Radiological findings of denosumab treatment for giant cell tumours of bone

A Case of Giant Cell Tumor of the Fibula

N/a.

Efficacy and safety of denosumab de‑escalation in giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a locally aggressive intermediate bone tumor. Denosumab has shown effectiveness in GCTB treatment; however, the benefits of denosumab de-escalation for unresectable GCTB have not been well discussed. The present study investigated the efficacy and safety of denosumab de-escalation for GCTB. The medical records of 9 patients with unresectable GCTB or resectable GCTB not eligible for resection, who received de-escalated denosumab treatment at Okayama University Hospital (Okayama, Japan) between April 2014 and December 2021, were retrospectively reviewed. The denosumab treatment interval was gradually extended to every 8, 12 and 24 weeks. The radiographic changes and clinical symptoms during standard and de-escalated denosumab therapy were assessed. The denosumab interval was de-escalated after a median of 12 months of a standard 4-weekly treatment. Imaging showed that the re-ossification of osteolytic lesions obtained with the 4-weekly treatment were sustained with 8- and 12-weekly treatments. The extraskeletal masses reduced significantly with standard treatment, while tumor reduction was sustained during de-escalated treatment. During the 24-weekly treatment, 2 patients remained stable, while 2 patients developed local recurrence. The clinical symptoms improved significantly with standard treatment and remained improved during de-escalated treatment. There were severe adverse events including osteonecrosis of the jaw (2 patients), atypical femoral fracture (1 patient) and malignant transformation of GCTB (1 patient). In conclusion, 12-weekly de-escalated denosumab treatment showed clinical benefits as a maintenance treatment in patients with unresectable GCTB, in addition to sustained stable tumor control and improved clinical symptoms with standard treatment. A 24-weekly treatment can also be administered, with careful attention paid to detecting local recurrence.

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.

Diagnosis and monitoring denosumab therapy of giant cell tumors of bone: radiologic-pathologic correlation

OBJECTIVE

To determine the value of CT and dynamic contrast-enhanced (DCE-)MRI for monitoring denosumab therapy of giant cell tumors of bone (GCTB) by correlating it to histopathology.

MATERIALS AND METHODS

Patients with GCTB under denosumab treatment and monitored with CT and (DCE-)MRI (2012-2021) were retrospectively included. Imaging and (semi-)quantitative measurements were used to assess response/relapse. Tissue samples were analyzed using computerized segmentation for vascularization and number of neoplastic and giant cells. Pearson's correlation/Spearman's rank coefficient and Kruskal-Wallis tests were used to assess correlations between histopathology and radiology.

RESULTS

Six patients (28 ± 8years; five men) were evaluated. On CT, good responders showed progressive re-ossification (+7.8HU/month) and cortical remodeling (woven bone). MRI showed an SI decrease relative to muscle on T1-weighted (-0.01 A.U./month) and on fat-saturated T2-weighted sequences (-0.03 A.U./month). Time-intensity-curves evolved from a type IV with high first pass, high amplitude, and steep wash-out to a slow type II. An increase in time-to-peak (+100%) and a decrease in Ktrans (-71%) were observed. This is consistent with microscopic examination, showing a decrease of giant cells (-76%), neoplastic cells (-63%), and blood vessels (-28%). There was a strong statistical significant inverse correlation between time-to-peak and microvessel density (ρ = -0.9, p = 0.01). Significantly less neoplastic (p = 0.03) and giant cells (p = 0.04) were found with a time-intensity curve type II, compared to a type IV. Two patients showed relapse after initial good response when stopping denosumab. Inverse imaging and pathological findings were observed.

CONCLUSION

CT and (DCE-)MRI show a good correlation with pathology and allow adequate evaluation of response to denosumab and detection of therapy failure.

