Systemic treatment in advanced phyllodes tumor of the breast: a multi-institutional European retrospective case-series analyses.

BACKGROUND: We aimed at investigating outcome of systemic treatments in advanced breast PT. METHODS: All cases of advanced breast PT treated with systemic treatments from 1999 to 2019, in one of the referral sarcoma centers involved in the study, were retrospectively reviewed. RESULTS: 56 female patients were identified. Median age was 52 (range of 25-76) years. Patients received a median number of 2 systemic treatments (range of 1-4). Best responses according to RECIST were 1 (3.7%) CR, 11 (40.7%) PR, 6 (22.2%) SD, 9 (33.3%) PD with anthracyclines plus ifosfamide (AI); 2 (16.7%) PR, 4 (33.3%) SD, 6 (50.0%) PD with anthracycline alone; 3 (18.8%) PR, 4 (25.0%) SD, 9 (56.3%) PD with high-dose ifosfamide given as a continuous infusion (HD-IFX); 3 (20.0%) SD, 12 (80.0%) PD with a gemcitabine-based regimen (with 2 patients not evaluable); 1 (8.3%) PR, 2 (16.7%) SD, 9 (75.0%) PD with trabectedin (with 1 patient not evaluable); 1 (16.7%) PR, 1 (16.7%) SD, 4 (66.7%) PD with tyrosine-kinase inhibitors (TKI). The median PFS were 5.7 (IQR 2.5-9.1) months with AI; 3.2 (IQR 2.2-5.0) months with anthracycline alone; 3.4 (IQR 1.4-6.7) months with HD-IFX; 2.1 (IQR 1.4-5.2) months with gemcitabine-based chemotherapy; 1.8 (IQR 0.7-6.6) months with trabectedin; 3.4 (IQR 3.1-3.8) months with TKI. With a median follow-up of 35.3 (IQR 17.6-66.9) months, OS from the start of first-line systemic treatment was 15.2 (IQR 7.6-39.6) months. CONCLUSION: In this series of advanced PT (to our knowledge, the largest reported so far), AI was associated with a high rate of responses, however, with a median PFS of 5.7 months. Other systemic treatments were poorly active.

Final analysis of the randomized trial on imatinib as an adjuvant in localized gastrointestinal stromal tumors (GIST) from the EORTC Soft Tissue and Bone Sarcoma Group (STBSG), the Australasian Gastro-Intestinal Trials Group (AGITG), UNICANCER, French Sarcoma Group (FSG), Italian Sarcoma Group (ISG), and Spanish Group for Research on Sarcomas (GEIS)☆.

BACKGROUND: In 2004, we started an intergroup randomized trial of adjuvant imatinib versus no further therapy after R0-R1 surgery in localized, high/intermediate-risk gastrointestinal stromal tumors (GIST) patients. Interim analysis results were published in 2015 upon recommendation from an independent data review committee. We report the final outcome of the study. PATIENTS AND METHODS: This was a randomized, open-label, multicenter phase III trial carried out at 112 hospitals in 12 countries. Patients were randomized to 2 years of imatinib, 400 mg daily, or no further therapy after surgery. The primary endpoint was imatinib failure-free survival (IFFS), while relapse-free survival (RFS), relapse-free interval (RFI), overall survival (OS) and toxicity were secondary endpoints. Adjusting for the interim analyses, results on IFFS were assessed on a 4.3% significance level; for the other endpoints, 5% was used. RESULTS: Nine hundred and eight patients were randomized between January 2005 and October 2008: 454 to imatinib and 454 to observation; 835 patients were eligible. With a median follow-up of 9.1 years, 5 (10)-year IFFS was 87% (75%) in the imatinib arm versus 83% (74%) in the control arm [hazard ratio (HR) = 0.87, 95.7% confidence interval (CI) (0.65; 1.15), P = 0.31]; RFS was 70% versus 63% at 5 years and 63% versus 61% at 10 years, [HR = 0.71, 95% CI (0.57; 0.89), P = 0.002]; OS was 93% versus 92% at 5 years and 80% versus 78% at 10 years [HR = 0.88, 95% CI (0.65; 1.21), P = 0.43]. Among 526 patients with high-risk GIST by local pathology, 10-year IFFS and RFS were 69% versus 61%, and 48% versus 43%, respectively. CONCLUSIONS: With 9.1 years of follow-up, a trend toward better long-term IFFS in imatinib-treated patients was observed in the high-risk subgroup. Although the difference was not statistically significant and the surrogacy value of such an endpoint is not validated, this may be seen as supporting the results reported by the Scandinavian/German trial, showing a sustained small but significant long-term OS benefit in high-risk GIST patients treated with 3 years of adjuvant imatinib.

