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

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.

Indications for fertility preservation not included in the 2017 Japan Society of Clinical Oncology Guideline for Fertility Preservation in Pediatric, Adolescent, and Young Adult Patients treated with gonadal toxicity, including benign diseases

In recent years, local governments in Japan have established a public financial support system for fertility preservation in pediatric, adolescent, and young adult cancer patients. Fertility preservation has become popular for patients with cancers included in the gonadal toxicity risk classification of the 2017 edition of the Guideline for Fertility Preservation in Children, Adolescents and Young Adult Cancer Patients from the Japan Society of Clinical Oncology. However, patients with cancer and non-cancer diseases that are not included in the Guideline's gonadal toxicity risk classification also often receive treatment that may affect fertility, but they are often denied the opportunity of fertility preservation because no public financial support is available for diseases not listed in the Guideline. The national research project proposes including these diseases in the indications and treatment for fertility preservation. Therefore, we cooperated with the Japan Society for Fertility Preservation and the Ministry of Health, Labour and Welfare research group to solicit opinions from experts in each therapeutic area and reviewed the literature and overseas guidelines. This paper summarizes the findings of the project. We believe that it will be an important source of information for clinicians treating patients who need fertility preservation but note that the appropriateness of fertility preservation for the disorders listed in this report needs to be continuously reviewed as medical care advances.

Establishment and characterization of the NCC-GCTB4-C1 cell line: a novel patient-derived cell line from giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a rare osteolytic intermediate bone tumor that harbors a pathogenic H3F3A gene mutation and exhibits characteristic histology. The standard curative treatment for GCTB is complete surgical resection, but it frequently results in local recurrence and, more rarely, metastasis. Therefore, effective multidisciplinary treatment is needed. Although patient-derived tumor cell lines are promising tools for preclinical and basic research, there are only four available cell lines for GCTB in public cell banks. Thus, the aim of this study was to establish a novel GCTB cell line. Using surgically resected tumor tissues from a patient with GCTB, we established a cell line named NCC-GCTB4-C1. The cells harbored the typical H3F3A gene mutation and exhibited constant proliferation and invasive capabilities. After characterizing NCC-GCTB4-C1 cell behaviors, we conducted high-throughput screening of 214 anti-tumor drugs and identified seven effective drugs. Comparing the results of high-throughput screening using NCC-GCTB4-C1 cell line with the results using NCC-GCTB1-C1, NCC-GCTB2-C1, and NCC-GCTB3-C1 cell lines that we previously established, four drugs were in common effective. This study showed potential drugs for the treatment of GCTB. These data indicate that NCC-GCTB4-C1 has the potential to be a powerful tool in preclinical and basic research on GCTB.

Cell Biology of Giant Cell Tumour of Bone: Crosstalk between m/wt Nucleosome H3.3, Telomeres and Osteoclastogenesis

Giant cell tumour of bone (GCTB) is a rare and intriguing primary bone neoplasm. Worrisome clinical features are its local destructive behaviour, its high tendency to recur after surgical therapy and its ability to create so-called benign lung metastases (lung 'plugs'). GCTB displays a complex and difficult-to-understand cell biological behaviour because of its heterogenous morphology. Recently, a driver mutation in histone H3.3 was found. This mutation is highly conserved in GCTB but can also be detected in glioblastoma. Denosumab was recently introduced as an extra option of medical treatment next to traditional surgical and in rare cases, radiotherapy. Despite these new insights, many 'old' questions about the key features of GCTB remain unanswered, such as the presence of telomeric associations (TAs), the reactivation of hTERT, and its slight genomic instability. This review summarises the recent relevant literature of histone H3.3 in relation to the GCTB-specific G34W mutation and pays specific attention to the G34W mutation in relation to the development of TAs, genomic instability, and the characteristic morphology of GCTB. As pieces of an etiogenetic puzzle, this review tries fitting all these molecular features and the unique H3.3 G34W mutation together in GCTB.

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.

Targeted and immuno-based therapies in sarcoma: mechanisms and advances in clinical trials

Sarcomas represent a distinct group of rare malignant tumors with high heterogeneity. Limited options with clinical efficacy for the metastatic or local advanced sarcoma existed despite standard therapy. Recently, targeted therapy according to the molecular and genetic phenotype of individual sarcoma is a promising option. Among these drugs, anti-angiogenesis therapy achieved favorable efficacy in sarcomas. Inhibitors targeting cyclin-dependent kinase 4/6, poly-ADP-ribose polymerase, insulin-like growth factor-1 receptor, mTOR, NTRK, metabolisms, and epigenetic drugs are under clinical evaluation for sarcomas bearing the corresponding signals. Immunotherapy represents a promising and favorable method in advanced solid tumors. However, most sarcomas are immune "cold" tumors, with only alveolar soft part sarcoma and undifferentiated pleomorphic sarcoma respond to immune checkpoint inhibitors. Cellular therapies with TCR-engineered T cells, chimeric antigen receptor T cells, tumor infiltrating lymphocytes, and nature killer cells transfer show therapeutic potential. Identifying tumor-specific antigens and exploring immune modulation factors arguing the efficacy of these immunotherapies are the current challenges. This review focuses on the mechanisms, advances, and potential strategies of targeted and immune-based therapies in sarcomas.

Current Concepts in the Treatment of Giant Cell Tumors of Bone

Simple Summary

According to the 2020 World Health Organization classification, a giant cell tumor of bone is an intermediate malignant bone tumor. Denosumab treatment before curettage should be avoided due to the increased risk of local recurrence. Administration of denosumab before en bloc resection of the giant cell tumors of the pelvis and spine facilitates en bloc resection. Nerve-sparing surgery after embolization is a possible treatment for giant cell tumors of the sacrum. Denosumab therapy with or without embolization is indicated for inoperable giant cell tumors of the pelvis, spine, and sacrum. A wait-and-see approach is recommended for lung metastases at first, then denosumab should be administered to the growing lesions. Radiotherapy is not recommended owing to the risk of malignant transformation. Local recurrence after 2 years or more should be indicative of malignant transformation. This review summarizes the treatment approaches for non-malignant and malignant giant cell tumors of bone.

Abstract

The 2020 World Health Organization classification defined giant cell tumors of bone (GCTBs) as intermediate malignant tumors. Since the mutated H3F3A was found to be a specific marker for GCTB, it has become very useful in diagnosing GCTB. Curettage is the most common treatment for GCTBs. Preoperative administration of denosumab makes curettage difficult and increases the risk of local recurrence. Curettage is recommended to achieve good functional outcomes, even for local recurrence. For pathological fractures, joints should be preserved as much as possible and curettage should be attempted. Preoperative administration of denosumab for pelvic and spinal GCTBs reduces extraosseous lesions, hardens the tumor, and facilitates en bloc resection. Nerve-sparing surgery after embolization is a possible treatment for sacral GCTBS. Denosumab therapy with or without embolization is indicated for inoperable pelvic, spinal, and sacral GCTBs. It is recommended to first observe lung metastases, then administer denosumab for growing lesions. Radiotherapy is associated with a risk of malignant transformation and should be limited to cases where surgery is impossible and denosumab, zoledronic acid, or embolization is not available. Local recurrence after 2 years or more should be indicative of malignant transformation. This review summarizes the treatment approaches for non-malignant and malignant GCTBs.

