Bone mineral density and fracture rate in response to intravenous and oral bisphosphonates in adult osteogenesis imperfecta

Psychosocial Outcomes of Pain and Pain Management in Adults with Osteogenesis Imperfecta: A Qualitative Study

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and fractures, short stature, dental abnormalities, hearing loss, scoliosis, and chronic pain. Despite a growing literature on the functional outcomes of OI, limited research has explicitly examined the psychosocial outcomes of pain within OI. Adults with OI (N = 15) were interviewed to understand pain-related experiences through a thematic analysis of semi-structured interview data. Research team members, genetic research experts, and OI clinicians developed an interview guide focused on topics related to pain and mental health challenges. Participants' transcripts were coded by two independent coders; codes were then merged across coders and quotation outputs were subsequently abstracted (paraphrased then thematically classified) to identify common themes. Themes related to pain management variability regarding pain type, pain risk management and accessibility, pain outcomes (e.g., behavior, cognitive, affective), and pain exacerbating factors (e.g., individual, contextual) were identified. Participants reported chronic and acute pain, and despite the inaccessibility and stigmatization of pain medications (e.g., opioids), pharmacological treatments were the most common pain management approach. Participants reported negative pain outcomes, such as limited daily functioning and activity participation, fear, anger, anxiety, depression, and difficulty concentrating. Lastly, participants suggested that lack of physician and community knowledge on chronic pain in OI indirectly exacerbates both subjective pain intensity and outcomes. Although limited by a small, nondiverse sample, the current study provides valuable exploration of the unique pain experiences of adults with OI that may have implications for proactive management, treatment development, and clinician training.

Current and Developing Pharmacologic Agents for Improving Skeletal Health in Adults with Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder characterized by increased bone fragility largely caused by defects in structure, synthesis, or post-translational processing of type I collagen. Drugs currently used to improve skeletal health in OI were initially developed to treat osteoporosis and clinical trials are ongoing to study their effectiveness in OI adults. Additionally, novel bone-protective agents are in preclinical studies and various phases of OI clinical trials. This review summarizes current knowledge on available pharmacologic agents and current drug trials involving OI participants. A PubMed online database search of all study types published in the English language using the terms "osteogenesis imperfecta," "OI," and "brittle bone disease" was performed in August 2022. Articles screened were restricted to adults. A ClinicalTrials.gov database search of all studies involving "osteogenesis imperfecta" was performed in August 2023. Although clinical trial data are limited, bisphosphonates and teriparatide may be useful in improving bone mineral density. As of yet, no clinical trials are available that adequately evaluate the usefulness of current therapies in reducing fracture risk. Several therapeutics, including teriparatide, setrusumab, anti-TGF-β antibodies, and allogeneic stem cells, are being studied in clinical trials. Preclinical studies involving Dickkopf-1 antagonists present promising data in non-OI bone disease, and could be useful in OI. Research is ongoing to improve therapeutic options for adults with OI and clinical trials involving gene-editing may be possible in the coming decade.

Approach to the Patient: Pharmacological Therapies for Fracture Risk Reduction in Adults With Osteogenesis Imperfecta

CONTEXT

Osteogenesis imperfecta (OI) is a genetic disorder characterized by increased bone fragility largely caused by defects in structure, synthesis, or post-translational processing of type I collagen. The effectiveness of medications used for fracture reduction in adults with OI is understudied and practice recommendations are not well established. Drugs currently used to improve skeletal health in OI were initially developed to treat osteoporosis. Oral and intravenous bisphosphonates have been shown to improve bone mineral density (BMD) in adults with OI and are commonly used; however, conclusive data confirming fracture protection are lacking. Similarly, teriparatide appears to increase BMD, an effect that seems to be limited to individuals with type I OI. The role of denosumab, abaloparatide, romosozumab, and estradiol/testosterone in adult OI have not been systematically studied. Anti-sclerostin agents and transforming growth factor-beta antagonists are under investigation in clinical trials.

OBJECTIVE

This review summarizes current knowledge on pharmacologic treatment options for reducing fracture risk in adults with OI.

METHODS

A PubMed online database search of all study types published in the English language using the terms "osteogenesis imperfecta," "OI," and "brittle bone disease" was performed in June 2022. Articles screened were restricted to adults. Additional sources were identified through manual searches of reference lists.

CONCLUSION

Fracture rates are elevated in adults with OI. Although clinical trial data are limited, bisphosphonates and teriparatide may be useful in improving BMD. Further research is needed to develop medications for adults with OI that will lead to definite fracture rate reduction.

Bone Mass, Density, Geometry, and Stress-Strain Index in Adults With Osteogenesis Imperfecta Type I and Their Associations With Physical Activity and Muscle Function Parameters

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous heritable connective tissue disorder mainly characterized by bone fragility and increased fracture risk. This study investigated bone parameters in adults with OI type I and their relationship with physical activity and muscle function parameters in comparison with controls. A total of 27 (15 women, 12 men) adults with OI type I and 27 healthy age- and sex-matched controls, with mean age 45 years (range 18-72 years), were included. Peripheral quantitative computed tomography was performed at the lower leg and forearm to assess muscle density, muscle and fat cross-sectional area (CSA) (66% site), and trabecular (4% site) and cortical bone parameters (66% site) at radius and tibia. Physical activity (step count and moderate-to-vigorous physical activity [MVPA]) was assessed by accelerometry, muscle function parameters by Leonardo mechanography (single two-legged jump - peak power), and hand grip dynamometry (maximal hand grip strength). Overall, the OI type I group had significantly lower muscle CSA at the lower leg and forearm, lower trabecular and cortical bone mineral content, lower polar stress-strain index (SSIp), and smaller cortices but higher cortical bone mineral density and lower step count and MVPA in comparison with controls. Maximal hand grip strength was positively associated with SSIp at radius (p = 0.012) in the control group but not in the OI type I group (p = 0.338) (difference in associations: p = 0.012). No other significantly different associations between bone and muscle function parameters or physical activity (step count or MVPA) were found in the OI type I versus control group. We conclude that adults with OI type I have smaller bones, lower trabecular bone mass, lower estimates of bone strength, and higher cortical density in comparison with controls and that there are some indications of a disturbed biomechanical muscle-bone relationship in adults with OI type I. © 2022 American Society for Bone and Mineral Research (ASBMR).

