Osteonecrosis of the Jaw and Rebound Hypercalcemia in Young People Treated With Denosumab for Giant Cell Tumor of Bone

Rebound hypercalcaemia timing is associated with cumulative weight-based denosumab dose for central giant cell granuloma treatment in children despite a dose weaning regimen

Central giant cell granulomas (CGCG) are locally destructive, non-neoplastic lesions that express receptor activator of nuclear factor-κB (RANK) and RANK ligand. Denosumab, a monoclonal antibody against RANK ligand, is licensed in skeletally mature patients, with less experience in children who are at risk of rebound hypercalcaemia. We describe the response to denosumab in five skeletally immature children with CGCG. Denosumab was started aged 2.1 to 11.6 years, for 8 to 22 months, with a cumulative dose of 9.6 to 58.8 mg/kg. Three patients followed a weaning protocol (using reducing dose frequency and zoledronic acid). Denosumab ossified all lesions. Three patients had subsequent surgery, and one had recurrence. All had rebound hypercalcaemia, 8.9-47 weeks (median 23.3 weeks) after the last treatment dose. Four presented with symptomatic hypercalcaemia and acute kidney injury. Cumulative denosumab treatment dose/kg positively correlated with (1) time to rebound after the last treatment dose (r2 = 0.94, p = 0.006); and (2) length of admission for hypercalcaemia treatment (r2 = 0.87, p = 0.02). All patients had increased bone mineral density and metaphyseal sclerosis that improved after stopping denosumab. One had a clavicular fracture at the intersection of normal and high-density bone. We propose that rebound hypercalcaemia should be an anticipated consequence of stopping denosumab in skeletally immature patients and exists on a spectrum. A higher cumulative denosumab dose/kg increases the time to rebound hypercalcaemia and its severity. Further work is needed to establish the lowest dose and the shortest treatment duration to balance effective treatment with minimising side effects.

Hypercalcemia in children induced by denosumab: a case report and an analysis of the FDA adverse event reporting system database

BACKGROUND

The potential risks of denosumab on pediatric patients have raised concerns about its safety. This article aims to analyze the adverse effects of denosumab in minors, with a specific focus on hypercalcemia.

RESEARCH DESIGN AND METHODS

A case study involving a child was analyzed. The OpenVigil 2.1 was utilized to extract adverse event data from the FAERS database, focusing on denosumab as the primary suspect drug in pediatric patients. The study also reviewed published cases of children developing hypercalcemia after discontinuing denosumab.

RESULTS

The incidence of denosumab induced hypercalcemia in individuals under 18 years old is significantly higher than the overall incidence. The signal value for hypercalcemia was higher in the male group and was highest in the adolescent group. Hypercalcemia usually appeared approximately 4 months after denosumab discontinuation. Males had a higher peak blood calcium level. Patients aged 0-11 years had a higher average peak serum calcium compared to aged 12-17 years.

CONCLUSIONS

This study highlights the risk of hypercalcemia after discontinuation of denosumab in minors, with young age and male gender identified as potential high-risk factors. These findings offer valuable safety warnings and preventative measures for the secure administration of this drug in pediatric populations.

DENO Research Group, de la Calva C, Angulo M, González-Rojo P, Peiró A, Machado P, Cebrián JL, García-Maroto R, Valcárcel A, Puertas P, Valero-Cifuentes G, Pablos Ó, Maireles M, Fontalva ML, Chaves I, Orce A, Coll-Mesa L, Pérez I, González F, Sanz MDC, Gracia I. A Multicenter Study by the DENO Research Group on the Use of Denosumab in Giant-Cell Tumors of the Bone

Background/Objectives: Despite the therapeutic potential of denosumab for the treatment of giant-cell tumors of the bone (GCTBs), there is a lack of standardization in treatment protocols. Methods: We present a multicenter, retrospective, descriptive study conducted across the seven hospitals in Spain affiliated with the DENO Research Group. Seventy-three patients diagnosed with GCTB and treated with denosumab were included and stratified according to treatment strategy-neoadjuvant (n = 38), adjuvant (n = 8), and single treatment (n = 27). Results: Patients in the neoadjuvant group received denosumab for a median of 6.1 months, with reintroduction after surgery in 25.8% of all cases. Among the neoadjuvant patients treated with curettage, recurrence was 35.5%, with no association with denosumab treatment duration (p = 0.274) nor with denosumab reintroduction after surgery (p = 0.405). In the adjuvant group, those who completed treatment received denosumab for 15.3 months, while those still undergoing therapy received it for a median of 12.8 months; only one case (12.5%) recurred. Recurrence rates in neoadjuvant and adjuvant treatment strategies were not different (p = 0.394). Patients treated only with denosumab and no longer on treatment had received it for 34.2 months, with 31.3% recurrence; those still on treatment had received it for 51.8 months, with 25.0% recurrence. Across all strategies, more than 85% of patients reported favorable clinical outcomes, and only 43.8% presented adverse events. No deaths occurred during this study. Conclusions: Although patients who experienced recurrence during neoadjuvant treatment had longer durations of denosumab administration, the difference was not statistically significant. Similarly, recurrence rates did not differ significantly, whether denosumab was reintroduced after surgery or not. Among the patients treated with curettage, recurrence rates were comparable between neoadjuvant and adjuvant strategies. Discontinuation of the single treatment did not necessarily result in disease progression.

Bone Health in Paediatric Inflammatory Bowel Disease

Paediatric inflammatory bowel disease (IBD) is often complicated by bone loss resulting in an increased risk of fractures and impaired quality of life. Underlying inflammation, nutritional deficiencies and glucocorticoid therapy are some of the factors contributing to secondary osteoporosis in IBD. Optimising nutrition, dietary supplementation and timely screening are essential in preventing bone loss. Bisphosphonate therapy remains the cornerstone of medical management of osteoporosis. This review explores the various mechanisms contributing towards poor bone health in IBD and the recent advances in diagnostic and preventive approaches along with updates in management strategies.

Rebound hypercalcemia after denosumab cessation during follow-up after surgical treatment for parathyroid carcinoma: case report and literature review

Denosumab is a potent antiresorptive medication, commonly used in the treatment of osteoporosis, as well as in a variety of other diseases. Potential adverse rebound effects after its cessation include a loss in bone mineral density and an increased risk of osteoporotic fractures. Hypercalcemia is a less frequently reported rebound phenomenon after denosumab discontinuation, that may pose a diagnostic challenge to physicians as a rare non-parathyroid hormone (PTH) dependent cause of hypercalcemia. In our case, a 47-year-old male presented with rebound hypercalcemia after denosumab cessation during follow-up after surgical treatment for parathyroid carcinoma. This non-PTH-dependent hypercalcemia resolved after re-initiation of denosumab. We performed a systematic literature review on rebound hypercalcemia after denosumab cessation and identified 52 individual patient cases. Children appear to be more prone to developing rebound hypercalcemia, which could be attributed to their higher baseline bone turnover, underlying conditions, or denosumab dosage regimens. In most cases, patients initially presented with acute and often severe symptoms of hypercalcemia that occur from 1.75 to 9 months after denosumab cessation (4 to 9 months in adults). Most effective treatment approaches to sufficiently decrease serum calcium levels were bisphosphonates or re-administration of denosumab. A watch and wait strategy may be sufficient in asymptomatic cases, which are less common and probably underdiagnosed. Subsequent antiresorptive treatment after denosumab cessation, which is a common practice in osteoporosis treatment, may reduce the risk of rebound hypercalcemia. As denosumab is a frequently used drug in patients with advanced malignant diseases and rebound hypercalcemia with low PTH levels may raise the suspicion for skeletal metastases, awareness of this rebound effect may be for particular relevance in such settings.