Tumor microenvironment in giant cell tumor of bone: evaluation of PD-L1 expression and SIRPα infiltration after denosumab treatment

Giant cell tumor of bone (GCTB) is an intermediate malignant bone tumor that is locally aggressive and rarely metastasizes. Denosumab, which is a receptor activator of nuclear factor kappa B ligand (RANKL) inhibitor, can be used to treat GCTB. We focused on potential immunotherapy for GCTB and investigated the tumor microenvironment of GCTB. Programmed death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) expression and signal-regulatory protein alpha (SIRPα), forkhead box P3 (FOXP3), and cluster of differentiation 8 (CD8) infiltration were assessed by immunohistochemical studies of 137 tumor tissues from 96 patients. Of the naive primary specimens, 28% exhibited PD-L1 expression and 39% exhibited IDO1 expression. There was significantly more SIRPα⁺, FOXP3⁺, and CD8⁺ cell infiltration in PD-L1- and IDO1-positive tumors than in PD-L1- and IDO1-negative tumors. The frequency of PD-L1 expression and SIRPα⁺ cell infiltration in recurrent lesions treated with denosumab was significantly higher than in primary lesions and recurrent lesions not treated with denosumab. PD-L1 expression and higher SIRPα⁺ cell infiltration were significantly correlated with shorter recurrence-free survival. PD-L1 and SIRPα immune checkpoint inhibitors may provide clinical benefit in GCTB patients with recurrent lesions after denosumab therapy.

Late Local Recurrence of Bone Giant Cell Tumors Associated with an Increased Risk for Malignant Transformation

Simple Summary

In giant cell tumor of bone (GCTB), an intermediate malignant bone tumor, approximately 4% of cases can undergo malignant transformation. We analyzed risk factors for malignant transformation of GCTB treated without radiotherapy and retrospectively reviewed medical files of 461 patients with GCTB of the extremities who had undergone surgery alone, with no radiotherapy or denosumab therapy. Malignant transformation occurred in 15 of 461 patients (3.3%) at a median follow-up period of 192 months. The median follow-up duration was 89.4 months. Multivariate analysis revealed that local recurrence was an independent prognostic factor for unfavorable malignant transformation. The interval between the last surgery to local recurrence and malignant transformation was longer than that to local recurrence of benign GCTB, with a median of 15.2 (IQR, 5.2–25.4) years versus 1.3 (IQR, 0.8–2.6) months, respectively (p < 0.001). Late local recurrence of GCTB is associated with a higher risk of malignant transformation.

Abstract

In giant cell tumor of bone (GCTB), an intermediate malignant bone tumor, approximately 4% of all cases undergo malignant transformation. Accordingly, we analyzed risk factors for malignant transformation of GCTB treated without radiotherapy. We retrospectively reviewed medical records of 530 patients with GCTB of the extremities, admitted and treated at two institutions between January 1980 and December 2019. Overall, 4 patients with primary malignant GCTB, 4 patients with missing data, 3 patients with a history of radiotherapy, 22 patients with a follow-up of less than 6 months, and 36 patients who received denosumab were excluded. Accordingly, 461 patients were included for further analysis. Malignant transformation was observed in 15 of 461 patients (3.3%) at a median follow-up period of 192 months. The median follow-up duration was 89.4 months. Multivariate analysis revealed that local recurrence was an independent prognostic factor for unfavorable malignant transformation (Hazard ratio [HR], 11.33; 95% confidence interval [CI] 2.33–55.13; p = 0.003 for once versus none and HR, 11.24; 95% CI, 1.76–71.96; and p = 0.011 for twice or more versus none). The interval between the last surgery to local recurrence and malignant transformation was longer than that to local recurrence of benign GCTB, with a median of 15.2 years (interquartile range [IQR], 5.2–25.4) versus 1.3 months (IQR, 0.8–2.6), respectively (p < 0.001). Late local recurrence of GCTB is associated with a higher risk of malignant transformation.

Rechallenge of denosumab in jaw osteonecrosis of patients with unresectable giant cell tumour of bone: a case series analysis and literature review

Objectives

Giant cell tumour of bone (GCTB) is a rare tumour, generally managed with surgery. Treatment of the very rare unresectable advanced/metastatic GCTB is challenging and denosumab is the only current available medical option, an anti-RANKL monoclonal antibody inhibiting osteolysis. An uncommon but severe and treatment-limiting adverse event of denosumab is the osteonecrosis of the jaw (ONJ). The clinical management of GCTB patients stopping denosumab for medication-related (MR)-ONJ and the possible reintroduction of denosumab after MR-ONJ resolution is matter of debate. We performed a retrospective study to describe the incidence, clinical features and outcome of MR-ONJ in unresectable GCTB patients treated with denosumab at our Institution.

Design and setting

Retrospective, single-institutional study.

Participants

Adult patients receiving denosumab as antineoplastic therapy for GCTB and experiencing MR-ONJ at Fondazione IRCCS Istituto Nazionale Tumori of Milan between January 2008 and July 2019.

Main outcome measures

Incidence, time of onset and clinical features of MR-ONJ.

Results

29 patients with locally advanced and/or metastatic GCTB treated with denosumab were identified. At a median follow-up of 70 months (range 1–125), 4 (13.8%) patients experienced MR-ONJ while on treatment, after 125, 119, 85 and 41 months of denosumab, respectively. All patients showed an ongoing tumour stabilisation with denosumab at the MR-ONJ onset and in all cases denosumab was stopped. All four patients were treated with ozone therapy. Two are waiting for surgery, two were already operated on. Both of them experienced disease progression and were thus rechallenged with denosumab. One is still on therapy after 25 months. The other had an MR-ONJ relapse after 39 months and was treated again with ozone therapy and surgery. She is under surveillance, GCTB being currently stable.

Conclusion

A clinical algorithm of denosumab rechallenge after complete resolution of MR-ONJ in progressing GCTB patients should be prospectively validated.

Multiple Pulmonary Metastases of Recurrent Giant Cell Tumor of Bone with Expression of VEGFR-2 Successfully Controlled by Denosumab and Apatinib: A Case Report and Literature Review

Giant cell tumor of bone (GCTB) is a rare, benign, but locally aggressive bone tumor. It has a high tendency for local recurrence, which may increase the incidence of lung metastasis. Currently, an optimal treatment strategy has not been established because of the rarity of pulmonary metastatic GCTB. Denosumab is the preferred regimen for unresectable metastatic lesions; however, there are no alternative treatment options when patients are resistant to denosumab. Apatinib is a small-molecule tyrosine kinase inhibitor that selectively competes for the vascular endothelial growth factor receptor 2 (VEGFR-2) ATP binding site, and several studies have analyzed the effectiveness of apatinib in advanced or metastatic tumors. However, there is no report of apatinib as an anti-angiogenesis therapy for pulmonary metastatic GCTB to date. Here, we present a case of a 26-year-old female who was diagnosed with recurrent and pulmonary metastatic GCTB. Immunohistochemical (IHC) staining indicated that the tumor cells were positive for VEGFR-2. Denosumab was administered to control the metastases; nevertheless, disease progression was confirmed after four months of treatment. Given the IHC results and rapid disease progression, apatinib was added to the treatment strategy. After 42 months of treatment, the patient showed noticeable symptomatic improvement and considerable tumor shrinkage.

