved functional outcome using measures to assess lower extremity function (Continuous Summary Physical Performance Score and Timed Up and Go- secondary outcomes). Although the primary analysis will be based on data from 0 to 3 months, whether the benefit of ABALOPARATIDE on fracture healing wanes over time is unclear, making a longer follow-up important to extend knowledge on the persistence of early ABALOPARATIDE effect on these outcomes. Therefore, the investigators will extend this study with 9 months of open label ABALOPARATIDE to determine if any potential differences between the placebo and ABALOPARATIDE groups during the 3 months of treatment are evident and persist over time, even in patients who use ABALOPARATIDE after the three month placebo controlled intervention. If ABALOPARATIDE can improve fracture healing, this study will have an impact on the treatment of persons with pelvic fracture who are not surgical candidates and often face severe pain, chronic immobility, and loss of function in the elderly. A positive finding of accelerated healing of pelvic fractures would also encourage study of ABALOPARATIDE for treatment of other osteoporotic fractures.