Treatment updates on tenosynovial giant cell tumor.

PURPOSE OF REVIEW: Diffuse-type tenosynovial giant cell tumor (dt-TGCT) is a benign clonal neoplastic proliferation arising from the synovium. Patients are often symptomatic, require multiple surgical procedures during their lifetime, and have reduced quality of life (QoL). Surgery is the main treatment with relapse rates ranging from 14 to 55%. The treatment strategy for patients with dt-TGCT is evolving. The purpose of this review is to describe current treatment options, and to highlight recent developments in the knowledge of the molecular pathogenesis of dt-TGCT as well as related therapeutic implications. RECENT FINDINGS: TGCT cells overexpress colony-stimulating factor 1 (CSF1), resulting in recruitment of CSF1 receptor (CSF1R)-bearing macrophages that are polyclonal and make up the bulk of the tumor, has led to clinical trials with CSF1R inhibitors. These inhibitors include small molecules such as pexidatinib, imatinib, nilotinib, DCC-3014 (vimseltinib), and the monoclonal antibody RG7155 (emactuzumab). SUMMARY: In conclusion, D-TGCT impairs patients' QoL. The evidence that the pathogenetic loop of D-TGCT can be inhibited has changed the therapeutic armamentarium for this condition. Clinical trials of agents that target CSF1R are currently ongoing. All this new evidence should be taken into consideration within multidisciplinary management.

Radiosynoviorthesis: almost seventy years of experience but still somewhat fameless.

Radiosynoviorthesis (RSO) or radiation synovectomy has been practiced for more than half a century, but in many parts of the world, it is still relatively unknown and not used to its full potential in the standard care for chronic, persistent or recurrent synovitis. The working mechanism of RSO is simple yet elegant. Radiopharmaceutical particles are, after injection in the affected synovial joint, gobbled up by phagocytizing subsynovial inflammatory cells. As a consequence, the synovium will be irradiated locally resulting in synovial cell necrosis and inhibition of cell proliferation, which eventually leads to a decrease in the inflammatory response in the joint cavity. In this review RSO is once again brought to the attention and common indications for RSO are discussed. Also, appropriate activities of the administrated radiopharmaceuticals and coadministrated glucocorticoids are provided. Furthermore, a detailed database-assisted chronological overview of published literature of RSO in inflammatory and non-inflammatory diseases, like rheumatoid arthritis, psoriatic arthritis, osteoarthritis and osteochrondomatosis, hemophilic hemarthrosis and pigmented villonodular synovitis (PVNS) is provided. Based upon the published literature an indication of level of evidence of RSO is discussed. There is evidence that RSO is effective in persistent synovitis in patients with a variety of causes for synovitis, although the effectiveness seems to decrease over time. In these patients, RSO may not be used to its full potential in many parts of the world. Results in of RSO in hemophilia patients with hemarthrosis are favourable, however the evidence for the effectiveness of RSO in these patients is less firm and mainly based on case series. The evidence for the efficacy of RSO as adjuvant therapy in PVNS is, at best, of very low quality.

Management of Pigmented Villonodular Synovitis (PVNS): an Orthopedic Surgeon's Perspective.

PURPOSE OF REVIEW: Pigmented villonodular synovitis (PVNS) or tenosynovial giant cell tumor (TGCT) encompasses a wide spectrum of disease and is divided into localized and diffuse variants. Surgical resection remains the principal treatment for nearly all localized type disease and most diffuse type. Recent mechanistic understanding of the disease led to drug discovery that has opened new avenues for patients with recalcitrant disease. In this manuscript, we review the current treatment options for TGCT, presenting outcomes from traditional surgical approaches as well as those from nonsurgical approaches. RECENT FINDINGS: Arthroscopic and/or open surgery remains the mainstay of treatment for TGCT for the vast majority of patients. While radiosynoviorthesis and external beam radiation have been used for recalcitrant disease, recent understanding of the colony stimulating factor 1 receptor (CSF1R) pathway and its paracrine and autocrine role in TGCT has led to the development of targeted inhibitors. Their optimal role and efficacy are unclear due to limited number of high-quality studies and contradictory results; however, recent and ongoing studies suggest there may be a role for their use, especially in diffuse and/or refractory disease. Surgery remains the most common treatment for TGCT, however, there may be an increasing role for adjuvant therapies, including the new targeted agents. Weighing the side effects of these treatments against the symptomatic benefit on a patient-by-patient basis in this benign disease remains critical.