Personalized medicine modality based on patient-derived xenografts from a malignant transformed GCTB harboring H3F3A G34W mutation

Background

The function of H3F3A G43W mutation, which has been observed in almost all GCTB, remains poorly characterized. Breakthrough in malignant GCTB has been trapped by the lack of clinical available drugs, limited canonical patient samples and paucity of fidelity preclinical models.

Methods

Tumor samples obtained from a malignant GCTB was implanted in immunodeficient mice for the generation of PDX. Histological examination and short tandem repeat (STR) were used for inherited features analyses. An epigenetic/transcriptional targeted compound library was selected for drug screening. The in vivo effects of selected drug were validated in PDX model.

Results

We established the PDX model with recurrent malignant GCTB specimens, histological examination and STR analyses revealed that PDX and their corresponding parental patients shared the same STRs and histologic features, suggesting common origins. ITF-2357 was the most significant compound with an IC50 lower than 0.1 uM. The results of the drug screening and in vivo PDX validation demonstrated that ITF-2357 might be a promising drug targeted H3F3A G34W mutation MGCTBs.

Conclusion

Our study demonstrates that PDX model maintained the same histologic and genetic features as those in the original patient. targeting HDAC through ITF-2357 effectively overcomes malignant GCTB progression in vitro and in vivo.

Translational potential statement

As PDX retain the principal histologic and genetic characteristics of the primary tumors, mad it a valuable research tool in predictive clinical efficacy. In this study, we first established a malignant GCTB PDX model, which might further accelerate the progress of drug development in malignant GCTB.

Giant cell tumor of the thoracic spine causing acute paraplegia-a case report

Giant cell tumors (GCT) are rare and account for approximately 5% of all primary bone tumors. GCTs in the spine make up less than 10% of all GCTs, and less than 5% of all primary spinal tumors. Less than 10% of spinal GCTs occur above the sacrum and cases involving the thoracic spine are seldom reported in the literature. In our case the patient presented with acute paraplegia of bilateral lower extremities after being seen in the emergency department a day earlier. An MRI and CT scan demonstrated near complete destruction of T8 vertebral body with a possible pathologic lesion and fracture associated with dorsal and ventral spinal cord compression and significant signal change within the spinal cord. She underwent T7-T9 laminectomy with excisional biopsy and was subsequently diagnosed with a primary GCT of the thoracic spine. She was definitively treated with resection and T4-12 fusion and 120 mg of denosumab. At four years post follow-up there has been no recurrence of the tumor to date. This is a more acute presentation than has previously been reported. Patients with GCT of the spine typically present with pain and may have further progression to neurologic deficit. This patient's rapid onset of paraplegia is more acute than has been previously reported in the literature. The authors believe that prompt surgical excision and treatment with denosumab can completely resolve GCT of the thoracic spine.

Role of denosumab before resection and reconstruction in giant cell tumors of bone: a single-centered retrospective cohort study

BACKGROUND

Denosumab has been approved by Food and Drug Authority in 2013 for use in surgically unresectable Giant cell tumor (GCT) to achieve resectable tumor margins. The aim of this study is to investigate the functional outcome and surgical convenience with the use of neoadjuvant denosumab before resection and reconstruction in Campanacci grade III GCT.

METHODS

We retrospectively reviewed 70 cases of Campanacci grade III GCT receiving resection and reconstruction between January 2014 and December 2019. They were stratified into two groups: one group of 29 patients received once-weekly denosumab 120 mg for 4-weeks before resection and reconstruction, while the other group of 41 patients did not receive denosumab before resection and reconstruction. Quality of life by musculoskeletal tumor society score where 0-7 means poor, 8-14 means fair, 15-22 means good; above 22 means excellent, incidence of tumor recurrence, intraoperative duration in minutes and postoperative positive margins were assessed for each cohort after 12 months follow-up.

RESULTS

There was no significant difference in musculoskeletal tumor society score (25.75 vs. 27.41; P  = 0.178), incidence of recurrence (3.45% vs. 4.88%; P  < 0.001), and postoperative positive margins (10.34% vs. 4.88%; P  = 0.38) for both groups. However, the intraoperative duration (133.38 vs. 194.49; P  < 0.001) was significantly higher in the non-denosumab group compared with denosumab group.

CONCLUSIONS

Neoadjuvant denosumab is equally effective considering postoperative functional outcomes and surgical convenience except intraoperative duration where it is highly helpful in saving the operating time duration. Easier identification, resection and lesser reconstruction are the key surgical convenience offered by neoadjuvant denosumab.

Immuno-PET Molecular Imaging of RANKL in Cancer

PURPOSE

The involvement of RANK/RANKL signaling in the tumor microenvironment (TME) in driving response or resistance to immunotherapy has only very recently been recognized. Current quantification methods of RANKL expression suffer from issues such as sensitivity, variability, and uncertainty on the spatial heterogeneity within the TME, resulting in conflicting reports on its reliability and limited use in clinical practice. Non-invasive molecular imaging using immuno-PET is a promising approach combining superior targeting specificity of monoclonal antibodies (mAb) and spatial, temporal and functional information of PET. Here, we evaluated radiolabeled anti-RANKL mAbs as a non-invasive biomarker of RANKL expression in the TME.

EXPERIMENTAL DESIGN

Anti-human RANKL mAbs (AMG161 and AMG162) were radiolabeled with ⁸⁹Zr using the bifunctional chelator DFO in high yield, purity and with intact binding affinity. After assessing the biodistribution in healthy CD-1 nude mice, [⁸⁹Zr]Zr-DFO-AMG162 was selected for further evaluation in ME-180 (RANKL-transduced), UM-SCC-22B (RANKL-positive) and HCT-116 (RANKL-negative) human cancer xenografts to assess the feasibility of in vivo immuno-PET imaging of RANKL.

RESULTS

[⁸⁹Zr]Zr-DFO-AMG162 was selected as the most promising tracer for further validation based on biodistribution experiments. We demonstrated specific accumulation of [⁸⁹Zr]Zr-DFO-AMG162 in RANKL transduced ME-180 xenografts. In UM-SCC-22B xenograft models expressing physiological RANKL levels, [⁸⁹Zr]Zr-DFO-AMG162 imaging detected significantly higher signal compared to control [⁸⁹Zr]Zr-DFO-IgG2 and to RANKL negative HCT-116 xenografts. There was good visual agreement with tumor autoradiography and immunohistochemistry on adjacent slides, confirming these findings.

