Skeletal changes in rats given daily subcutaneous injections of recombinant human parathyroid hormone (1-34) for 2 years and relevance to human safety

Hypoparathyroidism: an update on new therapeutic approaches

BACKGROUND

Hypoparathyroidism is a rare endocrine disease characterized by insufficient parathyroid hormone (PTH) secretion by the parathyroid glands, leading to hypocalcemia. In contrast to most hormone deficiencies for which hormone replacement is currently the mainstay of therapy, hypoparathyroidism has conventionally been treated with calcium supplements and active analogs of vitamin D. Although the advent of a replacement therapy with 1-34 and 1-84 PTH represented a major step in the therapeutic history of hypoparathyroidism, several new molecules and different management strategies have recently been developed.

PURPOSE

This review investigates the therapeutic approaches currently under investigation for the treatment of hypoparathyroidism. Clinical trials results have been considered and discussed.

Indications and adverse events of teriparatide: based on FDA adverse event reporting system (FAERS)

Background

Teriparatide is approved for osteoporosis. Post-marketing surveillance is critical given its widespread use.

Objective

To investigate adverse events (AEs) associated with teriparatide using the FAERS database, compare association strengths for key AEs, and explore potential applications to provide clinical reference.

Methods

FAERS data from 2004 to 2023 were analyzed. Reports where teriparatide was the primary suspect drug were included. Adverse events were mapped to System Organ Classes and Preferred Terms. Disproportionality analysis using ROR, PRR, BCPNN and EBGM algorithms was conducted to detect safety signals.

Results

Out of 107,123 reports with teriparatide as the primary suspect, key AEs identified included pain in extremity (PRR: 4.54), muscle spasms (PRR: 5.11), fractures (PRR range: 17.67-552.95), and increased calcium levels (PRR: 50.73). Teriparatide exhibited a stronger association with increased calcium levels (PRR: 50.73) compared to fractures (PRR range: 17.67-552.95). Notably, only 10.86% of AE reports were submitted by physicians and another 10% by other health professionals. Subset analyses showed a higher consistency of reported AEs from health professionals compared to the general dataset. Off-label uses were noted in conditions such as arthritis (0.57%) and cancer (0.12%). For osteoporosis, main AEs were pain (18.2%), fractures (12.4%), muscle spasms (7.7%), and nausea (6.5%), while glucocorticoid-induced osteoporosis AEs included fractures (24.1%), pain (13.2%), decreased bone density (9.8%), and nausea (5.1%).

Conclusion

Our findings provide real-world safety data on teriparatide, revealing key AEs and their association strengths. The low proportion of reports by healthcare professionals suggests the need for cautious interpretation. Continuous vigilance and further research are imperative to guide teriparatide's clinical use.

Anti-osteoporosis effect of bioactives in edible medicinal plants: a comprehensive review

Current treatments for osteoporosis include a calcium-rich diet, adequate exercise, and medication. Many synthetic drugs, although fast-acting, can cause a range of side effects for patients when taken over a long period, such as irritation of the digestive tract and a burden on the kidneys. As the world's population ages, the prevalence of osteoporosis is increasing, and the development of safe and effective treatments is urgently needed. Active compounds in edible and medicinal homologous plants have been used for centuries to improve bone quality. It is possible to employ them as dietary supplements to prevent osteoporosis. In this review, we analyze the influencing factors of osteoporosis and systematically summarize the research progress on the anti-osteoporosis effects of active compounds in edible and medicinal homologous plants. The literature suggests that some naturally occurring active compounds in edible and medicinal homologous plants can inhibit bone loss, prevent the degeneration of bone cell microstructure, and reduce bone fragility through alleviating oxidative stress, regulating autophagy, anti-inflammation, improving gut flora, and regulating estrogen level with little side effects. Our review provides useful guidance for the use of edible and medicinal homologous plants and the development of safer novel anti-osteoporosis dietary supplements.

Sclerostin inhibition in rare bone diseases: Molecular understanding and therapeutic perspectives

Sclerostin emerges as a novel target for bone anabolic therapy in bone diseases. Osteogenesis imperfecta (OI) and X-linked hypophosphatemia (XLH) are rare bone diseases in which therapeutic potential of sclerostin inhibition cannot be ignored. In OI, genetic/pharmacologic sclerostin inhibition promoted bone formation of mice, but responses varied by genotype and age. Serum sclerostin levels were higher in young OI-I patients, while lower in adult OI-I/III/IV. It's worth investigating whether therapeutic response of OI to sclerostin inhibition could be clinically predicted by genotype and age. In XLH, preclinical/clinical data suggested factors other than identified FGF23 contributing to XLH. Higher levels of circulating sclerostin were detected in XLH. Sclerostin inhibition promoted bone formation in Hyp mice, while restored phosphate homeostasis in age-/gender-dependent manner. The role of sclerostin in regulating phosphate metabolism deserves investigation. Sclerostin/FGF23 levels of XLH patients with/without response to FGF23-antibody warrants study to develop precise sclerostin/FGF23 inhibition strategy or synergistic/additive strategy. Notably, OI patients were associated with cardiovascular abnormalities, so were XLH patients receiving conventional therapy. Targeting sclerostin loop3 promoted bone formation without cardiovascular risks. Further, blockade of sclerostin loop3-LRP4 interaction while preserving sclerostin loop2-ApoER2 interaction could be a potential precise sclerostin inhibition strategy for OI and XLH with cardiovascular safety. The Translational Potential of this Article. Preclinical data on the molecular understanding of sclerostin inhibition in OI and therapeutic efficacy in mouse models of different genotypes, as well as clinical data on serum sclerostin levels in patients with different phenotypes of OI, were reviewed and discussed. Translationally, it would facilitate to develop clinical prediction strategies (e.g. based on genotype and age, not just phenotype) for OI patients responsive to sclerostin inhibition. Both preclinical and clinical data suggested sclerostin as another factor contributing to XLH, in addition to the identified FGF23. The molecular understanding and therapeutic effects of sclerostin inhibition on both promoting bone anabolism and improving phosphate homostasis in Hyp mice were reviewed and discussed. Translationaly, it would facilitate the development of precise sclerostin/FGF23 inhibition strategy or synergistic/additive strategy for the treatment of XLH. Cardiovascular risk could not be ruled out during sclerostin inhibition treatment, especially for OI and XLH patients with cardiovascular diseases history and cardiovascular abnormalities. Studies on the role of sclerostin in inhiting bone formation and protecting cardiovascular system were reviewed and discussed. Translationaly, blockade of sclerostin loop3-LRP4 interaction while preserving sclerostin loop2-ApoER2 interaction could be a potential precise sclerostin inhibition strategy for OI and XLH with cardiovascular safety.

ICH S1 prospective evaluation study and weight of evidence assessments: commentary from industry representatives

Industry representatives on the ICH S1B(R1) Expert Working Group (EWG) worked closely with colleagues from the Drug Regulatory Authorities to develop an addendum to the ICH S1B guideline on carcinogenicity studies that allows for a weight-of-evidence (WoE) carcinogenicity assessment in some cases, rather than conducting a 2-year rat carcinogenicity study. A subgroup of the EWG composed of regulators have published in this issue a detailed analysis of the Prospective Evaluation Study (PES) conducted under the auspices of the ICH S1B(R1) EWG. Based on the experience gained through the Prospective Evaluation Study (PES) process, industry members of the EWG have prepared the following commentary to aid sponsors in assessing the standard WoE factors, considering how novel investigative approaches may be used to support a WoE assessment, and preparing appropriate documentation of the WoE assessment for presentation to regulatory authorities. The commentary also reviews some of the implementation challenges sponsors must consider in developing a carcinogenicity assessment strategy. Finally, case examples drawn from previously marketed products are provided as a supplement to this commentary to provide additional examples of how WoE criteria may be applied. The information and opinions expressed in this commentary are aimed at increasing the quality of WoE assessments to ensure the successful implementation of this approach.

Dickkopf-1 (DKK1) blockade mitigates osteogenesis imperfecta (OI) related bone disease

BACKGROUND

The current treatment of osteogenesis imperfecta (OI) is imperfect. Our study thus delves into the potential of using Dickkopf-1 antisense (DKK1-AS) to treat OI.

METHODS

We analysed serum DKK1 levels and their correlation with lumbar spine and hip T-scores in OI patients. Comparative analyses were conducted involving bone marrow stromal cells (BMSCs) and bone tissues from wild-type mice, untreated OI mice, and OI mice treated with DKK1-ASor DKK1-sense (DKK1-S).