Long-term evaluation of anabolic and anti-resorptive agents in adults with familial osteoporosis due to pro205ala variant of the col1a1 gene

INTRODUCTION

Osteogenesis imperfecta (OI) is a rare disorder with variable clinical presentation, commonly caused by mutations in collagen type I genes. OI affects both bone quality and density resulting in fractures and deformity. The effectiveness of bisphosphonates in the treatment of adult OI remains unclear. Small, randomised trials have shown increases in BMD, but without fracture rate reduction.

AIM

We report the results of BMD of a family harbouring C 613 C>G substitution in exon 8 of Col1A1 gene leading to Pro205Ala missense variant, as well as the results of long term treatment of a mother and daughter with this mutation.

Omics Profiling of S2P Mutant Fibroblasts as a Mean to Unravel the Pathomechanism and Molecular Signatures of X-Linked MBTPS2 Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by low bone density, bone fragility and recurrent fractures. The characterization of its heterogeneous genetic basis has allowed the identification of novel players in bone development. In 2016, we described the first X-linked recessive form of OI caused by hemizygous MBTPS2 missense variants resulting in moderate to severe phenotypes. MBTPS2 encodes site-2 protease (S2P), which activates transcription factors involved in bone (OASIS) and cartilage development (BBF2H7), ER stress response (ATF6) and lipid metabolism (SREBP) via regulated intramembrane proteolysis. In times of ER stress or sterol deficiency, the aforementioned transcription factors are sequentially cleaved by site-1 protease (S1P) and S2P. Their N-terminal fragments shuttle to the nucleus to activate gene transcription. Intriguingly, missense mutations at other positions of MBTPS2 cause the dermatological spectrum condition Ichthyosis Follicularis, Atrichia and Photophobia (IFAP) and Keratosis Follicularis Spinulosa Decalvans (KFSD) without clinical overlap with OI despite the proximity of some of the pathogenic variants. To understand how single amino acid substitutions in S2P can lead to non-overlapping phenotypes, we aimed to compare the molecular features of MBTPS2-OI and MBTPS2-IFAP/KFSD, with the ultimate goal to unravel the pathomechanisms underlying MBTPS2-OI. RNA-sequencing-based transcriptome profiling of primary skin fibroblasts from healthy controls (n = 4), MBTPS2-OI (n = 3), and MBTPS2-IFAP/KFSD (n = 2) patients was performed to identify genes that are differentially expressed in MBTPS2-OI and MBTPS2-IFAP/KFSD individuals compared to controls. We observed that SREBP-dependent genes are more downregulated in OI than in IFAP/KFSD. This is coupled to alterations in the relative abundance of fatty acids in MBTPS2-OI fibroblasts in vitro, while no consistent alterations in the sterol profile were observed. Few OASIS-dependent genes are suppressed in MBTPS2-OI, while BBF2H7- and ATF6-dependent genes are comparable between OI and IFAP/KFSD patients and control fibroblasts. Importantly, we identified genes involved in cartilage physiology that are differentially expressed in MBTPS2-OI but not in MBTPS2-IFAP/KFSD fibroblasts. In conclusion, our data provide clues to how pathogenic MBTPS2 mutations cause skeletal deformities via altered fatty acid metabolism or cartilage development that may affect bone development, mineralization and endochondral ossification.

Long-term follow-up of a cat with an undetermined osteoporotic bone disease managed with multiple intramedullary pins

Case summary

Osteogenesis imperfecta (OI) is an inherited disorder related to the synthesis of type 1 collagen. Clinical signs of pain from the fracture of fragile bones are common. A 3-month-old male Chinchilla cat was presented for lameness and pain from a right femoral fracture. After surgical repair using intramedullary pins, and since repeated fractures occurred and there is little information about genes causing OI in cats, various examinations were performed to discriminate other diseases that could cause the pathological fracture. Primary hyperparathyroidism and nutritional or renal secondary hyperparathyroidism were ruled out through blood tests and ultrasonography. Quantitative CT confirmed low trabecular bone mineral density compared with normal cats. Radiography and histopathological examination revealed thin cortical bone. OI was tentatively diagnosed and long-term follow-up of the surgical repair was reviewed. Fractures were treated using intramedullary Kirschner wires. The same method of intramedullary pinning was then applied preventively to protect several other long bones by improving stress distribution and bending resistance. Follow-up was performed for 3 years until the patient’s death due to undetermined reasons.

Relevance and novel information

Although the patient underwent repeated fractures and bone unions, and needed medication for pain management sometimes, it was generally able to live as a companion cat. Therefore, palliative preventive intramedullary pinning could be used for long-term management of patients suspected of OI.