Investigation of Giant Cell Tumor of Bone and Tissue Engineering Approaches for the Treatment of Giant Cell Tumor of Bone

Primary bone tumors such as Ewing sarcoma, osteosarcoma, and chondrosarcoma, secondary bone tumors developed from progressive malignancies, and metastasized bone tumors are more prevalent and studied descriptively through biology and medical research. Less than 0.2% of cancer diagnoses are caused by rare bone-originating tumors, which despite being rare are particularly difficult due to their high death rates and substantial disease burden. A giant cell tumor of bone (GCTB) is an intramurally invasive but rare and benign type of bone tumor, which seldom metastasizes. The most often prescribed medication for GCTB is Denosumab, a RANKL (receptor activator of nuclear factor κB ligand) inhibitor. Because pharmaceutical drug companies rely on two-dimensional and animal models, current approaches for investigating the diverse nature of tumors are insufficient. Cell line based medication effectiveness and toxicity studies cannot predict tumor response to antitumor medicines. It has already been investigated in detail why molecular pathways do not reproduce in vitro, a phenomenon known as flat biology. Due to physiological differences between human beings and animals, animal models do not succeed in identifying side effects of the treatment, emulating metastatic growth, and establishing the link between cancer and the immune system. This review summarizes and discusses GCTB, the disease, its cellular composition, various bone tumor models, and their properties and utilization in research. As a result, this study delves deep into in vitro testing, which is vital for scientists and physicians in various fields, including pharmacology, preclinical investigations, tissue engineering, and regenerative medicine.

Characterization of denosumab treatment response in giant cell tumors of bone with dynamic contrast-enhanced MRI

RATIONALE AND OBJECTIVES

Denosumab is a monoclonal antibody used neo-adjuvantly in giant cell tumor of bone (GCTB) to facilitate surgery, or long term for axial tumors where surgery comes with high morbidity. Time intervals for treatment effects to occur are unclear and monitoring tools are limited, complicating optimal drug dose titration. We assessed changes in time intensity curve (TIC) - derived perfusion features on DCE-MRI in GCTB during denosumab treatment and evaluated the duration of treatment effects on tumor perfusion.

MATERIALS AND METHODS

Patients with GCTB who underwent dynamic contrast enhanced (DCE) MRI before (t = 0) and after 3 (t = 3), 6 (t = 6) or 12 (t = 12) months of denosumab treatment were retrospectively included in a single center. Regions of interest were placed on tumor compartments with visually most intense enhancement and TICs were created. Time-to-enhancement (TTE), wash-in rate (WIR), maximal relative enhancement (MRE), and area-under-the-curve (AUC) were calculated. Differences in perfusion features were calculated with the Wilcoxon signed-rank test.

RESULTS

In all 24 patients decreased perfusion on DCE-MRI after start of denosumab treatment was seen. TTE increased between t = 0 and t = 3 (p < 0.001). WIR, MRE and AUC decreased between t = 0 and t = 3 (p < 0.001, p = 0.01 and p = 0.02, respectively). No significant differences in features were found between t = 3 and t = 6 or t = 6 and t = 12. No significant perfusion differences in primary versus recurrent, or axial versus appendicular tumors, were found.

CONCLUSION

MRI perfusion significantly changed in GCTB within 3 months of denosumab treatment compared to baseline. No further significant change occurred between 3 and 6, and 6 and 12 months of treatment. These findings suggest that evaluation of treatment response and subsequent consideration of maintenance with lower doses of denosumab, may already be indicated after 3 months. In cases where long term denosumab is the preferred therapy, monitoring change in tumor characteristics on DCE-MRI may aid optimal drug dose titration, minimizing side effects.

Giant Cell Tumour of Bone: A Comprehensive Review of Pathogenesis, Diagnosis, and Treatment

The benign aggressive tumour known as a giant cell tumour of bone (GCTB) frequently affects the knee bones. Patients suffering from GCTB present with pain, swelling, joint effusion, loss of ability to bear weight on the involved extremity and a restriction in the range of motion of the afflicted joint may also exist, depending on the tumour's size. GCTB makes up 20% of benign skeletal tumours and 5% of all primary bone tumours. Although it has an equal distribution of the sexes, the majority reveal a higher frequency among women. Eighty per cent of GCTB instances were recorded in patients between the ages of 20 and 50 during the third decade. The femur, tibia and radius are where GCTB is most frequently discovered. Lesions can be rated using the Campanacci grading method based on the plain radiograph's results. Plain radiography, CT and MRI are used to diagnose the tumour. Surgery is the only curative treatment which is determined by the Campanacci grade and the tumour's location. Recurrence of GCTB is observed in about 25% of patients, with curettage being associated with rates as high as 50%. We evaluated the GCTB-related articles and summarised the developments in diagnosis, treatment and reducing risk of recurrence.

