Gorham-Stout Disease Successfully Treated With Sirolimus and Zoledronic Acid Therapy

Treatment for Gorham-Stout syndrome with a combination of teriparatide and denosumab

Gorham-Stout syndrome is an aggressive, non-hereditary, and rare disease affecting bone metabolism. Its etiology and pathogenesis remain elusive. The syndrome manifests with diverse clinical symptoms, often leading to frequent misdiagnoses and presenting challenges in treatment. In this study, we report a case of cranial and maxillary osteolysis in a 47-year-old female patient with somatic mutations in the VEGF-A, VEGF-B, and VEGF-C genes and the EPHB4 gene. After treatment with bisphosphonates, this patient still had persistent resorption of the mandible, but switching to a teriparatide and denosumab combination yielded substantial improvement. This study is the first report to show that teriparatide combined with denosumab can be used to treat Gorham-Stout syndrome.

Terminology and Classifications of Vascular Lesions Based on Molecular Identification

The majority of the vascular anomalies are seen in the head and neck region. Even though the incidence of this anomaly could be construed as a rare disease entity, with only 5% of overall affliction, the lack of knowledgeable management has disfigured many. A comprehensive understanding of this benign yet complex life-changing entity is essential. A historical perspective, pathophysiology-logical evolution, and the current knowledge of management modalities are essential for rendering clinical care in this subspecialty care. We propose a very succint Head and Neck Surgical classification for vascular anamolies, which has been a good guide for surgical approaches.

Case Report and Literature Review: Bisphosphonate, Sirolimus, and Atenolol Treatment in a 4-Year-Old Child Diagnosed with Gorham-Stout Disease

We report a 4-year-old with Gorham-Stout disease (GSD) who was treated with a combination of bisphosphonate, sirolimus, and atenolol. A previously healthy 4-year-old girl presented with back pain after falling on her back 2 months prior. Thoracolumbar spine X-ray revealed diffuse compression spinal fractures in T9-L2. Magnetic resonance imaging (MRI) confirmed multiple compression fractures at T9-L5 and revealed a paraspinal mass along the T1-L1 level. Based on clinical, radiological, and histopathological findings, Gorham-Stout disease was diagnosed. Treatment with sirolimus (0.5 mg twice daily, 1.6 mg/m2) was initiated and intravenous bisphosphonate (pamidronate, 1 mg/kg for 3 days, total 3 mg/kg every 4 months) was added for back pain; she had immediate improvement in back pain. After 9 months with this treatment, she had a mild increase in paraspinal lymphangiomatosis and aggravation in T9-L5 compression fractures; atenolol was administered. The patient underwent 11 months of combination treatment with bisphosphonate, sirolimus, and atenolol, and MRI showed mild degree of reduction in the paraspinal lesions at L1-L5. The patient is currently in stable condition with no back pain or side effects. The triple combination treatment with bisphosphonate, sirolimus, and atenolol may be helpful in stabilizing the disease course of GSD.

Complex Lymphatic Anomalies: Report on a Patient Registry Using the Latest Diagnostic Guidelines

Objective: Generalized lymphatic anomaly (GLA), Gorham-Stout disease (GSD), kaposiform lymphangiomatosis (KLA), and central conducting lymphatic anomaly (CCLA) are rare, multisystem lymphatic disorders, referred to as complex lymphatic anomalies (CLAs). Their etiology remains poorly understood; however, somatic activating mutations have recently been discovered, and the results of targeted treatments are promising. This study aimed to elaborate on the phenotypic description of CLA. Methods: Thirty-six consecutive patients were recruited for the "GLA/GSD Registry" of the University Hospital of Freiburg, Germany (2015-2021). Clinical data were prospectively collected provided that a signed informed consent form was obtained. The latest proposed diagnostic guidelines were retrospectively applied. Results: Thirty-two patients (38% males) were included in the study; 15 GLA, 10 GSD, 3 KLA, and 4 CCLA patients were identified. Eighty-four percent already had symptoms by the age of 15 years. Osteolysis and periosseous soft-tissue infiltration were associated with GSD (p < 0.001 and p = 0.011, respectively), ascites and protein-losing enteropathy with CCLA (p = 0.007 and p = 0.004, respectively), and consumption coagulopathy with KLA (p = 0.006). No statistically significant differences were found in organ involvement, distribution of osteolytic lesions, number of affected bones and fractures. Twenty-five patients had complications; one patient with GLA died despite multimodal treatment. Spontaneous regression was seen in one patient with untreated KLA. Conclusions: CLA are rare, and their overlapping clinical presentations make differential diagnosis difficult. The characterization of our case series contributes to the phenotypic description and differentiation of these four clinical entities. A further understanding of their pathogenesis is crucial for evaluating targeted therapies and optimizing medical care.