Osteogenesis Imperfecta: Skeletal Outcomes After Bisphosphonate Discontinuation at Final Height

Intravenous cyclical bisphosphonates are widely used to treat children with moderate to severe osteogenesis imperfecta (OI). Bisphosphonates are often discontinued when growth is completed, but subsequent skeletal changes have not been studied in detail. We assessed 31 patients (22 females) with OI who had started intravenous bisphosphonates (either pamidronate or zoledronic acid) before 13 years of age, were treated for at least 2 years (range 4.7-15.7 years), and discontinued treatment after completion of growth, when their age ranged from 13.4 to 20.0 years (mean 16.4 years). At 4 years after treatment discontinuation, lumbar spine areal bone mineral density (BMD) had increased by 4% (p < 0.05). Peripheral quantitative computed tomography of the radius showed a decrease in trabecular volumetric BMD at the distal metaphysis of 19% but an increase in cortical volumetric BMD of 4% (p < 0.05 for both). None of the patients sustained a new vertebral compression fracture during follow-up. The proportion of patients with new long-bone fractures was higher in the 2 years before treatment discontinuation than in the last 2 years of follow-up (42% and 16%, respectively; p < 0.05). © 2019 American Society for Bone and Mineral Research.

A Multicenter Observational Cohort Study to Evaluate the Effects of Bisphosphonate Exposure on Bone Mineral Density and Other Health Outcomes in Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is characterized by low bone mass and bone fragility. Using data from a large cohort of individuals with OI from the Osteogenesis Imperfecta Foundation's linked clinical research centers, we examined the association between exposure to bisphosphonate (BPN) treatment (past or present) and lumbar spine (LS) areal bone mineral density (aBMD), fractures, scoliosis, and mobility. From 466 individuals, we obtained 1394 participant‐age LS aBMD data points. Though all OI subtypes were examined, primary analyses were restricted to type I OI (OI‐1). Using linear regression, we constructed expected OI‐1 LS aBMD‐for‐age curves from the data from individuals who had never received BPN. LS aBMD in those who had been exposed to BPN was then compared with the computed expected aBMD. BPN exposure in preadolescent years (age <14 years) was associated with a LS aBMD that was 9% more than the expected computed values in BPN‐naïve individuals (p < 0.01); however, such association was not observed across all ages. Exposure to i.v. BPN and treatment duration >2 years correlated with LS aBMD in preadolescent individuals. BPN exposure also had a significant association with non‐aBMD clinical outcome variables. Logistic regression modeling predicted that with BPN exposure, a 1‐year increase in age would be associated with an 8.2% decrease in fracture probability for preadolescent individuals with OI‐1, compared with no decrease in individuals who had never received any BPN (p < 0.05). In preadolescent individuals with OI‐1, a 0.1 g/cm² increase in LS aBMD was associated with a 10.6% decrease in scoliosis probability, compared with a 46.8% increase in the BPN‐naïve group (p < 0.01). For the same changes in age and LS aBMD in preadolescent individuals, BPN exposure was also associated with higher mobility scores (p < 0.01), demonstrating that BPN treatment may be associated with daily function. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Osteoporosis in premenopausal women

PURPOSE OF REVIEW

The scope of this review was to review the newest developments in the context of the existing knowledge on premenopausal bone fragility. Fragility fractures are common in postmenopausal women and men and diagnostic criteria for osteoporosis have been agreed and multiple pharmacological treatments have been developed over the last 25 years. In premenopausal women, fragility fractures and very low bone mass are uncommon and osteoporosis in premenopausal women has therefore attracted much less interest.

RECENT FINDINGS

Recent studies have highlighted that lifestyle and dietary habits affect premenopausal bone mass. Bone mass may be improved by sufficient intake of calcium and vitamin D together with increased physical activity in premenopausal women with idiopathic osteoporosis. If pharmacological treatment is needed, teriparatide has been demonstrated to efficiently increase bone mass; however, no fracture studies and no comparative studies against antiresorptive therapies have been conducted. Pregnancy affects bone turnover and mass significantly, but pregnancy-associated osteoporosis is a rare and heterogeneous condition.

SUMMARY

The diagnosis of osteoporosis should only be considered in premenopausal women with existing fragility fractures, diseases or treatments known to cause bone loss or fractures. Secondary causes of osteoporosis should be corrected or treated if possible. The women should be recommended sufficient intake of calcium and vitamin and physical activity. In women with recurrent fractures or secondary causes that cannot be eliminated, for example glucocorticoid or cancer treatment, pharmacological intervention with bisphosphonates or teriparatide (not in the case of cancer) may be considered.

Developments in rare bone diseases and mineral disorders

In the last decade, there have been a number of significant advances made in the field of rare bone diseases. In this review, we discuss the expansion of the classification system for osteogenesis imperfecta (OI) and the resultant increase in therapeutic options available for management of OI. Bisphosphonates remain the most widely used intervention for OI, although the effect on fracture rate reduction is equivocal. We review the other therapies showing promising results, including denosumab, teriparatide, sclerostin, transforming growth factor β inhibition and gene targeted approaches. X-linked hypophosphataemia (XLH) is the most common heritable form of osteomalacia and rickets caused by a mutation in the phosphate regulating endopeptidase gene resulting in elevated serum fibroblast growth factor 23 (FGF23) and decreased renal phosphate reabsorption. The traditional treatment is phosphate replacement. We discuss the development of a human anti-FGF23 antibody (KRN23) as a promising development in the treatment of XLH. The current management of primary hypoparathyroidism is replacement with calcium and active vitamin D. This can be associated with under or over replacement and its inherent complications. We review the use of recombinant parathyroid hormone (1-84), which can significantly reduce the requirements for calcium and vitamin D resulting in greater safety and quality of life for individuals with hypoparathyroidism. The use of receptor activator of nuclear factor κB ligand infusions in the treatment of a particular form of osteopetrosis and enzyme replacement therapy for hypophosphatasia are also discussed.