Antiresorptive and anti-angiogenic drug therapy in the pediatric population with reference to medication-related osteonecrosis of the jaw

The objective of this study was to identify the prevalence of osteonecrosis of the jaw in a pediatric population with systemic therapeutic exposure to an antiresorptive, anti-angiogenic, and/or immunomodulating drug (ARAID), and in particular in the subgroup of patients who had undergone invasive dental treatment. This was a retrospective cohort study performed at a single center. The investigation included pediatric patients who had undergone systemic therapy with ARAIDs and who began receiving ARAID therapy at ≤16 years of age. The study included 482 patients who received ARAIDs between January 2011 and January 2021. The most common medication class was bisphosphonates (45.0%), followed by mTOR inhibitors (30.1%) and anti-angiogenics (17.8%). No diagnosis of osteonecrosis of the jaw was observed. From this population, 26 patients were noted to have undergone invasive dental treatment. The duration from treatment to the invasive procedure ranged from 0 to 5.9 years. Medication-related osteonecrosis of the jaw is extremely rare among the pediatric population - much less common when compared to the adult population. Prospective cohort studies and continued evaluation will help determine the incidence and prevalence of medication-related osteonecrosis of the jaw in pediatric patients.

Management of RANKL-mediated Disorders With Denosumab in Children and Adolescents: A Global Expert Guidance Document

CONTEXT

Denosumab is an effective treatment for many receptor activator of nuclear factor kappa-B ligand (RANKL)-mediated disorders but there are potential safety considerations and limited data to guide its use in children and adolescents.

OBJECTIVE

This document seeks to summarize the evidence and provide expert opinion on safe and appropriate use of denosumab in pediatric RANKL-mediated disorders.

PARTICIPANTS

Ten experts in pediatric bone and mineral medicine from 6 countries with experience in the use of denosumab participated in the creation of this document.

EVIDENCE

Data were sourced from the published literature, primarily consisting of case reports/series and review articles because of the lack of higher level evidence. Expert opinion of the authors was used substantially when no published data were available.

CONCLUSION

Denosumab is an effective treatment for RANKL-mediated disorders in children and adolescents but is often not curative and, in some cases, is best used in conjunction with surgical or other medical treatments. Careful multidisciplinary planning is required to define the goals of treatment and expert oversight needed to manage the risk of mineral abnormalities. Substantive, collaborative research efforts are needed to determine optimal treatment regimens and minimize risks.

Denosumab in Giant Cell Rich Tumors of Bone: An Open-Label Multicenter Phase II Study

BACKGROUND

Since giant cell tumors of bone (GCTB) and other giant cell rich tumors of bone (GCRTB) share the histological presence of osteoclastic giant cells and expression of RANK/RANKL, we hypothesized that GCRTB will respond similarly to denosumab as GCTB. The primary objective of this study was to determine the efficacy of denosumab in patients with GCRTB that have recurred or require morbid surgery.

METHODS

In this open-label, multicenter, phase II trial, patients with GCRTB were included (June 2018-March 2020). Recruitment was stopped because of low accrual. Patients received denosumab (120 mg) subcutaneously (SC) on day 1 of every 4-week cycle with a loading dose of 120 mg SC on days 8 and 15.

RESULTS

Three patients were enrolled. One withdrew consent before start of study. The remaining patients had central giant cell granuloma of the jawbone (CGCG). Median treatment duration was 15 cycles (range 12-18). In both subjects, improvement in ossification of lesions was seen. Median follow-up was 28.5 months (range 20-37). One patient developed a recurrence for which surgery was performed.

CONCLUSION

Due to critical emerging real-world data of denosumab in GCRTBs, the study was prematurely stopped and not supportive of use of denosumab for this indication. (ClinicalTrials.gov Identifier: NCT03605199).

Current therapies and future prospective for locally aggressive mesenchymal tumors

Locally aggressive mesenchymal tumors comprise a heterogeneous group of soft tissue and bone tumors with intermediate histology, incompletely understood biology, and highly variable natural history. Despite having a limited to absent ability to metastasize and excellent survival prognosis, locally aggressive mesenchymal tumors can be symptomatic, require prolonged and repeat treatments including surgery and chemotherapy, and can severely impact patients' quality of life. The management of locally aggressive tumors has evolved over the years with a focus on minimizing morbid treatments. Extensive oncologic surgeries and radiation are pillars of care for high grade sarcomas, however, play a more limited role in management of locally aggressive mesenchymal tumors, due to propensity for local recurrence despite resection, and the risk of transformation to a higher-grade entity following radiation. Patients should ideally be evaluated in specialized sarcoma centers that can coordinate complex multimodal decision-making, taking into consideration the individual patient's clinical presentation and history, as well as any available prognostic factors into customizing therapy. In this review, we aim to discuss the biology, clinical management, and future treatment frontiers for three representative locally aggressive mesenchymal tumors: desmoid-type fibromatosis (DF), tenosynovial giant cell tumor (TSGCT) and giant cell tumor of bone (GCTB). These entities challenge clinicians with their unpredictable behavior and responses to treatment, and still lack a well-defined standard of care despite recent progress with newly approved or promising experimental drugs.

Surgical Management and Denosumab for Aneurysmal Bone Cysts of the Spine in an Australian Tertiary Paediatric Centre

Aneurysmal bone cysts (ABC) are rare osteolytic, benign but often locally aggressive tumours of the long bones or vertebrae. For spinal ABC, surgical management, embolisation or sclerotherapy alone often carry high morbidity and/or high recurrence rates. Interruption of receptor activator of nuclear factor-kappa B ligand (RANKL) signalling holds promise as an effective therapeutic strategy for these tumours. We aimed to review the approach to surgical management and evaluate the efficacy and safety of denosumab for ABC of the spine in children. Retrospective review of 7 patients treated with denosumab using a standardised protocol for ABC of the spine in a tertiary paediatric centre. Surgical intervention was only conducted if there was spinal instability or significant neurological impairment. Denosumab 70 mg/m² was given 4-weekly for at least 6 months, followed by 2 doses of zoledronate 0.025 mg/kg, aiming to prevent rebound hypercalcaemia. All patients achieved stability of the spine and resolution of neurological impairment, if present. Six patients achieved metabolic remission and have ceased denosumab without recurrence to date; the other showed clinical and radiological improvement without complete metabolic remission. Three patients developed symptomatic hypercalcaemia 5-7 months after cessation of denosumab, requiring additional bisphosphonate treatment. We present our algorithm for the surgical and medical management of paediatric spinal ABC. Denosumab produced a radiological and metabolic response in all patients, with complete remission in most. Follow-up time was not long enough to evaluate the endurance of response after cessation in some patients. Incidence of rebound hypercalcaemia in this paediatric cohort was high, prompting a change to our protocol.