GEIS-21: a multicentric phase II study of intensive chemotherapy including gemcitabine and docetaxel for the treatment of Ewing sarcoma of children and adults: a report from the Spanish sarcoma group (GEIS).

BACKGROUND: First Spanish trial of Ewing sarcoma (ES) including adults and children with the aim to test the efficacy of Gemcitabine and Docetaxel (G/D) in newly diagnosed high-risk (HR) patients. METHODS: This was a prospective, multicentric, non-randomised, open study for patients ⩽40 years with newly diagnosed ES. HR patients (metastatic, axial-pelvic primaries or bone marrow micrometastasis) received 2 window cycles of G/D. Patients with an objective response (OR) to G/D received 12 monthly cycles of G/D after completion of mP6. The primary end point was the OR rate to the G/D window phase and the event-free survival (EFS) and overall survival (OS) for all patients. The study is registered at ClinicalTrials.gov (identifier: NCT00006734). RESULTS: Forty-three patients were enroled, median age 17 years (range, 3-40). After a median follow-up of 43.4 months, the 5-year OS rate is 55.0% (95% CI, 41-74%) with an EFS of 50.0% (95% CI, 36-68%). The 5-year OS and EFS rates for standard risk (SR) patients was 76.0% (95% CI, 57-100%) and 71.0% (CI, 54-94%); for HR 36.0% (CI, 20-65%) and 29.0% (CI, 15-56%). Twelve of 17 (70.6%) high-risk (HR) patients showed an OR (7 PR and 5 SD) to G/D window therapy. The 5-year OS rate for patients ⩽18 years of age was 74.0% (CI, 56-97%) and 31.0% for >18 years (95% CI, 15-66%), P<0.001. Grade 4 adverse events during mP6 occurred in 28/39 of patients (72%) and did not correlate with age. Multivariate survival analyses with <18 vs ⩾18 and risk groups significant differences, P<0.00001. Using a Cox model for OS, both age and risk group were statistically significant (P=0.0011 and P=0.0065, respectively). CONCLUSIONS: Age at diagnosis is an independent prognostic factor superior to the presence of metastases with 18 years as the strongest cut-off. The mP6 regimen provided survival curves that plateau at 3 years and G/D produced significant responses in HR-ES that is worth further exploring.

Gemcitabine plus sirolimus for relapsed and progressing osteosarcoma patients after standard chemotherapy: a multicenter, single-arm phase II trial of Spanish Group for Research on Sarcoma (GEIS).

BACKGROUND: Patients with relapsed unresectable osteosarcoma represents an unmet need, so active and safe systemic treatments are required. Fas cell surface death receptor and mammalian target of rapamycin pathways are implicated in progressing osteosarcoma, and we had preclinical and clinical experience with a scheme that targets both pathways. Therefore, we designed a phase II trial with gemcitabine plus rapamycin, to determine the efficacy and safety, in this subset of patients. PATIENTS AND METHODS: A multicenter, single-arm phase II trial was sponsored by the Spanish Group for Research on Sarcoma. Osteosarcoma patients, relapsed or progressing after standard chemotherapy and unsuitable for metastasectomy received gemcitabine and rapamycin p.o. 5 mg/day except for the same day of gemcitabine administration, and the day before. The main end point was 4-month progression-free survival rate (PFSR), with the assumption that rates higher than 40% would be considered as an active regimen. Translational research aimed to correlate biomarkers with the clinical outcome. RESULTS: Thirty-five patients were enrolled and received at least one cycle. PFSR at 4 months was 44%, and after central radiologic assessment, 2 partial responses and 14 stabilizations (48.5%) were reported from 33 assessable patients. The most frequent grade 3-4 adverse events were: neutropenia (37%), thrombocytopenia (20%), anemia (23%), and fatigue (15%); however, only three patients had febrile neutropenia. Positive protein expression of RRM1 significantly correlated with worse PFS and overall survival, while positivity of P-ERK1/2 was correlated with significant better overall survival. CONCLUSION: Gemcitabine plus sirolimus exhibits satisfactory antitumor activity and safety in this osteosarcoma population, exceeding the prespecified 40% of 4-month PFSR. The significant correlation of biomarkers with clinical outcome encourages further prospective investigation.