RESULTS

Significant inverse correlations were noted between serum DKK1 levels and lumbar spine (correlation coefficient = - 0.679, p = 0.043) as well as hip T-scores (correlation coefficient = - 0.689, p = 0.042) in OI patients. DKK1-AS improved bone mineral density (p = 0.002), trabecular bone volume/total volume fraction (p < 0.001), trabecular separation (p = 0.010), trabecular thickness (p = 0.001), trabecular number (p < 0.001), and cortical thickness (p < 0.001) in OI mice. DKK1-AS enhanced the transcription of collagen 1α1, osteocalcin, runx2, and osterix in BMSC from OI mice (all p < 0.001), resulting in a higher von Kossa-stained matrix area (p < 0.001) in ex vivo osteogenesis assays. DKK1-AS also reduced osteoclast numbers (p < 0.001), increased β-catenin and T-cell factor 4 immunostaining reactivity (both p < 0.001), enhanced mineral apposition rate and bone formation rate per bone surface (both p < 0.001), and decreased osteoclast area (p < 0.001) in OI mice. DKK1-AS upregulated osteoprotegerin and downregulated nuclear factor-kappa B ligand transcription (both p < 0.001). Bone tissues from OI mice treated with DKK1-AS exhibited significantly higher breaking force compared to untreated OI mice (p < 0.001).

CONCLUSIONS

Our study elucidates that DKK1-AS has the capability to enhance bone mechanical properties, restore the transcription of osteogenic genes, promote osteogenesis, and inhibit osteoclastogenesis in OI mice.

Exploring Chronic Hypocalcemia: Insights into Autoimmune Polyglandular Syndrome Type 1-A Case Study and Literature Review

Hypocalcemia is a common occurrence in pediatric patients, attributed to various causes and presenting with diverse clinical manifestations. A prompt evaluation is necessary to determine its underlying cause, whether it presents acutely or chronically, and to tailor treatment based on its severity. Among the potential causes of chronic hypocalcemia, primary hypoparathyroidism stands out. The case of a seven-year-old male patient with hypocalcemia reported in this article serves as an illustration, wherein targeted next-generation sequencing revealed a homozygous p.R257X mutation in the AIRE gene, indicative of autoimmune polyendocrine syndrome type 1 (APS-1). It poses challenges due to its multisystemic nature and involvement of specific autoantibodies, often leading to underdiagnosis, owing to its rarity, varied manifestations, and incomplete penetrance. A comprehensive review of the APS-1 literature was conducted to provide insights into the clinical manifestations, genetic spectrum, potential immunological mechanisms, and current medical strategies. Additionally, the recognition of AIRE gene mutations is crucial for facilitating genetic diagnosis, prognosis, and potential treatment strategies for APS-1. The management of such cases involves individualized approaches to treatment, regular monitoring, medication adjustments, and the early identification of associated conditions.

2,4'-Dihydroxybenzophenone Exerts Bone Formation and Antiosteoporotic Activity by Stimulating the β-Catenin Signaling Pathway

2,4'-Dihydroxybenzophenone (DHP) is an organic compound derived from Garcinia xanthochymus, but there have been no reports on its biochemical functions and bioavailability. In this study, we evaluated whether DHP affects osteoblast differentiation and activation in MC3T3-E1 preosteoblast cells, as well as antiosteoporotic activity in zebrafish larvae. Nontoxic concentrations of DHP-treated MC3T3-E1 preosteoblast cells increased alkaline phosphatase (ALP) activation and mineralization in a concentration-dependent manner, accompanied by higher expression of osteoblast-specific markers, including Runt-related transcription factor 2 (RUNX2), osterix, and ALP. Consistent with the data in MC3T3-E1 preosteoblast cells, DHP upregulated osteoblast-specific marker genes in zebrafish larvae and simultaneously enhanced vertebral formation. We also revealed that DHP increased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9 and the total expression of β-catenin in the cytosol and markedly increased the localization of β-catenin into the nucleus. Furthermore, DHP restored the prednisolone (PDS)-induced marked decrease in ALP activity and mineralization, as well as osteoblast-specific marker expression. In PDS-treated zebrafish, DHP also alleviated PDS-induced osteoporosis by restoring vertebral formation and osteoblast-related gene expression. Taken together, these results suggest that DHP is a potential osteoanabolic candidate for treating osteoporosis by stimulating osteoblast differentiation.

Low-Intensity Pulsed Ultrasound Maintains Bone Mass After Withdrawal of Human Parathyroid Hormone in Ovariectomized Mice

The intermittent injection of teriparatide, a recombinant fragment of human parathyroid hormone (PTH 1-34), activates anabolic activity on bone turnover. However, the PTH administration period is limited to 2 years. Thus, sequential therapy after discontinuation of PTH is required. Low-intensity pulsed ultrasound (LIPUS) has been widely used for bone fracture healing. In this study, we examined the effects of LIPUS on bone mass after PTH withdrawal in ovariectomized (OVX) model mice. The LIPUS-non-irradiated femoral trabecular bone mineral density (BMD) in the treated after PTH withdrawal was significantly decreased. Meanwhile, the femoral BMD in the OVX + PTH-LIPUS group was remarkably higher than that of the OVX group. Additionally, mRNA expression of Runx2, Osterix, Col1a1, and ALP increased significantly following LIPUS irradiation after PTH withdrawal. These results suggest that LIPUS protected against femoral trabecular BMD loss and up-regulated the osteogenic factors following PTH withdrawal in OVX mice.

A practical guide to the diagnosis and management of osteoporosis in childhood and adolescence

Osteoporosis in childhood distinguishes itself from adulthood in four important ways: 1) challenges in distinguishing otherwise healthy children who have experienced fractures due to non-accidental injury or misfortunate during sports and play from those with an underlying bone fragility condition; 2) a preponderance of monogenic "early onset" osteoporotic conditions that unveil themselves during the pediatric years; 3) the unique potential, in those with residual growth and transient bone health threats, to reclaim bone density, structure, and strength without bone-targeted therapy; and 4) the need to benchmark bone health metrics to constantly evolving "normal targets", given the changes in bone size, shape, and metabolism that take place from birth through late adolescence. On this background, the pediatric osteoporosis field has evolved considerably over the last few decades, giving rise to a deeper understanding of the discrete genes implicated in childhood-onset osteoporosis, the natural history of bone fragility in the chronic illness setting and associated risk factors, effective diagnostic and monitoring pathways in different disease contexts, the importance of timely identification of candidates for osteoporosis treatment, and the benefits of early (during growth) rather than late (post-epiphyseal fusion) treatment. While there has been considerable progress, a number of unmet needs remain, the most urgent of which is to move beyond the monotherapeutic anti-resorptive landscape to the study and application of anabolic agents that are anticipated to not only improve bone mineral density but also increase long bone cross-sectional diameter (periosteal circumference). The purpose of this review is to provide a practical guide to the diagnosis and management of osteoporosis in children presenting to the clinic with fragility fractures, one that serves as a step-by-step "how to" reference for clinicians in their routine clinical journey. The article also provides a sightline to the future, emphasizing the clinical scenarios with the most urgent need for an expanded toolbox of effective osteoporosis agents in childhood.

Daily administration of parathyroid hormone slows the progression of basic multicellular units in the cortical bone of the rabbit distal tibia

Basic Multicellular Units (BMUs) conduct bone remodeling, a critical process of tissue turnover which, if imbalanced, can lead to disease, including osteoporosis. Parathyroid hormone (PTH 1-34; Teriparatide) is an osteoanabolic treatment for osteoporosis; however, it elevates the rate of intra-cortical remodeling (activation frequency) leading, at least transiently, to increased porosity. The purpose of this study was to test the hypothesis that PTH not only increases the rate at which cortical BMUs are initiated but also increases their progression (Longitudinal Erosion Rate; LER). Two groups (n = 7 each) of six-month old female New Zealand white rabbits were both administered 30 μg/kg of PTH once daily for a period of two weeks to induce remodeling. Their distal right tibiae were then imaged in vivo by in-line phase contrast micro-CT at the Canadian Light Source synchrotron. Over the following two weeks the first group (PTH) received continued daily PTH while the second withdrawal group (PTHW) was administrated 0.9 % saline. At four weeks all animals were euthanized, their distal tibiae were imaged by conventional micro-CT ex vivo and histomorphometry was performed. Matching micro-CT datasets (in vivo and ex vivo) were co-registered in 3D and LER was measured from 612 BMUs. Counter to our hypothesis, mean LER was lower (p < 0.001) in the PTH group (30.19 ± 3.01 μm/day) versus the PTHW group (37.20 ± 2.77 μm/day). Despite the difference in LER, osteonal mineral apposition rate (On.MAR) did not differ between groups indicating the anabolic effect of PTH was sustained after withdrawal. The slowing of BMU progression by PTH warrants further investigation; slowed resorption combined with elevated bone formation rate, may play an important role in how PTH enhances coupling between resorption and formation within the BMU. Finally, the prolonged anabolic response following withdrawal may have utility in terms of optimizing clinical dosing regimens.