Difficult Therapeutic Decisions in Gorham-Stout Disease-Case Report and Review of the Literature

Gorham-Stout disease (GSD) is a very rare, life-threatening condition characterized by the proliferation of lymphatic vessels and osteolysis. Unfortunately, no standard treatment has been determined for management of GSD. The available therapies are not equally effective and carry substantial side-effects. We report a 42-year-old female with GSD manifested in multifocal osteolysis and chronic chylothorax and ascites. The combined treatment with sirolimus and zoledronic acid due to its synergism of action was introduced. To our knowledge, this is the first Polish case report of adult patients with Gorham-Stout disease.

How we approach the use of sirolimus and new agents: Medical therapy to treat vascular anomalies

Vascular anomalies (VAs) are a heterogeneous group of primarily congenital tumors and malformations. The International Society for the Study of Vascular Anomalies (ISSVA) has developed a standard classification of these disorders, creating a uniform approach to their diagnosis. Recent discoveries evaluating the genetic causes of VAs have revealed that they are due to mutations in cancer pathways, including the PI3K/AKT/mTOR and RAS/MAPK/MEK pathways. These discoveries have led to improved phenotype-genotype correlation and have expanded medical therapy for this group of unique disorders.

How we approach the diagnosis and management of complex lymphatic anomalies

Complex lymphatic anomalies (CLA) are congenital diseases of the lymphatic circulation system that are associated with significant morbidity and early mortality. While guidelines for the comprehensive evaluation of the CLA were recently published, the diagnostic approach and medical management are not standardized. This article presents the clinical features of four CLA: Gorham-Stout disease, generalized lymphatic anomaly, kaposiform lymphangiomatosis, and central collecting lymphatic anomaly. We also offer three cases from the authors' practice and our views on diagnostic testing and disease management including supportive care, medical therapies, and other interventions.

Indications and Limitations of Sirolimus in the Treatment of Vascular Anomalies-Insights From a Retrospective Case Series

BACKGROUND

Despite recent developments, the role of sirolimus in the heterogeneous spectrum of vascular anomalies is yet to be defined, in terms of indication, dosage, and therapy duration, recognizing both its potential and limitations.

METHODS

We retrospectively analyzed 16 children with vascular anomalies treated with sirolimus in two pediatric centers between 2014 and 2020 [male: n = 7, the median age at diagnosis: 4.6 months (range, 0-281.4)]. In addition, repetitive volumetric analyses of the vascular anomalies were performed when possible (11 cases).

RESULTS

Ten patients were diagnosed with vascular malformations and 6 with vascular tumors. The mean therapy duration was 27.2 months (range, 3.5-65). The mean sirolimus level was 8.52 ng/ml (range, 5.38-12.88). All patients except one with central conducting lymphatic anomaly responded to sirolimus, with the most noticeable volume reduction in the first 4-6 months. Additional administration of vincristine was needed in five patients with kaposiform hemangioendothelioma and yielded a response, even in cases, refractory to sirolimus monotherapy. As a single agent, sirolimus led to impressive improvement in a patient with another vascular tumor-advanced epithelioid hemangioendothelioma. Complicated vascular malformations required long-term sirolimus therapy. Side effects of sirolimus included mucositis and laboratory abnormalities. No major infectious episodes were recorded. An infant with COVID-19, diagnosed while on sirolimus therapy, presented with a mild course.

CONCLUSION

In the current series, we reported limitations of sirolimus as monotherapy, addressing the need to redefine its indications, and explore combination regimens and multimodal treatment strategies. Tools for objective evaluation of response trends over time could serve as a basis for the establishment of future therapeutic algorithms.

A narrative review of the role of sirolimus in the treatment of congenital vascular malformations

OBJECTIVE

Vascular malformations arise from defects in the morphologic development of the vascular system and can have an impact on quality of life and/or lead to severe complications. To date, vascular malformations are frequently managed by invasive techniques, after which recurrence is common. Sirolimus, a downstream inhibitor of the phosphatidylinositol 3 kinase/AKT pathway and best known for its immunosuppressive effect, has been used off-label for lesions for which approved therapies were associated with unsatisfactory results or recurrence. The aim of this study was to review the available data on the effect of sirolimus on the size and symptoms of different types of malformations and to summarize the main safety issues.