Nilotinib in locally advanced pigmented villonodular synovitis: a multicentre, open-label, single-arm, phase 2 trial.

BACKGROUND: Pigmented villonodular synovitis (alternatively known as diffuse-type giant cell tumour) is a rare, locally aggressive tumour driven by a specific translocation resulting in the overexpression of colony-stimulating factor 1 (CSF1). CSF1 receptor (CSF1R) inhibitors (ie, tyrosine kinase inhibitors and antibodies) induce a response in patients with pigmented villonodular synovitis. We investigated the safety and efficacy of a CSF1R tyrosine kinase inhibitor, nilotinib, in patients with locally advanced non-resectable pigmented villonodular synovitis. METHODS: In this phase 2, open-label, single-arm study, we enrolled patients from 11 cancer centres of hospitals in four countries (France, Netherlands, Italy, and Australia). Eligible patients were aged at least 18 years with a WHO performance status of 2 or less, and histologically confirmed progressive or relapsing pigmented villonodular synovitis that was inoperable, or resectable only with mutilating surgery. Patients received oral nilotinib (400 mg twice per day) until disease progression, unacceptable toxicity, or completion of 1 year of treatment. The primary endpoint was the proportion of patients who were progression free at 12 weeks, which was centrally assessed according to Response Evaluation Criteria in Solid Tumors version 1.1. Analyses were by modified intention to treat (ie, all patients with no major protocol violations who were treated with nilotinib for at least 3 weeks were included). All participants who received at least one dose of study drug were included in the safety analyses. This study is registered with ClinicalTrials.gov, number NCT01261429, and the results presented here are the final analysis of the trial. FINDINGS: Between Dec 15, 2010, and Sept 28, 2012, we enrolled 56 patients with pigmented villonodular synovitis and treated them with nilotinib. Five (9%) patients discontinued study treatment before week 12; therefore, 51 patients were evaluable for the primary endpoint at 12 weeks. The estimated proportion of patients who were progression free at 12 weeks was 92·6% (95% credible interval 84·3-97·9). 54 (96%) of 56 patients had a treatment-related adverse event. Six (11%) of 56 patients had at least one grade 3 treatment-related adverse event (headache, dizziness, and hepatic disorders [n=1], pruritus and toxidermia [n=1], diarrhoea [n=1], increased γ-glutamyl transferase concentration [n=1], anorexia [n=1], and increased headache [n=1]). No grade 4 or 5 adverse events were reported. One patient had a treatment-related serious adverse event (toxidermia) and two patients had serious adverse events not considered to be related to the study drug (borderline ovarian tumour [n=1] and pilonidal cyst excision [n=1]). INTERPRETATION: More than 90% of patients with locally advanced unresectable progressive pigmented villonodular synovitis achieved disease control with 12 weeks of nilotinib treatment. These results indicate that CSF1R tyrosine kinase inhibitors have anti-tumour activity with manageable toxicity in patients with inoperable progressive pigmented villonodular synovitis. Randomised trials investigating the efficacy of nilotinib for patients with unresectable pigmented villonodular synovitis are warranted. FUNDING: Novartis, Institut National du Cancer, EuroSARC, French National Cancer Institute, General Directorate of Care Supply, Lyon Research Innovation for Cancer, L'Agence nationale de la recherche, Laboratory of Excellence, Fondation ARC pour la recherche sur le cancer, Ligue contre le Cancer (comité de l'Ain), Info Sarcomes, and Association DAM'S.

CSF-1R Inhibitor Development: Current Clinical Status.

PURPOSE OF REVIEW: Colony-stimulating factor 1 receptor (CSF-1R) and its ligands, CSF-1 and interleukin 34 (IL-34), regulate the function and survival of tumor-associated macrophages, which are involved in tumorigenesis and in the suppression of antitumor immunity. Moreover, the CSF-1R/CSF-1 axis has been implicated in the pathogenesis of pigmented villonodular synovitis (PVNS), a benign tumor of the synovium. As advanced or metastatic malignant solid tumors and relapsed/refractory PVNS remain unresolved therapeutic problems, new approaches are needed to improve the outcome of patients with these conditions. RECENT FINDINGS: In solid tumors, targeting CSF-1R via either small molecules or antibodies has shown interesting results in vitro but limited antitumor activity in vivo. Concerning PVNS, clinical trials assessing CSF-1R inhibitors have revealed promising initial outcomes. Blocking CSF-1/CSF-1R signaling represents a promising immunotherapy approach and several new potential combination therapies for future clinical testing.

