Histomorphometric changes following treatment for osteoporosis

Update on the clinical use of trabecular bone score (TBS) in the management of osteoporosis: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), and the International Osteoporosis Foundation (IOF) under the auspices of WHO Collaborating Center for Epidemiology of Musculoskeletal Health and Aging

PURPOSE

Trabecular bone score (TBS) is a grey-level textural measurement acquired from dual-energy X-ray absorptiometry lumbar spine images and is a validated index of bone microarchitecture. In 2015, a Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) published a review of the TBS literature, concluding that TBS predicts hip and major osteoporotic fracture, at least partly independent of bone mineral density (BMD) and clinical risk factors. It was also concluded that TBS is potentially amenable to change as a result of pharmacological therapy. Further evidence on the utility of TBS has since accumulated in both primary and secondary osteoporosis, and the introduction of FRAX and BMD T-score adjustment for TBS has accelerated adoption. This position paper therefore presents a review of the updated scientific literature and provides expert consensus statements and corresponding operational guidelines for the use of TBS.

METHODS

An Expert Working Group was convened by the ESCEO and a systematic review of the evidence undertaken, with defined search strategies for four key topics with respect to the potential use of TBS: (1) fracture prediction in men and women; (2) initiating and monitoring treatment in postmenopausal osteoporosis; (3) fracture prediction in secondary osteoporosis; and (4) treatment monitoring in secondary osteoporosis. Statements to guide the clinical use of TBS were derived from the review and graded by consensus using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

A total of 96 articles were reviewed and included data on the use of TBS for fracture prediction in men and women, from over 20 countries. The updated evidence shows that TBS enhances fracture risk prediction in both primary and secondary osteoporosis, and can, when taken with BMD and clinical risk factors, inform treatment initiation and the choice of antiosteoporosis treatment. Evidence also indicates that TBS provides useful adjunctive information in monitoring treatment with long-term denosumab and anabolic agents. All expert consensus statements were voted as strongly recommended.

CONCLUSION

The addition of TBS assessment to FRAX and/or BMD enhances fracture risk prediction in primary and secondary osteoporosis, adding useful information for treatment decision-making and monitoring. The expert consensus statements provided in this paper can be used to guide the integration of TBS in clinical practice for the assessment and management of osteoporosis. An example of an operational approach is provided in the appendix. This position paper presents an up-to-date review of the evidence base, synthesised through expert consensus statements, which informs the implementation of Trabecular Bone Score in clinical practice.

Inadequate response to treatment reveals persistent osteoclast bone resorption in osteoporotic patients

Several drugs are able to reduce fracture risk in osteoporotic patients. Incident fractures occur despite good adherence to treatment. Inadequate response has been found related to high serum bone biomarkers of bone turnover. We here aimed to analyze bone microarchitecture and cellular profiles of inadequate responders. We retrospectively analyzed bone biopsies from patients with major fractures despite long-term treatment (inadequate responder [IR] n = 31) in comparison to patients with untreated osteoporosis (U-OP, n = 31) and controls without osteoporosis (Ctrl, n = 16). Bone samples were analyzed by histomorphometry and micro-computed tomography. Clinical and bone turnover markers and bone mineral density were assessed. As compared with U-OP patients, IRs were older (mean age 69.7 ± 8.8 vs 63.3 ± 9.3 years, p = 0.007) and had lower mean hip bone mineral density (0.685 ± 0.116 vs 0.786 ± 0.093 g/cm²), p = 0.019 and T-score (-2.3 ± 0.769 vs -1.6 ± 0.900, p = 0.032). BV/TV was lower for IRs than U-OP patients and Ctrls (13.9 ± 3.8% vs 15.2 ± 5.1 and 17.6 ± 5.2%, p = 0.044) as was trabecular thickness (145.6 ± 23.1 vs 160.5 ± 22.7 and 153.7 ± 21.4 μm, p = 0.033). Mean structure model index was lower for IRs than U-OP patients (1.9 ± 0.806 vs 2.4 ± 0.687, p = 0.042) and osteoclast number was higher for IRs than U-OP patients and Ctrls (0.721 ± 0.611 vs 0.394 ± 0.393 and 0.199 ± 0.071 mm^-2, p < 0.001). The mean Obl.S/BS was lower for IRs than U-OP patients and Ctrls (1.2 ± 1.3 vs 1.9 ± 1.4 and 3.0 ± 0.638 mm^-2, p < 0.0001), and the mean number of labelled surfaces was lower for IRs than U-OP patients (51.6% vs 87%, p = 0.002). Cortical parameters did not significantly differ. We show an imbalance of bone remodeling in favor of bone resorption in IRs. The persistence of high bone resorption suggests insufficient inhibition of bone resorption that could explain the incident fractures with anti-osteoporotic drug use. Adaptation to treatment should be considered to inhibit bone resorption and prevent further fractures.

