Safety and efficacy of teriparatide treatment for severe osteoporosis in patients with Duchenne muscular dystrophy

The use of bisphosphonate and testosterone in young people with Duchenne muscular dystrophy: an international clinician survey

OBJECTIVES

Delayed puberty and osteoporosis are significant challenges in boys with Duchenne muscular dystrophy (DMD). The current International Care Considerations for DMD recommend bisphosphonate after first fracture and testosterone for delayed puberty from 12 years. This study aimed to investigate the current clinical practices of clinicians managing osteoporosis and testosterone treatment in DMD.

METHODS

An online survey was circulated to paediatric clinicians involved in the management of bone health and puberty in DMD via patient groups (UK, USA, Italy, Israel).

RESULTS

A total of 51/105 (48 %) responses were received. For osteoporosis, vertebral fracture of any grade (86 %) and long bone fracture (67 %) were the most common indications for starting bisphosphonates, with IV zoledronate being the most used agent (86 %). Approaches varied in managing bisphosphonate side effects, and transitioning care to adult specialists. Opinions differed on starting bisphosphonate before fracture. Fourty-nine clinicians managing pubertal disorders reported initiating testosterone for delayed puberty typically between 12 and 14 years, with majority prescribing intramuscular injections (96 %). Duration of testosterone therapy varied, with some using short-term courses and others continuing until adulthood.

CONCLUSIONS

This international survey highlights variability in the management of osteoporosis and delayed puberty in DMD. Recommendations on management of side-effects of IV bisphosphonate, osteoporosis therapy during transition, and longer-term treatment into adulthood is required. There is a need for further guidance on testosterone therapy, particularly in regard to monitoring after discontinuation and the threshold for re-initiation of treatment.

Pharmacological and non-pharmacological therapies for prevention and treatment of osteoporosis in Duchenne Muscular Dystrophy: A systematic review

BACKGROUND

Long term glucocorticoid treatment in Duchenne Muscular Dystrophy (DMD) is associated with a high incidence of fragility fractures. This systematic review aims to assess the current evidence for pharmacological and non-pharmacological treatment for osteoporosis in children and adults with DMD.

METHODS

Three online databases (Embase, Medline, Cochrane Library) were searched for studies that evaluated interventions for treatment or prevention of osteoporosis in DMD. Included studies had to report changes in bone mineral density (BMD) or bone mineral content (BMC) Z-scores or fracture incidence.

RESULTS

Nineteen studies were identified, including twelve that evaluated bisphosphonate, three evaluated testosterone (2 studies of the same patient group), one evaluated vitamin D/calcium, one teriparatide, and two evaluated vibration therapy. Only two randomised-controlled trials were found, one of intravenous bisphosphonate and one of vibration therapy. Changes in lumbar spine BMD ranged from -0.3 to +1.3 in studies of bisphosphonate and - 0.2 to 0.0 with vibration therapy, whereas this was +0.38 with testosterone and + 0.9 with vitamin D/calcium. There was limited information on impact on fracture in all studies. None of the pharmacological studies involved a fracture naïve group at baseline. In addition, none addressed a group of individuals over 18 years at baseline.

CONCLUSION

This systematic review provides evidence for the effectiveness of bisphosphonate therapy in improving bone density in children and adolescents with DMD. However, there is less information on the impact on fracture. The review did not find studies exclusively in those over 18 years old with DMD and limited information on non-bisphosphonate pharmacological agents.

Pubertal induction therapy in pediatric patients with Duchenne muscular dystrophy

Objectives

We conducted a scoping review and analyzed the medical literature on PubMed to assess any potential short-term and long-term benefits of pubertal induction in patients with DMD.

Content

We identified six articles from our research cumulatively reporting clinical data from 58 pediatric patients with DMD, of age between 12 and 17.7 years. All of them were on glucocorticoid therapy with variable duration and the longest follow-up of 11.7 years. In all patients, the induction protocol was successful (leading to appearance of secondary sexual characteristics); no secondary effects were reported by any analyzed studies. Three papers reported an objective improvement of patients’ quality of life, while in four there was a benefit on the bone profile.