Primary hyperparathyroidism and sarcoma: A case report and literature review

ABSTRACT

The relationship between primary hyperparathyroidism (PHPT) and bone sarcoma is debatable, especially after wider use of teriparatide treatment, concerns have intensified on the issue. Extensive search in English literature revealed 10 cases reported having PHPT and sarcomas. Besides, three cases of bone sarcoma occurring after teriparatide treatment had been reported. Hereby, we report a 51-year-old woman with a prolonged history of PHPT. She was diagnosed with chondrosarcoma 9 years after refusal and lack of treatment for PHPT. She was cured surgically for both chondrosarcoma and parathyroid adenoma at 1-year interval. So far, large cohorts did not show an increase in the incidence of bone sarcomas in PHPT. Several case observations, including the current one, as well as data from in vitro and rat studies, pointed out prolonged parathormone exposure, may be a risk for bone sarcomas. Under these circumstances, a safer attitude on individual basis would be the prevention of prolonged parathormone exposures.

The Risk of Developing Osteosarcoma After Teriparatide Use: A Systematic Review

Teriparatide is a recombinant human parathyroid hormone analog with anabolic mechanism of action utilized in the treatment of osteoporosis with well-established clinical efficacy. Its use is significantly hindered due to label warnings resulting from pre-clinical rat studies demonstrating an increased risk of osteosarcoma. However, clinical trials and post-marketing surveillance studies did not demonstrate any increased risk of osteosarcoma, even after prolonged periods of surveillance reaching up to 15 years, with most of the identified cases of osteosarcomas being solitary and predominantly attributed to other factors. This systematic review provides a comprehensive overview of the currently available literature and provides the highest level of clinical evidence towards demonstrating the lack of any substantial evidence towards osteosarcoma development in patients utilizing TPTD.

Genetic activation of glycolysis in osteoblasts preserves bone mass in type I diabetes

Type I diabetes (T1D) impairs bone accrual in patients, but the mechanism is unclear. Here in a murine monogenic model for T1D, we demonstrate that diabetes suppresses bone formation resulting in a rapid loss of both cortical and trabecular bone. Single-cell RNA sequencing uncovers metabolic dysregulation in bone marrow osteogenic cells of diabetic mice. In vivo stable isotope tracing reveals impaired glycolysis in diabetic bone that is highly responsive to insulin stimulation. Remarkably, deletion of the insulin receptor reduces cortical but not trabecular bone. Increasing glucose uptake by overexpressing Glut1 in osteoblasts exacerbates bone defects in T1D mice. Conversely, activation of glycolysis by Pfkfb3 overexpression preserves both trabecular and cortical bone mass in the face of diabetes. The study identifies defective glucose metabolism in osteoblasts as a pathogenic mechanism for osteopenia in T1D, and furthermore implicates boosting osteoblast glycolysis as a potential bone anabolic therapy.

Managing Early Onset Osteoporosis: The Impact of Premature Ovarian Insufficiency on Bone Health

Premature ovarian insufficiency is a reproductive endocrine disorder characterized by the cessation of ovarian function before the age of 40 years. Although the etiopathology of POI remains largely unknown, certain causative factors have been identified. Individuals affected by POI are at an increased risk of experiencing bone mineral density (BMD) loss. Hormonal replacement therapy (HRT) is recommended for patients with POI to mitigate the risk of decreased BMD, starting from the time of diagnosis until reaching the average age of natural menopause. Various studies have compared the dose-effect relationship of estradiol supplementation, as well as different HRT formulations on BMD. The impact of oral contraception on reduced BMD or the potential benefits of adding testosterone to estrogen replacement therapy are still subjects of ongoing discussion. This review provides an overview of the latest advancements in the diagnosis, evaluation, and treatment of POI as it relates to BMD loss.

Molecular test of Paget's disease of bone in families not linked to SQSTM1 gene mutations

Purpose

Paget's disease of bone (PDB) is a focal metabolic bone disorder characterized by an increased bone remodeling. Fifteen to 40 % of PDB patients have a familial form with an autosomal dominant inheritance. Disease-causing mutations of the SQSTM1 gene have been linked to PDB in about 40 % of families whereas genes linked to the remaining families are unknown. Several single nucleotide polymorphisms (SNPs) have been associated with PDB in unrelated patient non-carriers of a SQSTM1 mutation. The current clinical practice guidelines still recommend the measure of serum total alkaline phosphatase (sALP) for PDB screening. In unrelated individual non-carriers of SQSTM1 mutations, we previously developed a genetic test combining male sex with five genetic markers (rs499345, rs5742915, rs2458413, rs3018362, rs2234968), giving rise to an area under the curve (AUC) for PDB phenotype of 0.73 (0.69; 0.77). A combination of male sex with total calcium corrected for albumin and Procollagen type I N-terminal propeptide (P1NP), had an AUC of 0.82 (0.73; 0.92). Combining both genetic and biochemical tests increased the AUC to 0.89 (0.83; 0.95).

Objective

This study aimed at estimating the performance of our previous test of PDB, in families not linked to SQSTM1 mutations with disease-causing genes yet unknown, and at developing a new algorithm if the performance is not satisfactory.

Methods

We genotyped the five SNPs cited above, and measured calcium corrected for albumin and P1NP in 181 relatives, with PDB or not, from 19 PDB families not linked to SQSTM1 mutations. Bivariate and multivariate logistic regression models including male sex were fitted to search for a molecular test that could best detect PDB in these families. A receiving operating characteristics analysis was done to establish a cut-off point for continuous variables.

Results

Logistic regression estimates of our previous molecular test gave rise to a high sensitivity of 78 %, 97 % and 88 % for the genetic, biochemical, and combined test but the specificity was very low, 35 %, 11 % and 21 %, respectively. This poor specificity persisted even when the cut-off point was changed. We then generated in these families, new logistic regression estimates but on the same parameters as mentioned above, giving rise to an AUC of 0.65 (0.55; 0.75) for the genetic test, of 0.84 (0.74; 0.94) for the biochemical test, and 0.89 (0.82; 0.96) for the combination test, the latter having a sensitivity of 96 % and specificity of 57 %. By comparison serum P1NP alone gave rise to an AUC of 0.84 (0.73; 0.94), with a sensitivity of 71 % and a specificity of 79 %.

Conclusion

In PDB families not linked to SQSTM1 mutations, the estimates of our previous molecular test gave rise to a poor specificity. Using new estimates, the biochemical and combined tests have similar predictive abilities than our former test. Serum P1NP is a bone marker of interest for the screening for PDB in families not linked to SQSTM1 mutations.

Classification of osteogenesis imperfecta: Importance for prophylaxis and genetic counseling

Osteogenesis imperfecta (OI) is a genetically heterogeneous monogenic disease characterized by decreased bone mass, bone fragility, and recurrent fractures. The phenotypic spectrum varies considerably ranging from prenatal fractures with lethal outcomes to mild forms with few fractures and normal stature. The basic mechanism is a collagen-related defect, not only in synthesis but also in folding, processing, bone mineralization, or osteoblast function. In recent years, great progress has been made in identifying new genes and molecular mechanisms underlying OI. In this context, the classification of OI has been revised several times and different types are used. The Sillence classification, based on clinical and radiological characteristics, is currently used as a grading of clinical severity. Based on the metabolic pathway, the functional classification allows identifying regulatory elements and targeting specific therapeutic approaches. Genetic classification has the advantage of identifying the inheritance pattern, an essential element for genetic counseling and prophylaxis. Although genotype-phenotype correlations may sometimes be challenging, genetic diagnosis allows a personalized management strategy, accurate family planning, and pregnancy management decisions including options for mode of delivery, or early antenatal OI treatment. Future research on molecular pathways and pathogenic variants involved could lead to the development of genotype-based therapeutic approaches. This narrative review summarizes our current understanding of genes, molecular mechanisms involved in OI, classifications, and their utility in prophylaxis.

Treatment of Osteoporosis With Anabolic Agents and the Risk of Primary Bone Cancers: A Study of 44,728 Patients Treated With Teriparatide and Abaloparatide

INTRODUCTION

Bone anabolic agents can benefit orthopaedic patients perioperatively and improve outcomes after fragility fractures. However, preliminary animal data raised concern for the potential development of primary bony malignancies after treatment with these medications.