Effects of Odanacatib on Bone Structure and Quality in Postmenopausal Women With Osteoporosis: 5-Year Data From the Phase 3 Long-Term Odanacatib Fracture Trial (LOFT) and its Extension

Odanacatib (ODN), a selective oral inhibitor of cathepsin K, was an investigational agent previously in development for the treatment of osteoporosis. In this analysis, the effects of ODN on bone remodeling/modeling and structure were examined in the randomized, double-blind, placebo-controlled, event-driven, Phase 3, Long-term Odanacatib Fracture Trial (LOFT; NCT00529373) and planned double-blind extension in postmenopausal women with osteoporosis. A total of 386 transilial bone biopsies, obtained from consenting patients at baseline (ODN n = 17, placebo n = 23), month 24 (ODN n = 112, placebo n = 104), month 36 (ODN n = 42, placebo n = 41), and month 60 (ODN n = 27, placebo n = 20) were assessed by dynamic and static bone histomorphometry. Patient characteristics at baseline and BMD changes over 5 years for this subset were comparable to the overall LOFT population. Qualitative assessment of biopsies revealed no abnormalities. Consistent with the mechanism of ODN, osteoclast number was higher with ODN versus placebo over time. Regarding bone remodeling, dynamic bone formation indices in trabecular, intracortical, and endocortical surfaces were generally similar in ODN-treated versus placebo-treated patients after 2 years of treatment. Regarding periosteal modeling, the proportion of patients with periosteal double labels and the bone formation indices increased over time in the ODN-treated patients compared with placebo. This finding supported the observed numerical increase in cortical thickness at month 60 versus placebo. In conclusion, ODN treatment for 5 years did not reduce bone remodeling and increased the proportion of patients with periosteal bone formation. These results are consistent with the mechanism of action of ODN, and are associated with continued BMD increases and reduced risk of fractures compared with placebo in the LOFT Phase 3 fracture trial. © 2020 American Society for Bone and Mineral Research.

Update on the safety and efficacy of teriparatide in the treatment of osteoporosis

Following the completion of the Fracture Prevention Trial, teriparatide was approved by the United States Food and Drug Administration and the European Medicine Agency as the first therapeutic anabolic agent for the treatment of postmenopausal women with severe osteoporosis. It subsequently received additional approval for the treatment of osteoporosis in men, and for the treatment of osteoporosis associated with glucocorticoid therapy in men and women at risk of fracture. In this review, we summarize the most important data concerning PTH 1-34 therapy before 2016 in the treatment of osteoporosis, and report some outstanding results published in the last 2 years. New data on safety will also discussed, together with the state of art of nonclassical utilization. Finally, in view of the recent approval of biosimilars, possible future landscapes are discussed.

State of the art in osteoporosis risk assessment and treatment

BACKGROUND

Osteoporosis constitutes a major public health problem, through its association with age-related fractures, particularly of the hip, vertebrae, distal forearm, and humerus. Over recent decades, it has evolved from being viewed as an inevitable consequence of ageing, to being recognised as a serious and eminently treatable disease.

MATERIALS AND METHODS

In this article, we review the literature pertaining to the epidemiology of osteoporosis, associated health burden, approaches to risk assessment and treatment.

RESULTS

Although there is some evidence that fracture incidence has reached a plateau, or even started to decline, in the developed world, an ageing population and adoption of westernised lifestyles in transitioning populations is leading to an increasing burden of osteoporosis across the world. Whilst the clinical definition of osteoporosis has been based solely on bone mineral density, the prediction of fracture at the individual level has been improved by consideration of clinical risk factors in tools such as FRAX®, derived from a greater understanding of the epidemiology of osteoporosis. Such advances in approaches to primary and secondary prevention of fractures, coupled with elucidation of the underlying biology, and the development of a range of highly effective antiosteoporosis medications, have enabled a step change in our ability to prevent osteoporosis-related fractures. However, there remains a substantial disparity between the number of individuals at high fracture risk and number treated globally.

CONCLUSION

Urgent work is needed at the level of health care systems, national and international policy, and in communication with patients and public, to ensure that all patients who should receive treatment for osteoporosis actually do so.

New anabolic therapies for osteoporosis

Osteoporosis is characterized by low bone mass and qualitative structural abnormalities of bone tissue, leading to increased bone fragility that results in fractures. Pharmacological therapy is aimed at decreasing the risk of fracture, mainly correcting the imbalance between bone resorption and formation at the level of bone remodeling units. Anabolic therapy has the capability to increase bone mass to a greater extent than traditional antiresorptive agents. The only currently available drug licensed is parathyroid hormone 1-34 (teriparatide); new drugs are on the horizon, targeting the stimulation of bone formation, and therefore improving bone mass, structure and ultimately skeletal strength. These are represented by abaloparatide (a 34-amino acid peptide which incorporates critical N-terminal residues, shared by parathyroid hormone and parathyroid hormone-related protein, followed by sequences unique to the latter protein) and romosozumab (an antibody to sclerostin). In the future, the availability of new anabolic treatment will allow a more extensive utilization of additive and sequential approach, with the goal of both prolonging the period of treatment and, more importantly, avoiding the side effects consequent to long-term use of traditional drugs.