A systematic review of radiomics in giant cell tumor of bone (GCTB): the potential of analysis on individual radiomics feature for identifying genuine promising imaging biomarkers

PURPOSE

To systematically assess the quality of radiomics research in giant cell tumor of bone (GCTB) and to test the feasibility of analysis at the level of radiomics feature.

METHODS

We searched PubMed, Embase, Web of Science, China National Knowledge Infrastructure, and Wanfang Data to identify articles of GCTB radiomics until 31 July 2022. The studies were assessed by radiomics quality score (RQS), transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) statement, checklist for artificial intelligence in medical imaging (CLAIM), and modified quality assessment of diagnostic accuracy studies (QUADAS-2) tool. The radiomic features selected for model development were documented.

RESULTS

Nine articles were included. The average of the ideal percentage of RQS, the TRIPOD adherence rate and the CLAIM adherence rate were 26%, 56%, and 57%, respectively. The risk of bias and applicability concerns were mainly related to the index test. The shortness in external validation and open science were repeatedly emphasized. In GCTB radiomics models, the gray level co-occurrence matrix features (40%), first order features (28%), and gray-level run-length matrix features (18%) were most selected features out of all reported features. However, none of the individual feature has appeared repeatably in multiple studies. It is not possible to meta-analyze radiomics features at present.

CONCLUSION

The quality of GCTB radiomics studies is suboptimal. The reporting of individual radiomics feature data is encouraged. The analysis at the level of radiomics feature has potential to generate more practicable evidence for translating radiomics into clinical application.

Giant cell tumor of bone: An update, including spectrum of pathological features, pathogenesis, molecular profile and the differential diagnoses

Giant cell tumor of bone (GCTB) is an enigmatic tumor. Despite its benign histological appearance and clinical behavior in most cases, it is associated with recurrences, uncommonly metastasis, and rarely with a malignant transformation. During the last few years, there has been a significant evolution in the diagnosis and management of GCTB, including discoveries related to the underlying pathogenesis (RANK/RANK/OPG pathway), with treatment-related implications in the form of denosumab (approved inhibitor for targeting RANKL), leading to improved surgical resections, especially in cases of recurrent, large and borderline resectable tumors. Lately, a specific Histone mutation, namely H3.3G34W underlying almost all GCTBs has been discovered, further leading to the identification of a highly sensitive and specific immunohistochemical antibody marker, H3.3G34W, which is very useful for an exact diagnosis of a GCTB, including its differentiation from its various mimics, which has significant implications. This review describes clinicopathological features of a GCTB, including its variable features, recent concepts, underlying pathogenesis, post-denosumab related changes and various entities that constitute its differential diagnosis, including their molecular signatures, with treatment-related implications.

Malignant Transformation of Giant Cell Tumour of Bone: A Review of Literature and the Experience of a Referral Centre

Giant cell tumour of bone (GCTB) is a benign, locally aggressive primary bone neoplasm that represents 5% of all bone tumours. The principal treatment approach is surgery. Although generally GCTB is considered only a locally aggressive disease, it can metastasise, and lung metastases occur in 1–9% of patients. To date, only the use of denosumab has been approved as medical treatment for GCTB. Even more rarely, GCTB undergoes sarcomatous transformation into a malignant tumour (4% of all GCTB), but history of this malignant transformation is unclear and unpredictable. Considering the rarity of the event, the data in the literature are few. In this review, we summarise published data of GCTB malignant transformation and we analyse three cases of malignant transformation of GCTB, evaluating histopathology, genetics, and radiological aspects. Despite the rarity of this event, we conclude that a strict follow up is recommended to detect early malignant transformation.

Global Prevalence and Risk of Local Recurrence following Cryosurgery of Giant Cell Tumour of Bone: A Meta-Analysis

Simple Summary

Giant cell tumours are benign but locally aggressive and can potentially metastasise to the lungs. Reducing the risk of local recurrence while maintaining limb function and minimising adverse consequences is the best therapeutic strategy in treating giant cell tumours. Based on our observation through this meta-analysis, cryosurgery is one of the viable treatment options that can provide good oncologic and functional outcomes with minimal complication rates.