Osteogenesis imperfecta: diagnosis and treatment

PURPOSE OF REVIEW

Here we summarize the diagnosis of osteogenesis imperfecta, discuss newly discovered genes involved in osteogenesis imperfecta, and review the management of this disease in children and adults.

RECENT FINDINGS

Mutations in the two genes coding for collagen type I, COL1A1 and COL1A2, are the most common cause of osteogenesis imperfecta. In the past 10 years, defects in at least 17 other genes have been identified as responsible for osteogenesis imperfecta phenotypes, with either dominant or recessive transmission. Intravenous bisphosphonate infusions are the most widely used medical treatment. This has a marked effect on vertebra in growing children and can lead to vertebral reshaping after compression fractures. However, bisphosphonates are less effective for preventing long-bone fractures. At the moment, new therapies are under investigation.

SUMMARY

Despite advances in the diagnosis and treatment of osteogenesis imperfecta, more research is needed. Bisphosphonate treatment decreases long-bone fracture rates, but such fractures are still frequent. New antiresorptive and anabolic agents are being investigated but efficacy and safety of these drugs, especially in children, need to be better established before they can be used in clinical practice.

Efficacy of teriparatide vs neridronate in adults with osteogenesis imperfecta type I: a prospective randomized international clinical study

Osteogenesis imperfecta (OI) is an hereditary disease characterized by low bone mass, increased bone fragility, short stature, and skeletal deformities, few treatment options are currently available. Neridronate is an amino-bisphosphonate, licensed in Italy for the treatment of OI and Paget's disease of bone. A characteristic property of neridronate is that it can be administered both intravenously and intramuscularly, providing an useful system for administration in homecare. Neridronate appears to increase Bone Mineral Density (BMD) in adults with OI and reduces bone resorption by inhibition of osteoclastic activity. Teriparatide (recombinant 1-34 N terminal sequence of human parathyroid hormone) is the first anabolic agent approved for the treatment of patients with osteoporosis and has been reported to increase bone formation by stimulating osteoblast differentiation, osteoblast function, and survival. The results of this study showed a promising role of teriparatide in the therapy of OI type I.

Using humeral nail for surgical reconstruction of femur in adolescents with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a rare inherited connective tissue disorder caused by mutation of collagen which results in a wide spectrum of clinical manifestations including long bone fragility fractures and deformities. While the treatment for these fractures was recommended as using intramedullary fixation for minimizing stress concentration, the selection of the best implant in the adolescent OI patients for the surgical reconstruction of femur was still problematic, due to anatomy distortion and implant availability. We are reporting the surgical modification by using a humeral nail for femoral fixation in three adolescent OI patients with favorable outcomes.

BPS804 Anti-Sclerostin Antibody in Adults With Moderate Osteogenesis Imperfecta: Results of a Randomized Phase 2a Trial

This 21-week, open-label, phase 2a trial aimed to evaluate the pharmacodynamics and safety of multiple, escalating infusions of BPS804, a neutralizing, anti-sclerostin antibody, in adults with moderate osteogenesis imperfecta (OI). Patients received BPS804 (three escalating doses each separated by 2 weeks [5, 10, and 20 mg/kg]) or no treatment (reference group). The primary efficacy endpoints were mean changes from baseline to day 43 in: procollagen type 1 N-terminal propeptide (P1NP), procollagen type 1 C-terminal propeptide (P1CP), bone-specific alkaline phosphatase (BSAP), osteocalcin (OC), and type 1 collagen cross-linked C-telopeptide (CTX-1). Mean change from baseline to day 141 in lumbar spine areal bone mineral density (aBMD) was also assessed. BPS804 safety and tolerability were assessed every 2 weeks. Overall, 14 adults were enrolled (BPS804 group: n = 9, mean age 30.7 years, mean aBMD Z-score -2.6; reference group, n = 5, mean age 27.4 years, mean aBMD Z-score -2.2). In the BPS804 group, P1NP, P1CP, BSAP, and OC were increased by 84% (p < 0.001), 53% (p = 0.003), 59% (p < 0.001), and 44% (p = 0.012), respectively, versus baseline (reference: P1NP, +6% [p = 0.651]; P1CP, +5% [p = 0.600]; BSAP, -13% [p = 0.582]; OC, -19% [p = 0.436]). BPS804 treatment downregulated CTX-1 by 44% from baseline (reference: -7%; significance was not tested for this biomarker), and increased aBMD by 4% (p = 0.038; reference group: +1%; p = 0.138). BPS804 was generally well tolerated. There were 32 adverse events reported in nine patients; none was suspected to be treatment-related. There were no treatment-related fractures. BPS804 stimulates bone formation, reduces bone resorption, and increases lumbar spine aBMD in adults with moderate OI. This paves the way for a longer-term, phase 3 trial into the efficacy, safety, and tolerability of BPS804 in patients with OI. © 2017 American Society for Bone and Mineral Research.