Summary

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder that affects approximately 1 in 5,000 live-born male children. Because of early and chronic exposure to glucocorticoids, used as standards of care, pubertal development may be variable. While some boys experience a normal pubertal growth spurt, others have testosterone levels below the normal range for age and require pubertal induction therapy to achieve an adequate testicular volume, development of secondary sexual characteristics, and peak bone mass. When and how to use pubertal induction therapy in pediatric patients with DMD is still object of controversy.

Outlook

The reported evidence of testosterone therapy in patients with DMD is still limited to small cohort sizes, which suggest efficacy and psychosocial benefits.

Approach to the Pediatric Patient With Glucocorticoid-Induced Osteoporosis

Glucocorticoid (GC) therapy remains the cornerstone of treatment for many conditions of childhood and an important cause of skeletal and endocrine morbidity. Here, we discuss cases that bring to life the most important concepts in the management of pediatric GC-induced osteoporosis (pGIO). Given the wide variety of underlying conditions linked to pGIO, we focus on the fundamental clinical-biological principles that provide a blueprint for management in any clinical context. In so doing, we underscore the importance of longitudinal vertebral fracture phenotyping, how knowledge about the timing and risk of fractures influences monitoring, the role of bone mineral density in pGIO assessments, and the impact of growth-mediated "vertebral body reshaping" after spine fractures on the therapeutic approach. Overall, pGIO management is predicated upon early identification of fractures (including vertebral) in those at risk, and timely intervention when there is limited potential for spontaneous recovery. Even a single, low-trauma long bone or vertebral fracture can signal an osteoporotic event in an at-risk child. The most widely used treatments for pediatric osteoporosis, intravenous bisphosphonates, are currently recommended first-line for the treatment of pGIO. It is recognized, however, that even early identification of bone fragility, combined with timely introduction of the most potent bisphosphonate therapies, may not completely prevent osteoporosis progression in all contexts. Therefore, prevention of first-ever fractures in the highest-risk settings is on the horizon, where there is also a need to move beyond antiresorptives to the study of anabolic agents.

A Parent Project Muscular Dystrophy-sponsored International Workshop Report on Endocrine and Bone Issues in Patients with Duchenne Muscular Dystrophy: An Ever-changing Landscape

In April 2023, over 30 experts and advocates from four countries met in Rome, Italy to discuss unmet needs in endocrine and bone health care for individuals with Duchenne muscular dystrophy (DMD). Despite recent advances in muscle-targeted therapy, long-term glucocorticoids (GC) remain the backbone of treatment for the foreseeable future. This affirms the need to intensify efforts that will mitigate serious complications of GC therapy, including unexpected mortality due to fat embolism syndrome following bone injury and also unrecognized adrenal suppression, early loss of ambulation linked to excess weight and/or fragility fracture, adverse cardiometabolic effects of GC, the psychosocial impact of profound growth and pubertal delay/hypogonadism, and the burden to families arising from monitoring and treating endocrine and skeletal complications of GC therapy. Delegates discussed: 1. The impact of GC therapy on the heart, 2. Predictors of fragility fractures and experience with intravenous and oral bisphosphonates plus teriparatide, 3. The effect of hormonal therapy on muscle-bone health, 4. Adrenal suppression, 5. Weight management, 6. Puberty, sexuality, fertility and gender identity, 7. The impact of early GC initiation, 8. Emerging knowledge about vamorolone (a novel dissociative steroid) and its effects on muscle, bone and endocrine health, and 9. Experiences implementing an endocrine-bone health management strategy nation-wide (in the UK). At the conclusion of the meeting, it was agreed that an endocrine-bone working group should be struck to continue the narrative, following which the International OPTIMIZE DMD Consortium was ignited to move the dial in these important areas.

Poor bone health in Duchenne muscular dystrophy: a multifactorial problem beyond corticosteroids and loss of ambulation

Duchenne muscular dystrophy (DMD) is a progressive, fatal muscle wasting disease caused by X-linked mutations in the dystrophin gene. Alongside the characteristic muscle weakness, patients face a myriad of skeletal complications, including osteoporosis/osteopenia, high susceptibility to vertebral and long bone fractures, fat embolism post-fracture, scoliosis, and growth retardation. Those skeletal abnormalities significantly compromise quality of life and are sometimes life-threatening. These issues were traditionally attributed to loss of ambulation and chronic corticosteroid use, but recent investigations have unveiled a more intricate etiology. Factors such as vitamin D deficiency, hormonal imbalances, systemic inflammation, myokine release from dystrophic muscle, and vascular dysfunction are emerging as significant contributors as well. This expanded understanding illuminates the multifaceted pathogenesis underlying skeletal issues in DMD. Present therapeutic options are limited and lack specificity. Advancements in understanding the pathophysiology of bone complications in DMD will offer promising avenues for novel treatment modalities. In this review, we summarize the current understanding of factors contributing to bone problems in DMD and delineate contemporary and prospective multidisciplinary therapeutic approaches.