Abstract

The challenge in the surgical treatment of giant cell tumours of bone is the relatively high recurrence rate after curettage alone. The use of a local adjuvant following curettage, on the other hand, has lowered the rate of recurrence. This systematic review and meta-analysis aimed to investigate the prevalence and risk of local recurrence of giant cell tumours of the bone after cryosurgery and the subsequent complications. Web of Science, Scopus, ScienceDirect, PubMed, and Google Scholar were searched to identify articles published until 13 October 2021. A random-effects model was used to examine the pooled prevalence and risk ratio (RR) of local recurrence in patients with giant cell tumours after cryosurgery with 95% confidence intervals (CIs). This study was registered with PROSPERO (CRD42020211620). A total of 1376 articles were identified, of which 38 studies (n = 1373, 46.2% male) were included in the meta-analysis. Following cryosurgery, the pooled prevalence of local recurrence in giant cell tumours was estimated as 13.5% [95% CI: 9.3–17.8, I² = 63%], where European subjects exhibited the highest prevalence (24.2%). Compared to other local adjuvants. The RR of local recurrence following cryosurgery was 0.85 (95% CI: 0.63–1.17, I² = 15%), which was not statistically significant compared to other local adjuvants. We found 3.9% fracture, 4.0% infection, 2.1% nerve injury, and 1.5% skin necrosis as the common complications. Based on the sensitivity analyses, this study is robust and reliable. This meta-analysis estimated a low prevalence of local recurrence of giant cell tumours with low complications following cryosurgery. Thus, it can be one of the adjuvant options for treating giant cell tumours.

Updated concepts in treatment of giant cell tumor of bone

PURPOSE OF REVIEW

Giant cell tumors of bone (GCTB) are intermediate, locally aggressive primary bone tumors. For conventional GCTB, surgery remains treatment of choice. For advanced GCTB, a more important role came into play for systemic therapy including denosumab and bisphosphonates over the last decade.

RECENT FINDINGS

In diagnostics, focus has been on H3F3A (G34) driver mutations present in GCTB. The most frequent mutation (G34W) can be detected using immunohistochemistry and is highly specific in differentiating GCTB from other giant cell containing tumors. PD-L1 expression can be used as biological marker to predict higher recurrence risks in GCTB patients.The use of bisphosphonate-loaded bone cement is under investigation in a randomized controlled trial. A new technique consisting of percutaneous microwave ablation and bisphosphonate-loaded polymethylmethacrylate cementoplasty was proposed for unresectable (pelvic) GCTB.Increased experience with use of denosumab raised concern on elevated recurrence rates. However, conclusions of meta-analyses should be interpreted with risk of indication bias in mind. Several small studies are published with short-course denosumab (varying from 3 to 6 doses). One small trial directly compared denosumab and zoledronic acid, with no statistical differences in radiological and clinical outcome, and nonsignificantly higher recurrence rate after denosumab. As bisphosphonates directly target neoplastic stromal cells in GCTB, larger directly comparative trials are still warranted.

SUMMARY

Neoadjuvant denosumab is highly effective for advanced GCTB, and a short-course is advised to facilitate surgery, whereas increased recurrence rates remain of concern. Randomized controlled trials are conducted on bisphosphonate-loaded bone cement and on optimal dose and duration of neoadjuvant denosumab. PD-L1 could be a potential new therapy target in GCTB.

Malignant Transformation of Giant Cell Tumor of Bone and the Association with Denosumab Treatment: A Radiology and Pathology Perspective

Objective

Malignancy in giant cell tumor of bone (mGCTB) is categorized as primary (concomitantly with conventional GCTB) or secondary (after radiotherapy or other treatment). Denosumab therapy has been suggested to play a role in the etiology of secondary mGCTB. In this case series from a tertiary referral sarcoma center, we aimed to find distinctive features for malignant transformation in GCTB on different imaging modalities. Furthermore, we assessed the duration of denosumab treatment and lag time to the development of malignancy.

Methods

From a histopathology database search, 6 patients were pathologically confirmed as having initial conventional GCTB and subsequently with secondary mGCTB.