Best practices for the management of local-regional recurrent chordoma: a position paper by the Chordoma Global Consensus Group.

Chordomas are rare, malignant bone tumors of the skull-base and axial skeleton. Until recently, there was no consensus among experts regarding appropriate clinical management of chordoma, resulting in inconsistent care and suboptimal outcomes for many patients. To address this shortcoming, the European Society of Medical Oncology (ESMO) and the Chordoma Foundation, the global chordoma patient advocacy group, convened a multi-disciplinary group of chordoma specialists to define by consensus evidence-based best practices for the optimal approach to chordoma. In January 2015, the first recommendations of this group were published, covering the management of primary and metastatic chordomas. Additional evidence and further discussion were needed to develop recommendations about the management of local-regional failures. Thus, ESMO and CF convened a second consensus group meeting in November 2015 to address the treatment of locally relapsed chordoma. This meeting involved over 60 specialists from Europe, the United States and Japan with expertise in treatment of patients with chordoma. The consensus achieved during that meeting is the subject of the present publication and complements the recommendations of the first position paper.

Short, full-dose adjuvant chemotherapy (CT) in high-risk adult soft tissue sarcomas (STS): long-term follow-up of a randomized clinical trial from the Italian Sarcoma Group and the Spanish Sarcoma Group.

BACKGROUND: To report on long-term results of a phase 3 trial comparing three versus five cycles of adjuvant chemotherapy (CT) with full-dose epirubicin+ifosfamide in high-risk soft tissue sarcomas (STS). METHODS: Patients (pts) were randomized to receive three preoperative cycles of epirubicin 120 mg/m2 and ifosfamide 9 g/m2 (Arm A) or to receive the same three preoperative cycles plus two postoperative cycles (Arm B). Radiotherapy could be either delivered in the preoperative or in the postoperative setting. Non-inferiority of the primary end point, OS, was assessed by the confidence interval of the hazard ratio (HR; Arm A/Arm B) derived from Cox model. RESULTS: Between January 2002 and April 2007, 164 pts were assigned to arm A and 164 to arm B. At a median follow-up (FU) of 117 months (IQ range 103-135 months), 123 deaths were recorded: 58 in Arm A and 65 in Arm B. Ten-year OS was 61% for the entire group of patients: 64% in Arm A and 59% in Arm B. The intention-to-treat analysis confirmed that three cycles were not inferior to five cycles (one-sided 95% upper confidence limit was 1.24). A per protocol analysis was consistent with these results. Pts with leiomyosarcoma and undifferentiated pleomorphic sarcoma (UPS) had the lowest, and the highest response rates, respectively. Consistently, Leiomyosarcoma and UPS had the worse and the best prognosis, respectively. CONCLUSIONS: At a longer FU, the non-inferiority of three cycles of a full-dose conventional CT in comparison to five is confirmed. Response to therapy is also confirmed to be associated with better survival. This regimen is currently tested within an ongoing international trial against three cycles of a neoadjuvant histology-tailored CT (ClinicalTrials.gov Identifier: NCT01710176).

Synovial sarcoma: characteristics, challenges, and evolving therapeutic strategies.

Synovial sarcoma (SS) is a rare and aggressive disease that accounts for 5%-10% of all soft tissue sarcomas. Although it can occur at any age, it typically affects younger adults and children, with a peak incidence in the fourth decade of life. In >95% of cases, the oncogenic driver is a translocation between chromosomes X and 18 that leads to the formation of the SS18::SSX fusion oncogenes. Early and accurate diagnosis is often a challenge; optimal outcomes are achieved by referral to a specialist center for diagnosis and management by a multidisciplinary team as soon as SS is suspected. Surgery with or without radiotherapy and/or chemotherapy can be effective in localized disease, especially in children. However, the prognosis in the advanced stages is poor, with treatment strategies that have relied heavily on traditional cytotoxic chemotherapies. Therefore, there is an unmet need for novel effective management strategies for advanced disease. An improved understanding of disease pathology and its molecular basis has paved the way for novel targeted agents and immunotherapies that are being investigated in clinical trials. This review provides an overview of the epidemiology and characteristics of SS in children and adults, as well as the patient journey from diagnosis to treatment. Current and future management strategies, focusing particularly on the potential of immunotherapies to improve clinical outcomes, are also summarized.