METHODS

A literature search in Pubmed, Embase, Web of Science, and SCOPUS was performed. Case reports, case series, and clinical trials evaluating the effect of sirolimus in vascular malformations were eligible for this review. Fully terminated studies published between January 2010 and May 2019 reporting an evaluable response on size and/or symptoms were included. Relevant data on lesion size, symptoms, side effects and duration of treatment were extracted as reported in the study. Additionally, we reported 10 unpublished cases who were treated in UZ Leuven.

RESULTS

The literature review included 68 articles, describing 324 patients. The median duration of therapy was 12 months (range, 1-60 months). After 6 months of treatment, the size of the malformation had at least decreased in 67% of patients with common venous malformations (VM), in 93% of patients with blue rubber bleb nevus syndrome and in all patients with verrucous VM. The size of lymphatic malformations improved in more than 80% of the patients, even in the case of extensive involvement such as in Gorham-Stout disease and generalized lymphatic anomaly. In addition, the majority of patients with syndromic vascular malformations experienced a decrease in size and reported symptoms improved in almost all patients, regardless of the type of malformation. Side effects were common (53%) but usually mild; mucositis and bone marrow suppression were the most common. Regrowth or recurrence of symptoms occurred in 49% of patients who discontinued treatment. Comparable effects were seen in our own patients.

CONCLUSIONS

This review shows that sirolimus is effective in decreasing the size and/or symptoms of particularly lymphatic malformations as well as VMs. Although common, side effects were usually mild. Nevertheless, clinical trials are needed to confirm the safety and effectivity of sirolimus and to identify the required serum levels and duration of treatment.

Gorham-Stout disease of the mandible, manubrium and cervical spine presenting as bilateral chylothorax

Gorham-Stout disease (GSD) is an extremely rare musculoskeletal disease of unknown aetiology characterised by non-neoplastic proliferation of vascular and lymphatic channels causing massive osteolysis, typically affecting younger individuals. Chylothorax is a known complication of GSD which is postulated to occur from thoracic spine involvement leading to pleural or thoracic duct invasion. In our case, bilateral chylothorax developed in a 60-year-old woman without any thoracic spine involvement of her disease, challenging the proposed mechanism. Despite bilateral pleural drainage and escalating doses of sirolimus, she ultimately developed respiratory failure and shock and succumbed to her illness. Overall survival of GSD is unknown, but when complicated by chylothorax, prognosis is typically poor. GSD represents a diagnostic and management challenge due to the paucity of knowledge surrounding its aetiology and management. These patients require multidisciplinary coordinated care. It is also important to note its high mortality when associated with chylothorax in particular.

Kaposiform lymphangiomatosis treated with multimodal therapy improves coagulopathy and reduces blood angiopoietin-2 levels

Kaposiform lymphangiomatosis (KLA) is a rare, life-threatening congenital lymphatic malformation. Diagnosis is often delayed due to complex indistinct symptoms. Blood angiopoietin-2 (ANG2) levels are elevated in KLA and may be useful as a biomarker to monitor disease status. We report a 7-year-old male child with easy bruising, inguinal swelling, and consumptive coagulopathy, diagnosed with KLA. A multimodal treatment regimen of prednisone, sirolimus, vincristine, and adjunctive zoledronate was used. Plasma ANG2 levels were highly elevated at diagnosis but decreased during treatment. The patient showed significant clinical improvement over a 38-month period and normalization of ANG2 levels correlated with resolution of the coagulopathy.

Gorham-Stout disease successfully treated with sirolimus (rapamycin): a case report and review of the literature

BACKGROUND

Gorham-Stout disease (GSD) is a rare disease characterized by bone lesions and osteolysis. Therapy usually involves surgical resection. Sirolimus (Rapamycin) is used in some patients with GSD but the efficacy and safety of Sirolimus remains unclear. We propose that Sirolimus may be a novel therapeutic for GSD and present a case and review of literature that supports this.

CASE PRESENTATION

We presented a 1-year-old boy with GSD involving osteolysis of the right humerus with fracture of the left femur complicated by an effusion in the right pleural cavity. X-rays showed osteolysis in the right clavicle. A large pleural effusion was observed on the right-side, and the left lung was significantly compressed. X-rays also showed a fracture of the left femur. A femoral biopsy was performed that showed necrotic tissue in the cortical bone and a large number of irregularly shaped capillaries that proliferated within the necrotic tissue. Dilated lymphatic vessels were seen adjacent to the cortex, with fibrous tissue hyperplasia. We prescribed sirolimus, which is an oral mTOR inhibitor, for two consecutive years. The boy recovered well without other progressive bone lesions and participates in normal daily activities. His growth and development are the same as that of his peers.