Results

At the time of mGCTB diagnosis, 2 cases were treated with denosumab only, 2 with denosumab and surgery, 1 with multiple curettages and radiotherapy, and 1 with surgery only. In the 4 denosumab treated patients, the mean lag time to malignant transformation was 7 months (range 2–11 months). Imaging findings suspicious of malignant transformation related to denosumab therapy are the absence of fibro-osseous matrix formation and absent neocortex formation on CT, and stable or even increased size of the soft tissue component.

Conclusion

In 4 patients treated with denosumab, secondary mGCTB occurred within the first year after initiation of treatment. Radiotherapy-associated mGCTB has a longer lag time than denosumab-associated mGCTB. Close clinical and imaging follow-up during the first months of denosumab therapy is key, as mGCTB tends to have rapid aggressive behavior, similar to other high-grade sarcomas. Nonresponders should be (re) evaluated for their primary diagnosis of conventional GCTB.

Denosumab for central giant cell granuloma in an Australian tertiary paediatric centre

BACKGROUND

Central giant cell granulomas (CGCG) are rare osteolytic, benign but often locally aggressive tumours of bone. Surgical curettage may not be possible in extensive lesions and resection carries high morbidity, especially in growing children, and previous medical therapies have had variable efficacy and 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.

AIMS

To evaluate the efficacy and safety of our protocol for denosumab treatment of CGCG in children.

METHODS

Retrospective review of 4 patients treated with denosumab using a standardised protocol for CGCG in a tertiary paediatric centre. Denosumab 70 mg/m² was given 4-weekly, followed by 2 doses of zoledronate 0.025 mg/kg, aimed at preventing rebound hypercalcaemia.

RESULTS

Treatment of CGCG resulted in metabolic remission in all patients, but recurrence, detected by positron emission tomography (PET), occurred at 6 months in three patients and 12 months in one patient. Three patients developed symptomatic hypercalcaemia 4-5 months and one patient asymptomatic hypercalcaemia 7 months after cessation of denosumab, with 3 requiring additional bisphosphonate treatment.

CONCLUSIONS

Denosumab produced a radiological and metabolic response in our patients, but metabolic recurrence occurred in all patients. PET imaging was effective for monitoring treatment response and early detection of recurrence. Incidence of rebound hypercalcaemia in this paediatric cohort was high. We present proposed changes to our protocol with the aim of producing sustained remission and preventing rebound hypercalcaemia.

Denosumab in Giant Cell Tumor of Bone: Multidisciplinary Medical Management Based on Pathophysiological Mechanisms and Real-World Evidence

Simple Summary

The widely accepted local therapy in extremity giant cell tumor of bone (GCTB) is surgery, in the form of extended intralesional curettage with adequate disease clearance and retention of the limb, wherever possible. Denosumab is a relevant therapy option for advanced GCTB, to benefit tumor response and surgical down-staging. Most GCTB patients with localized disease can be successfully treated with surgical curettage; patients with primary unresectable lesions or metastases may experience long-term clinical and radiological remission and pain control with denosumab treatment, and in this clinical situation, denosumab is currently the treatment of choice.

Abstract

(1) Despite the benign nature of the giant cell tumor of bone (GCTB), it shows a local recurrence rate of up to 50% and a chance of malignant transformation. The widely accepted local therapy in extremity GCTB is surgery, in the form of extended intralesional curettage with adequate disease clearance and retention of the limb, wherever possible. Denosumab, a human monoclonal antibody directed against the RANKL and associated inhibition of the RANKL pathway, is a relevant therapy option for advanced GCTB, to benefit tumor response and surgical down-staging. (2) The literature review of patients with GCTB treated with denosumab is performed via PubMed, using suitable keywords from January 2009 to January 2021. (3) Current indications for denosumab use are not definitively clear and unambiguous. Most GCTB patients with localized disease can be successfully treated with surgical curettage, and the role of denosumab in preoperative therapy in this patient population remains unclear. (4) However, patients with primary unresectable lesions or metastases may experience long-term clinical and radiological remission and pain control with denosumab treatment, and in this clinical situation, denosumab is currently the treatment of choice.