METHODS

This investigation examined 44,728 patients older than 50 years who were prescribed teriparatide or abaloparatide and compared them with a matched control group to evaluate risk of primary bone cancer development. Patients younger than 50 years with a history of cancer or other risk factors of bony malignancy were excluded. A separate cohort of 1,241 patients prescribed an anabolic agent with risk factors of primary bone malignancy, along with 6,199 matched control subjects, was created to evaluate the effect of anabolic agents. Cumulative incidence and incidence rate per 100,000 person-years were calculated as were risk ratios and incidence rate ratios.

RESULTS

The overall risk of primary bone malignancy development for risk factor-excluded patients in the anabolic agent-exposed group was 0.02%, compared with 0.05% in the nonexposed group. The incidence rate per 100,000 person-years was calculated at 3.61 for the anabolic-exposed patients and 6.46 for control subjects. A risk ratio of 0.47 (P = 0.03) and incidence rate ratio of 0.56 (P = 0.052) were observed for the development of primary bone malignancies in patients undergoing treatment with bone anabolic agents. Among high-risk patients, 5.96% of the anabolic-exposed cohort developed primary bone malignancies and 8.13% of nonexposed patients developed primary bone malignancy. The risk ratio was 0.73 (P = 0.01), and the incidence rate ratio was 0.95 (P = 0.67).

CONCLUSION

Teriparatide and abaloparatide can safely be used for osteoporosis and orthopaedic perioperative management without increased risk of development of primary bone malignancy.

Micro Ribonucleic Acid-29a (miR-29a) Antagonist Normalizes Bone Metabolism in Osteogenesis Imperfecta (OI) Mice Model

Osteogenesis imperfecta (OI) is not curative nowadays. This study tried to unriddle the therapeutic potential of micro ribonucleic acid-29a (miR-29a) antagonist in treating OI in a mouse animal model (B6C3Fe a/a-Col1a2oim/J). We showed that the expression levels of miR-29a were higher in bone tissues obtained from the OI mice than from wild-type mice demonstrated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and in situ hybridization assay. We established lentivirus-shuttled vector expressing miR-29a antisense oligonucleotide (miR-29a-AS) and miR-29a precursors (pre-miR-29a), showing that the inferior bony architecture in micro-computed tomography and pertinent morphometric parameters could be rescued by miR-29a-AS and deteriorated by pre-miR-29a. The decreased proliferating cell nuclear antigen (PCNA), increased Dickkopf-1 (DKK1), and decreased β-catenin expression in OI mice could be accentuated by pre-miR-29a and normalized by miR-29a-AS. The decreased osteogenesis and increased osteoclastogenesis in OI mice could also be accentuated by pre-miR-29a and normalized by miR-29a-AS. miR-29a-AS did not seem to possess severe hepatic or renal toxicities.

Is parathyroid allotransplantation a viable option in the treatment of permanent hypoparathyroidism? A review of the literature

BACKGROUND

The standard clinical treatment for hypoparathyroidism, replacement of calcium and vitamin metabolites (calcitriol), has been used for decades; however, evidence points to its inefficiency in acting on the pathophysiology of the disease, which may precipitate or aggravate conditions already related to hypoparathyroidism. Therapies based on recombinant human parathyroid hormone have emerged in recent years but still have low availability due to their high cost. Parathyroid allotransplantation (Pt-a) has been reported as a strategy for treating more severe cases.

METHODS

This narrative review highlights relevant aspects of conventional permanent hypoparathyroidism treatment and provides a comprehensive and critical review of the reports of applications of Pt-a, especially those carried out in recent years. Particular focus is placed on the following key points: parathyroid immunogenicity, immunosuppression regimens (short-term or chronic), techniques to reduce the expression of immunogenic molecules, follow-up time, and reductions in calcium and vitamin D supplementation.

CONCLUSION

Pt-a has been considered a safe and relatively low-cost therapy and is believed to have the potential to cure the disease, in addition to treating symptoms. However, there is considerable heterogeneity in treatment protocols; therefore, more studies are required to improve the standardization of the procedure and thus improve the consistency of outcomes.

Murine Animal Models in Osteogenesis Imperfecta: The Quest for Improving the Quality of Life

Osteogenesis imperfecta is a rare genetic disorder characterized by bone fragility, due to alterations in the type I collagen molecule. It is a very heterogeneous disease, both genetically and phenotypically, with a high variability of clinical phenotypes, ranging from mild to severe forms, the most extreme cases being perinatal lethal. There is no curative treatment for OI, and so great efforts are being made in order to develop effective therapies. In these attempts, the in vivo preclinical studies are of paramount importance; therefore, serious analysis is required to choose the right murine OI model able to emulate as closely as possible the disease of the target OI population. In this review, we summarize the features of OI murine models that have been used for preclinical studies until today, together with recently developed new murine models. The bone parameters that are usually evaluated in order to determine the relevance of new developing therapies are exposed, and finally, current and innovative therapeutic strategies attempts considered in murine OI models, along with their mechanism of action, are reviewed. This review aims to summarize the in vivo studies developed in murine models available in the field of OI to date, in order to help the scientific community choose the most accurate OI murine model when developing new therapeutic strategies capable of improving the quality of life.

Endocrine-related adverse conditions in patients receiving immune checkpoint inhibition: an ESE clinical practice guideline

Immune checkpoint inhibitors (ICI) have revolutionized cancer treatment but are associated with significant autoimmune endocrinopathies that pose both diagnostic and treatment challenges. The aim of this guideline is to provide clinicians with the best possible evidence-based recommendations for treatment and follow-up of patients with ICI-induced endocrine side-effects based on the Grading of Recommendations Assessment, Development, and Evaluation system. As these drugs have been used for a relatively short time, large systematic investigations are scarce. A systematic approach to diagnosis, treatment, and follow-up is needed, including baseline tests of endocrine function before each treatment cycle. We conclude that there is no clear evidence for the benefit of high-dose glucocorticoids to treat endocrine toxicities with the possible exceptions of severe thyroid eye disease and hypophysitis affecting the visual apparatus. With the exception of thyroiditis, most endocrine dysfunctions appear to be permanent regardless of ICI discontinuation. Thus, the development of endocrinopathies does not dictate a need to stop ICI treatment.

A Vitronectin-Derived Peptide Restores Ovariectomy-Induced Bone Loss by Dual Regulation of Bone Remodeling

BACKGROUND

Bone remodeling is tightly regulated through bone resorption and bone formation; imbalances in bone remodeling can cause various pathological conditions such as osteoporosis. Antiresorptive agents commonly used for treating osteoporosis do not substantially reverse osteoporotic bone loss.

METHODS

We evaluated the effects of the RVYFFKGKQYWE motif (residues 270-281; VnP-16) of human vitronectin on the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and osteoclastogenesis of bone marrow-derived macrophages. The effects of VnP-16 were also assessed in a mouse model of estrogen deficiency-induced osteoporosis (ovariectomized female C57BL/6 mice). To assay whether VnP-16 can reverse ovariectomy-induced bone loss, synthetic peptides or vehicle were subcutaneously injected into ovariectomized mice once a week for 4 weeks (n = 10/group). To evaluate the bone restorative effects of VnP-16, in-vivo micro-computed tomography analysis and histological staining were performed.

RESULTS

VnP-16 induced osteogenic differentiation of hMSCs and inhibited the RANKL-RANK-TRAF6 axis in the osteoclastogenesis signaling pathway. Furthermore, systemic administration of VnP-16 reversed ovariectomy-induced bone loss in the femoral neck, distal femur and lumbar spine by increasing osteoblast differentiation and promoting bone formation, and concomitantly decreasing osteoclastogenesis and inhibiting bone resorption. The bone restorative effect of VnP-16 was observed one week after subcutaneous administration, and although the timing of the effect differed according to bone location, it persisted for at least 3 weeks.

CONCLUSION

Our findings suggest that VnP-16 is a potential therapeutic agent for treating osteoporosis that mediates its effects through dual regulation of bone remodeling.

Teriparatide treatment in severe osteoporosis - a controlled 10-year follow-up study

BACKGROUND

Teriparatide was the first anabolic agent recommended for the treatment of osteoporosis. Long-term real-world, controlled studies are not available. The purpose was to evaluate the long-term effects of treatment with teriparatide on fractures and Health Related Quality of Life in subjects with established osteoporosis in comparison with placebo treated patients with osteoporosis and the general population.