Medication-Related Osteonecrosis of the Jaws (MRONJ) in Children and Young Patients-A Systematic Review

Medication-related osteonecrosis of the jaw (MRONJ) is defined by the American Association of Oral and Maxillofacial Surgeons (AAOMS) as the presence of an exposed bone area in the maxillofacial region, present for more than eight weeks in patients treated with the use of antiresorptive or antiangiogenic agents, with no history of radiation or metastatic disease. Bisphosphonates (BF) and denosumab (DS) are widely used in adults for the management of patients with cancer and osteoporosis, and recently there has been an increase in their use in child and young patients for the management of disorders such as osteogenesis imperfecta (OI), glucocorticoid-induced osteoporosis, McCune-Albright syndrome (MAS), malignant hypercalcemia, and others. There are differences between case reports in adults compared to child and young patients related to the use of antiresorptive/antiangiogenic drugs and the development of MRONJ. The aim was to analyze the presence of MRONJ in children and young patients, and the relation with oral surgery. A systematic review, following the PRISMA search matrix based on the PICO question, was conducted in PubMed, Embase, ScienceDirect, Cochrane, Google Scholar, and manual search in high-impact journals between 1960 and 2022, publications in English or Spanish, including randomized and non-randomized clinical trials, prospective and retrospective cohort studies, cases and controls studies, and series and case reports. A total of 2792 articles were identified and 29 were included; all of them published between 2007 and 2022, identifying 1192 patients, 39.68% male and 36.24% female, aged 11.56 years old on average, using these drugs mainly for OI (60.15%); 4.21 years on average was the therapy time and 10.18 drug doses administered on average; oral surgery was observed in 216 subjects, reporting 14 cases of MRONJ. We concluded that there is a low presence of MRONJ in the child and youth population treated with antiresorptive drugs. Data collection is weak, and details of therapy are not clear in some cases. Deficiencies in protocols and pharmacological characterization were observed in most of the included articles.

Osteoporosis in children and adolescents: how to treat and monitor?

Osteoporosis is a condition of increased bone fragility associated with fractures. Apart from primary genetic osteoporotic conditions, secondary osteoporosis in children is being increasingly recognized. As a result, there is growing interest in its prevention and treatment. Important goals of care are to prevent fractures, increase bone mass and trabecular and cortical thickness, reshape vertebral fractures, prevent (or correct) skeletal deformities, and improve mobility, independence, and quality of life. Secondary pediatric osteoporosis is often of multifactorial origin since affected children frequently have more than one acquired factor that is detrimental to bone health. Typical conditions causing osteoporosis are leukemias, progressive muscle or neurological disorders, as well as chronic inflammatory conditions and their treatment. Management of children with osteoporosis involves a multidisciplinary team involving pediatric experts from different subspecialties. With regard to prevention and early intervention, it is important to provide optimal management of any underlying systemic conditions including avoidance, or dose-reduction, of osteotoxic medications. Basic supporting life-style measures, such as appropriate nutrition, including adequate calcium intake and vitamin D, and physical activity are recommended, where possible. When pediatric treatment criteria for osteoporosis are met, antiresorptive drugs constitute the first pharmacological line treatment.

CONCLUSION

This clinical review focuses on the prevention, treatment, and follow-up of children with, or at risk of developing, osteoporosis and the transition from pediatric to adult care.

WHAT IS KNOWN

• Osteoporosis and associated fractures can cause significant morbidity and reduce the quality of life. • The developing skeleton has huge potential for recovery and reshaping, thus early detection of fractures, assessment of recovery potential, and treatment of children with osteoporosis can prevent future fractures, deformities, and scoliosis, improve function and mobility, and reduce pain.

WHAT IS NEW

• Osteoporosis in children and adolescents requires a multidisciplinary approach with a thorough assessment of recovery potential, and indication for therapy should be personalized. • Although bisphosphonates still represent the drug most commonly used to increase bone mass, improve mobility, and reduce pain and recurrence of fractures, new agents are being developed and could be beneficial in children with specific conditions.

Progress on Denosumab Use in Giant Cell Tumor of Bone: Dose and Duration of Therapy

Giant cell tumor of bone (GCTB) is an aggressive non-cancerous bone tumor associated with risks of sarcoma and metastasis. Once malignancy occurs, the prognosis is generally poor. Surgery remains the main treatment for GCTB. Multidisciplinary management is a feasible option for patients wherein surgical resection is not an option or for those with serious surgery-related complications. Denosumab is an anti-nuclear factor kappa B ligand approved for the treatment of postmenopausal women with osteoporosis, bone metastases, and advanced or inoperable GCTB. However, the guidelines for treating GCTB are unclear; its short-term efficacy and safety in inoperable patients have been demonstrated. Lengthier therapies (high cumulative doses) or pre-operative adjuvant therapy may be associated with severe complications and high local recurrence rates. Short-term administration helps attain satisfactory local control and functionality. As a result, lately, the impact of different doses and lengths of treatment on the efficacy of denosumab in GCTB treatment, the incidence of complications, and recurrence rates have gained attention. The efficacy and safety of denosumab against GCTB, its impact on imaging assessment, related complications, and recurrence of GCTB were previously reviewed. For further research direction, this paper reviews the progress of studies evaluating the impact of the dose and duration of denosumab therapy for GCTB.

Siglec-15 as a New Perspective Therapy Target in Human Giant Cell Tumor of Bone

The main features of a giant cell tumor of bone (GCTB) are frequent recurrence and aggressive osteolysis, which leads to a poor prognosis in patients. Although the treatment methods for a GCTB, such as scraping and resection, effectively inhibit the disease, the tendency toward malignant transformation remains. Therefore, it is important to identify new treatment methods for a GCTB. In this study, we first found high Siglec-15 expression in GCTB tissues, which was significantly associated with Campanacci staging and tumor recurrence. In Spearman's analysis, Siglec-15 expression was significantly correlated with Ki-67 levels in tumor tissues. In vitro, the mRNA and protein levels of Siglec-15 were high in GCTB stromal cells (Hs737. T), and Siglec-15 knockdown inhibited the biological characteristics of GCTB stromal cells. The RNA sequencing results enabled a prediction of the downstream genes by using the Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and MCODE analyses, and the findings showed that CXCL8 was significantly regulated by Siglec-15 and might be a promising downstream target gene of Siglec-15. Therefore, Siglec-15 may be a potential immunotherapy target for a GCTB.

High doses of zoledronic acid induce differential effects on femur and jawbone microstructure

OBJECTIVES

The aim of this study is to investigate the long-term effects on jaw and femur bone induced by oncologic doses of zoledronic acid in a young rat model.

MATERIAL AND METHODS

Six 12-week-old male Wistar rats received zoledronic acid (0.6 mg/kg) and six control rats received saline solution in the same volume. Compounds were administered intraperitoneally in five doses every 28 days. Euthanasia was performed 150 days after therapy onset. After animal sacrifice, their mandibles and femurs were scanned ex vivo using a high-resolution (14 μm) micro-computed tomography. Morphometric bone parameters were calculated using CT-Analyzer (Bruker, Belgium) between the first and second mandibular molars and in the distal femur metaphysis and epiphysis.