PIGMENTED VILLONODULAR SYNOVITIS IN A RETICULATED GIRAFFE (GIRAFFA CAMELOPARDALIS).

: A 17-yr-old, female, captive-born reticulated giraffe ( Giraffa camelopardalis ) presented with acute-onset lameness of the right metacarpophalangeal (fetlock) joint. Despite multiple courses of treatment, the lameness and swelling progressively worsened over a 3.5-yr period, and the giraffe was euthanized. At necropsy, gross and microscopic changes in the right, front fetlock and associated flexor tendon sheath included villous synovial hyperplasia and the formation of discrete pigmented nodules within synovial membranes. Histologically, the nodules were composed of abundant, fibrous connective tissue with heavy macrophage infiltration, hemosiderin deposition, and distinctive, multinucleated cells that resembled osteoclasts. These findings were consistent with pigmented villonodular synovitis (PVNS), a rare condition affecting both humans and animals. Although the pathophysiology of PVNS is poorly understood, lesions exhibit features of both neoplastic and reactive inflammatory processes. This case report represents, to the authors' knowledge, the first description of PVNS in a nondomestic ungulate.

Current Systemic Treatment Options for Tenosynovial Giant Cell Tumor/Pigmented Villonodular Synovitis: Targeting the CSF1/CSF1R Axis.

OPINION STATEMENT: Adequate surgical resection remains the treatment of choice for tenosyovial giant cell tumor (TGCT). However, diffuse type TGCT (D-TGCT) is more difficult to resect and has a higher rate of recurrence (up to 50 %), which is often multiple. D-TGCT is rarely lethal and only rare cases of metastases have been described. Nevertheless, patients might have a significant decline in their quality of life due to multiple operations, which may sometimes result in a partial loss of function of the affected joint and may also be associated with perioperative morbidity and secondary arthrosis. As of today, no systemic treatment is approved for this rare disease. The aims of systemic therapy in the context of a non-lethal tumor are to reduce surgical morbidity and to preserve function and patient quality of life. Because TGCT is associated with characteristic cytogenetic abnormalities resulting in the overexpression of CSF1, systemic therapies targeting the CSF1/CSF1R axis (imatinib, nilotinib, emactuzumab, and PLX3397) have been tested in patients with locally advanced or relapsed D-TGCT. The more recent and more specific CSF1R inhibitors have shown a very interesting clinical activity with acceptable toxicity in early phase trials. These results will need to be confirmed in larger, ideally randomized, trials. But the high rate of clinical and functional improvement seen in some patients with advanced D-TGCT, often after multiple operations, suggests that these inhibitors will likely have a role in the management of patients with an inoperable disease; the definition of "inoperable TGCT" still requires refinement to reach a consensus. Another point that will need to be addressed is that of "the optimal duration of therapy" for these patients. Indeed, we and others have observed often prolonged clinical benefit and symptomatic relief even after treatment was stopped, with both monoclonal antibodies and tyrosine kinase inhibitors. Responses were observed very early on with emactuzumab and PLX3397, and patients experienced significant symptom improvement within a few weeks of starting therapy (2-4 weeks). Another possible application of CSF1R inhibitors could be used either as a preoperative or postoperative therapy for patients with operable TGCT. However, we currently lack sufficient follow-up to adequately address these questions which will each require specific trial designs. Overall, the striking clinical activity of CSF1R specific inhibitors in TGCT has created great enthusiasm among clinicians, and further development of these agents is clearly medically needed. Nevertheless, further investigations are necessary to validate those treatments and assess how to best incorporate them among other treatment modalities into the overall therapeutic strategy for a given patient.

Isolated limb perfusion as a treatment option for rare types of tumours.