Efficacy of immune checkpoint inhibitors in alveolar soft-part sarcoma: results from a retrospective worldwide registry.

BACKGROUND: Conventional cytotoxic drugs are not effective in alveolar soft-part sarcoma (ASPS). Immune checkpoint (programmed cell death protein 1/programmed death-ligand 1) inhibitors (ICIs) are promising drugs in ASPS. A worldwide registry explored the efficacy of ICI in ASPS. MATERIALS AND METHODS: Data from adult patients diagnosed with ASPS and treated with ICI for advanced disease in expert sarcoma centers from Europe, Australia and North America were retrospectively collected, including demographics and data related to treatments and outcome. RESULTS: Seventy-six ASPS patients, with a median age at diagnosis of 25 years (range 3-61 years), were registered. All patients received ICI for metastatic disease. Immunotherapy regimens consisted of monotherapy in 38 patients (50%) and combination in 38 (50%) (23 with a tyrosine kinase inhibitor). Among the 68 assessable patients, there were 3 complete responses and 34 partial responses, translating into an overall response rate of 54.4%. After a median follow-up of 36 months [95% confidence interval (CI) 32-40 months] since the start of immunotherapy, 45 (59%) patients have progressed on ICI, with a median progression-free survival (PFS) of 16.3 months (95% CI 8-25 months). Receiving ICI in first line (P = 0.042) and achieving an objective response (P = 0.043) correlated with a better PFS. Median estimated overall survival (OS) from ICI initiation has not been reached. The 12-month and 24-month OS rates were 94% and 81%, respectively. CONCLUSIONS: This registry constitutes the largest available series of ASPS treated with ICI. Our results suggest that the ICI treatment provides long-lasting disease control and prolonged OS in patients with advanced ASPS, an ultra-rare entity with limited active therapeutic options.

SEOM Clinical Guideline of management of soft-tissue sarcoma (2020).

Soft-tissue sarcomas constitute an uncommon and heterogeneous group of tumors of mesenchymal origin. Diagnosis, treatment, and management should be performed by an expert multidisciplinary team. MRI/CT of the primary tumor and biopsy is mandatory before any treatment. Wide surgical resection with tumor-free tissue margin is the mainstay for localized disease. Radiotherapy is indicated in large, deep, high-grade tumors, or after marginal resection not suitable for re-excision. Perioperative chemotherapy should be discussed for high-risk sarcomas of the extremities and trunk-wall. In the case of oligometastatic disease, patients should be considered for local therapies. First-line treatment with anthracyclines (or in combination with ifosfamide) is the treatment of choice. Other drugs have shown activity in second-line therapy and in specific histological subtypes but options are limited and thus, a clinical trial should always be discussed.

The paediatric cancer clinical research landscape in Spain: a 13-year multicentre experience of the new agents group of the Spanish Society of Paediatric Haematology and Oncology (SEHOP).

PURPOSE: Early phase trials are crucial in developing innovative effective agents for childhood malignancies. We report the activity in early phase paediatric oncology trials in Spain from its beginning to the present time and incorporate longitudinal data to evaluate the trends in trial characteristics and recruitment rates. METHODS: Members of SEHOP were contacted to obtain information about the open trials at their institutions. The study period was split into two equal periods for analysis: 2007-2013 and 2014-2020. RESULTS: Eighty-one trials and two molecular platforms have been initiated. The number of trials has increased over the time of the study for all tumour types, with a predominance of trials available for solid tumours (66%). The number of trials addressed to tumours harbouring specific molecular alterations has doubled during the second period. The proportion of industry-sponsored compared to academic trials has increased over the same years. A total of 565 children and adolescents were included, with an increasing trend over the study period. For international trials, the median time between the first country study approval and the Spanish competent authority approval was 2 months (IQR 0-6.5). Fourteen out of 81 trials were sponsored by Spanish academic institutions. CONCLUSIONS: The number of available trials, and the number of participating patients, has increased in Spain from 2007. Studies focused on molecular-specific targets are now being implemented. Barriers to accessing new drugs for all ranges of age and cancer diseases remain. Additionally, opportunities to improve academic research are still required in Spain.