CONCLUSIONS

[⁸⁹Zr]Zr-DFO-AMG162 can detect heterogeneous RANKL expression in the TME of human cancer xenografts, supporting further translation of RANKL immuno-PET to evaluate tumor RANKL distribution in patients.

Denosumab for Effective Tumor Size Reduction in Patients With Giant Cell Tumors of the Bone: A Systematic Review and Meta-Analysis

BACKGROUND

Denosumab is a human monoclonal antibody that has been used successfully in the treatment of giant cell tumors of bone. These tumors are rare and, in principle, benign, but they are highly aggressive, locally advanced, osteolytic bone tumors that can metastasize to the lungs. Denosumab is an effective treatment when these tumors cannot be surgically removed or when surgical resection is likely to lead to severe morbidity (eg, loss of limbs or joints). The aim of this systematic review and meta-analysis was to investigate patients with giant cell tumors of bone who experienced tumor progression during treatment with denosumab and to compare them with patients who experienced reduction of their giant cell tumors of bone during treatment with denosumab.

METHODS

Embase, Cochrane Library, and MEDLINE/PubMed databases were searched for trials submitted by January 7, 2020, that reported the efficacy and safety of denosumab in patients with giant cell tumors of bone.

RESULTS

Sixty studies were reviewed, involving a total of 1074 patients who had giant cell tumors of bone and were treated with denosumab. Of the 60 studies, 58% of the patients were from case series studies, 39% from open-label phase II studies, and 3% from case reports. The response rate for denosumab as a treatment for giant cell tumors of bone was 97.5%, with statistical significance (P < .0001). Pain in the limbs was statistically the most common adverse event for denosumab treatment in case series studies (P < .0001). No treatment-related deaths occurred in the reviewed studies.

CONCLUSION

Cumulative evidence supports the addition of surgery to optimal medical therapy with denosumab to reduce tumor size, clinical symptoms, and mortality among patients with giant cell tumors of bone.

Radiological Assessment of Giant Cell Tumour of Bone in the Sacrum: From Diagnosis to Treatment Response Evaluation

Giant cell tumour of bone (GCTB) typically occurs in young adults from 20-40 years old. Although the majority of lesions are located in the epi-metaphyses of the long bones, approximately one third of tumours is located in the axial skeleton, of which only 4% in the sacrum. Sacral tumours tend to be large at the time of presentation, and they present with aggressive features such as marked cortical destruction and an associated soft tissue component. The 2020 World Health Organisation classification of Soft Tissue and Bone Tumours describes GCTB as neoplasm which is locally aggressive and rarely metastasizing. The tumour contains three different cell types: neoplastic mononuclear stromal cells, macrophages and osteoclast-like giant cells. Two tumour subtypes were defined: conventional GCTB and malignant GCTB. Only 1-4% of GCTB is malignant. In this review article, we will discuss imaging findings at the time of diagnosis to guide the musculoskeletal radiologist in reporting these tumours. In addition, imaging for response evaluation after various treatment options will be addressed, such as surgery, radiotherapy, embolization and denosumab. Specific findings will be presented per imaging modality and illustrated by cases from our tertiary sarcoma referral center. Common postoperative and post radiotherapy findings in GCTB of the sacrum on MRI will be discussed.

Anti-IL17 antibody Secukinumab therapy is associated with ossification in giant cell tumor of bone: a case report of pathologic similarities and therapeutic potential similar to Denosumab

Background

Giant cell tumor of bone is a benign, locally aggressive neoplasm. Surgical resection is the preferred treatment method. However, for cases in which resection poses an increased risk to the patient, denosumab (anti-RANKL monoclonal antibody) is considered. Secukinumab is an anti-IL-17 antibody that is used in psoriatic arthritis to reduce bone resorption and articular damage.

Case presentation

One case of giant cell tumor of bone (GCTB) in a patient treated with secukinumab for psoriatic arthritis demonstrated findings significant for intra-lesional calcifications. Histologic examination showed ossification, new bone formation, and remodeling. A paucity of osteoclast type giant cells was noted. Real-time quantitative polymerase-chain-reaction (qRT-PCR) analysis revealed decreased osteoclast function compared to treatment-naive GCTB.

Conclusions

Secukinumab may play a role in bone remodeling for GCTB. Radiologists, surgeons, and pathologists should be aware of this interaction, which can cause lesional ossification. Further research is required to define the therapeutic potential of this drug for GCTB and osteolytic disease.

Denosumab Treatment for Giant Cell Tumors, Aneurysmal Bone Cysts, and Fibrous Dysplasia-Risks and Benefits

PURPOSE OF REVIEW

This review summarizes current understanding of the role of denosumab, an inhibitor of receptor activator of nuclear kappa-B ligand (RANKL), in the management of 3 skeletal neoplasms: giant cell tumors, aneurysmal bone cysts, and fibrous dysplasia.

RECENT FINDINGS

A growing body of literature supports denosumab use in giant cell tumors, a neoplasm in which RANKL plays a clear pathogenic role. Comparatively less data is available in aneurysmal bone cysts and fibrous dysplasia; however, the pathogenic similarity of these disorders to giant cell tumors, as well as encouraging preliminary data, suggests denosumab may be useful. Denosumab's inhibitory effects on bone turnover are fully reversible after drug discontinuation. This raises important unanswered questions for clinical management, including potential risks of tumor recurrence and bone turnover rebound. Denosumab is a promising potential treatment for skeletal neoplasms. However, its clinical use is impacted by ongoing safety concerns related to postdiscontinuation rebound, particularly in children. There is a critical need to understand denosumab treatment and discontinuation effects on tumor recurrence and to develop strategies for long-term treatment in patients who cannot be managed surgically.

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.

The Role of Denosumab for Surgical Outcomes in Patients with Giant Cell Tumour of Bone: A Systematic Review

Background: The role of denosumab in patients with resectable giant cell tumour of bone remains unclear. We asked the following research question: for patients (aged ≥ 12 years) with resectable giant cell tumour of bone, what are the benefits and harms of denosumab compared with no denosumab in terms of (1) facilitation of surgery (operative time, blood loss), (2) disease recurrence, (3) pain control, (4) disease stability, and (5) adverse effects (e.g., malignant transformation, osteonecrosis of jaw, atypical femur fracture)? One previous systematic review addressed only one outcome-disease recurrence. Therefore, we undertook this new systematic review to address the above five outcomes. Methods: MEDLINE, EMBASE, PubMed, and Cochrane Database of Systematic Reviews databases were searched on June 30, 2020. Results: This systematic review included one previous systematic review and five comparative studies. Due to poor quality, non-randomized studies fraught with selection bias, it is difficult to determine if a significant difference exists in the outcomes for surgical giant cell tumour of bone with perioperative denosumab. There were no reported cases of adverse effects from denosumab. Conclusion: To date, there is insufficient evidence to understand the value of denosumab in the perioperative setting in patients with giant cell tumour of bone.