Efficacy of Bisphosphonates on Bone Mineral Density and Fracture Rate in Patients With Osteogenesis Imperfecta: A Systematic Review and Meta-analysis

Epidemiological evidence suggests that bisphosphonates are the most promising drugs for patients with osteogenesis imperfecta (OI). However, data on this issue are controversial. We conducted a meta-analysis to assess the efficacy of bisphosphonates on bone mineral density (BMD) and fracture rate in patients with OI. Electronic databases were searched to find relevant studies. Two reviewers independently identified relevant randomized controlled trials, which evaluated the efficacy of bisphosphonates in patients with OI. Outcome measures were fracture incidence and BMD changes in different skeletal sites. A total of 9 randomized controlled trials including 557 patients were identified. Meta-analysis demonstrated a beneficial effect of bisphosphonates on spine BMD Z-score and area BMD (in grams per square centimeter) %. Patients treated with bisphosphonates had a lower risk of fracture [risk ratio (RR) = 0.80; 95% confidence interval (CI): 0.66-0.97] compared with those in control groups. In children, bisphosphonates were efficacious in reducing fractures (RR = 0.80; 95% CI: 0.66-0.97), where in adults, bisphosphonates seemed equivalent to placebo in that respect (RR = 0.82; 95% CI: 0.42-1.59), although no significant difference was noted between these 2 RRs (test of interaction, z = -0.07; P = 0.94). There was also no significant difference in reducing fractures between oral and intravenous bisphosphonates (P = 0.23). This study showed that bisphosphonates could increase the BMD and reduce the risk of facture in patients with OI. There was no enough evidence to identify any differences in efficacy between oral and intravenous bisphosphonates on fracture reduction, as well as between children and adults.

Enhanced Wnt signaling improves bone mass and strength, but not brittleness, in the Col1a1(+/mov13) mouse model of type I Osteogenesis Imperfecta

Osteogenesis Imperfecta (OI) comprises a group of genetic skeletal fragility disorders. The mildest form of OI, Osteogenesis Imperfecta type I, is frequently caused by haploinsufficiency mutations in COL1A1, the gene encoding the α1(I) chain of type 1 collagen. Children with OI type I have a 95-fold higher fracture rate compared to unaffected children. Therapies for OI type I in the pediatric population are limited to anti-catabolic agents. In adults with osteoporosis, anabolic therapies that enhance Wnt signaling in bone improve bone mass, and ongoing clinical trials are determining if these therapies also reduce fracture risk. We performed a proof-of-principle experiment in mice to determine whether enhancing Wnt signaling in bone could benefit children with OI type I. We crossed a mouse model of OI type I (Col1a1(+/Mov13)) with a high bone mass (HBM) mouse (Lrp5(+/p.A214V)) that has increased bone strength from enhanced Wnt signaling. Offspring that inherited the OI and HBM alleles had higher bone mass and strength than mice that inherited the OI allele alone. However, OI+HBM and OI mice still had bones with lower ductility compared to wild-type mice. We conclude that enhancing Wnt signaling does not make OI bone normal, but does improve bone properties that could reduce fracture risk. Therefore, agents that enhance Wnt signaling are likely to benefit children and adults with OI type 1.

Italian association of clinical endocrinologists (AME) position statement: drug therapy of osteoporosis

Treatment of osteoporosis is aimed to prevent fragility fractures and to stabilize or increase bone mineral density. Several drugs with different efficacy and safety profiles are available. The long-term therapeutic strategy should be planned, and the initial treatment should be selected according to the individual site-specific fracture risk and the need to give the maximal protection when the fracture risk is highest (i.e. in the late life). The present consensus focused on the strategies for the treatment of postmenopausal osteoporosis taking into consideration all the drugs available for this purpose. A short revision of the literature about treatment of secondary osteoporosis due both to androgen deprivation therapy for prostate cancer and to aromatase inhibitors for breast cancer was also performed. Also premenopausal females and males with osteoporosis are frequently seen in endocrine settings. Finally particular attention was paid to the tailoring of treatment as well as to its duration.

Orthopaedic Considerations for the Adult With Osteogenesis Imperfecta

Osteogenesis imperfecta is a heritable group of collagen-related disorders that affects up to 50,000 people in the United States. Although the disease is most symptomatic in childhood, adults with osteogenesis imperfecta also are affected by the sequelae of the disease. Orthopaedic manifestations include posttraumatic and accelerated degenerative joint disease, kyphoscoliosis, and spondylolisthesis. Other manifestations of abnormal collagen include brittle dentition, hearing loss, cardiac valve abnormalities, and basilar invagination. In general, nonsurgical treatment is preferred for management of acute fractures. High rates of malunion, nonunion, and subsequent deformity have been reported with both closed and open treatment. When surgery is necessary, surgeons should opt for load-sharing intramedullary devices that span the entire length of the bone; locking plates and excessively rigid fixation generally should be avoided. Arthroplasty may be considered for active patients, but the procedure frequently is associated with complications in this patient population. Underlying deformities, such as malunion, bowing, rotational malalignment, coxa vara, and acetabular protrusio, pose specific surgical challenges and underscore the importance of preoperative planning.

Advances in the Classification and Treatment of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a rare disorder of type 1 collagen with 13 currently identified types attributable to inherited abnormalities in type 1 collagen amount, structure, or processing. The disease is characterized by an increased susceptibility to bony fracture. In addition to the skeletal phenotype, common additional extraskeletal manifestations include blue sclerae, dentinogenesis imperfecta, vascular fragility, and hearing loss. Medical management is focused on minimizing the morbidity of fractures, pain, and bone deformities by maximizing bone health. Along with optimizing Vitamin D status and calcium intake and physical/occupational therapy, individualized surgical treatment may be indicated. Pharmacological therapy with bisphosphonate medications is now routinely utilized for moderate to severe forms and appears to have a good safety profile and bone health benefits. New therapies with other anti-resorptives as well as anabolic agents and transforming growth factor (TGF)β antibodies are in development. Other potential treatment modalities could include gene therapy or mesenchymal cell transplant. In the future, treatment choices will be further individualized in order to reduce disease morbidity and mortality.