RESULTS

The treatment group as compared to the controls showed a significantly (p < .05) increased bone quantity (↑BV/TV, ↓Po[Tot], ↑Tb.Th), bone density (↑TMD, ↑BMD), and osteosclerosis of the trabecular bone (↓Tb.Sp, ↓Conn.Dn, ↓Tb.Pf, ↓SMI) in all anatomical sites. Bone remodeling suppression due to zoledronic acid treatment was more pronounced (p < .05) in the femoral metaphysis relative to the mandible and epiphysis. The exploratory linear discriminant analysis showed that for the mandible, it was mainly the bone quantity-related morphometric indices (BV/TV and Tb.Th), while for the femoral epiphysis and metaphysis, it was bone structure-related (Tb.Pf and Tb.N), which are of primary importance to study the treatment effect.

CONCLUSION

High doses of bisphosphonates can differently affect the bone quantity, density, and structure in long bones and jawbones. In the metaphysis, bone changes were primarily concentrated in the region of the growth plate. Future studies may consider the use of bone morphometric indices to evaluate the effect of bisphosphonates.

Rebound hypercalcemia post-denosumab cessation in metastatic breast cancer

Denosumab delays and prevents skeletal related events in patients with malignancy-related bony metastases. Rarely, denosumab discontinuation can lead to rebound hypercalcemia in the setting of increased bone resorption. We describe the case of a 49-year-old breast cancer survivor who developed rebound hypercalcemia after cessation of long-term denosumab. She had been treated with 42 doses of denosumab between August 2013 and March 2020 and 8 months after her last dose of denosumab developed symptomatic hypercalcemia. Parathyroid hormone levels were suppressed, and active malignancy was excluded based on biochemical and radiological testing. She required treatment with intravenous bisphosphonates on three separate occasions in order to achieve long-term normalization of her hypercalcemia. Rebound hypercalcemia post-denosumab cessation is a rare but serious complication that clinicians should be aware of.

Translational Strategies to Target Metastatic Bone Disease

Metastatic bone disease is a common and devastating complication to cancer, confounding treatments and recovery efforts and presenting a significant barrier to de-escalating the adverse outcomes associated with disease progression. Despite significant advances in the field, bone metastases remain presently incurable and contribute heavily to cancer-associated morbidity and mortality. Mechanisms associated with metastatic bone disease perpetuation and paralleled disruption of bone remodeling are highlighted to convey how they provide the foundation for therapeutic targets to stem disease escalation. The focus of this review aims to describe the preclinical modeling and diagnostic evaluation of metastatic bone disease as well as discuss the range of therapeutic modalities used clinically and how they may impact skeletal tissue.

Drug Treatment of Low Bone Mass and Other Bone Conditions in Pediatric Patients

Osteoporosis may affect young individuals, albeit infrequently. In childhood, bone mass increases, reaching its peak between the second and third decades; then, after a period of stability, it gradually declines. Several conditions, including genetic disorders, chronic diseases, and some medications, can have an impact on bone homeostasis. Diagnosis in young patients is based on the criteria defined by the International Society for Clinical Densitometry (ISCD), published in 2013. High risk factors should be identified and monitored. Often simple interventions aimed to eliminate the underlying cause, to minimize the negative bone effects linked to drugs, or to increase calcium and vitamin D intake can protect bone mass. However, in selected cases, pharmacological treatment should be considered. Bisphosphonates remain the main therapeutic agent for children with significant skeletal fragility and are also useful in a large number of other bone conditions. Denosumab, an anti-RANKL antibody, could become a potential alternative treatment. Clinical trials to evaluate the long-term effects and safety of denosumab in children are ongoing.

Mechanisms of acute hypercalcemia in pediatric patients following the interruption of Denosumab

PURPOSE

Denosumab is a fully human monoclonal anti-RANK-L antibody that is clinically used to counteract the bone loss induced by exacerbated osteoclast activity. Indeed, its binding to RANK-L prevents the interaction RANK-L/receptor RANK that is essential for osteoclastogenesis and bone resorbing activity. Although there are many medications available to treat bone loss diseases, including bisphosphonates, Denosumab is highly effective since it reduces the bone erosion. The use in pediatric patients is safe. However, some concerns are related to the interruption of the treatment. Indeed, in this study, we reported hypercalcemia in two pediatric patients and alterations of circulating osteoclast precursors.

METHODS

Peripheral Blood Mononuclear Cells (PBMC) were isolated from two pediatric patients with hypercalcemia after Denosumab interruption and from 10 controls. Cytofluorimetric analysis and in vitro osteoclastogenesis experiments were performed.

RESULTS

Increase of CD16^-CD14⁺CD11b⁺ cells was revealed in PBMC from patients reflecting the enhanced in vitro osteoclastogenesis.

CONCLUSION

Our data suggest that precautions must be taken when Denosumab therapy is interrupted and gradual decrease of dose and/or timing of treatment should be performed. To prevent the onset of hypercalcemia that could be in the discontinuation phase, cytofluorimetric analysis of PBMC should be performed to evaluate osteoclast precursors.

Drug-Related Hypercalcemia

This review focuses on the commonly prescribed medicaments that can be responsible for hypercalcemia, considering the prevalence, the predominant pathophysiological mechanisms, and the optimal medical management of each drug-induced hypercalcemia. Vitamin D supplements and 1α-hydroxylated vitamin D analogues increase intestinal calcium absorption, renal calcium reabsorption as well as bone resorption. In patients with hypoparathyroidism receiving recombinant human PTH, transient hypercalcemia can occur because of overtreatment, usually during acute illness. Thiazide-induced hypercalcemia is mainly explained by enhanced renal proximal calcium reabsorption, changing preexistent asymptomatic normocalcemic or intermittently hypercalcemic hyperparathyroidism into the classic hypercalcemic hyperparathyroidism. Lithium causes hypercalcemia mainly by drug-induced hyperparathyroidism.

Hypercalcemia following discontinuation of denosumab therapy: A systematic review

Denosumab is a monoclonal antibody that has been approved to treat osteoporosis, skeletal metastasis, and giant cell tumor of bone in skeletally mature patients. Due to its potential adverse effects on normal bone growth, its use has not yet been approved in skeletally immature patients; however, the use of this agent in such patients with overt or dysregulated bone resorptive conditions has been explored in recent years. While most studies have proven the effectiveness of denosumab in controlling the progression of various disorders in skeletally immature patients, they have also revealed that refractory hypercalcemia often follows the discontinuation of denosumab treatment, raising a concern over the use of this agent in these patients. Thus, this study was designed to better understand the pathology of this condition through a systematic review of the published literature. Our analysis suggests that this condition has a potential male predisposition, that there is a correlation between the duration of denosumab treatment and patient age, and that this condition often occurs within 3 months after the last administration of denosumab in skeletally immature patients but is significantly less likely in adults. These results may further underscore that high bone formation and bone turnover rates are critically associated with hypercalcemia after the discontinuation of denosumab. In contrast, given that not all skeletally immature patients develop hypercalcemia, it is probable that other unidentified factors are involved in the pathology of this condition.

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Rebound hypercalcemia often follows denosumab cessation in juveniles.

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Although relatively rare, rebound hypercalcemia can occur in adults.

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Rebound hypercalcemia may have a male predisposition in juveniles.

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Treatment duration of denosumab required to trigger hypercalcemia correlates with age.

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Onset of hypercalcemia is significantly earlier in juveniles than in adults.