Profiling of three H3F3A-mutated and denosumab-treated giant cell tumors of bone points to diverging pathways during progression and malignant transformation

Giant cell tumor of bone (GCTB) is a locally aggressive lesion of intermediate malignancy. Malignant transformation of GCTB is a rare event. In 2013, the humanized monoclonal antibody against receptor activator of nuclear factor-κb-Ligand (RANKL) denosumab was approved for treatment of advanced GCTB. Since then, several reports have questioned the role of denosumab during occasional malignant transformation of GCTB. We report on three patients with H3F3A-mutated GCTBs, treated with denosumab. The tissue samples were analysed by histomorphology, immunohistochemistry, and in two instances by next generation panel sequencing of samples before and after treatment. One patient had a mutation of ARID2 in the recurrence of the GCTB under treatment with denosumab. One patient developed a pleomorphic sarcoma and one an osteoblastic osteosarcoma during treatment. Sequencing revealed a persisting H3F3A mutation in the osteosarcoma while the pleomorphic sarcoma lost the H3F3A mutation; however, a FGFR1 mutation, both in the recurrence and in the pleomorphic sarcoma persisted. In addition, the pleomorphic sarcoma showed an AKT2 and a NRAS mutation. These data are inconclusive concerning the role denosumab plays in the event of malignant progression/transformation of GCTB and point to diverging pathways of tumor progression of GCTB associated with this treatment.

Denosumab Treatment for Giant Cell Tumor of the Spine Including the Sacrum

STUDY DESIGN

This was a subanalysis of an international, multicenter, open-label study.

OBJECTIVE

The aim of this study was to assess the efficacy and safety of denosumab in a subset of patients with giant cell tumors of bone (GCTB) of the spine including the sacrum from an international, open-label, single-arm, phase 2 study (ClinicalTrials.gov: NCT00680992).

SUMMARY OF BACKGROUND DATA

Standard GCTB treatment is surgical removal, either by curettage or resection, combined with intraoperative adjuvant therapy; however, some sites may not be amenable to resection (e.g., skull, spine).

METHODS

Adults or skeletally mature adolescents with pathologically confirmed GCTB of the spine including the sacrum, and radiologically measurable evidence of active disease, were included. Patients received denosumab (120 mg subcutaneously) once every 4 weeks during the treatment phase, with loading doses on days 8 and 15 of the first cycle. Patients had surgically unsalvageable GCTB (Cohort 1), had planned surgery expected to result in severe morbidity (Cohort 2), or were enrolled from a previous GCTB study (Cohort 3).

RESULTS

Overall, 132 patients were included in the safety analysis (103 in Cohort 1, 24 in Cohort 2, and five in Cohort 3); 131 patients were included in the efficacy analysis. Kaplan-Meier estimated probabilities of disease progression or recurrence were 3% (95% confidence interval [CI], 0.0-6.2) at year 1 and 7.4% (95% CI, 2.1-12.7) at years 3 and 5 in Cohort 1, and not estimable in Cohorts 2 and 3. Of 23 patients (Cohort 2) with surgery planned at baseline, 10 (43%) had on-study surgery; of these, one patient had reported disease progression or recurrence after the on-study surgery. Clinical benefit was reported in 83% of patients overall (all cohorts).

CONCLUSION

Results from the analysis suggest that denosumab is potentially effective treatment for patients with GCTB of the spine including the sacrum. The adverse event profile was consistent with the full study population.Level of Evidence: 2.

Pictilisib Enhances the Antitumor Effect of Doxorubicin and Prevents Tumor-Mediated Bone Destruction by Blockade of PI3K/AKT Pathway

Despite advances in neoadjuvant chemotherapy, outcomes for patients with osteosarcoma resistant to first-line chemotherapy have been dismal for decades. There is thus an urgent need to develop novel targeted drugs to effectively treat refractory osteosarcoma. Dysregulation in the PI3K/AKT pathway has been observed during the development of osteosarcoma. Herein, we first evaluated p-AKT (Ser473) expression levels in osteosarcoma tissue using high-throughput tissue microarrays. Then, we demonstrated the role of pictilisib, a novel potent PI3K inhibitor, in osteosarcoma and related osteolysis. Functional studies of pictilisib in osteosarcoma cell lines and bone marrow-derived macrophages were performed in vitro. Patient-derived xenografts and orthotopic mouse models were used to assess the effects of pictilisib in vivo. The results showed that positive p-AKT expression levels after neoadjuvant chemotherapy were significantly associated with tumor cell necrosis rate. Pictilisib effectively inhibited the proliferation of osteosarcoma through G0/G1-S phase cell cycle arrest, and enhanced the sensitivity of osteosarcoma to doxorubicin, although it failed to induce cell apoptosis alone. In addition, pictilisib inhibited differentiation of osteoclasts and bone resorption in vitro and tumor-related osteolysis in vivo via inhibition of the PI3K/AKT/GSK3β and NF-κB pathways. Pictilisib combined with conventional chemotherapy drugs represents a potential treatment strategy to suppress tumor growth and bone destruction in p-AKT-positive patients.

Malignancy in giant cell tumor of bone: analysis of an open-label phase 2 study of denosumab

Background

Giant cell tumor of bone (GCTB) is a rare osteoclastogenic stromal tumor. GCTB can rarely undergo malignant transformation. This post hoc analysis evaluated and classified malignancies in patients with GCTB who received denosumab.

Methods

This analysis was conducted on patients with pathologically confirmed GCTB and measurable active disease treated with denosumab 120 mg subcutaneously once every 4 weeks, with loading doses on study days 8 and 15, as part of a phase 2, open-label, multicenter study. We identified potential cases of malignancy related to GCTB through an independent multidisciplinary review or medical history, associated imaging or histopathologic reports, and disease course. The findings were summarized and no statistical analysis was performed.

Results

Twenty of five hundred twenty-six patients (3.8%) who received at least one dose of denosumab were misdiagnosed with GCTB that was later discovered to be malignancies: five primary malignant GCTB, five secondary malignant GCTB, four sarcomatous transformations, and six patients with other malignancies (giant cell-rich osteosarcoma, undifferentiated pleomorphic sarcoma, spindle cell sarcoma, osteogenic sarcoma, phosphaturic mesenchymal tumor of mixed connective tissue type, and fibrosarcoma/malignant fibrous histiocytoma). Many malignancies were present before denosumab was initiated (8 definitive cases, 7 likely cases), excluding potential involvement of denosumab in these cases. Signs associated with potential misdiagnoses of GCTB included poor mineralization with denosumab treatment, rapid relapse in pain, or a failure of the typical dramatic improvement in pain normally observed with denosumab.

Conclusions

Although rare, GCTB can undergo malignant transformation, and rates in this study were consistent with previous reports. Signs of poor mineralization or lack of response to denosumab treatment may warrant close monitoring.