Malignant giant cell tumour of bone: a review of clinical, pathological and imaging features

Giant cell tu mour accounts for up to 5% of all bone tumours and malignant giant cell tumour arises in < 10% of cases, representing sarcomatous transformation. Primary malignant giant cell tumour of bone occurs when sarcomatous tissue is observed within conventional giant cell tumour histologically on initial presentation. Secondary malignant giant cell tumour of bone occurs in a region of previously treated giant cell tumour, with most cases arising due to prior radiotherapy. Malignancy in giant cell tumour of bone does not have any unique clinical or imaging features compared to conventional aggressive disease. Historically, malignant giant cell tumour of bone has a poor prognosis which is worse in cases of secondary malignancy. This article aims to present the clinical, pathological and imaging features of MGCTB based on a review of the literature and illustrated by examples from our experience.

State of the Art and New Concepts in Giant Cell Tumor of Bone: Imaging Features and Tumor Characteristics

Giant cell tumor of bone (GCTB) is classified as an intermediate malignant tumor due to its locally aggressive behavior, burdened by high local recurrence rate. GCTB accounts for about 4-5% of all primary bone tumors and typically arises in the metaphysis and epiphyses of the long tubular bones. Mutation of gene H3F3A is at the basis of GCTB etiopathogenesis, and its immunohistochemical expression is a valuable method for practical diagnosis, even if new biomarkers have been identified for early diagnosis and for potential tumor recurrence prediction. In the era of computer-aided diagnosis, imaging plays a key role in the assessment of GCTB for surgical planning, patients' prognosis prediction and post treatment evaluation. Cystic changes, penetrating irregular margins and adjacent soft tissue invasion on preoperative Magnetic Resonance Imaging (MRI) have been associated with a higher rate of local recurrence. Distance from the tumor edge to the articular surface and thickness of unaffected cortical bone around the tumor should be evaluated on Computed Tomography (CT) as related to local recurrence. Main features associated with local recurrence after curettage are bone resorption around the graft or cement, soft tissue mass formation and expansile destruction of bone. A denosumab positive response is represented by a peripherical well-defined osteosclerosis around the lesion and intralesional ossification. Radiomics has proved to offer a valuable contribution in aiding GCTB pre-operative diagnosis through clinical-radiomics models based on CT scans and multiparametric MR imaging, possibly guiding the choice of a patient-tailored treatment. Moreover, radiomics models based on texture analysis demonstrated to be a promising alternative solution for the assessment of GCTB response to denosumab both on conventional radiography and CT since the quantitative variation of some radiomics features after therapy has been correlated with tumor response, suggesting they might facilitate disease monitoring during post-denosumab surveillance.

Denosumab for craniofacial fibrous dysplasia: duration of efficacy and post-treatment effects

Denosumab has been advocated as a potential treatment for the rare skeletal disorder fibrous dysplasia (FD); however, there is limited data to support safety and efficacy, particularly after drug discontinuation. We report a case of successful treatment of aggressive craniofacial FD with denosumab, highlighting novel insights into the duration of efficacy, surrogate treatment markers, and discontinuation effects. A 13-year-old girl presented with persistent pain and expansion of a maxillary FD lesion, which was not responsive to repeated surgical procedures or bisphosphonates. Pre-treatment biopsy showed high RANKL expression and localization with proliferation markers. Denosumab therapy was associated with improved pain, decreased bone turnover markers, and increased lesion density on computed tomography scan. During 3.5 years of treatment, the patient developed increased non-lesional bone density, and after denosumab discontinuation, she developed hypercalcemia managed with bisphosphonates. Pain relief and lesion stability continued for 2 years following treatment, and symptom recurrence coincided with increased bone turnover markers and decreased lesion density back to pre-treatment levels. This case highlights the importance of considering the duration of efficacy when treating patients with FD and other nonresectable skeletal neoplasms that require long-term management.

New Target for Precision Medicine Treatment of Giant-Cell Tumor of Bone: Sunitinib Is Effective in the Treatment of Neoplastic Stromal Cells with Activated PDGFRβ Signaling

Simple Summary

The purpose of this study was to analyze differential cell signaling in response to denosumab treatment to identify and subsequently inhibit molecular targets in the neoplastic stromal cell population, which poses a risk for tumor recurrence. Using phosphoprotein arrays, a distinct signaling profile was detected in GCTB tissues treated with denosumab, a specific RANKL antibody, which coincided with the RTK profile in derived cell lines. PDGFRβ was selected as a promising receptor target, and its inhibition by the small-molecule inhibitor sunitinib resulted in potent inhibition of cell proliferation in vitro. The addition of sunitinib to denosumab resulted in the disappearance of both multinuclear giant cells and neoplastic stromal cells, as reported here. Thus, sunitinib could become an effective addition to denosumab in the treatment of GCTB with activated PDGFRβ.