Recent developments in osteogenesis imperfecta

Osteogenesis imperfecta (OI) is an uncommon genetic bone disease associated with brittle bones and fractures in children and adults. Although OI is most commonly associated with mutations of the genes for type I collagen, many other genes (some associated with type I collagen processing) have now been identified. The genetics of OI and advances in our understanding of the biomechanical properties of OI bone are reviewed in this article. Treatment includes physiotherapy, fall prevention, and sometimes orthopedic procedures. In this brief review, we will also discuss current understanding of pharmacologic therapies for treatment of OI.

A randomized, double blind, placebo-controlled trial of alendronate treatment for fibrous dysplasia of bone

CONTEXT

Fibrous dysplasia (FD) is a rare skeletal disorder, resulting in deformity, fracture, functional impairment, and pain. Bisphosphonates have been advocated as a potential treatment.

OBJECTIVE

To determine the efficacy of alendronate for treatment of FD.

DESIGN

Two-year randomized, double-blind, placebo-controlled trial.

SETTING

Clinical research center.

PATIENTS

Forty subjects with polyostotic FD (24 adults, 16 children). Subjects were randomized and stratified by age.

INTERVENTIONS

Study drug was administered over a 24 month period in 6 month cycles (6 months on, 6 months off). Alendronate dosing was stratified: 40 mg daily for subjects >50 kg, 20 mg for 30-50 kg, 10 mg for 20-30 kg.

MAIN OUTCOME MEASURES

Primary endpoints were bone turnover markers, including serum osteocalcin, and urinary NTX-telopeptides. Secondary endpoints included areal bone mineral density (aBMD), pain, skeletal disease burden score, and functional parameters including the 9-min walk test and manual muscle testing.

RESULTS

Clinical data was collected on 35 subjects who completed the study. There was a decline in NTX-telopeptides in the alendronate group (P = .006), but no significant difference in osteocalcin between groups. The alendronate group had an increase in areal BMD in normal bone at the lumbar spine (P = .006), and in predetermined regions of FD (P < .001). There were no significant differences in pain scores, skeletal disease burden scores, or functional parameters between the groups.

CONCLUSIONS

Alendronate treatment led to a reduction in the bone resorption marker NTX-telopeptides, and improvement in aBMD, but no significant effect on serum osteocalcin, pain, or functional parameters.

Treatment of osteogenesis imperfecta in adults

BACKGROUND

Osteogenesis imperfecta (OI) is a heterogeneous rare connective tissue disorder commonly caused by mutations in the collagen type I genes. Pharmacological treatment has been most extensively studied in children, and there are only few studies comprising adult OI patients.

OBJECTIVES

i) To review the literature on the current medical management of OI in children and adults, and thereby identify unmet medical needs and ii) to present an overview of possible future treatment options.

RESULTS

Individualization and optimization of OI treatment in adults remain a challenge, because available treatments do not target the underlying collagen defect, and available literature gives weak support for treatment decisions for adult patients.

CONCLUSIONS

Bisphosphonates are still the most widely used pharmacological treatment for adult OI, but the current evidence supporting this is sparse and investigations on indications for choice and duration of treatment are needed.

Adult Brtl/+ mouse model of osteogenesis imperfecta demonstrates anabolic response to sclerostin antibody treatment with increased bone mass and strength

Treatments to reduce fracture rates in adults with osteogenesis imperfecta are limited. Sclerostin antibody, developed for treating osteoporosis, has not been explored in adults with OI. This study demonstrates that treatment of adult OI mice respond favorably to sclerostin antibody therapy despite retention of the OI-causing defect.

INTRODUCTION

Osteogenesis imperfecta (OI) is a heritable collagen-related bone dysplasia, characterized by brittle bones with increased fracture risk. Although OI fracture risk is greatest before puberty, adults with OI remain at risk of fracture. Antiresorptive bisphosphonates are commonly used to treat adult OI, but have shown mixed efficacy. New treatments which consistently improve bone mass throughout the skeleton may improve patient outcomes. Neutralizing antibodies to sclerostin (Scl-Ab) are a novel anabolic therapy that have shown efficacy in preclinical studies by stimulating bone formation via the canonical wnt signaling pathway. The purpose of this study was to evaluate Scl-Ab in an adult 6 month old Brtl/+ model of OI that harbors a typical heterozygous OI-causing Gly > Cys substitution on Col1a1.

METHODS

Six-month-old WT and Brtl/+ mice were treated with Scl-Ab (25 mg/kg, 2×/week) or Veh for 5 weeks. OCN and TRACP5b serum assays, dynamic histomorphometry, microCT and mechanical testing were performed.

RESULTS

Adult Brtl/+ mice demonstrated a strong anabolic response to Scl-Ab with increased serum osteocalcin and bone formation rate. This anabolic response led to improved trabecular and cortical bone mass in the femur. Mechanical testing revealed Scl-Ab increased Brtl/+ femoral stiffness and strength.

CONCLUSION

Scl-Ab was successfully anabolic in an adult Brtl/+ model of OI.

Evaluation of teriparatide treatment in adults with osteogenesis imperfecta

BACKGROUND

Adults with osteogenesis imperfecta (OI) have a high risk of fracture. Currently, few treatment options are available, and bone anabolic therapies have not been tested in clinical trials for OI treatment.