BACKGROUND: Isolated limb perfusion (ILP) is an established and effective treatment for advanced melanoma and soft tissue sarcomas of the extremities with a high overall response rate. The aim of this study was to describe our experience of ILP for more rare types of tumours. METHODS: Patients with Merkel cell carcinoma (MCC) (n = 4), squamous cell carcinoma (SCC) (n = 2), B-cell lymphoma (n = 1), desmoid tumours (n = 3), pigmented villonodular synovitis (PVNS) (n = 1) and giant cell tumour (n = 1) were treated with ILP and analysed retrospectively. RESULTS: The four patients with in-transit MCC had three complete responses (CR) and one partial response (PR); the two patients with SCC had one CR and one stable disease (SD); the patients with desmoid tumours had two PR and one SD. A CR was also observed for the patient with a giant cell tumour, but the patient with PVNS had a SD. The patient with cutaneous metastases of B-cell lymphoma showed a CR, however with rapid systemic progression. Local toxicity according to Wieberdink was grade II in 10 patients (83%) and grade III in two patients (17%). CONCLUSIONS: These results show that ILP can be used as a treatment option also for more rare disease entities when other treatments have failed.

CSF1R inhibition with emactuzumab in locally advanced diffuse-type tenosynovial giant cell tumours of the soft tissue: a dose-escalation and dose-expansion phase 1 study.

BACKGROUND: Diffuse-type tenosynovial giant cell tumour (dt-GCT) of the soft tissue (alternatively known as pigmented villonodular synovitis), an orphan disease with unmet medical need, is characterised by an overexpression of colony-stimulating factor 1 (CSF1), and is usually caused by a chromosomal translocation involving CSF1. CSF1 receptor (CSF1R) activation leads to the recruitment of CSF1R-expressing cells of the mononuclear phagocyte lineage that constitute the tumor mass in dt-GCT. Emactuzumab (RG7155) is a novel monoclonal antibody that inhibits CSF1R activation. We have assessed the safety, tolerability and activity of emactuzumab in patients with Dt-GCT of the soft tissue. METHODS: In this phase 1, first-in-human dose-escalation and dose-expansion study, eligible patients were aged 18 years or older with dt-GCT of the soft tissue with locally advanced disease or resectable tumours requiring extensive surgery, an Eastern Cooperative Oncology Group performance status of 1 or less, measurable disease according to Response Evaluation Criteria In Solid Tumors version 1.1, and adequate end-organ function. Patients with GCT of the bone were not eligible. Patients received intravenous emactuzumab at 900 mg, 1350 mg, or 2000 mg every 2 weeks in the dose-escalation phase and at the optimal biological dose in a dose-expansion phase. The primary objective was to evaluate the safety and tolerability of emactuzumab, and to determine the maximum tolerated dose or optimal biological dose. All treated patients were included in the analyses. Expansion cohorts are currently ongoing. This study is registered with ClinicalTrials.gov, number NCT01494688. FINDINGS: Between July 26, 2012, and Oct 21, 2013, 12 patients were enrolled in the dose-escalation phase. No dose-limiting toxicities were noted in the dose-escalation cohort; on the basis of pharmacokinetic, pharmacodynamic, and safety information, we chose a dose of 1000 mg every 2 week for the dose-expansion cohort, into which 17 patients were enrolled. Owing to different cutoff dates for safety and efficacy readouts, the safety population comprised 25 patients. Common adverse events after emactuzumab treatment were facial oedema (16 [64%] of 25 patients), asthenia (14 [56%]), and pruritus (14 [56%]). Five serious adverse events (periorbital oedema, lupus erythematosus [occurring twice], erythema, and dermohypodermitis all experienced by one [4%] patient each) were reported in five patients. Three of the five serious adverse events-periorbital oedema (one [4%]), lupus erythematosus (one [4%]), and dermohypodermitis (one [4%])-were assessed as grade 3. Two other grade 3 events were reported: mucositis (one [4%]) and fatigue (one [4%]). 24 (86%) of 28 patients achieved an objective response; two (7%) patients achieved a complete response. INTERPRETATION: Further study of dt-GCT is warranted and different possibilities, such as an international collaboration with cooperative groups to assure appropriate recruitment in this rare disease, are currently being assessed. FUNDING: F Hoffmann-La Roche.