DISCUSSION AND CONCLUSION

Gorham-Stout disease is a rare and enigmatic disease characterized by the presentation of an intraosseous lymphatic anomaly (LM), which results in progressive bone resorption. Based on this case report and a literature review, we conclude that sirolimus may be an effective alternative medication for GSD.

Lymphatics in bone arise from pre-existing lymphatics

Bones do not normally have lymphatics. However, individuals with generalized lymphatic anomaly (GLA) or Gorham-Stout disease (GSD) develop ectopic lymphatics in bone. Despite growing interest in the development of tissue-specific lymphatics, the cellular origin of bone lymphatic endothelial cells (bLECs) is not known and the development of bone lymphatics has not been fully characterized. Here, we describe the development of bone lymphatics in mouse models of GLA and GSD. Through lineage-tracing experiments, we show that bLECs arise from pre-existing Prox1-positive LECs. We show that bone lymphatics develop in a stepwise manner where regional lymphatics grow, breach the periosteum and then invade bone. We also show that the development of bone lymphatics is impaired in mice that lack osteoclasts. Last, we show that rapamycin can suppress the growth of bone lymphatics in our models of GLA and GSD. In summary, we show that bLECs can arise from pre-existing LECs and that rapamycin can prevent the growth of bone lymphatics.

A Child with Early-Onset Gorham-Stout Disease Complicated by Chylothorax: Near-Complete Regression of Bone Lesions with Interferon and Bisphosphonate Treatment

We report a case of Gorham-Stout disease (GSD) complicated by chylothorax and treated with a combination therapy with interferon and bisphosphonates. This treatment may be helpful in improving the usually unfavorable prognosis of GSD beginning with a chylothorax before 1 year of age, and in reducing bone lesions. Moreover, the use of bisphosphonates appears to be useful in treating pain.

Gorham-Stout disease of the malleolus: a rare case report

Background

Gorham-Stout disease, also known as vanishing bone disease, idiopathic massive osteolysis, is a rare entity of unknown etiopathology. This disease is characterized by destruction of osseous matrix and proliferation of lymphatic vascular structures and associated with massive regional osteolysis. It has a variable clinical presentation and is commonly considered as a benign disease with a progressive tendency and an unpredictable prognosis. The diagnosis is made by exclusion and based on combination with histological, radiological, and clinical features. Despite that several therapeutic options have shown certain efficacy, the effective treatment still remains controversial and there is no standard treatment to be recommended.

Case presentation

A previously healthy 40-year-old man presented with right lateral malleolus pain after an ankle sprain and was referred to our hospital. The radiographs indicated rapid massive bone destruction in the distal right lateral malleolus with an unclear margin. Based on the combination with histological, radiological, and clinical features, the diagnosis of Gorham-Stout disease was made. Considering that the residual function of malleolus had to be protected, prior bisphosphonate was used to control the progression of lesion, followed by surgical resection and biological reconstruction with autologous fibular bone grafting. The patient was followed up 8 years after surgery, he presented without progression and recurrence.

Conclusions

We depict a case of Gorham-Stout disease at the right lateral malleolus and was successfully controlled by medication and surgical intervention. Based on the prior effective medical treatment, resection with biological reconstruction is a useful approach to treat Graham-Stout disease in bone.

Complex Lymphatic Anomalies and Therapeutic Options

Complex lymphatic anomalies include a variety of disorders with overlapping clinical, histological and imaging features. The often-confusing nomenclature used for lymphatic anomalies limits timely diagnosis and treatment. The updated 2018 classification of the International Society for the Study of Vascular Anomalies divides lymphatic anomalies into several subsets.¹ Newer imaging techniques including intranodal and magnetic resonance lymphangiography have improved our understanding of anatomy and function of the lymphatic system. Advances in medical, interventional, and surgical treatments have opened a realm of new therapeutic options for patients with complex lymphatic disorders.

Management of Gorham Stout disease with skull-base defects: Case series of six children and literature review

BACKGROUND

Gorham-Stout disease (GSD) is a rare lymphatic disorder which results in bone destruction. Defects of the skull base are difficult to manage, we describe cases to better understand the disease and discuss treatment.