METHODS

A 10-year follow-up was performed after a prospective, open-labelled study with teriparatide 20 μg given subcutaneously daily for a mean of 18 months (range 14-24 months) in 40 women, mean age 69 years, with osteoporosis and vertebral compression. Placebo treated women, n = 25, mean age 60 years, from a randomized, double-blind, placebo-controlled growth hormone trial with daily subcutaneous injections for 18 months, with osteoporosis were used as controls. Dual energy x-ray absorptiometry and questionnaires were performed at start, after 18 months, after 36 months and after 10 years. Women, n = 233, of similar age from a random population sample, also served as controls and were followed in parallel. All fractures were X-ray verified.

RESULTS

Fractures decreased from 100 to 35% in the teriparatide treated patients (p < 0.0001) to similar levels as in the population sample, 25 to 28% at start and after 10 years, respectively. Bone mineral density increased on teriparatide but returned to levels at treatment start after 10 years. Health Related Quality of Life was lower in the teriparatide group than in the population (p < 0.001) before and, after treatment and at 10 years.

CONCLUSIONS

Anabolic hormonal treatment with teriparatide reduced fracture prevalence to similar levels as in the general population at 10 years' follow-up. Health Related Quality of Life was low in osteoporosis and unaffected by bone specific treatment.

Anabolic therapy for osteoporosis: update on efficacy and safety

Anabolic agents for the treatment of osteoporosis increase bone density, improve bone strength, and reduce fracture risk. They are distinguished from antiresorptive drugs by their property of increasing osteoblastic bone formation. Teriparatide and abaloparatide are parathyroid hormone receptor agonists that increase bone remodeling with bone formation increasing more than bone resorption. Romosozumab is a humanized monoclonal antibody to sclerostin that has a "dual effect" of increasing bone formation while decreasing bone resorption. The bone forming effects of anabolic therapy appear to be self-limited, making it imperative that it be followed by antiresorptive therapy to enhance or consolidate the beneficial effects achieved. Teriparatide, abaloparatide, and romosozumab each have unique pharmacological properties that must be appreciated when using them to treat patients at high risk for fracture. Clinical trials have shown a favorable balance of expected benefits and possible risks. Anabolic therapy is superior to bisphosphonates for high-risk patients, with greater benefit when initial treatment is with an anabolic agent followed by an antiresorptive drug, rather than the reverse sequence of therapy. Recent clinical practice guidelines have included recommendations with examples of patients who are candidates with anabolic therapy.

Bioactive, full-length parathyroid hormone delivered using an adeno-associated viral vector

Delivering the parathyroid hormone (PTH) gene has been attempted preclinically in a handful of studies, but delivering full-length PTH (1-84) using adeno-associated viral (AAV) vectors has not. Given the difficulty in achieving therapeutic levels of secreted proteins using gene therapy, this study seeks to determine the feasibility of doing so with PTH. An AAV vector was used to deliver human PTH driven by a strong promoter. We demonstrate the ability to secrete full-length PTH from various cell types in vitro. PTH secretion from hepatocytes was measured over time and a fluorescent marker was used to compare the secretion rate of PTH in various cell types. Potency was measured by the ability of PTH to act on the PTH receptors of osteosarcoma cells and induced proliferation. PTH showed potency in vitro by inducing proliferation in two osteosarcoma cell lines. In vivo, AAV was administered systemically in immunocompromised mice which received xenografts of osteosarcoma cells. Animals that received the highest dose of AAV-PTH had higher liver and plasma concentrations of PTH. All dosing groups achieved measurable plasma concentrations of human PTH that were above the normal range. The high-dose group also had significantly larger tumors compared to control groups on the final day of the study. The tumors also showed dose-dependent differences in morphology. When looking at endocrine signaling and endogenous bone turnover, we observed a significant difference in tibial growth plate width in animals that received the high-dose AAV as well as dose-dependent changes in blood biomarkers related to PTH. This proof-of-concept study shows promise for further exploration of an AAV gene therapy to deliver full-length PTH for hypoparathyroidism. Additional investigation will determine efficacy in a disease model, but data shown establish bioactivity in well-established models of osteosarcoma.

Antagonizing microRNA-19a/b augments PTH anabolic action and restores bone mass in osteoporosis in mice

Postmenopausal bone loss often leads to osteoporosis and fragility fractures. Bone mass can be increased by the first 34 amino acids of human parathyroid hormone (PTH), parathyroid hormone‐related protein (PTHrP), or by a monoclonal antibody against sclerostin (Scl‐Ab). Here, we show that PTH and Scl‐Ab reduce the expression of microRNA‐19a and microRNA‐19b (miR‐19a/b) in bone. In bones from patients with lower bone mass and from osteoporotic mice, miR‐19a/b expression is elevated, suggesting an inhibitory function in bone remodeling. Indeed, antagonizing miR‐19a/b in vivo increased bone mass without overt cytotoxic effects. We identified TG‐interacting factor 1 (Tgif1) as the target of miR‐19a/b in osteoblasts and essential for the increase in bone mass following miR‐19a/b inhibition. Furthermore, antagonizing miR‐19a/b augments the gain in bone mass by PTH and restores bone loss in mouse models of osteoporosis in a dual mode of action by supporting bone formation and decreasing receptor activator of NF‐κB ligand (RANKL)‐dependent bone resorption. Thus, this study identifies novel mechanisms regulating bone remodeling, which opens opportunities for new therapeutic concepts to treat bone fragility.

Lipid nanoparticle-mediated silencing of osteogenic suppressor GNAS leads to osteogenic differentiation of mesenchymal stem cells in vivo

Approved drugs for the treatment of osteoporosis can prevent further bone loss but do not stimulate bone formation. Approaches that improve bone density in metabolic diseases are needed. Therapies that take advantage of the ability of mesenchymal stem cells (MSCs) to differentiate into various osteogenic lineages to treat bone disorders are of particular interest. Here we examine the ability of small interfering RNA (siRNA) to enhance osteoblast differentiation and bone formation by silencing the negative suppressor gene GNAS in bone MSCs. Using clinically validated lipid nanoparticle (LNP) siRNA delivery systems, we show that silencing the suppressor gene GNAS in vitro in MSCs leads to molecular and phenotypic changes similar to those seen in osteoblasts. Further, we demonstrate that these LNP-siRNAs can transfect a large proportion of mice MSCs in the compact bone following intravenous injection. Transfection of MSCs in various animal models led to silencing of GNAS and enhanced differentiation of MSCs into osteoblasts. These data demonstrate the potential for LNP delivery of siRNA to enhance the differentiation of MSCs into osteoblasts, and suggests that they are a promising approach for the treatment of osteoporosis and other bone diseases.

Teriparatide and osteosarcoma risk: history, science, elimination of boxed warning, and other label updates

The phase 3 trials of the bone anabolic drug teriparatide were prematurely terminated because of a preclinical finding of osteosarcoma in rats treated with high doses of teriparatide for near lifetime. Even so, results from these and subsequent clinical trials showed efficacy and tolerability. Based on the phase 3 results and additional preclinical investigations, Forteo (teriparatide) was approved for use in the United States with an indication for the treatment of osteoporosis in patients at high risk for fracture, a boxed warning regarding potential risk of osteosarcoma, a 2‐year lifetime limitation of use, other risk mitigations, and a requirement to assess for risk of osteosarcoma in humans treated with teriparatide. Subsequent investigations included five real‐world studies directed at assessing a connection between teriparatide and osteosarcoma risk in humans. The early studies did not identify an increased risk of osteosarcoma but were inadequate to sufficiently characterize risk, given the low incidence of this rare form of bone cancer. Learning from these efforts, two studies were undertaken using claims data to identify large cohorts of patients treated with teriparatide and assess whether these patients were found to have osteosarcoma by linking pharmacy claims data with data from cancer registries. These studies showed no increase in osteosarcoma in patients using teriparatide compared with unexposed groups, as well as to the expected population‐based background incidence of the disease. Based on this real‐world evidence and the totality of data collected from postmarketing use and other clinical investigations, the label was updated in 2020. The changes included addition of information from large observational studies using real‐world evidence, removal of the boxed warning, and a revision of the 2‐year lifetime limitation. Thus, observational studies with large sample sizes using real‐world data can provide supportive evidence to facilitate regulatory decisions including the elimination of a boxed warning. © 2022 Eli Lilly and Company. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Assessing the incidence of osteosarcoma among teriparatide-treated patients using linkage of commercial pharmacy and state cancer registry data, contributing to the removal of boxed warning and other labeling changes

BACKGROUND

Teriparatide, a recombinant human parathyroid hormone analogue, is associated with increased bone mineral density and a decreased risk of fractures. A dose-dependent increase in the incidence of osteosarcoma was observed in toxicology studies conducted in rats. The primary objective of this study was to estimate the incidence of osteosarcoma over a 10-year period among teriparatide-treated patients versus patients unexposed to teriparatide with osteoporosis and patients in the general population using national pharmacy dispensing data linked with data from participating state cancer registries (SCRs) in the US.