Epithelioid hemangioendothelioma, an ultra-rare cancer: a consensus paper from the community of experts.

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, translocated, vascular sarcoma. EHE clinical behavior is variable, ranging from that of a low-grade malignancy to that of a high-grade sarcoma and it is marked by a high propensity for systemic involvement. No active systemic agents are currently approved specifically for EHE, which is typically refractory to the antitumor drugs used in sarcomas. The degree of uncertainty in selecting the most appropriate therapy for EHE patients and the lack of guidelines on the clinical management of the disease make the adoption of new treatments inconsistent across the world, resulting in suboptimal outcomes for many EHE patients. To address the shortcoming, a global consensus meeting was organized in December 2020 under the umbrella of the European Society for Medical Oncology (ESMO) involving >80 experts from several disciplines from Europe, North America and Asia, together with a patient representative from the EHE Group, a global, disease-specific patient advocacy group, and Sarcoma Patient EuroNet (SPAEN). The meeting was aimed at defining, by consensus, evidence-based best practices for the optimal approach to primary and metastatic EHE. The consensus achieved during that meeting is the subject of the present publication.

Prognostic time dependence of deletions affecting codons 557 and/or 558 of KIT gene for relapse-free survival (RFS) in localized GIST: a Spanish Group for Sarcoma Research (GEIS) Study.

BACKGROUND: To assess whether deletions involving codons 557 and/or 558 (critical deletions) of exon 11 of KIT are relevant in the prognosis of relapse-free survival (RFS) in gastrointestinal stromal tumor (GIST) patients with a long follow-up. PATIENTS AND METHODS: A univariate and multivariate analysis for RFS were carried out on 162 localized GIST patients over the entire follow-up period and over the intervals 0-4 years and >4 years. Factors assessed among others were Fletcher/National Institutes of Health and Miettinen-Lasota/Armed Forces Institute of Pathology (M-L/AFIP) risk categories, critical deletions and non-deletion-type mutation (NDTM) within exon 11 of KIT. RESULTS: Multivariate analyses revealed that M-L/AFIP [relative risk (RR) 11.45, confidence interval (CI) 4.40-29.76, for the high-risk subgroup and RR 5.97, CI 2.09-17.06, for the intermediate subgroup] and critical deletions (RR 3.05, CI 1.59-5.85) were independent prognostic factors for RFS for the first 4 years and for the entire follow-up period. Beyond 4 years, the high-risk M-L/AFIP subgroup (RR 8.12, CI 1.48-44.4) and NDTM (RR 6.42, CI 1.17-35.12) were independent prognostic factors for RFS. The median follow-up was 84 months. CONCLUSION: Critical deletions represent a time-dependent prognostic factor limited to the first 4 years after surgery, which could help identify a subset with higher and earlier risk for relapse in GIST patients.

Gastrointestinal stromal tumors (GISTs): SEAP-SEOM consensus on pathologic and molecular diagnosis.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract, with an incidence of 1.1 cases/100,000 inhabitants/year. A group of experts from the Spanish Society of Pathology and the Spanish Society of Oncology met to discuss a brief update on GISTs and agree on aspects relating to the pathological and molecular diagnosis of these tumors. GISTs are generally solitary, well-circumscribed lesions of variable size (<10 mm-35 cm) that may present with intra- or extra-luminal parietal growth or a mixed-type (hourglass) growth pattern. Histologically, they are unencapsulated neoplasms displaying expansive growth and spindle-shaped (70%), epithelioid (20%), or mixed cellularity (10%). Mitotic activity is generally moderate or low and should be evaluated only in areas with high cellularity or higher mitotic frequency. The great majority of GISTs harbour mutually exclusive activating mutations in genes coding for the type III receptor tyrosine kinases KIT and PDGFRA; less commonly, GISTs have also been reported to display mutations elsewhere, including BRAF and NF1 and SDH-complex genes. The method most widely used to detect KIT and PDGFRA mutations is amplification of the exons involved by polymerase chain reaction followed by direct sequencing (Sanger method) of these amplification products. Molecular analyses should always specify the type of analysis performed, the region or mutations evaluated, and the sensitivity of the detection method employed.