Osteoporosis and Bone Fragility in Children: Diagnostic and Treatment Strategies

The incidence of osteoporosis in children is increasing because of the increased survival rate of children with chronic diseases and the increased use of bone-damaging drugs. As childhood bone fragility has several etiologies, its management requires a thorough evaluation of all potentially contributing pathogenetic mechanisms. This review focuses on the main causes of primary and secondary osteoporosis and on the benefits and limits of the different radiological methods currently used in clinical practice for the study of bone quality. The therapeutic and preventive strategies currently available and the most novel diagnostic and treatment strategies are also presented. Optimal management of underlying systemic conditions is key for the treatment of bone fragility in childhood. DXA still represents the gold standard for the radiologic evaluation of bone health in children, although other imaging techniques such as computed tomography and ultrasound evaluations, as well as REMS, are increasingly studied and used. Bisphosphonate therapy is the gold standard for pharmacological treatment in both primary and secondary pediatric osteoporosis. Evidence and experience are building up relative to the use of monoclonal antibodies such as denosumab in cases of poor response to bisphosphonates in specific conditions such as osteogenesis imperfecta, juvenile Paget's disease and in some cases of secondary osteoporosis. Lifestyle interventions including adequate nutrition with adequate calcium and vitamin D intake, as well as physical activity, are recommended for prevention.

A systematic literature review and meta-analysis of the effectiveness of vitamin D supplementation for patients with Duchenne muscular dystrophy

We conducted a systematic literature review and meta-analysis on the effectiveness of vitamin D supplementation in maintaining or restoring vitamin D levels in Duchenne muscular dystrophy. Due to a lack of randomised controlled trials, cross-sectional and retrospective and prospective cohort studies were taken as the best available evidence. Inclusion criteria included reporting mean serum vitamin D levels in a supplement-taking group. After screening 102 records; 13 were included in a narrative synthesis and eight of these in a meta-analysis. We show that current dosing regimens are preventing severe deficiency but are not effective at maintaining sufficient vitamin D levels within the Duchenne population. Despite high levels of daily vitamin D supplementation (>1000 International Units), at least 20 % of people with Duchenne remain vitamin D deficient. No significant association between dose and serum vitamin D levels was found (r2 = 0.3, p = 0.237). A meta-analysis of mean serum vitamin D levels across eight studies also revealed substantial variability in response to vitamin D supplementation and high heterogeneity (I2 = 99.59 %). These data could impact on an individual's risk and severity of osteoporosis and vertebral fractures.

Bone health in Duchenne muscular dystrophy: clinical and biochemical correlates

PURPOSE

An increased fracture risk is commonly reported in Duchenne muscular dystrophy (DMD). Our aim was to investigate bone mineral density (BMD) and bone turnover, including sclerostin, and their association with markers of cardiac and respiratory performance in a cohort of DMD subjects.

METHODS

In this single center, cross sectional observational study, lumbar spine (LS) BMD Z-scores, C-terminal telopeptide of procollagen type I (CTX) and osteocalcin (BGP), as bone resorption and formation markers, respectively, and sclerostin were assessed. Left ventricular ejection fraction (LVEF) and forced vital capacity (FVC) were evaluated. Clinical prevalent fractures were also recorded.

RESULTS

Thirty-one patients [median age = 14 (12-21.5) years] were studied. Ambulant subjects had higher LS BMD Z-scores compared with non-ambulant ones and subjects with prevalent clinical fractures [n = 9 (29%)] showed lower LS BMD Z-scores compared with subjects without fractures. LS BMD Z-scores were positively correlated with FVC (r = 0.50; p = 0.01), but not with glucocorticoid use, and FVC was positively associated with BGP (r = 0.55; p = 0.02). In non-ambulant subjects, LS BMD Z-scores were associated with BMI (r = 0.54; p = 0.02) and sclerostin was associated with age (r = 0.44; p = 0.05). Age, BMI, FVC and sclerostin were independently associated with LS BMD Z-score in a stepwise multiple regression analysis. Older age, lower BMI, FVC and sclerostin were associated with lower LS BMD Z-scores.