METHODS

Retrospective study including all patients treated for GSD skull-base defects. Medical records, clinical, imaging and treatment data were studied. A systematic review of the literature included case reports of the diseases for further analysis.

RESULTS

6 patients (5 males, 1 female) were included. Mean age at diagnosis was 3.5 years (range 0-10). Follow-up was of 5.2 years. Patients were divided into Naso-temporal (NT) and Vertebro-temporal (VT) groups following anatomical location. NT patients (4 patients) all had petrous defects extending anteriorly, including sphenoid, ethmoidal and mandibular defects. They all had cerebro-spinal fluid leak (CSF) and recurrent meningitis (range from 3 to 7). Two of those patients had sequelae including deafness, paralysis and epilepsy. VT patients (2 patients) all had temporal, occipital bone and cervical vertebrae defects. None had CSF leaks but both died from medullar compression (preceded by tetraparesis in one case). Overall, five out of six patients had type I Chiari malformation. Interferon seemed to be the most efficient medical treatment. Surgery included petrectomy, endonasal surgery for CSF leak management and neurosurgery for medullar management but could not guarantee long-term effects.

CONCLUSION

Main issues in skull base defects are CSF leaks and medullar compressions. Surgical treatment is necessary in both cases but can only be satisfactory if general medical treatment can stabilise the disease.

Gorham-Stout Syndrome of the Shoulder Girdle Successfully Controlled by Antiresorptive Agents: A Report of 2 Cases

CASE

Gorham-Stout disease (GSD) is a rare disorder characterized by massive bone destruction. Consensus is lacking on the effective treatment strategies for GSD. This report presents 2 cases of GSD, a 47-year-old man and a 72-year-old woman, involving the shoulder girdle which were successfully controlled by antiresorptive agents including bisphosphonates and denosumab, the antireceptor activator of nuclear factor-κB ligand antibody.

CONCLUSIONS

These 2 cases suggest that antiresorptive agents targeting osteoclasts can be efficacious therapeutic options for GSD. This is the first case of GSD we are aware of which showed good response to denosumab treatment.

Chylous Manifestations and Management of Gorham-Stout Syndrome

Gorham-Stout disease (GSD) was first described by Gorham and colleagues in 1954, but its precise mechanism and cause remain to be elucidated. In this condition, voluminous and potentially fatal chylous effusions into the thorax can occur. Herein, we describe a case of GSD in which the patient presented with massive pleural effusions and mottled osteolytic bone lesions. We performed multiple operations, including thoracic duct ligation using video-assisted thoracoscopic surgery and thoracotomic decortication, but these procedures did not succeed in preventing recurrent pleural effusion and chest wall lymphedema. After administering sirolimus (0.8 mg/m², twice a day) and propranolol (40 mg, twice a day), the process of GSD in this patient has been controlled for more than 2 years.

Clinical application of molecular genetics in lymphatic malformations

Objectives

To describe the clinical presentation of lymphatic malformations (LM) and genotypically associated disorders and to summarize the recent literature regarding the genetic etiology of LM and provide a biologic correlation to medical and surgical management.

Results

LM are congenital lesions derived from a developmental abnormality of the lymphatic vessels. The severity of disease varies widely and complications can occur with higher staged disease and those associated with a known constellation of symptoms. Somatic mutations of the PIK3CA gene have been found to be an etiologic factor in the development of LM and associated overgrowth syndromes. Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor that inhibits the pathway downstream of PIK3CA. Preliminary studies in select groups of patients suggest that sirolimus has a role in the medical management of certain aspects of this disease.

Conclusions

Discovery of LM molecular genetics has led to the possibility of targeted therapies and highlights the importance of precision medicine in rare diseases. Identifying genetic mutations in larger cohorts of patients with LM will lead to additional insights. Knowledge of the genetic basis for disease can then lead to discovery of directed medical therapy. A specific molecular diagnosis can also help families understand better why their child is different and provide accurate counseling for subsequent pregnancies.

Level of Evidence

6.

Sirolimus Therapy as Perioperative Treatment of Gorham-Stout Disease in the Thoracic Spine: A Case Report

CASE

Gorham-Stout disease (GSD) is a rare entity that is marked by progressive osteolysis and bone resorption. A 14-year-old boy who was being followed for scoliosis presented with a marked curve progression and kyphoscoliosis. Imaging revealed osteolysis of the posterior elements and the ribs, suggestive of GSD. The structural compromise threatened spinal cord compression. Preoperative sirolimus therapy was initiated to stabilize the disease prior to corrective instrumentation. A biopsy specimen that was obtained at the time of instrumentation showed lymphatic vascular spaces consistent with GSD. Sirolimus therapy with the addition of bisphosphonate therapy was continued postoperatively.