METHODS

Patients aged 18 years or older with a dispensed teriparatide prescription formed two different cohorts: Teriparatide-Osteoporosis (Teriparatide-OP) was formed by matching teriparatide patients to unexposed patients with osteoporosis and Teriparatide-General Population (Teriparatide-GP) was formed by matching teriparatide patients to general population patients with a dispensed prescription for a medication other than teriparatide. Matching was performed using select demographics and other variables. Study cohorts were linked to SCR data to ascertain osteosarcoma status. To account for missing outcome data from non-participating SCRs, two analytic approaches were used: the first adjusted the person-time at-risk using a coverage fraction and the second restricted the analyses to patients from states with participating SCRs.

RESULTS

There were 18 osteosarcoma cases across four study cohorts: the same three cases in the Teriparatide-OP and Teriparatide-GP cohorts, six cases in the Osteoporosis cohort, and nine cases in the General Population cohort. For the analysis using the coverage fraction the incidence rate ratio (IRR) comparing the Teriparatide-OP and Teriparatide-GP cohorts to the Osteoporosis and General Population cohorts was 1.0 (95% CI: 0.2, 4.5) and 1.3 (95% CI: 0.2, 5.1), respectively. When restricting the analysis to patients from states with participating SCRs, the IRR was 0.6 (95% CI: 0.1, 3.6) and 0.8 (95% CI 0.1, 4.0), respectively.

CONCLUSION

The estimates of association between teriparatide and osteosarcoma were imprecise due to the small number of observed osteosarcoma cases. However, the incidence of osteosarcoma observed in each study cohort was within the expected range given background rates for the US general population. The evidence generated by this study, in conjunction with other real-world studies evaluating the risk of osteosarcoma, was used to support changes to the US teriparatide label (including removal of the black box warning regarding potential risk of osteosarcoma) and expand treatment options for patients with osteoporosis.

Safety and Efficacy of PTH 1-34 and 1-84 Therapy in Chronic Hypoparathyroidism: A Meta-Analysis of Prospective Trials

Hypoparathyroidism is the only endocrine deficiency for which hormone replacement therapy is not the standard of care. Although conventional treatments may control hypocalcaemia, other complications such as hyperphosphatemia, kidney stones, peripheral calcifications, and bone disease remain unmet needs. This meta-analysis (PROSPERO registration number CRD42019126881) aims to evaluate and compare the efficacy and safety of PTH_1-34 and PTH_1-84 in restoring calcium metabolism in chronic hypoparathyroidism. EMBASE, PubMed, and CENTRAL databases were searched for randomized clinical trials or prospective studies published between January 1996 and March 2021. English-language trials reporting data on replacement with PTH_1-34 or PTH_1-84 in chronic hypoparathyroidism were selected. Three authors extracted outcomes, one author performed quality control, all assessed the risk of biases. Overall, data from 25 studies on 588 patients were analyzed. PTH therapy had a neutral effect on calcium levels, while lowering serum phosphate (-0.21 mmol/L; 95% confidence interval [CI], -0.31 to -0.11 mmol/L; p < 0.001) and urinary calcium excretion (-1.21 mmol/24 h; 95% CI, -2.03 to -0.41 mmol/24 h; p = 0.003). Calcium phosphate product decreased under PTH_1-84 therapy only. Both treatments enabled a significant reduction in calcium and calcitriol supplementation. PTH therapy increased bone turnover markers and lumbar spine mineral density. Quality of life improved and there was no difference in the safety profile between PTH and conventionally treated patients. Results for most outcomes were similar for the two treatments. Limitations of the study included considerable population overlap between the reports, incomplete data, and heterogeneity in the protocol design. In conclusion, the meta-analysis of data from the largest collection to date of hypoparathyroid patients shows that PTH therapy is safe, well-tolerated, and effective in normalizing serum phosphate and urinary calcium excretion, as well as enabling a reduction in calcium and vitamin D use and improving quality of life. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Urolithin B suppressed osteoclast activation and reduced bone loss of osteoporosis via inhibiting ERK/NF-κB pathway

Objectives

The main target of current drugs for alleviating bone loss is osteoclasts. However, the long‐term application of such drugs will also cause side effects. Therefore, it is of great need to develop new and safer therapeutics for osteoporosis. In recent years, drug development based on gut microbiota has gradually attracted attention. This manuscript investigates the inhibitory effect of urolithin B (UB) on osteoclastogenesis and differentiation in vitro and in ovariectomized (OVX) mice.

Materials and Methods

CCK‐8 was used to analyse the cytotoxicity of UB; BMMs cells were differentiated into osteoclasts by RANKL, and respectively treated with 1, 5, and 25 μmol/L UB during this process. After one week of intervention, tartrate‐resistant acid phosphatase (TRAP) staining was used to analyse the number and average area of osteoclasts. F‐actin staining and immunofluorescence staining were conducted to evaluate the morphology and function of osteoclasts. Bone resorption function of osteoclasts was detected by Pit Formation Assay. The expression of osteoclast‐related protein genes in RAW264.7 cells were investigated via western blot and RT‐PCR assays. Western blot analysis of RANKL‐mediated activation of MAPK/NF‐κB pathway after 0, 5, 15, 30, 60 min of intervention. For in vivo experiments, OVX mice received intraperitoneal injection of 10, 50 mg/kg every two days, 8 weeks later, the femurs of mice were taken for morphological analysis, and the serum content of CTX‐1, a bone metabolism index, was analysed.

Results

UB could inhibit the osteoclast differentiation of rankl‐induced bone marrow macrophages (BMMs) and RAW264.7 cells in vitro, suppress the uptake activity of hydroxyapatite and expression of osteoclast‐related gene MMP9, CTSK, NFATc1 and c‐fos. Furthermore, UB repressed the rankl‐induced phosphorylation and degradation of IκB and the phosphorylation of P65 in the NF‐κB pathway of RAW264.7 cells, and also down‐regulated the phosphorylation level of ERK in the MAPK pathway. For in vivo studies, UB‐treated OVX mice showed more significant improved various parameters of distal femur compared with the control group, with fewer NFATc1, MMP9 and TRAP‐positive osteoclasts in bone tissues, and less serum content of CTX‐1.

Conclusion

Urolithin B attenuated bone loss in OVX mice by inhibiting the formation and activation of osteoclasts via down‐regulation of the ERK/NF‐κB signalling pathway.

[Experience in using teriparatide for the treatment of postoperative hypoparathyroidism in hemodialysis patients]

The frequency of chronic postoperative hypoparathyroidism after total parathyroidectomy for secondary and tertiary hyperparathyroidism in patients with end-stage renal failure, according to various authors, can reach 20% or more. Prescribing active metabolites of vitamin D and calcium it is not always sufficient for achievement of target goals. This dictates the need for replacement therapy with recombinant parathyroid hormone. Teriparatide is the only drug of this series approved by the American Food and Drug Administration (FDA) and registered in the Russian Federation. However, it is registered as an anabolic anti-osteoporotic drug and is not indicated for the treatment of chronic hypoparathyroidism. The use of teriparatide in postoperative hypoparathyroidism in patients receiving renal replacement therapy with programmed hemodialysis in the Russian Federation has not been previously studied. Data on this issue is also limited in foreign literature. However, it is a potential treatment option for hemodialysis patients with chronic hypoparathyroidism and severe bone disorders. In this article, we present 2 clinical cases of substitution and anabolic therapy with teriparatide in this cohort of patients.

Repurposed and investigational disease-modifying drugs in osteoarthritis (DMOADs)

In spite of a major public health burden with increasing prevalence, current osteoarthritis (OA) management is largely palliative with an unmet need for effective treatment. Both industry and academic researchers have invested a vast amount of time and financial expense to discover the first diseasing-modifying osteoarthritis drugs (DMOADs), with no regulatory success so far. In this narrative review, we discuss repurposed drugs as well as investigational agents which have progressed into phase II and III clinical trials based on three principal endotypes: bone-driven, synovitis-driven and cartilage-driven. Then, we will briefly describe the recent failures and lessons learned, promising findings from predefined post hoc analyses and insights gained, novel methodologies to enhance future success and steps underway to overcome regulatory hurdles.