CONCLUSION

In a cohort of DMD patients, our data confirm low LS BMD Z-scores, mainly in non-ambulant subjects and irrespective of the glucocorticoid use, and suggest that FVC and sclerostin are independently associated with LS BMD Z-scores.

The effect of oral bisphosphonate therapy on vertebral morphometry and fractures in patients with Duchenne muscular dystrophy and glucocorticoid-induced osteoporosis

INTRODUCTION/AIMS

Glucocorticoid-induced osteoporosis with vertebral fractures is frequent in patients with Duchenne muscular dystrophy (DMD). In this study, we evaluated the effects of oral bisphosphonate (BP) therapy on the prevalence and severity of vertebral fractures by vertebral morphometry assessment.

METHODS

We reviewed the records and radiographs of patients with DMD who had been treated with oral BP (weekly alendronate) and had undergone routine spine radiographic monitoring for glucocorticoid-induced osteoporosis at Cincinnati Children's Hospital Medical Center between 2010 and 2017. Study outcomes were thoracic and lumbar vertebral fracture prevalence and severity, assessed by Genant semiquantitative grading of vertebral morphometry, for up to 5 years of treatment.

RESULTS

Fifty-two patients (median age, 11.8 years; 88% prepubertal; 31% nonambulatory) had been treated with long-term glucocorticoids (median duration, 4.7 years at BP start). Most patients (75%) had mild vertebral height loss or fractures (Genant grade = 0 or 1) at baseline. The prevalence of vertebral fractures at each year of treatment was not statistically different from that at baseline (P = .08-1.00). Serial radiographs showed no longitudinal change in severity by Genant grade in most vertebrae (64%-80%). Improvement in vertebral fracture grade was observed in some patients.

DISCUSSION

We observed stable prevalence of vertebral fractures and no change in severity by Genant grade in most vertebrae for up to 5 years of treatment. Oral BP may mitigate development or progression of vertebral fractures and be beneficial for secondary prevention of glucocorticoid-induced osteoporosis in this population.

What Is New in Pediatric Bone Health

BACKGROUND

This review paper aims to report on the last 5 years of relevant research on pediatric bone health in regard to nutrition and obesity, ethnic disparities, common orthopaedic conditions, trauma, spine, and sports medicine.

METHODS

A search of the PubMed database was completed using the following terms: bone health, Vitamin D, pediatric, adolescent, sports medicine, fractures, spine, scoliosis, race, ethnicity, obesity, Slipped Capital Femoral Epiphysis, Osteogenesis Imperfecta, Duchenne's Muscular Dystrophy, neuromuscular, and cancer. Resultant papers were reviewed by study authors and determined to be of quality and relevance for description in this review. Papers from January 1, 2015 to August 31, 2020 were included.

RESULTS

A total of 85 papers were selected for review. General results include 7 key findings. (1) Obesity inhibits pediatric bone health with leptin playing a major role in the process. (2) Socioeconomic and demographic disparities have shown to have a direct influence on bone health. (3) Vitamin D deficiency has been linked to an increased fracture risk and severity in children. (4) Formal vitamin D monitoring can aid with patient compliance with treatment. (5) Patients with chronic medical conditions are impacted by low vitamin D and need ongoing monitoring of their bone health to decrease their fracture risk. (6) Vitamin D deficiency in pediatrics has been correlated to low back pain, spondylolysis, and adolescent idiopathic scoliosis. Osteopenic patients with AIS have an increased risk of curve progression requiring surgery. Before spine fusion, preoperative screening for vitamin D deficiency may reduce complications of fractures, insufficient tissue repair, loosening hardware, and postoperative back pain. (7) Increasing youth sports participation has resulted in increased bone health related injuries. However, improved understanding of Relative Energy Deficiency in Sport effects on bone health has recently occurred.

CONCLUSIONS

Increasing awareness of bone health issues in children will improve their recognition and treatment. Further research is needed on diagnosis, treatment, outcomes, and most importantly prevention of pediatric bone health diseases.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.