SEOM Clinical Guideline for gastrointestinal sarcomas (GIST) (2016).

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract, and this disease has served as a paradigmatic model for successful rational development of targeted therapies. The introduction of tyrosine kinase inhibitors with activity against KIT/PDGFRA in both localized and advanced stages has remarkably improved the survival in a disease formerly deemed resistant to all systemic therapies. The Spanish Society of Medical Oncology (SEOM) guidelines provide a multidisciplinary and updated consensus for the diagnosis and treatment of GIST patients. We strongly encourage that the managing of these patients should be performed within multidisciplinary teams in reference centers.

SEOM Clinical Guideline of management of soft-tissue sarcoma (2016).

Soft-tissue sarcomas are uncommon and heterogeneous tumors of mesenchymal origin. A soft-tissue mass that is increasing in size, greater than 5 cm, or located under deep fascia are criteria for suspicion of sarcoma. Diagnosis, treatment, and management should preferably be performed by a multidisciplinary team in reference centers. MRI and lung CT scan are mandatory for local and distant assessment. A biopsy indicating histological type and grade is needed previous to the treatment. Wide surgical resection with tumor-free tissue margin is the primary treatment for localized disease. Radiotherapy is indicated in large, deep, high-grade tumors, or after marginal resection not likely of being improved with reexcision. Neoadjuvant and adjuvant chemotherapy improve survival in selected cases, usually in high-grade sarcomas of the extremities. In the case of metastatic disease, patients with exclusive lung metastasis could be considered for surgery. First-line treatment with anthracyclines (or in combination with ifosfamide) is the treatment of choice. New drugs have shown activity in second-line therapy and in specific histological subtypes.

Follow-up strategies for patients with gastrointestinal stromal tumour treated with or without adjuvant imatinib after surgery.

BACKGROUND: Patients with gastrointestinal stromal tumour (GIST) are often followed up after surgery with longitudinally repeated imaging examinations to detect recurrence early. Studies on follow-up of GIST patients are few, the optimal follow-up methods are unknown and the recommendations for follow-up vary in guidelines. METHODS: We reviewed the current evidence for follow-up of patients treated with surgery alone and of patients who were treated with adjuvant or neoadjuvant imatinib. RESULTS: Imaging of the abdomen and the pelvis with computerised tomography (CT) or magnetic resonance imaging (MRI) usually suffices, since metastases are uncommon at other sites. The frequency of imaging may be adjusted with the risk of recurrence with time. Very low risk GISTs are very frequently cured with surgery and usually require no regular follow-up after complete surgery, and annual CT of the abdomen and the pelvis for 5 years suffices for most patients with a low to intermediate risk for recurrence. Most high-risk patients are treated with imatinib for at least 3 years after surgery. CT or MRI may be carried out 6-monthly during adjuvant imatinib, 3 to 4-monthly during the 2 years that follow discontinuation of imatinib when the risk of recurrence is high, and then at 6-12 month intervals to complete 10 years of follow-up. Recurrence after the first 10 years of follow-up is infrequent. CONCLUSIONS: The follow-up schedules are best tailored with the risk of recurrence. The risk of recurrence should be estimated with the prognostic tools that consider the most relevant prognostic factors.

Giant cell tumour of bone: new treatments in development.

Giant cell tumour of bone (GCTB) is a benign osteolytic tumour with three main cellular components: multinucleated osteoclast-like giant cells, mononuclear spindle-like stromal cells (the main neoplastic components) and mononuclear cells of the monocyte/macrophage lineage. The giant cells overexpress a key mediator in osteoclastogenesis: the RANK receptor, which is stimulated in turn by the cytokine RANKL, which is secreted by the stromal cells. The RANK/RANKL interaction is predominantly responsible for the extensive bone resorption by the tumour. Historically, standard treatment was substantial surgical resection, with or without adjuvant therapy, with recurrence rates of 20-56 %. Studies with denosumab, a monoclonal antibody that specifically binds to RANKL, resulted in dramatic treatment responses, which led to its approval by the United States Food and Drugs Administration (US FDA). Recent advances in the understanding of GCTB pathogenesis are essential to develop new treatments for this locally destructive primary bone tumour.