The Clinical Effect of Topical Application of Tranexamic Acid in Arthroscopic Synovectomy of Pigmented Villonodular Synovitis of the Knee.

This study investigated the clinical effect of topical application of tranexamic acid (TXA) in arthroscopic synovectomy of pigmented villonodular synovitis (PVNS) of the knee. Eighty patients who were diagnosed with unilateral knee PVNS underwent arthroscopic synovectomies from January 2017 to January 2021 and were retrospectively investigated in this study. Patients were divided into two groups: group A was the control group, whereas patients in group B received an intra-articular injection of 50 mL of TXA (1 g:100 mL) immediately after the synovectomies. The primary outcome measurement was the drainage volume of the affected knee in each postoperative stage, as well as the hematological parameters. Secondary outcomes included visual analog scale score, knee range of motion, and Lysholm score. Postoperative complications were also recorded. A lower volume of drainage was found in group B than in group A on postoperative day (POD) 1, on POD 2, and in total (POD 1, P=.000; POD 2, P=.000; total, P=.000). A lower visual analog scale pain score in group B was noticed on POD 1 (P=.000) and POD 2 (P=.005). Range of motion (P=.019) and Lysholm score (P=.001) were significantly superior in group B compared with group A on POD 14. Regarding complications, 3 patients in group A and 1 patient in group B developed deep venous thrombosis after surgery. Hematomas were found intra-articularly in 5 patients in group A during follow-up. Intraarticular topical application of TXA was effective in reducing postoperative bleeding and early postoperative pain for patients who underwent arthroscopic synovectomy of PVNS. [Orthopedics. 2023;46(3):e179-e185.].

Efficacy of imatinib mesylate for the treatment of locally advanced and/or metastatic tenosynovial giant cell tumor/pigmented villonodular synovitis.

BACKGROUND: Pigmented villonodular synovitis (PVNS) (also known as diffuse-type giant cell tumor) and tenosynovial giant cell tumors (TGCT) are rare, usually benign neoplasms that affect the synovium and tendon sheaths in young adults. These tumors are driven by the overexpression of colony stimulating factor-1 (CSF1). CSF1 is expressed by a minority of tumor cells, which, in turn attract non-neoplastic inflammatory cells that express CSF1 receptor (CSF1R) through a paracrine effect. METHODS: Imatinib mesylate (IM) blocks CSF1R, and previous case reports indicated that it also exerts antitumor activity in PVNS. The authors conducted a multi-institutional retrospective study to assess the activity of IM in patients with locally advanced/metastatic PVNS/TGCT. RESULTS: Twenty-nine patients from 12 institutions in Europe, Australia, and the United States were included. There were 13 men, the median age was 41 years, and the most common site of disease was the knee (n = 17; 59%). Two patients had metastatic disease to the lung and/or bone. Five of 27 evaluable patients had Response Evaluation in Solid Tumor (RECIST) responses (overall response rate, 19%; 1 complete response and 4 partial responses), and 20 of 27 patients (74%) had stable disease. Symptomatic improvement was noted in 16 of 22 patients (73%) who were assessable for symptoms. Despite a high rate of symptomatic improvement and a favorable safety profile, 6 patients discontinued because of toxicity, and 4 patients decided to discontinue IM for no clear medical reason. CONCLUSIONS: IM displayed interesting activity in patients with PVNS/TGCT, providing proof of concept for targeting CSF1R in this disease. The authors concluded that the benefits of alleviating morbidity in patients with localized PVNS/TGCT must be balanced against the potential toxicity of chronic drug therapy.

Pigmented villonodular synovitis therapy with MSCF-1 inhibitors.

PURPOSE OF REVIEW: Giant cell tumor of tendon sheath and pigmented villonodular synovitis are synovial-based diseases that are generally treated by surgery. For aggressive and recurrent tumors, treatment alternatives are needed. This review explores a targeted therapeutic strategy. RECENT FINDINGS: Imatinib, a tyrosine kinase inhibitor, blocks expression of colony stimulating factor 1 (CSF1) by a small subpopulation of tumor cells that recruit CSF1-bearing nonneoplastic cells. Limited clinical data support the efficacy and side effect profile of imatinib in stabilizing disease in most patients. SUMMARY: Imatinib along with other such inhibitors and monoclonal antibodies to CSF1R are putative drugs that may play an important role in the treatment of these tumors.