Jaw osteonecrosis in patients treated with denosumab 120 mg with regular dental monitoring: 4-year retrospective study

Background: Medication-related osteonecrosis of the jaw (MRONJ) is an expected, but rare adverse effect of denosumab. There are few data denosumab 120 mg related MRONJ occurrence when regular dental monitoring is planned. International and French recommendations do not detail the schedule of the follow-up visits, allowing local interpretations. Methods: The aim of this retrospective study was to describe our local experience of regular dental monitoring in patients receiving denosumab 120 mg. We included all ≥18-year-old patients exposed to denosumab 120 mg, bisphosphonate- and denosumab-naive, and with regular dental monitoring (pre-treatment and every 4 months after denosumab initiation) at the University Hospital Center, France, from 2015 to 2019. The crude incidence of denosumab-related osteonecrosis of the jaw was estimated per 100 person-years (95% confidence interval). Results: During the study period, 251 patients were included, of whom 77 did not attend the 1st follow-up visit at 4 months. Almost all patients had osteonecrosis of the jaw risk factors. Ten MRONJ cases were reported (four stage 0 and six stage 1). The crude incidence rate was 5.1 per 100 person-years (95% CI: 1.9–8.2). Denosumab was stopped in all patients who developed MRONJ, with favorable outcome for 3 cases and stabilization in 4 cases after osteonecrosis of the jaw management. Conclusion: This study suggested that a regular dental follow-up every 4 months may be a suitable option for prevention and early detection/treatment of MRONJ. A randomized study should be performed to determine the best dental monitoring schedule.

Denosumab in the management of Aneurysmal bone cyst

BACKGROUND

Aneurysmal bone cyst (ABC) is a benign, locally aggressive tumour that arises predominantly in long bones and spine. Following the encouraging results of denosumab use in Giant Cell Tumors (GCT) and the histological similarities between ABC and GCT, the interest on the role of denosumab in the therapeutic arsenal of the most advanced ABC is growing. The purpose of this literature review is to investigate the current state of knowledge about the use of denosumab in ABCs.

METHODS

A literature research was conducted through PUBMED, COCHRANE and GOOGLE SCHOLAR using the keywords "aneurysmal bone cyst" AND "denosumab". Seventeen articles were included.

RESULTS

A total of 43 cases were reported in the literature. There were 23 males, 20 females. The mean age was 15,9±8,1 year. Pain relief and neurological improvement were rapid and sustained. Radiological assessment showed ossification and/or volume reduction in 36/39 patients. Eight patients (18,6%) presented a recurrence after or during denosumab therapy of whom 7 were adults. Adverse events occurred in 11 patients, 5 of them were admitted to the intensive care unit due to hypercalcemia.

CONCLUSION

Denosumab use in non-surgical ABCs has shown a positive impact in pain and neurological symptoms. The oncological outcome remains unclear with a recurrence rate of 18,6% during/after denosumab therapy, mostly in adults. However, regarding the potential clinical benefits, its use might be discussed in the most advanced cases. Further research and clinical trials are mandatory to precise its belonging in the therapeutic arsenal.

Successful denosumab treatment for central giant cell granuloma in a 9-year-old child

BACKGROUND

Denosumab is a nonsurgical treatment option for central giant cell granulomas (CGCG), especially in aggressive lesions.

CASE REPORT

We describe a 9-year-old girl with an aggressive maxillary CGCG successfully treated with denosumab, avoiding a mutilating surgery after intralesional corticosteroid injections failed, and the lesion continued to rapidly grow. During denosumab treatment, she developed a self-limiting area of osteonecrosis in the maxillary alveolar bone, which rapidly resolved after antibiotic therapy. Six months after denosumab discontinuation, a maxillary surgical recontour was performed. Two weeks after surgery, the patient presented vomiting, pallor, dehydration, but no fever. Blood tests revealed severe hypercalcemia and acute renal dysfunction. After discarding thyroid, parathyroid, and adrenal alterations, a diagnosis of severe rebound hypercalcemia after denosumab treatment was made. Treatment consisted of hyperhydration, calcium pamidronate, and methylprednisolone, restoring calcium levels to normal.

CONCLUSION

After 2 years of follow-up, she remains on orthodontic treatment, with no recurrences or other episodes of hypercalcemia.

Response to Denosumab in 2 Children With Recurrent Giant Cell Tumor of the Bone With Pulmonary Metastasis

Giant cell tumor of the bone (GCTB) is an uncommon bone tumor, usually localized, and rarely presents at <20 years of age. Denosumab, a fully human monoclonal antibody against RANKL (receptor activator of nuclear factor κB ligand), is approved for the treatment of unresectable GCTB in skeletally mature individuals. We present a case series of 2 pediatric patients with recurrent GCTB with pulmonary metastasis, with clinical response to denosumab therapy.

Chondroblastoma Expresses RANKL by RNA In Situ Hybridization and May Respond to Denosumab Therapy

Lesions of bone featuring osteoclast-like giant cells comprise a diverse group of entities, including giant cell tumor (GCT) of bone, chondroblastoma, and aneurysmal bone cyst, among others. The receptor activator of nuclear factor-κB ligand (RANKL) has been implicated in the pathogenesis of GCT of bone and may play a role in the pathogenesis of other giant cell-rich lesions as well. In addition, RANKL inhibitors (denosumab) have also been shown to have some efficacy in treating some giant cell-rich lesions. Herein, we examine RANKL expression by RNA in situ hybridization in a total of 84 osseous lesions with a focus on chondroblastoma, GCT, fibrous dysplasia, and aneurysmal bone cyst. The lesions were tested for RANKL expression using a chromogenic RNA in situ hybridization assay. RANKL expression was identified in 24/25 (96%) GCT, 24/26 (92%) chondroblastomas, 6/7 (86%) aneurysmal bone cysts, and 3/16 (19%) patients with fibrous dysplasia. RANKL expression was statistically lower in chondroblastoma and aneurysmal bone cyst compared with GCT. RANKL reactivity in fibrous dysplasia was exclusively seen in the 3 cases with osteoclast-type giant cells. Our results indicate a high proportion of chondroblastomas, GCTs, and aneurysmal bone cysts express RANKL while reactivity in fibrous dysplasia is dependent on the presence of osteoclast-type giant cells. On the basis of the success of denosumab therapy for GCTs, our results indicate that it may be a potential therapeutic option in other primary osseous tumors.

Mechanisms of Bone Fragility: From Osteogenesis Imperfecta to Secondary Osteoporosis

Bone material strength is determined by several factors, such as bone mass, matrix composition, mineralization, architecture and shape. From a clinical perspective, bone fragility is classified as primary (i.e., genetic and rare) or secondary (i.e., acquired and common) osteoporosis. Understanding the mechanism of rare genetic bone fragility disorders not only advances medical knowledge on rare diseases, it may open doors for drug development for more common disorders (i.e., postmenopausal osteoporosis). In this review, we highlight the main disease mechanisms underlying the development of human bone fragility associated with low bone mass known to date. The pathways we focus on are type I collagen processing, WNT-signaling, TGF-ß signaling, the RANKL-RANK system and the osteocyte mechanosensing pathway. We demonstrate how the discovery of most of these pathways has led to targeted, pathway-specific treatments.