Evaluating Osteogenic Differentiation of Osteoblastic Precursors Upon Intermittent Administration of PTH/IGFBP7

Parathyroid hormone (PTH) 1–34 is the first anabolic agent approved for the treatment of osteoporosis. Preclinical evidence shows a potential association between PTH and osteosarcoma. The mechanisms mediating the bone- and neoplasm-forming effects of PTH remain incompleted understood, few studies on the role of Insulin-like growth factor-binding protein 7 (IGFBP7) in mediating the anabolic effects of PTH has been reported. Intermittent PTH administration was found to increase the expression of IGFBP7 in mesenchymal stem cells (MSCs) and pre-osteoblasts. The results indicated that the anabolic effects of PTH were interrupted when knockdown of IGFBP7, while supplementation with IGFBP7 protein could enhance the bone-forming efficacy of PTH and regulate the signaling pathways. Moreover, bone healing was accelerated by the administration of IGFBP7 along with PTH in a mouse model of fracture. The obtained results proved that IGFBP7 was necessary for the anabolic effects of PTH, and combined administration of PTH and IGFBP7 showed stronger bone-forming effects relative to administration of PTH alone.

Current Trends in Adjuvant Therapies for Medication-Related Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) is a refractory disease, and a standard protocol for its treatment has not yet been established. In addition, owing to the old age of MRONJ patients and various complications, treatment goals focus on relieving the symptoms and improving the quality of life. For this reason, different treatments such as conservative, surgical, and adjunctive treatments have been attempted. In particular, adjunctive treatment, which is effective for promoting healing and reducing recurrence, is gaining increasing interest, and several studies and clinical trials related to it have been published. Representative adjuvant therapies include teriparatide, recombinant human bone morphogenetic protein-2, hyperbaric oxygen, photobiomodulation and platelet concentrates. All have generally shown beneficial effects; however, no standard protocol for adjunctive treatment exists. Therefore, in this literature review, we briefly summarized the different adjuvant therapies and reviewed clinical reports to help decide whether to use adjuvant therapies in treating patients with MRONJ.

Short Cyclic Regimen With Parathyroid Hormone (PTH) Results in Prolonged Anabolic Effect Relative to Continuous Treatment Followed by Discontinuation in Ovariectomized Rats

Despite the potent effect of intermittent parathyroid hormone (PTH) treatment on promoting new bone formation, bone mineral density (BMD) rapidly decreases upon discontinuation of PTH administration. To uncover the mechanisms behind this adverse phenomenon, we investigated the immediate responses in bone microstructure and bone cell activities to PTH treatment withdrawal and the associated long-term consequences. Unexpectedly, intact female and estrogen-deficient female rats had distinct responses to the discontinuation of PTH treatment. Significant tibial bone loss and bone microarchitecture deterioration occurred in estrogen-deficient rats, with the treatment benefits of PTH completely lost 9 weeks after discontinuation. In contrast, no adverse effect was observed in intact rats, with sustained treatment benefit 9 weeks after discontinuation. Intriguingly, there is an extended anabolic period during the first week of treatment withdrawal in estrogen-deficient rats, during which no significant change occurred in the number of osteoclasts, whereas the number of osteoblasts remained elevated compared with vehicle-treated rats. However, increases in number of osteoclasts and decreases in number of osteoblasts occurred 2 weeks after discontinuation of PTH treatment, leading to significant reduction in bone mass and bone microarchitecture. To leverage the extended anabolic period upon early withdrawal from PTH, a cyclic administration regimen with repeated cycles of on and off PTH treatment was explored. We demonstrated that the cyclic treatment regimen efficiently alleviated the PTH withdrawal-induced bone loss, improved bone mass, bone microarchitecture, and whole-bone mechanical properties, and extended the treatment duration. © 2021 American Society for Bone and Mineral Research (ASBMR).

Management of patients at very high risk of osteoporotic fractures through sequential treatments

Osteoporosis care has evolved markedly over the last 50 years, such that there are now an established clinical definition, validated methods of fracture risk assessment and a range of effective pharmacological agents. Currently, bone-forming (anabolic) agents, in many countries, are used in those patients who have continued to lose bone mineral density (BMD), patients with multiple subsequent fractures or those who have fractured despite treatment with antiresorptive agents. However, head-to-head data suggest that anabolic agents have greater rapidity and efficacy for fracture risk reduction than do antiresorptive therapies. The European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) convened an expert working group to discuss the tools available to identify patients at high risk of fracture, review the evidence for the use of anabolic agents as the initial intervention in patients at highest risk of fracture and consider the sequence of therapy following their use. This position paper sets out the findings of the group and the consequent recommendations. The key conclusion is that the current evidence base supports an "anabolic first" approach in patients found to be at very high risk of fracture, followed by maintenance therapy using an antiresorptive agent, and with the subsequent need for antiosteoporosis therapy addressed over a lifetime horizon.

Vitamin D deficiency in children with cerebral palsy: A narrative review of epidemiology, contributing factors, clinical consequences and interventions

Sufficient vitamin D levels are necessary, not only for mineralization, normal growth and development of bones, but also for the prevention of fatal chronic diseases like diabetes mellitus, metabolic syndrome and cancer. This is of particular importance in children with neuro- and musculoskeletal disorders, especially cerebral palsy (CP). CP is a heterogeneous group of childhood developmental disability disorders described by uncharacteristic posture, balance, and movement. Patients with CP are at an increased risk of vitamin D deficiency and as a result reduced bone mineral density, bone fragility, osteopenia, and rickets. The present review aims to combine and summarize available evidence, regarding the epidemiology, underlying contributing factors, clinical consequences, and treatment interventions of vitamin D deficiency in children with CP.

Parathyroid Allotransplantation: A Systematic Review

Background: To date, there is no satisfactory treatment for patients with calcium and vitamin D supplementation refractive hypoparathyroidism. Parathyroid allotransplantation by design is a one-time cure through its restoration of the parathyroid function and, therefore, could be the solution. A systematic literature review is conducted in the present paper, with the aim of outlining the possibilities of parathyroid allotransplantation and to calculate its efficacy. Additionally, various transplantation characteristics are linked to success. Methods: This review is carried out according to the PRISMA statement and checklist. Relevant articles were searched for in medical databases with the most recent literature search performed on 9 December 2021. Results: In total, 24 articles involving 22 unique patient cohorts were identified with 203 transplantations performed on 148 patients. Numerous types of (exploratory) interventions were carried out with virtually no protocols that were alike: there was the use of (non-) cryopreserved parathyroid tissue combined with direct transplantation or pretreatment using in vitro techniques, such as culturing cells and macro-/microencapsulation. The variability increased further when considering immunosuppression, graft histology, and donor–recipient compatibility, but this was found to be reported in its entirety by exception. As a result of the large heterogeneity among studies, we constructed our own criterium for transplantation success. With only the studies eligible for our assessment, the pooled success rate for parathyroid allotransplantation emerged to be 46% (13/28 transplantations) with a median follow-up duration of 12 months (Q1–Q3: 8–24 months). Conclusions: Manifold possibilities have been explored around parathyroid allotransplantation but are presented as a double-edged sword due to high clinical diverseness, low expertise in carrying out the procedure, and unsatisfactory study quality. Transplantations carried out with permanent immunosuppression seem to be the most promising, but, in its current state, little could be said about the treatment efficacy with a high quality of evidence. Of foremost importance in pursuing the answer whether parathyroid allotransplantation is a suitable treatment for hypoparathyroidism, a standardized definition of transplantation success must be established with a high-quality trial.

Therapeutic Treatments for Osteoporosis-Which Combination of Pills Is the Best among the Bad?

Osteoporosis is a chronical, systemic skeletal disorder characterized by an increase in bone resorption, which leads to reduced bone density. The reduction in bone mineral density and therefore low bone mass results in an increased risk of fractures. Osteoporosis is caused by an imbalance in the normally strictly regulated bone homeostasis. This imbalance is caused by overactive bone-resorbing osteoclasts, while bone-synthesizing osteoblasts do not compensate for this. In this review, the mechanism is presented, underlined by in vitro and animal models to investigate this imbalance as well as the current status of clinical trials. Furthermore, new therapeutic strategies for osteoporosis are presented, such as anabolic treatments and catabolic treatments and treatments using biomaterials and biomolecules. Another focus is on new combination therapies with multiple drugs which are currently considered more beneficial for the treatment of osteoporosis than monotherapies. Taken together, this review starts with an overview and ends with the newest approaches for osteoporosis therapies and a future perspective not presented so far.