Abstract

Giant-cell tumor of bone (GCTB) is an intermediate type of primary bone tumor characterized by locally aggressive growth with metastatic potential. The aim of this study was to identify new druggable targets among the cell signaling molecules involved in GCTB tumorigenesis. Profiles of activated signaling proteins in fresh-frozen tumor samples and tumor-derived cell lines were determined using phosphoprotein arrays. Analysis of the obtained data revealed epidermal growth factor receptor (EGFR) and platelet-derived growth factor receptor beta (PDGFRβ) as potential targets, but only the PDGFR inhibitor sunitinib caused a considerable decrease in stromal cell viability in vitro. Furthermore, in the case of a 17-year-old patient suffering from GCTB, we showed that the addition of sunitinib to the standard treatment of GCTB with the monoclonal antibody denosumab resulted in the complete depletion of multinucleated giant cells and mononuclear stromal cells in the tumor tissue. To summarize, the obtained data showed that a specific receptor tyrosine kinase (RTK) signaling pattern is activated in GCTB cells and plays an important role in the regulation of cell proliferation. Thus, activated RTKs and their downstream signaling pathways represent useful targets for precision treatment with low-molecular-weight inhibitors or with other types of modern biological therapy.

The current standing on the use of denosumab in giant cell tumour of the bone

Giant cell tumour of the bone (GCTB) has been classically treated surgically. With the advent of denosumab, there is potential to use it as a targeted therapy to downstage the tumour and control its progression. Like all new therapies, the dosage, duration, and long-term effects of treatment can only be determined over the time through numerous trials and errors. The current recommendation of use of the monoclonal antibody is 3-4 months of neoadjuvant denosumab in patients with advanced GCTB for cases who were not candidates for primary curettage initially, and prolonged use for surgically unsalvageable GCTB. The use of Denosumab in the adjuvant setting to prevent recurrence is not established.

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.

The use of denosumab in the setting of acute pathological fracture through giant cell tumour of bone

Background

Denosumab (Xgeva^TM) is a fully human antibody to RANK-Ligand, an important signal mediator in the pathogenesis of giant cell tumour of bone (GCTB). The use of denosumab in the treatment of GCTB has changed the way in which these tumours are managed over the past years.

Case presentation

Described is the case of an acute fracture through a GCTB of the distal radius of a fit and well 32-year-old, non-smoking, female patient following a simple fall onto her outstretched, dominant hand. The aim was to enable joint sparing management for the patient, as opposed to an acute fusion procedure of the carpus. The patient underwent percutaneous k-wire fixation with application of plaster and immediate commencement with denosumab to halt the activity of the GCTB. Bone healing was rapid; plaster and k-wires were removed after 6 weeks. At 6 months denosumab, was ceased and an open curettage and grafting procedure of the tumour bed was undertaken (using MIIG X3, Wright Medical, aqueous calcium sulphate as graft material).

Conclusions

The use of denosumab in the acute setting of pathological fracture through giant cell tumour of bone allowing joint salvage has not been previously described. The treatment was well tolerated and functional outcomes are excellent, with very promising 4-year follow-up.

This novel approach may allow for more joint sparing strategies in the future for other patients in this difficult situation. Further cases will need to be gathered to establish this technique as a suitable treatment pathway.

Therapy-Related Imaging Findings in Patients with Sarcoma

Knowledge of imaging findings related to therapy administered to patients with sarcoma is pivotal in selecting appropriate care for these patients. Imaging studies are performed as surveillance in asymptomatic patients or because symptoms, including anxiety, develop. In addition to detection of recurrent disease and assessment of response to therapy, diagnosis of conditions related to therapy that may or may not need treatment has a marked positive impact on quality of life. The purpose of this review is to assist radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients in recognizing imaging findings related to therapy and not to activity of the previously treated sarcoma. Imaging findings are time dependent and often specific in relation to therapy given.