METHODS

79 adults with OI were randomized to receive 20 μg recombinant human parathyroid hormone (teriparatide) or placebo for 18 months in a double-blind, placebo-controlled trial. The primary endpoint was the percent change in areal bone mineral density (aBMD) of the lumbar spine (LS), as determined by dual-energy X-ray absorptiometry. Secondary endpoints included percent change in bone remodeling markers and vertebral volumetric BMD (vBMD) by quantitative computed tomography, estimated vertebral strength by finite element analysis, and self-reported fractures.

RESULTS

Compared with the placebo group, the teriparatide group showed increased LS aBMD (6.1% ± 1.0% vs. 2.8% ± 1.0% change from baseline; P < 0.05) and total hip aBMD (2.6% ± 1.0% vs. -2.4% ± 1.0% change; P < 0.001). Vertebral vBMD and strength improved with teriparatide therapy (18% ± 6% and 15% ± 3% change, respectively), but declined with placebo (-5.0% ± 6% and -2.0% ± 3% change; P < 0.05 for both comparisons). Serum procollagen type 1 N-terminal propeptide (P1NP) and urine collagen N-telopeptide (NTx) levels increased with teriparatide therapy (135% ± 14% and 64% ± 10% change, respectively). Teriparatide-induced elevation of P1NP levels was less pronounced in severe forms of OI (type III/IV) compared with the milder form (type I). Type I OI patients exhibited robust BMD increases with teriparatide; however, there was no observed benefit for those with type III/IV OI. There was no difference in self-reported fractures between the 2 groups.

CONCLUSIONS

Adults with OI, particularly those with less severe disease (type I), displayed a teriparatide-induced anabolic response, as well as increased hip and spine aBMD, vertebral vBMD, and estimated vertebral strength. Trial registration. Clinicaltrials.gov NCT00131469. Funding. The Osteoporosis Imperfecta Foundation, Eli Lilly and Co., the National Center for Advancing Translational Science (NCATS) at the NIH (grant no. UL1RR024140), and the Baylor College of Medicine General Clinical Research Center (grant no. RR00188).

Osteogenesis imperfecta in adults

A 42-year-old premenopausal woman with osteogenesis imperfecta presents to the metabolic bone clinic. She has a daughter with osteogenesis imperfecta who is seen regularly in a specialist pediatric clinic, but the patient herself hasn't had a clinical consultation in years. She has pain and stiffness in her back and is worried for her future bone health. The patient asks, "Am I going to fall apart?" She had numerous fractures in childhood, including fractures of her femur and wrist; fractured her ankles several times in her late teens; and had occasional fractures in adulthood. Her last fracture was a comminuted fracture of her humerus three years ago, when she stumbled and fell forward onto her hands and knees. The woman is hyperextensible and thinks her ankles feel weak. Her bone mineral density T scores are -2.6 at the lumbar spine and -1.9 at the total hip, and spine imaging shows several vertebral endplate deformities, but overall preservation of vertebral height. What are the available pharmacological and nonpharmacological strategies to preserve her skeletal health and function?

Osteoporosis in young adults: pathophysiology, diagnosis, and management

Postmenopausal osteoporosis is mainly caused by increased bone remodeling resulting from estrogen deficiency. Indications for treatment are based on low areal bone mineral density (aBMD, T-score  ≤ -2.5), typical fragility fractures (spine or hip), and more recently, an elevated 10-year fracture probability (by FRAX®). In contrast, there is no clear definition of osteoporosis nor intervention thresholds in younger individuals. Low aBMD in a young adult may reflect a physiologically low peak bone mass, such as in lean but otherwise healthy persons, whereas fractures commonly occur with high-impact trauma, i.e., without bone fragility. Furthermore, low aBMD associated with vitamin D deficiency may be highly prevalent in some regions of the world. Nevertheless, true osteoporosis in the young can occur, which we define as a T-score below -2.5 at spine or hip in association with a chronic disease known to affect bone metabolism. In the absence of secondary causes, the presence of fragility fractures, such as in vertebrae, may point towards genetic or idiopathic osteoporosis. In turn, treatment of the underlying condition may improve bone mass as well. In rare cases, a bone-specific treatment may be indicated, although evidence is scarce for a true benefit on fracture risk. The International Osteoporosis Foundation (IOF) convened a working group to review pathophysiology, diagnosis, and management of osteoporosis in the young, excluding children and adolescents, and provide a screening strategy including laboratory exams for a systematic approach of this condition.

The influence of ibandronate treatment on bone density and biochemical bone markers in patients with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is characterized by different signs including increased bone fragility, short stature, blue sclera, abnormal tooth growth and often secondary immobility. No curative therapy has been found for this rare disease up to now, and different pharmacological substances have been tried as treatment for severe forms of OI. Promising results were seen with intravenous bisphosphonates in the treatment of patients with OI. The aim of present study was to show the effect of intravenous ibandronate therapy on bone density and bone metabolism markers. We analyzed the data of 27 patients with the diagnosis of OI who were treated off-label with intravenous ibandronate. Ibandronate was administered by intravenous infusion every three months at a dosage of 0.3-2 mg. Bone turnover markers and bone density were measured before starting therapy and every three months during treatment. Bone density was measured by using an ultrasound imaging system providing an accurate image of the calcaneus and by evaluating broadband ultrasound attenuation (BUA). Twenty-seven patients were treated with intravenous ibandronate during the observation period. 18 were female. The mean age of all patients was 23.9 years ± 19.6 (range 4-63). Seventeen patients were categorized to have OI Type I, 5 patients to have OI Type III and 5 patients to have OI Type IV. There was a statistically significant decrease in total alkaline phosphatase (P<0.0001). We detected also a statistically significant decrease in the ratio urinary deoxypyridinoline/urinary creatinine (P=0.0048) and the ratio urinary pyridinoline/urinary creatinine (P<0.0001) respectively. There was also a statistically significant increase in serum magnesium (P=0.034) and BUA (P=0.0071). No statistically significant changes were seen for total serum calcium (P=0.16), the ratio of urine calcium/urine creatinine (P=0.29), alkaline phosphatase (isoform bone) (P=0.3), procollagen-I-peptide (P=0.5), osteocalcin (P=0.9), serum phosphatase (P=0.71), parathormone (P=0.11) and the ratio urine phosphatase/urine creatinine (P=0.58) Therapy with ibandronate in patients with OI leads to a normalisation of bone turnover markers and increasing bone density. Therefore serum alkaline phosphatase and bone density are possible parameters to monitor bisphosphonate treatment in patients with OI.