Trial registration

clinicaltrials.gov, (NCT00680992). Registered May 20, 2008.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07739-8.

The role of Denosumab in joint preservation for patients with giant cell tumour of bone

AIMS

Local recurrence remains a challenging and common problem following curettage and joint-sparing surgery for giant cell tumour of bone (GCTB). We previously reported a 15% local recurrence rate at a median follow-up of 30 months in 20 patients with high-risk GCTB treated with neoadjuvant Denosumab. The aim of this study was to determine if this initial favourable outcome following the use of Denosumab was maintained with longer follow-up.

METHODS

Patients with GCTB of the limb considered high-risk for unsuccessful joint salvage, due to minimal periarticular and subchondral bone, large soft tissue mass, or pathological fracture, were treated with Denosumab followed by extended intralesional curettage with the goal of preserving the joint surface. Patients were followed for local recurrence, metastasis, and secondary sarcoma.

RESULTS

A total of 25 patients with a mean age of 33.8 years (18 to 67) with high-risk GCTB received median six cycles of Denosumab before surgery. Tumours occurred most commonly around the knee (17/25, 68%). The median follow-up was 57 months (interquartile range (IQR) 13 to 88). The joint was salvaged in 23 patients (92%). Two required knee arthroplasty due to intra-articular fracture and arthritis. Local recurrence developed in 11 patients (44%) at a mean of 32.5 months (3 to 75) following surgery, of whom four underwent repeat curettage and joint salvage. One patient developed secondary osteosarcoma and another benign GCT lung metastases.

CONCLUSION

The use of Denosumab for joint salvage was associated with a higher than expected rate of local recurrence at 44%. Neoadjuvant Denosumab for joint-sparing procedures should be considered with caution in light of these results. Cite this article: Bone Joint J 2021;103-B(1):184-191.

Immunohistochemical Characterization of Giant Cell Tumor of Bone Treated With Denosumab: Support for Osteoblastic Differentiation

Giant cell tumor of bone is a locally aggressive, rarely metastasizing neoplasm. Evidence suggests that the neoplastic cells may be osteoblastic in differentiation. Standard treatment is surgical removal, but medical therapy with denosumab, an inhibitor of receptor activator of nuclear factor-κβ ligand, has become a component of patient management in select cases. Denosumab-treated giant cell tumor of bone (DT-GCTB) shows drastic morphologic changes including the presence of abundant bone. To further determine the relationship of the neoplastic cells to osteoblast phenotype, we performed a morphologic and immunohistochemical study on a series of DT-GCTB. Cases of DT-GCTB were retrieved from surgical pathology files, available slides were reviewed, and immunohistochemistry for H3.3 G34W, SATB2, and p63 was performed. The cohort included 31 tumors from 30 patients (2:3 male:female), ages 15 to 73 years (median=36 y). The morphology of post-denosumab-treated tumors ranged from tumors composed of an abundant bone matrix with few spindle cells to spindle cell-predominant tumors. Five had focal residual classic CGTB, and 2 manifested mild nuclear atypia. The majority expressed all markers: 86.2% for H3.3 G34W, 96.7% for SATB2, and 100% for p63. All markers stained the various tumor components including spindle cells and the cells on the surface of and within the treated tumor bone matrix. Most markers were also positive in reactive-appearing woven bone adjacent to tumor: 84.6% for H3.3 G34W, 100% for SATB2, and 68% for p63. These findings suggest that denosumab treatment of giant cell tumor of bone results in osteoblastic differentiation with bone production.

Preoperative Denosumab may increase the Risk of Local Recurrence of Giant-cell Tumor of Bone Treated with Curettage: A Systematic Review and Meta-analysis

Objective: This systematic review and meta-analysis aimed to determine the effect of preoperative denosumab on the local recurrence of giant-cell tumor of bone (GCTB) treated with curettage. Methods: PubMed, Embase, Cochrane Library, and Web of Science were comprehensively searched. The following data were analyzed using meta-analysis: local recurrence rate of patients receiving denosumab followed by curettage (denosumab group), local recurrence rate of patients receiving curettage only (control group), and a comparison of the local recurrence rates of the two groups. Results: Nine studies that contained 672 patients with GCTB were included in this review. Patients in the denosumab group (preoperative denosumab followed by curettage) had a higher risk of local recurrence compared with those in the control group (curettage only) (odds ratio = 3.04, 95% confidence interval = 1.48-6.22, P < 0.01). The association between preoperative denosumab and local recurrence remained significant in most of the subgroup analyses, except for those with sample sizes < 59 (P = 0.09), sacral GCTB (P = 0.42), and usage of postoperative denosumab (P = 0.38). Conclusions: Preoperative denosumab may increase the risk of local recurrence of GCTB treated with curettage and should be used with caution in the management of GCTB.

Current concepts in the treatment of giant cell tumour of bone

PURPOSE OF REVIEW

Giant cell tumour of bone (GCTB) is an intermediate, locally aggressive primary bone tumour. In addition to local therapy, new drugs became available for this disease. Denosumab, a receptor activator of nuclear factor κ-B-ligand inhibitor, was introduced as systemic targeted therapy for advanced or inoperable and metastatic GCTB. Also, the bisphosphonate zoledronic acid has activity in GCTB by directly targeting the neoplastic stromal cells.

RECENT FINDINGS

In a small RCT, bisphosphonates were successful in controlling tumour growth and a higher apoptotic index of tumour cells was seen after zoledronic acid versus controls. Although bisphosphonate-loaded bone cement has not been studied to a large extent, it does not seem harmful and may constitute a logical local adjuvant. From the largest clinical trial to date, the risk-to-benefit ratio for denosumab in patients with advanced GCTB remains favourable, also in facilitating less morbid surgery. Concerns have arisen that recurrence rates would be higher than after conventional treatment, ranging from 20 to 100% in a systematic review, although this may be because of bias. H3F3A (G34W) driver mutations are helpful in the differentiation between GCTB and other giant cell-containing malignancies. H3.3-G34W proved sufficient to drive tumourigenesis. The cumulative incidence of malignancy in GCTB is estimated at 4%, of which primary malignancy 1.6% and secondary malignancy 2.4%, the latter mainly after radiation. To date, a potential causal relationship between denosumab and pulmonary metastases has not been confirmed; if they do not behave indolently, it would be advised to reassess diagnosis and consider malignancy.

SUMMARY

Denosumab remains a highly effective treatment option for patients with advanced GCTB. A short duration of 2-4 months neoadjuvant denosumab is advised to facilitate less morbid surgery and prevent incomplete curettage by macroscopic tumour alterations. Reduced dose intensity is being studied to reduce long term side-effects. Further research on bisphosphonates and other targets including H3.3-G34W remains warranted.

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.

Advances in the Management of Pediatric Sarcomas

PURPOSE OF REVIEW

The prognosis of pediatric patients who present with metastatic or recurrent sarcomas remains poor. In this review, we summarize the advances in the management of metastatic and relapsed pediatric sarcoma by highlighting recent and future clinical trials.