DANCR Mediates the Rescuing Effects of Sesamin on Postmenopausal Osteoporosis Treatment via Orchestrating Osteogenesis and Osteoclastogenesis

As one of the leading causes of bone fracture in postmenopausal women and in older men, osteoporosis worldwide is attracting more attention in recent decades. Osteoporosis is a common disease mainly resulting from an imbalance of bone formation and bone resorption. Pharmaceutically active compounds that both activate osteogenesis, while repressing osteoclastogenesis hold the potential of being therapeutic medications for osteoporosis treatment. In the present study, sesamin, a bioactive ingredient derived from the seed of Sesamum Indicum, was screened out from a bioactive compound library and shown to exhibit dual-regulating functions on these two processes. Sesamin was demonstrated to promote osteogenesis by upregulating Wnt/β-catenin, while repressing osteoclastogenesis via downregulating NF-κB signaling . Furthermore, DANCR was found to be the key regulator in sesamin-mediated bone formation and resorption . In an ovariectomy (OVX)-induced osteoporotic mouse model, sesamin could rescue OVX-induced bone loss and impairment. The increased serum level of DANCR caused by OVX was also downregulated upon sesamin treatment. In conclusion, our results demonstrate that sesamin plays a dual-functional role in both osteogenesis activation and osteoclastogenesis de-activation in a DANCR-dependent manner, suggesting that it may be a possible medication candidate for osteoporotic patients with elevated DNACR expression levels.

Antitumor Effect of Sclerostin against Osteosarcoma

Simple Summary

Osteosarcoma is highly variable and heterogeneous, which is one of the reasons for its resistance to treatment. Because osteosarcoma is defined by abnormal bone formation, we hypothesize its suppression could lead to effective treatment for all types of osteosarcomas. Sclerostin is secreted by osteocytes and inhibits the canonical pathway by binding to LRP5/6, thereby suppressing bone formation. The resulting suppression of bone formation leads to bone loss and osteoporosis. Here, we investigated the antitumor effect of sclerostin against osteosarcoma and found that sclerostin suppressed the proliferative capacity and migratory ability of osteosarcoma cells.

Abstract

Various risk factors and causative genes of osteosarcoma have been reported in the literature; however, its etiology remains largely unknown. Bone formation is a shared phenomenon in all types of osteosarcomas, and sclerostin is an extracellular soluble factor secreted by osteocytes that prevents bone formation by inhibiting the Wnt signaling pathway. We aimed to investigate the antitumor effect of sclerostin against osteosarcoma. Osteosarcoma model mice were prepared by transplantation into the dorsal region of C3H/He and BALB/c-nu/nu mice using osteosarcoma cell lines LM8 (murine) and 143B (human), respectively. Cell proliferations were evaluated by using alamarBlue and scratch assays. The migratory ability of the cells was evaluated using a migration assay. Sclerostin was injected intraperitoneally for 7 days to examine the suppression of tumor size and extension of survival. The administration of sclerostin to osteosarcoma cells significantly inhibited the growth and migratory ability of osteosarcoma cells. Kaplan–Meier curves and survival data demonstrated that sclerostin significantly inhibited tumor growth and improved survival. Sclerostin suppressed the proliferative capacity and migratory ability of osteosarcoma cells. Osteosarcoma model mice inhibited tumor growth and prolonged survival periods by the administration of sclerostin. The effect of existing anticancer drugs such as doxorubicin should be investigated for future clinical applications.

Parathyroid Hormone 1 Receptor Signaling in Dental Mesenchymal Stem Cells: Basic and Clinical Implications

Parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) are two peptides that regulate mineral ion homeostasis, skeletal development, and bone turnover by activating parathyroid hormone 1 receptor (PTH1R). PTH1R signaling is of profound clinical interest for its potential to stimulate bone formation and regeneration. Recent pre-clinical animal studies and clinical trials have investigated the effects of PTH and PTHrP analogs in the orofacial region. Dental mesenchymal stem cells (MSCs) are targets of PTH1R signaling and have long been known as major factors in tissue repair and regeneration. Previous studies have begun to reveal important roles for PTH1R signaling in modulating the proliferation and differentiation of MSCs in the orofacial region. A better understanding of the molecular networks and underlying mechanisms for modulating MSCs in dental diseases will pave the way for the therapeutic applications of PTH and PTHrP in the future. Here we review recent studies involving dental MSCs, focusing on relationships with PTH1R. We also summarize recent basic and clinical observations of PTH and PTHrP treatment to help understand their use in MSCs-based dental and bone regeneration.

The WNT1G177C mutation specifically affects skeletal integrity in a mouse model of osteogenesis imperfecta type XV

The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV (OI-XV) has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteoblasts. Although such an influence was supported by subsequent studies, a mouse model of OI-XV remained to be established. Therefore, we introduced a previously identified disease-causing mutation (G177C) into the murine Wnt1 gene. Homozygous Wnt1^G177C/G177C mice were viable and did not display defects in brain development, but the majority of 24-week-old Wnt1^G177C/G177C mice had skeletal fractures. This increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix quality. Importantly, the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5, the latter mimicking the effect of sclerostin neutralization. Finally, transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix modifiers. Taken together, our data demonstrate that regulating bone matrix quality is a primary function of WNT1. They further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.

Dose-dependent effects of pharmaceutical treatments on bone matrix properties in ovariectomized rats

As both anabolic and anti-catabolic osteoporosis drugs affect bone formation and resorption processes, they may contribute to bone's overall mechanical behavior by altering the quality of the bone matrix. We used an ovariectomized rat model and a novel fracture mechanics approach to investigate whether treatment with an anabolic (parathyroid hormone) or anti-catabolic (alendronate) osteoporosis drugs will alter the organic and mineral matrix components and consequently cortical bone fracture toughness. Ovariectomized (at 5 months age) rats were treated with either parathyroid hormone or alendronate at low and high doses for 6 months (age 6–12 months). Specifically, treatment groups included untreated ovariectomized controls (n = 9), high-dose alendronate (n = 10), low-dose alendronate (n = 9), high-dose parathyroid hormone (n = 10), and low-dose parathyroid hormone (n = 9). After euthanasia, cortical microbeams from the lateral quadrant were extracted, notched, and tested in 3-point bending to measure fracture toughness. Portions of the bone were used to measure changes in the 1) organic matrix through quantification of advanced glycation end-products (AGEs) and non-collagenous proteins, and 2) mineral matrix through assessment of mineral crystallinity. Compared to the ovariectomized group, rats treated with high doses of parathyroid hormone and alendronate had significantly increased cortical bone fracture toughness, which corresponded primarily to increased non-collagenous proteins while there was no change in AGEs. Additionally, low-dose PTH treatment increased matrix crystallinity and decreased AGE levels. In summary, ovariectomized rats treated with pharmaceutical drugs had increased non-collagenous matrix proteins and improved fracture toughness compared to controls. Further investigation is required for different doses and longer treatment periods.

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Alendronate increases non-collagenous proteins and improves fracture toughness.

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Parathyroid hormone also increases collagen maturity and mineral crystallinity.

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Both treatments minimize accumulation of advanced glycation end-products.

Teriparatide in individuals with a prior history of radiation therapy-a case series

PURPOSE

Teriparatide is a highly effective anabolic therapy for use in patients with osteoporosis at elevated fracture risk but carries a warning about an increased risk of osteosarcoma based on findings from pre-approval animal studies. Since approval, follow-up of individuals treated with teriparatide has not shown an increased risk of osteosarcoma, but it is still recommended to avoid teriparatide in patients with risk factors for osteosarcoma. One such risk factor is radiotherapy; deciding whether to use teriparatide therapy in patients at high risk of fracture but with a history of radiotherapy is therefore a frequent clinical problem.

METHODS

We sought to identify whether clinicians are using teriparatide in patients with a history of radiotherapy despite the warning and to explore the rationale for this choice. Herein, we describe six cases where the likelihood of fracture, osteosarcoma, and the benefits of teriparatide treatment are assessed to determine the appropriateness of prescribing teriparatide in the setting of prior or concurrent radiotherapy.

RESULTS

All six patients had severe osteoporosis with limited treatment options. For those who completed 2 years of teriparatide, no further fractures during the follow-up period have occurred, and improvements in bone density (as measured by dual-energy X-ray absorptiometry) were observed.

CONCLUSION

Despite radiotherapy being a relative contraindication to teriparatide use, there may be a role for teriparatide in select cases where osteoporosis is complex and severe and where other treatment options are not suitable or have been exhausted. The risks vs. benefits of prescribing teriparatide in this population should always be carefully considered, and both the patient and treating oncologist should be educated on the potential risk of osteosarcoma development when teriparatide is continued during radiotherapy.