Mineral and Bone Consequences of High Dose Denosumab Therapy to Treat an Aneurysmal Bone Cyst, a Child Case Report

Aneurysmal bone cysts (ABCs) are rare benign pseudotumoral bone lesions with potential aggressive behavior due to the extensive destruction of surrounding bone. Traditionally, these tumors were treated with open surgery, but there is more and more a shift to less invasive procedures. In particular, treatment for spinal ABCs is generally unsatisfactory due to the risk of morbidity, neurological impairment and recurrence, and there is a need for innovative therapies. Denosumab has been reported as a useful treatment in giant cell tumors of bone (GCTB), so its efficacy has been tested also in other fibro-osseus lesions affecting children and adolescents, such as spinal aneurysmal bone cysts. The pediatric literature is limited to case reports and small series, all of which highlight the efficacy of this treatment on lesions growth and associated bone pain. Some of these reports have already reported well known side effects associated with denosumab, such as hypocalcemia at the beginning of the treatment, and rebound hypercalcemia at the discontinuation. The latter seems to be more frequent in children and adolescents than in adults, probably due to the higher baseline bone turnover in children. In addition, the use of denosumab in young patients could affect both bone modeling and remodeling, even if the consequences on the growing skeleton have not been reported in detail. Here we describe the case of a spinal ABC diagnosed in an 8-year old young boy which was not accessible to surgery but responded favorably to denosumab. Our aim is to describe the rapid changes in mineral and bone homeostasis in this patient, that required advice from the experts of the European Reference Network (ERN) for rare bone and endocrine diseases.

The Efficacy of Denosumab in the Management of a Tibial Paediatric Aneurysmal Bone Cyst Compromised by Rebound Hypercalcaemia

Surgery is the main treatment option for patients with aneurysmal bone cyst (ABC). We report our experience of using denosumab as an alternative treatment in a child with a multiply recurrent and unresectable tibial ABC. The efficacy and safety of denosumab in the paediatric population, and in the treatment of ABC, are still to be fully evaluated. We describe a 13-year-old boy with an extensive and aggressive ABC involving the proximal tibia, which had recurred following multiple previous surgeries. The patient had ongoing severe pain, was unable to weight-bear, and was at significant risk of pathological fracture. En bloc resection and embolization were not deemed viable, and a decision to use denosumab was made. He received 17 doses of subcutaneous denosumab (70 mg/m²) over a 27-month period, at increasing dose intervals. His symptoms significantly improved, and bony consolidation was observed within six months of treatment. He was able to walk without protection and fully weight-bear without any pain by 18 months. With an increase to a six-month dosing interval, the patient presented with a severe, symptomatic rebound hypercalcaemia requiring bisphosphonate therapy. This reoccurred on two further occasions. This case adds to the evidence that denosumab is effective in the treatment of ABC in paediatric patients, but there is a risk of rebound hypercalcaemia. Therefore, patient awareness and biochemical monitoring for rebound hypercalcaemia are essential.

Hypercalcemia upon denosumab withdrawal in primary hyperparathyroidism: a case report and literature review

Denosumab discontinuation is associated with a rapid increase in bone resorption and a decrease in bone mineral density. Spontaneous vertebral fractures may occur as a side effect of the rebound of bone resorption. Cases of rebound-linked hypercalcemia have also been described, moderate in women with osteoporosis and breast cancer and severe in children receiving oncological doses of denosumab. We report the case of an adult woman with primary hyperparathyroidism and moderate hypercalcemia, treated with denosumab for osteoporosis, who developed severe hypercalcemia and spontaneous vertebral fractures (SVFs) after denosumab discontinuation. An 86-year-old woman with densitometric osteoporosis was treated for 3 years with 60 mg of subcutaneous denosumab every 6 months. She was known to have primary hyperparathyroidism, with a serum albumin-corrected calcium of 2.82 mmol/l (NV 2.15-2.5) at the end of denosumab effect. Nine months after the last denosumab injection, she was hospitalized due to worsening overall health. Clinical evaluation revealed severe hypercalcemia (calcium 3.35 mmol/l). Very high values of bone turnover markers (BTMs) suggested a rebound effect due to denosumab discontinuation. An X-ray showed multiple new SVFs. After injection of denosumab 60 mg, serum calcium rapidly decreased and BTMs were dramatically reduced. A surgical approach by minimally invasive parathyroidectomy allowed for definite resolution of hyperparathyroidism and hypercalcemia. This case suggests that hypercalcemia can be a side consequence of denosumab discontinuation, which can become severe when other causes of hypercalcemia, such as primary hyperparathyroidism, are present.

Comparing the Surgical Response of Bisphosphonate-Related Versus Denosumab-Related Osteonecrosis of the Jaws

PURPOSE

The pathophysiology and treatment of medication-related osteonecrosis of the jaws (MRONJ) remain unclear after nearly two decades of recorded observation and discussion. The purpose of this study was to assess outcomes of surgical resection of MRONJ in patients exposed to denosumab.

MATERIALS AND METHODS

A literature review was performed in conjunction with experts at the University of Illinois at Chicago Library. The primary outcome of interest was surgical success defined by maintenance of complete mucosal closure without bone exposure and infection after surgical resection. Secondary interests included demographics, MRONJ stage, location of the focus of osteonecrosis, and the primary underlying disease necessitating antiresorptive treatment. Statistical analysis was performed by χ², analysis of variance, or t test (P < .05 and b = 0.2 or a power of 0.8).

RESULTS

A total of 70 articles were identified and 14 met inclusion criteria. Twenty patients were included (13 women; 7 men); age 61.8 years ± 12.9 (range 19 to 77); and MRONJ stage I (40.0%), II (35.0%), and III (25.0%). Most cases occurred in the mandible (65.0%), followed by the maxilla (30.0%). The success rate of surgical intervention for MRONJ secondary to denosumab was in 16 of 20 (80.0%) patients. Stage I MRONJ lesions achieved mucosal closure in 100% of patients, stage II in 71.4%, and stage III in 60.0%. The surgical success rate was 83.3% in the maxilla and 76.9% in the mandible.

CONCLUSIONS

The surgical success rate for MRONJ secondary to denosumab was 80.0%, similar to that reported in bisphosphonates of 85 to 95%; however, more evidence must be reported and analyzed.

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

Integration of denosumab therapy in the management of giant cell tumors of bone

A review of the literature indicated denosumab is gaining favorability in the oncology community, particularly with increasing frequency in GCTB. Will denosumab be the breakthrough GCTB treatment? Here, we provide a pertinent case example, a review of the literature regarding the history and basic science behind the use of denosumab for GCTB, highlight the newest insights into the dosing and duration of treatment, and note advancements in the field.

Long-term follow up after denosumab treatment for osteoporosis - rebound associated with hypercalcemia, parathyroid hyperplasia, severe bone mineral density loss, and multiple fractures: a case report

BACKGROUND

The rebound effect after stopping treatment with denosumab may be associated with rapid loss of the gains in bone mineral density achieved with treatment, high levels of bone remodeling markers, the occurrence of vertebral fractures, and even hypercalcemia.

CASE PRESENTATION

A 64-year-old osteoporotic Caucasian woman suffered from a fracture of her second lumbar vertebra in 2004. From January 2005, she was treated with denosumab for 9 years, with good densitometry results for her hip and lumbar areas, and no fractures over the last 6 years of treatment. Ten months after the treatment with denosumab was stopped, a cascade of vertebral fractures, including some in unusual locations (third thoracic vertebra), and multiple rib fractures in a context of hypercalcemia, suggested possible malignancy. A complete evaluation, including systemic, biological, and biopsy analyses, ruled out this hypothesis. The hypercalcemia was associated with normal plasma phosphate and vitamin D concentrations, and a high parathyroid hormone level, with an abnormal fixation of the lower lobe of the thyroid on sesta-methoxy-isobutyl-isonitrile scintigraphy. Histological analysis of the excised parathyroid tissue revealed hyperplasia. The associated thyroidectomy (goiter) led to the discovery of a thyroid papillary microcarcinoma.