RECENT FINDINGS

Research into the identification of novel therapies for refractory pediatric sarcomas continues to advance. Outcomes have not improved in several decades underlying a need for improved understanding of the biology behind these tumors and the identification of novel therapeutic molecular targets that can be exploited pharmacologically. Multiple challenges remain for novel therapy in sarcomas such as the selection of effective targets, management of toxicities, and the tumor microenvironment. Many unique challenges remain in the treatment of patients with refractory pediatric sarcomas. Multiple strategies and targets are under investigation that hold promise.

Adjuvant Alendronic Acid in the Management of Severe Cherubism: A Case Report and Literature Review

Cherubism is a rare disease of the jaws characterized by bilateral symmetrical painless expansion of the mandible and maxilla. In extreme cases, larger lesions can become exophytic and have profound functional and esthetic implications. Several pharmacologic agents have been trialed in the treatment of cherubism with variable success reported. Bisphosphonates have not been significantly studied in this setting. We present a case where oral alendronic acid was used as an adjuvant treatment after surgical debulking of the maxilla in a 13-year-old boy with a severe case of cherubism.

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.

The impact of curettage technique on local control in giant cell tumour of bone

INTRODUCTION

Although consensus has been reached regarding the main aspects of intralesional surgery for giant cell tumour of the bone (GCTB), debates continue about the most effective combination of local adjuvants. The purpose of study was to analyze the previous experience and determine the most effective curettage approach for GCTB.

METHODS

We summarized the findings from 89 papers published from 1962 to 2020 related to this subject. Database consisted of 137 treated groups that included 6441 patients who underwent different curettage techniques without pre-operative administration of bisphosphonates or RANKL inhibitors.

RESULTS

Recurrence rates after simple curettage ranged between 27 and 82% with a median value at 47%. The use of one or two local adjuvants reduced the incidence of recurrences approximately by 50% when compared with simple curettage. High-speed burring combined with chemical adjuvants or followed by poly(methyl methacrylate) cementation with or without bone grafting further improved the local control leading to good and excellent results; however, these were not documented in all studies. Simultaneous use of burring, chemical adjuvants, and cementation, which we named here as combined curettage, allowed to down local relapses to the range of 0-26%, with a median at 11%. Oncologic outcomes after combined curettage are significantly better when compared with simple curettage (p < 0.0001) and other variants of enhancement (p = 0.001).

CONCLUSIONS

Combined curettage appears to provide the most potent and comprehensive impact on residual tumour cells located in risk zones. This approach should be considered for locally advanced tumours when function-preserving surgery is planned. Additional comparative studies are required to define the optimal curettage enhancement for each individual patient.

Denosumab in Giant Cell Tumor of Bone: Current Status and Pitfalls

Denosumab is a monoclonal antibody against RANK ligand for treatment of giant cell tumor of bone (GCTB). Clinical trials and case series have demonstrated that denosumab is relevant to beneficial tumor response and surgical down-staging in patients of GCTB. However, these trials or case series have limitations with a short follow-up. Recent increasing studies revealed that denosumab probably increased the local recurrence risk in patients treated with curettage. This may be caused by the thicken bone margin of tumor that trapped tumor cells from curettage. The direct bone formation by tumor cells in the margin after denosumab treatment also contributed to the local recurrence. in vitro studies showed denosumab resulted in a cytostatic instead of a true cytotoxic response on neoplastic stromal cells. More importantly, denosumab-treated GCTB exhibited morphologic overlap with malignancy, and a growing number of patients of malignant transformation of GCTB during denosumab treatment have been reported. The optimal duration, long term safety, maintenance dose, and optimum indications remain to be elucidated. With these concerns in mind, this review warns that the denosumab therapy of GCTB should be applied with caution.

Denosumab for cancer-related bone loss

INTRODUCTION

Prolonged use of anti-cancer treatments in breast and prostate tumors alters physiological bone turnover leading to adverse skeletal related events, such as osteoporosis, loss of bone mass, and increased risk of fractures. These complications known as cancer treatment-induced bone loss (CTIBL) should be managed with bone targeting agents such as the bisphosphonates and denosumab. The latter is a monoclonal antibody against the receptor activator of nuclear factor-kB ligand (RANKL) that suppresses osteoclasts function and survival increasing bone mass.

AREAS COVERED

This review will focus on the mechanisms associated with bone loss induced by cancer treatments and the most recent evidence about the use of denosumab as preventive and therapeutic strategy to protect bone health. Moreover, we will discuss several key aspects regarding the clinical practical use of denosumab to optimize the management of CTLIB in breast and prostate cancer.

EXPERT OPINION

Denosumab treatment strongly prevents cancer therapies-related skeletal issues in breast and prostate cancer with a good safety profile. Adjuvant six-monthly denosumab delays the time to first fracture onset in early stage breast cancer patients with normal or altered bone mineral density (BMD). Similarly, denosumab treatment is able to prevent fractures and BMD loss in nonmetastatic prostate cancer patients.

Radiological findings of denosumab treatment for giant cell tumours of bone

Giant cell tumours of bone (GCTB) are benign giant cell-rich tumours typically occurring in the epi-metaphysis of skeletally mature patients. Despite their benign classification, GCTB may be locally aggressive with local recurrence as a challenging issue. Denosumab is a human monoclonal antibody that inhibits osteolysis via the RANK-RANK ligand pathway. There is currently no consensus on optimal treatment duration or imaging modality for monitoring patients on denosumab therapy. This review illustrates the radiological findings of GCTB on denosumab treatment seen on plain radiographs, CT, MRI, PET-CT and DEXA, with reference to the current literature. Recognizing imaging features indicative of a positive response to denosumab is important for therapeutic decision-making. Imaging findings with respect to duration of denosumab treatment, tumour upregulation during treatment, tumour recurrence and malignant transformation are discussed. The development of a sclerotic neocortex and varying degrees of matrix osteosclerosis are seen on plain radiographs. Reconstitution of subarticular bone and articular surface irregularity are optimally evaluated on CT which can also quantify tumour density. MRI demonstrates heterogeneous low signal matrix and is useful to assess decrease in size of cystic and/or soft tissue components of GCTB. A fat-suppressed fluid-sensitive MR sequence is important to detect tumour reactivation. Reduction in 18F-FDG-PET avidity represents an early sensitive sign of response to denosumab treatment. Regardless of imaging modality, close follow-up in a specialist centre and careful evaluation of nonresponders is necessary as local recurrence after cessation of denosumab treatment and malignant transformation of GCTB have been described.

Benign Osseous Tumors and Tumor-Like Conditions

We will provide an imaging-focused discussion of 3 benign bone tumors that do not fit in the categories of cartilaginous tumors or osteoid tumors. We have chosen giant cell tumor of bone, unicameral bone cyst, and fibrous dysplasia. All 3 of these entities are common enough that one does not have to be a musculoskeletal radiologist in a cancer hospital to encounter them occasionally, but none of them should be seen frequently.