Long-term follow-up of nilotinib in patients with advanced tenosynovial giant cell tumours: Long-term follow-up of nilotinib in TGCT.

BACKGROUND: Diffuse-type tenosynovial giant cell tumour (D-TGCT) is a non-malignant but locally aggressive tumour driven by overexpression of colony-stimulating factor-1 (CSF1). CSF1R inhibitors are potential therapeutic strategies for patients not amenable to surgery. We report here the long-term outcome of nilotinib in patients with advanced D-TGCT treated within a phase II prospective international study (ClinicalTrials.gov: NCT01261429). METHODS: Patients were enrolled between December 2010-September 2012 at 11 cancer centres. Eligible patients had histologically confirmed D-TGCT, not amenable to surgery. Patients received nilotinib until evidence of progression, toxicity or a maximum of one year. Long-term data were retrospectively collected after the completion of the phase II trial. Patients with nilotinib treatment ≥12 weeks and follow-up ≥12 months were included for long-term analysis. RESULTS: Forty-eight of 56 enrolled patients were included. Median treatment duration was 11 months; 31 (65%) patients completed the treatment protocol. After 102 months of follow-up (median; range 12-129), 25 patients (52%) had progression. The median progression-free survival (PFS) was 77 months. The five-year PFS rate was 53%. Fifteen patients (n = 15/46; 33%) experienced clinical worsening after 11 months (median). Twenty-seven patients (58%) received additional treatment, after which eleven patients (n = 11/27; 41%) had a second relapse. Nine patients required a subsequent treatment, primarily other CSF1R inhibitors (n = 6/9; 67%). No unfavourable long-term effects were observed. CONCLUSION: This long-term analysis of nilotinib for advanced D-TGCT showed that about half of the patients had progression and underwent additional treatment after 8.5 years follow-up. Contrarily, several patients had ongoing disease control after limited treatment duration, demonstrating the mixed effect of nilotinib.

Treatment of tenosynovial giant cell tumor and pigmented villonodular synovitis.

PURPOSE OF REVIEW: To review recent developments in the molecular pathogenesis of tenosynovial giant cell tumor (TGCT) or pigmented villonodular synovitis (PVNS) and its therapeutic implications. RECENT FINDINGS: TGCT or PVNS is a benign clonal neoplastic proliferation arising from the synovium characterized by a minor population of intratumoral cells that harbor a recurrent translocation. These cells overexpress CSF1, resulting in recruitment of CSF1R-bearing macrophages that are polyclonal and make up the bulk of the tumor. Inhibition of CSF1R using small molecule inhibitors such as imatinib, nilotinib or sunitinib can result in clinical, radiological and functional improvement in the affected joint. SUMMARY: Currently, surgery remains the treatment of choice for patients with TGCT/PVNS. Localized TGCT/PVNS is managed by marginal excision. Recurrences occur in 8-20% of patients and are easily managed by re-excision. Diffuse TGCT/PVNS tends to recur more often (33-50%) and has a much more aggressive clinical course. Patients are often symptomatic and require multiple surgical procedures during their lifetime. For patients with unresectable disease or multiple recurrences, systemic therapy using CSF1R inhibitors may help delay or avoid surgical procedures and improve functional outcomes.

Intraarticular adalimumab in a patient with pigmented villonodular synovitis.

Pigmented villonodular synovitis is a chronic inflammatory disease progressing with histological villonodular hyperplasia in synovium, fibrosis and accumulation of hemosiderin. Knee joint is frequently involved leading to severe joint damage and disability in untreated cases. Treatment options include surgical intervention or radio-synovectomy with intraarticular yttrium-90. The case presented here includes significant clinical and radiological disease regression after intraarticular adalimumab in a patient diagnosed with radiologically and histologically confirmed pigmented villonodular synovitis who did not consent to surgical intervention.

Long-term clinical activity, safety and patient-reported quality of life for emactuzumab-treated patients with diffuse-type tenosynovial giant-cell tumour.