CONCLUSIONS

We consider the consequences of this rebound effect, not only in terms of the major loss of bone density (return to basal values within 3 years) and the multiple disabling fracture episodes, but also in terms of the hypercalcemia observed in association with apparently autonomous tertiary hyperparathyroidism. Several cases of spontaneous reversion have been reported in children, but the intervention in our patient precluded any assessment of the possible natural course. The discovery of an associated thyroid neoplasm appears to be fortuitous. Better understanding of the various presentations of the rebound effect after stopping treatment with denosumab would improve diagnostic management of misleading forms, as in this case. Bisphosphonates could partially prevent this rebound effect.

Efficacy and safety of denosumab treatment in a prepubertal patient with cherubism

Background Denosumab is an inhibitor of receptor activator of nuclear factor kappa-B ligand, which strongly suppresses osteoclasts. Cherubism is a rare autosomal dominant disorder characterized by symmetrical swelling of the jaws, in which the bone is replaced by a fibrous granuloma containing osteoclast-like giant cells. Case presentation We report the efficacy and safety of denosumab treatment in a prepubertal boy with progressive cherubism. The treatment consisting of eight subcutaneous denosumab injections (120 mg/dose) in 6 months not only suppressed the expansion of the osteolytic lesions but also dramatically ossified them. However, a transiently decreased growth rate and rebounded asymptomatic hypercalcemia were associated with the treatment. Conclusions The present case demonstrated the therapeutic potential of denosumab for treatment of cherubism, although adverse effects, especially those on childhood growth, remain obscure. Further studies are needed to establish a safe and effective protocol for denosumab treatment of children.

Challenges of denosumab in giant cell tumor of bone, and other giant cell-rich tumors of bone

Purpose of review

Giant cell tumor of bone (GCTB) is an uncommon benign primary bone tumor, consisting of receptor activator of nuclear factor kappa-B (RANK) expressing reactive osteoclast-like giant cells and neoplastic spindle-shaped cells. Denosumab was approved by FDA in 2013 and by EMA in 2014 to treat adults and skeletally mature adolescents with unresectable GCTB or when resection is likely to result in severe morbidity. However, there is much discussion regarding the optimal applied treatment strategy.

Recent findings

Neoadjuvant treatment of GCTB with denosumab can effectively downstage tumors to facilitate less morbid surgery or completely avoid the need for resection, but there is concern about local recurrence postsurgery. Definitive treatment of unresectable GTCB improves symptoms and halts tumor progression. The optimal treatment duration is unclear and long-term treatment is associated with adverse events like osteonecrosis of the jaw (ONJ) and atypical femoral fractures. Denosumab maintenance dose interval is currently being investigated.

Summary

For the related but heterogenous group of giant cell rich tumors of bone, like aneurysmal bone cysts (ABC) and central giant cell granuloma (CGCG), denosumab is a new treatment modality under investigation. Given the effectiveness in GCTB, this could be a promising treatment option for selected patients with advanced disease.

Case Report: Safety and Efficacy of Denosumab in Four Children With Noonan Syndrome With Multiple Giant Cell Lesions of the Jaw

Noonan syndrome is a genetic disorder caused by mutations in the RAS/MAPK pathway. Multiple giant cell lesions are a rare sequelae of disruptions in this pathway, termed Noonan-like multiple giant cell lesions (NL/MGCLs). Medical management of these tumors rather than surgical intervention is preferential as the lesions are benign but locally destructive and recurring. This case series describes four male pediatric patients with Noonan syndrome and multiple giant cell lesions of the jaw treated with denosumab, a monoclonal antibody to receptor activator of nuclear factor kappa B ligand (RANKL), which has been approved for the treatment of malignant giant cell tumors in adults but not evaluated for safety or efficacy in children. All four pediatric patients responded clinically and radiographically to the treatment. Adverse events occurred in a predictable pattern and included hypocalcemia and joint pain during the initiation of treatment and symptomatic hypercalcemia after the cessation of treatment. Growth was not significantly impaired in these skeletally immature patients. This case series demonstrates how a weight-adjusted denosumab dose can effectively treat NL/MGCLs and provides laboratory data for consideration of the timing of monitoring for known side effects.

Hypercalcaemia after treatment with denosumab in children: bisphosphonates as an option for therapy and prevention?

BACKGROUND

Pharmacologic options for treatment of osteolytic diseases especially in children are limited. Although not licensed for use, denosumab, a fully humanized antibody to RANKL, is used in children with good effects. Among others, one possible indication are giant cell tumors and aneurysmatic bone cysts. However, there are reports of severe hypercalcemia during weeks to months after termination of denosumab, that are rarely seen in adults.

METHODS

We collected data of four patients, aged 6-17 years, who experienced severe hypercalcemia after completion of treatment with denosumab for unresectable giant cell tumors of bone or aneurysmal bone cysts and methods of their treatment. The detailed case information were described.

RESULTS

One patient was treated with long-term, high-dose steroid therapy, leading to typical Cushing's syndrome. Another patient was restarted on denosumab repeatedly due to relapses of hypercalcemia after every stop. Finally, in two patients, hypercalcemia ceased definitely after treatment with bisphosphonates. However, several applications were necessary to stabilize calcium levels.

CONCLUSIONS

There is a considerable risk of hypercalcemia as an adverse effect after denosumab treatment in children. Therapeutic and, preferably, preventive strategies are needed. Bisphosphonates seem to be an option for both, but effective proceedings still remain to be established.

Denosumab in patients with giant-cell tumour of bone: a multicentre, open-label, phase 2 study

BACKGROUND

Giant-cell tumour of bone (GCTB) is a rare, locally aggressive osteoclastogenic stromal tumour of the bone. This phase 2 study aimed to assess the safety and activity of denosumab in patients with surgically salvageable or unsalvageable GCTB.

METHODS

In this multicentre, open-label, phase 2 study done at 30 sites in 12 countries we enrolled adults and skeletally mature adolescents (aged ≥12 years) weighing at least 45 kg with histologically confirmed and radiographically measurable GCTB, Karnofsky performance status 50% or higher (Eastern Cooperative Oncology Group status 0, 1, or 2), and measurable active disease within 1 year of study enrolment. Patients had surgically unsalvageable GCTB (cohort 1), had surgically salvageable GCTB with planned surgery expected to result in severe morbidity (cohort 2), or were enrolled from a previous study of denosumab for GCTB (cohort 3). Patients received 120 mg subcutaneous denosumab once every 4 weeks during the treatment phase, with loading doses (120 mg subcutaneously) administered on study days 8 and 15 to patients in cohorts 1 and 2 (patients in cohort 3 did not receive loading doses). The primary endpoint was safety in terms of the type, frequency, and severity of adverse events; secondary endpoints included time to disease progression from cohort 1 and the proportion of patients without surgery at month 6 for cohort 2. The safety analysis set included all enrolled patients who received at least one dose of denosumab. This study is registered with ClinicalTrials.gov, number NCT00680992, and has been completed.