CONCLUSION

To our knowledge, this case report is the first to describe sirolimus therapy combined with surgery for GSD of the spine. The patient did well with consecutive medical optimization and surgical intervention, including postoperative sirolimus and bisphosphonate therapy.

Generalized lymphatic anomaly successfully treated with long-term, low-dose sirolimus

Generalized lymphatic anomaly is a rare, complex, lymphatic anomaly generally involving soft tissues, spleen, and bones. It can lead to focal skeletal fragility and pathologic effusions. A recent prospective trial of sirolimus for complicated vascular anomalies showed partial response in seven patients with generalized lymphatic anomaly treated with sirolimus with a target trough level of 10-15 ng/mL for 1 year (Adams et al). We describe successful treatment of generalized lymphatic anomaly with a lower-dose, long-term course of sirolimus.

Vascular anomaly cases for the pediatric hematologist oncologists-An interdisciplinary review

Vascular anomalies (VAs) are classified as tumors or malformations depending on their clinical characteristics, pathological diagnosis, and genomic information. Diagnosis can be challenging because of the heterogeneity of clinical presentation; thus, the best diagnosis and care are provided by an interdisciplinary team of specialists. Over the past 10 years, an increasing number of pediatric hematologist/oncologists are caring for patients with VAs secondary to new medical therapy options and clinical trials. This paper focuses on complicated VA issues often seen by the pediatric hematologist/oncologist. The paper reviews clinical pearls on diagnosis, histology, radiology, and treatment options.

Gorham-Stout Disease Presenting as Acute Unilateral Proptosis

Gorham-Stout disease (GSD) is a rare angiomatous disorder characterized by osteolysis. We report the case of a 66-year-old woman who developed sudden left eye proptosis and facial pain. Neuroimaging demonstrated a destructive mass involving the roof and lateral wall of the left orbit with adjacent abnormal orbital soft tissue. An initial biopsy of the soft tissue was nondiagnostic; however, transcranial biopsy of the orbital roof revealed an intraosseous cavernous angioma, with infiltration of orbital fat by angiomatous tissue. Despite resection of the orbital roof and lateral wall, the orbital lesion continued to expand, leading to signs of a compressive optic neuropathy. The patient then reported severe back pain, prompting imaging that demonstrated disseminated bony involvement of the axial skeleton, eventually leading to the diagnosis of GSD. The patient was treated with a bisphosphonate and a vascular endothelial growth factor inhibitor with stabilization of disease.

Zoledronic acid in metastatic osteosarcoma: encouraging progression free survival in four consecutive patients

Background

Zoledronic acid (ZA) is a third-generation bisphosphonate in widespread clinical use to reduce pain and skeletal events in patients from a variety of malignancies with bone metastases. Pre-clinical studies indicate that ZA inhibits osteosarcoma through direct anti-proliferative effects, immune activation and anti-angiogenic activity.

Methods

The purpose of this study was to evaluate the antitumor efficacy of ZA at standard dose until progression in patients with stage IV osteosarcoma lacking a standard of care treatment option proven to influence survival. Researchers retrospectively reviewed medical records of all patients at our institution with high-grade osteosarcoma presumed to be incurable due to metastases progressive after primary combination chemotherapy who received single agent ZA in an effort to delay progression.

Results

In our four-patient cohort following initiation of ZA, the median progression-free survival was 19 months, and median overall survival was 56+ months. Two of four patients have remained progression-free since starting ZA. The other two initially progressed after 18–20 months on ZA followed by metastasectomy of lung or dural metastases and further stability for over a year following resumption of ZA. After a 20-month progression-free interval on ZA alone, one patient had partial response following addition of pazopanib to ZA that likely contributed to long term disease control. The four patients experienced no significant toxicities despite protracted dosing of ZA for up to 5 years, and none have required chemotherapy since beginning ZA.

Conclusions

Single agent ZA was associated with encouraging progression-free survival in four consecutive patients with metastatic osteosarcoma. Prospective trials of single agent ZA are warranted as protracted maintenance therapy in surgically incurable osteosarcoma relapsed or refractory to first line combination chemotherapy with radiographically measurable metastases.