OBJECTIVES: This study investigated the safety, clinical activity and patient-reported outcomes of patients with diffuse-type tenosynovial giant-cell tumour (dTGCT) of the soft tissue who were treated with emactuzumab, a humanised anti-colony stimulating factor 1 receptor (CSF1R) monoclonal antibody and were followed up for up to 2 years after the start of treatment. METHODS: In this open-label phase 1 study (ClinicalTrials.govNCT01494688), patients received intravenous (IV) emactuzumab from 900 to 2000 mg every two weeks in the dose-escalation phase and at the optimal biological dose of 1000 mg with different schedules in the dose-expansion phase. Adverse event (AE) rates and biomarker assessments from tumour biopsies were analysed. Quality of life was assessed using a standard questionnaire (EuroQol-5D-3L) and the WOMAC® 3.1 Osteoarthritis Index. Tumour responses were determined with magnetic resonance imaging. RESULTS: Altogether, 63 patients were enrolled into the study. The most frequently reported AEs were pruritus, asthenia and oedema. In 36 patients for whom biopsy tissue was available a substantial decrease of CSF1R-positive and CD68/CD163-positive macrophages was detected. The independently reviewed best overall objective response rate (ORR) (Response Evaluation Criteria in Solid Tumors version 1.1) was 71%. Responses were durable, and an ORR of 70% and 64% was determined after one or two years after enrolment into the study. Clinical activity was accompanied by an improvement in EuroQol-5D-3L and particularly the joint disorder-specific WOMAC score. CONCLUSIONS: Systemic therapy of dTGCT patients with emactuzumab resulted in pronounced and durable responses associated with symptomatic improvement and a manageable safety profile.

Long term term follow-up of tyrosine kinase inhibitors treatments in inoperable or relapsing diffuse type tenosynovial giant cell tumors (dTGCT).

RATIONALE: CSF1R tyrosine kinase inhibitors (TKI) and antibodies yield response rates and tumor control in patients with diffuse type tenosynovial giant cell tumors (dTGCT). The long term management of patients with dTGCT treated with TKI is however not known. PATIENTS AND METHODS: We conducted a retrospective single center study on the 39 patients with advanced and/or inoperable dTGCT referred to the Centre Leon Berard for a medical treatment. The clinical characteristics and treatments of patients who had received at least one line of CSF1R TKI or Ab was collected from the electronic patient records and analyzed, after this study was approved by the Institutional Review Board of the Centre Leon Berard. Statistics were conducted using SPSS 23.0. RESULTS: Thirty-nine patients received at least one line of TKI among the 101 patients with histologically confirmed dTGCT refered to this center. Imatinib, nilotinib, pexidartinib, emactuzumab were the most frequently used agents. First line treatment was given for a median duration of 7 months. With a median follow-up from the initiation of TKI of 30 months, the progression-free rate at 30 months is 56% for the 39 patients. 15 patients had recurrent disease after first line CSF1R inhibitor: 12 (80%) received a 2nd line treatment for a median duration of 6 months and a median time to progression (TTP) of 12 months. Six patients had afterwards a recurrent disease and 5 (83%) received a 3rd line treatment for a median duration of 5 months and a median TTP of 9 months. Progression-free rate at 30 months was observed in 3 of 12 (25%) after line 2 and 1 of 5 (20%) after line 3. None of the patients refered died with a median follow-up of 67 months. CONCLUSIONS: CSF1R TKI or Ab provide prolonged tumor control and symptom relief for a majority of patients with inoperable or relapsing dTGCT, in first and subsequent lines. Multiple lines are required for close to 50% of patients with relapsing dTGCT.

Use of polymethylmethacrylate to treat pigmented villonodular synovitis in the posterior compartment of the knee.

Pigmented villonodular synovitis (PVNS) is a benign process that mainly affects the knee joint. There are two types of PVNS, a localised and a diffuse form. Although adjuvant therapies are possible, the treatment consists of arthroscopic or open synovectomy of the affected area. The most common complication is local recurrence. We report the case of a patient with PVNS and osteolysis of the femoral condyle, treated with anterior arthroscopic synovectomy and posterior approach for the treatment of the femoral condyle erosion. The bone erosion was treated with polymethylmethacrylate (PMMA) cement. There are no publications indexed in our knowledge that explain the treatment of PVNS associated with bone erosion by PMMA. Nine years after the procedure, the patient is leading a fully active life with no evidence of active disease.