Chondroblastoma's Lung Metastases Treated with Denosumab in Pediatric Patient

Chondroblastoma is a rare benign chondrogenic tumor that occurs in skeletally immature patients between ages 10 and 20 years old. In literature are reported few cases of lung metastases, mainly occurred after surgery or local recurrences. There is no evidence on the pathogenesis of lung metastasis, as well as pulmonary disease course. Few treatments for metastases with aggressive behavior were based on chemotherapy regimen employed in other sarcoma with no results or not satisfying ones. Denosumab is approved for treatment of giant cell tumors and it is under investigation for other giant cell-rich bone tumors. Here, we report a case of a 16-year-old male chondroblastoma of the left humerus with bilateral lung metastases at presentation and progressing during follow-up, treated with denosumab for almost 2 years. We confirm that denosumab treatment can be effective in controlling chondroblastoma metastasis and it has been a safe procedure in an adolescent patient.

Significance of EGFR/HER2 Expression and PIK3CA Mutations in Giant Cell Tumour of Bone Development

Giant Cell Tumour of Bone (GCTB) is a rare bone tumour. Locally aggressive and recurrent, it might evolve into pulmonary metastases. Our present work is aimed at investigating the involvement of the epidermal growth factor receptor (ErbB) family and its downstream effectors in the development and recurrence of GCTB. For this purpose, we used a cohort of 32 GCTB patients and we evaluated the clinicohistological features and the expression of RANKL, EGFR, and HER2. The mutation status of KRAS, PI3KCA, and PTEN gene as potential oncogene involved in GCTB was also evaluated. We found a significant correlation between advanced histological stages, overexpression of EGFR/HER2, and tumour recurrence. Moreover, two mutations were found in the PIK3CA gene: a missense mutation, 1634A>C, detected for the first time in GCTB patients, without influencing the stability of the protein, and a frameshift mutation, c.1658_1659delGTinsC, causing the loss of the protein kinase domain. Altogether, these results suggest that overexpression of HER2/EGFR, Campanacci, and histological stages could be used as a novel prognostic marker for GCTB recurrence.

Giant Cell Tumors of the Upper Extremity: Predictors of Recurrence

PURPOSE

Giant cell tumors (GCT) of the distal radius are thought to be more aggressive than in other locations. Therefore, the aim of this study was to investigate factors associated with recurrence of GCTs in the upper extremity.

METHODS

We retrospectively identified 82 patients who underwent primary surgical treatment for an upper extremity GCT. Tumors were located in the radius (n = 47), humerus (n = 17), ulna (n = 9), and hand (n = 9). Treatment consisted of either wide resection or amputation or intralesional resection with or without adjuvants. A multivariable logistic regression was performed including tumor grade, type of surgery, and tumor location, from which the percentage of contribution to the model of each variable was calculated.

RESULTS

The recurrence rate after intralesional resection was 48%; after wide resection or amputation, it was 12%. Two patients developed a pulmonary metastasis (2.4%). In multivariable analysis, intralesional resection was independently associated with recurrence. Intralesional resection had a 77% contribution to predict recurrence and the distal radius location had a 16% contribution in the predictive model.

CONCLUSIONS

As expected, intralesional resection was the strongest independent predictor of recurrence after surgical treatment for GCT. The distal radius location contributed to the prediction of giant cell tumor recurrence to a lesser extent.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Role of (Neo)adjuvant Denosumab for Giant Cell Tumor of Bone

OPINION STATEMENT

Denosumab is a RANK ligand inhibitor approved for the treatment of giant cell tumor of bone. While the role of denosumab in the setting of advanced and unresectable disease is well established, its role in surgically resectable disease is currently under discussion. Several prospective and retrospective series on neoadjuvant therapy in potentially resectable tumor with high morbidity surgery reported a relapse rate of 10-20% after resection and 30-40% after curettage. At the same time, less morbid surgery has obvious clinical advantages for the patient, and several studies have shown the efficacy of denosumab in downgrading of the surgical procedure. Currently, the role of neoadjuvant denosumab in operable GCTB is limited to selected cases in which a diffuse reactive bone formation and peripheral ossification can make an easier surgical procedure, for example, in tumors with a large soft tissue component. A planned resection may become less morbid when preoperative denosumab is administered. Whenever a segmental resection is thought to be indicated at diagnosis, denosumab may be considered in the neoadjuvant setting. A preoperative course of 6 months is considered safe and effective. Two case scenarios are presented and critically discussed. Because of the high recurrence rates after denosumab treatment followed by curettage, we discourage the use of denosumab when curettage is considered feasible. In this setting, a short course of preoperative denosumab (2-6 months) may be considered for highly selected cases, for example in pathological fractures. The role of adjuvant denosumab needs further investigation. Long-term disease control has been reported in case of non-surgical lesions, even after treatment interruption, but there is no consensus on ideal treatment duration and dosage for these scenarios. In all cases, multidisciplinary discussion with oncology, pathologist, radiologist, and surgeons is mandatory. Patient's comorbidities, dental conditions, and preferences, including family planning, should always be taken into account.

The two faces of giant cell tumor of bone

Giant cell tumor (GCT) is a bone-destructive benign neoplasm characterized by distinctive multinucleated osteoclast-like giant cells with osteolytic properties distributed among neoplastic stromal cells. GCT is locally aggressive with progressive invasion of adjacent tissues and occasionally displays malignant characteristics including lung metastasis. GCT is characterized genetically by highly recurrent somatic mutations at the G34 position of the H3F3A gene, encoding the histone variant H3.3, in stromal cells. This leads to deregulated gene expression and increased proliferation of mutation-bearing cells. However, when GCT complicates Paget disease of bone (GCT/PDB) it behaves differently, showing a more malignant phenotype with 5-year survival less than 50%. GCT/PDB is caused by a germline mutation in the ZNF687 gene, which encodes a transcription factor involved in the repression of genes surrounding DNA double-strand breaks to promote repair by homologous recombination. Identification of these driver mutations led to novel diagnostic tools for distinguishing between these two tumors and other osteoclast-rich neoplasms. Herein, we review the clinical, histological, and molecular features of GCT in different contexts focusing also on pharmacological treatments.

The evaluation and treatment of Paget's disease of bone

Paget's disease of bone is a localized skeletal disorder, which is more common in England and in countries to which the English migrated. In recent decades, the prevalence in most countries has decreased. A family history of the disorder is present in approximately 15% of patients. Patients may be asymptomatic and may be diagnosed accidently as a consequence of an elevated serum alkaline phosphatase level or a finding on an x-ray or nuclear bone scan. The diagnosis is made by x-ray but nuclear bone scans define the extent of the disease. Salmon calcitonin and bisphosphonate drugs have proven effective, but by far, the most effective therapy is a single 5 mg intravenous infusion of zoledronic acid. This can normalize alkaline phosphatase levels for up to 6.5 years. A variety of gene mutations may predispose individuals to develop the disease but environmental factors such as measles virus likely play an important role.