Pregnancy- and lactation-associated transient osteoporosis of both hips in a 32 year old patient with osteogenesis imperfecta

Combination of osteogenesis imperfecta (OI), pregnancy, and transient osteoporosis (TO) of the hip is rare, only a few cases have been published so far. We report a 32 year old woman with OI, with TO on the right hip in her late third trimester. Non-pharmacological measures such as non-weight-bearing resulted in complete remission. Shortly after weaning, TO of the contralateral hip developed and non-pharmacological measures remained ineffective this time. Under treatment with a prostaglandin I(2) analog (iloprost), i.v. bisphosphonate (pamidronate), calcium and vitamin D supplementation rapid improvement of pain and complete remission was achieved.

Bone geometry, density, and microarchitecture in the distal radius and tibia in adults with osteogenesis imperfecta type I assessed by high-resolution pQCT

Osteogenesis imperfecta (OI) is a hereditary disorder characterized by decreased biosynthesis or impaired morphology of type I collagen that leads to decreased bone mass and increased bone fragility. We hypothesized that patients with OI have altered bone microstructure and bone geometry. In this cross-sectional study we compared patients with type I OI to age- and gender-matched healthy controls. A total of 39 (13 men and 26 women) patients with OI, aged 53 (range, 21-77) years, and 39 controls, aged 53 (range, 21-77) years, were included in the study. Twenty-seven of the patients had been treated with bisphosphonates. High-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and distal tibia and dual-energy X-ray absorptiometry of total hip, femoral neck, trochanteric region, and the lumbar spine (L1-L4) were performed. The patients were shorter than the controls (159 ± 10 cm versus 170 ± 9 cm, p < 0.001), but had similar body weight. In OI, areal bone mineral density (aBMD) was 8% lower at the hip (p < 0.05) and 13% lower at the spine (p < 0.001) compared with controls. The trabecular volumetric bone mineral density (vBMD) was 28% lower in radius (p < 0.001) and 38% lower in tibia (p < 0.001) in OI compared with controls. At radius, total bone area was 5% lower in OI than in controls (p < 0.05). In the tibia, cortical bone area was 18% lower in OI (p < 0.001). In both radius and tibia the number of trabeculae was lower in patients compared to the controls (35% and 38%, respectively, p < 0.001 at both sites). Furthermore, trabecular spacing was 55% higher in OI in both tibia and radius (p < 0.001 at both sites) when compared with controls. We conclude that patients with type I OI have lower aBMD, vBMD, bone area, and trabecular number when compared with healthy age- and gender-matched controls.

Risedronate in adults with osteogenesis imperfecta type I: increased bone mineral density and decreased bone turnover, but high fracture rate persists

Bisphosphonates can increase bone mineral density (BMD) in children with osteogenesis imperfecta (OI). In this study of adults with OI type I, risedronate increased BMD at lumbar spine (but not total hip) and decreased bone turnover. However, the fracture rate in these patients remained high.

INTRODUCTION

Intravenous bisphosphonates given to children with OI can increase BMD and reduce fracture incidence. Oral and/or intravenous bisphosphonates may have similar effects in adults with OI. We completed an observational study of the effect of risedronate in adults with OI type I.

METHODS

Thirty-two adults (mean age, 39 years) with OI type I were treated with risedronate (total dose, 35 mg weekly) for 24 months. Primary outcome measures were BMD changes at lumbar spine (LS) and total hip (TH). Secondary outcome measures were fracture incidence, bone pain, and change in bone turnover markers (serum procollagen type I aminopropeptide (P1NP) and bone ALP). A meta-analysis of published studies of oral bisphosphonates in adults and children with OI was performed.

RESULTS

Twenty-seven participants (ten males and seventeen females) completed the study. BMD increased at LS by 3.9% (0.815 vs. 0.846 g/cm(2), p = 0.007; mean Z-score, -1.93 vs. -1.58, p = 0.002), with no significant change at TH. P1NP fell by 37% (p = 0.00041), with no significant change in bone ALP (p = 0.15). Bone pain did not change significantly (p = 0.6). Fracture incidence remained high, with 25 clinical fractures and 10 major fractures in fourteen participants (0.18 major fractures per person per year), with historical data of 0.12 fractures per person per year. The meta-analysis did not demonstrate a significant difference in fracture incidence in patients with OI treated with oral bisphosphonates.

CONCLUSIONS

Risedronate in adults with OI type I results in modest but significant increases in BMD at LS, and decreased bone turnover. However, this may be insufficient to make a clinically significant difference to fracture incidence.