FINDINGS

Between Sept 9, 2008, and Feb 25, 2016, 532 patients were enrolled: 267 in cohort 1, 253 in cohort 2, and 12 in cohort 3. At data cutoff on Feb 24, 2017, median follow-up was 58·1 months (IQR 34·0-74·4) in the overall patient population, and 65·8 months (40·9-82·4) in cohort 1, 53·4 months (28·2-64·1) in cohort 2, and 76·4 months (61·2-76·5) in cohort 3. During the treatment phase, the most common grade 3 or worse adverse events were hypophosphataemia (24 [5%] of 526 patients), osteonecrosis of the jaw (17 [3%], pain in extremity (12 [2%]), and anaemia (11 [2%]). Serious adverse events were reported in 138 (26%) of 526 patients; the most common were osteonecrosis of the jaw (17 [3%]), anaemia (6 [1%]), bone giant cell tumour (6 [1%]), and back pain (5 [1%]). 28 (5%) patients had positively adjudicated osteonecrosis of the jaw, four (1%) had atypical femur fracture, and four (1%) had hypercalcaemia occurring 30 days after denosumab discontinuation. There were four cases (1%) of sarcomatous transformation, consistent with historical data. Ten (2%) treatment-emergent deaths occurred (two of which were considered treatment-related; bone sarcoma in cohort 2 and sarcoma in cohort 1). Median time to progression or recurrence for patients in cohort 1 during the first treatment phase was not reached (28 [11%] of 262 patients had progression or recurrence). 227 (92%; 95% CI 87-95) of 248 patients who received at least one dose of denosumab in cohort 2 had no surgery in the first 6 months of the study.

INTERPRETATION

The types and frequencies of adverse events were consistent with the known safety profile of denosumab, which showed long-term disease control for patients with GCTB with unresectable and resectable tumours. Our results suggest that the overall risk to benefit ratio for denosumab treatment in patients with GCTB remains favourable.

FUNDING

Amgen.

Efficacy and safety of denosumab therapy for low bone mineral density in childhood cancer survivors: A report of preliminary experience

BACKGROUND

In childhood cancer survivors, low bone mineral density (BMD) is a bone-related consequence. Efficacy of denosumab, an effective therapy for adult patients with osteoporosis, remains unclear in children. This study aimed to investigate denosumab therapy efficacy for low BMD in childhood cancer survivors.

PROCEDURE

Between January 2014 and January 2018, we monitored lumbar BMD of children with cancer using dual-energy X-ray absorptiometry after completing chemotherapy with a 6-month interval. For patients with low BMD, defined as height-adjusted Z-scores of BMD < -1.5 in this study, calcium carbonate and vitamin D supplements were initially administered. When low BMD continued for at least 6 months, denosumab therapy was introduced. Calcium and vitamin D supplementation were continued in patients on denosumab. We investigated BMD change and adverse effects during denosumab therapy.

RESULTS

During the study period, 20 patients received denosumab treatment. Mean height-adjusted Z-score of BMD before denosumab treatment was -2.68 but increased to -2, -1.96, and -1.33 at 0.5, 1, and 1.5 years after denosumab treatment, respectively (P = .012). In addition, hypocalcemia occurred in 40% (8/20) of patients; three patients had hypocalcemic symptoms with numbness in all four limbs. All hypocalcemic patients, except one patient who died due to relapsed leukemia, recovered well after continuous calcium supplementation.

CONCLUSIONS

Denosumab is an effective treatment for low BMD in childhood cancer survivors. However, the complication of hypocalcemia might develop posttreatment.

Local Tumor Recurrence and Escape from Suppression of Bone Resorption With Denosumab Treatment in Two Adolescents With Giant Cell Tumors of Bone

Giant cell tumors of bone (GCTB) may be difficult to resect because of size or location. We describe two adolescents who were treated with denosumab and followed for tumoral and biochemical responses. Denosumab was effective in achieving sufficient regression to allow surgical resection and in preserving peritumor cortical bone. Reactivation of bone resorption markers was noted while the patients were receiving monthly denosumab. One patient suffered a local tumor recurrence. Denosumab was safe in enabling surgical resection of GCTB. However, the effect was transient, with an escape of resorption markers and tumor recurrence. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Challenges of delivery of dental care and dental pathologies in children and young people with osteogenesis imperfecta

BACKGROUND

Osteogenesis imperfecta (OI) is the most common inherited disorder of bone fragility in children, increasing fracture risk 100-fold and can feature dental and facial bone involvement causing additional morbidities.

AIM

To assess the utilisation of tertiary dental services by children and young people with OI attending a supra-regional multi-disciplinary OI service and review of the pathology identified and interventions undertaken.

DESIGN

Case notes review of the current caseload of children and young people (0-18 years) with OI at a large regional OI specialist centre (n = 92). Primary outcome was whether an initial dental assessment was arranged in a tertiary dental centre and the corresponding attendance.

RESULTS

49% had a tertiary dental assessment arranged, of whom 82% attended (one quarter requiring several appointments) and 18% did not attend (DNA).Those travelling > 100 miles had a DNA rate of 47%. Assessed children had dentinogenesis imperfecta (24%, 50% in Type III OI), radiographs (95%), caries (41%), required extraction under general anaesthesia (38%) and malocclusion (30%). 48% of the total cohort received bisphosphonates.

CONCLUSION

Tertiary dental assessment encountered barriers to uptake of recommended referral in all patients, often due to geographic factors of travel distance, yet when implemented did identify pathology in a large proportion and many resulted in dental intervention. These emphasise the relevance of specialist dental assessment in OI, particularly in the modern context of increased use of bisphosphonates. This is challenging to achieve and several models of delivery of care may need to be considered in this chronic childhood condition.

Acute hypercalcemia and excessive bone resorption following anti-RANKL withdrawal: Case report and brief literature review

Denosumab is an anti-RANKL antibody that is commonly used for the treatment of osteoporosis; in oncology, bisphosphonates and denosumab have become the standard therapies for the treatment and prevention of skeletal complications in patients with myeloma and solid tumors. In recent years, excessive bone remodeling following the discontinuation of denosumab has raised concerns. Several cases of hypercalcemia have been reported after the discontinuation of high-dose denosumab (120 mg every 4 weeks), mainly in children. In this study, we report a new case of severe refractory hypercalcemia in a 54-year-old woman who received high-dose denosumab for 5 years as an adjuvant therapy for breast cancer. She is currently in remission and undergoing treatment with anastrazole, an aromatase inhibitor. The peculiarities of this case are the presence of associated bone pain with subperiosteal bone resorption on hand X-rays, and diffuse, long bone diaphyseal uptake on a bone scan. Hyperparathyroidism has been ruled out, and existing evidence suggests that this high-level of bone remodeling could be due to a rebound hyperactivation of the RANKL pathway. In addition to rehydration, repeated use of i.v. bisphosphonates was required to control recurrent hypercalcemia. As hypercalcemia is a serious metabolic complication, a gradual dose reduction should be considered when interruption of high dose denosumab therapy is planned.

MHRA Drug Safety Update: denosumab (Xgeva) and rebound hypercalcaemia

Review of: Medical and Healthcare products Regulatory Agency. Denosumab for giant cell tumor of bone: risk of clinically significant hypercalcaemia following discontinuation. Drug Safety Update 2018;11(11);2.