Rare Primary Malignant Bone Sarcomas

Unraveling molecular signatures in rare bone tumors and navigating the cancer pathway landscapes for targeted therapeutics

Rare cancers (RCs), which account for over 20% of cancer cases, face significant research and treatment challenges due to their limited prevalence. This results in suboptimal outcomes compared to more common malignancies. Rare bone tumors (RBTs) constitute 5-10% of rare cancer cases and pose unique diagnostic complexities. The therapeutic potential of anti-cancer drugs for RBTs remains largely unexplored. Identifying molecular alterations in cancer-related genes and their associated pathways is essential for precision medicine in RBTs. Small molecule inhibitors and monoclonal antibodies targeting specific RBT-associated proteins show promise. Ongoing clinical trials aim to define RBT biomarkers, subtypes, and optimal treatment contexts, including combination therapies and immunotherapeutic agents. This review addresses the challenges in diagnosing, treating, and studying RBTs, shedding light on the current state of RBT biomarkers, potential therapeutic targets, and promising inhibitors. Rare cancers demand attention and innovative solutions to improve clinical outcomes.

Primary leiomyosarcoma of the bone: a case report

Primary leiomyosarcoma of the bone is rare. Histologically, it resembles leiomyosarcoma of soft tissue. Given the rarity of this entity, its diagnosis should be made only after clinical studies and workup have excluded metastasis from other sites. Herein, we describe an additional case of primary bone leiomyosarcoma. We report a 32-year-old female patient, who presented with right knee pain and was found to have a right distal femur mass by imaging studies. Biopsy showed a neoplasm composed of fascicles of spindle cells, arranged in different patterns, with significant pleomorphism. The tumor cells were positive for smooth muscle actin, focally positive for desmin and H-caldesmon. No other masses in the body were detected by imaging studies. The diagnosis of leiomyosarcoma of the bone was rendered. Given the broad diagnostic differential of primary bone leiomyosarcoma, it is important to be aware of this rare bone tumor phenotype and of its histomorphologic and immunohistochemical features for an accurate diagnosis.

Metastatic sarcomatoid carcinoma to bone

BACKGROUND AND OBJECTIVES

Distinguishing sarcomatoid carcinoma from primary sarcoma is clinically important. We sought to characterize metastatic sarcomatoid bone disease and its management.

METHODS

We analyzed the characteristics of all cases of sarcomatoid carcinoma to bone at a single institution from 2001 to 2021, excluding patients with nonosseous metastases. Survival was evaluated using the Kaplan-Meier method.

RESULTS

We identified 15 cases of metastatic sarcomatoid carcinoma to bone. In seven cases the primary cancer was unknown at presentation. Renal cell carcinoma was suspected or confirmed in nine cases. Nine patients presented with pathologic fracture and two with concomitant visceral metastases. All patients underwent image-guided core needle or open biopsy. Ten required surgery for discrete osseous metastases; in four cases definitive surgery was delayed (median delay, 19 days) due to inability to rule out sarcoma with frozen section. No patients required reoperation or had construct failure. Thirteen died of disease; median survival was 17.5 months (interquartile range, 6.2-25.1).

CONCLUSIONS

Metastatic sarcomatoid carcinoma is a clinically challenging entity. Multidisciplinary input and communication are key to identifying the primary carcinoma, locating osseous metastases, and defining an operative fixation that will survive the remainder of the patient's life.

Outcome of rare primary malignant bone sarcoma treated with multimodal therapy: Results from the EUROpean Bone Over 40 Sarcoma Study (EURO-B.O.S.S.)

BACKGROUND

Rare primary malignant bone sarcomas (RPMBS) account for 5%-10% of primary high-grade bone tumors and represent a major treatment challenge. The outcome of patients with RPMBS enrolled in the EUROpean Bone Over 40 Sarcoma Study (EURO-B.O.S.S) is presented.

METHODS

Inclusion criteria were as follows: age from 41 to 65 years and a diagnosis of high-grade spindle cell, pleomorphic, or vascular RPMBS. The chemotherapy regimen included doxorubicin 60 mg/m2 , ifosfamide 9 g/m2 , and cisplatin 90 mg/m2 ; postoperative methotrexate 8 g/m2 was added in case of a poor histologic response. Version 2.0 of the Common Terminology Criteria for Adverse Events, Kaplan-Meier curves, log-rank tests, and univariate Cox regression models were used.

RESULTS

In total, 113 patients were evaluable for analysis. The median patient age was 52 years (range, 40-66 years), and 67 patients were men. Eighty-eight tumors were categorized as undifferentiated pleomorphic sarcomas (UPS), 20 were categorized as leiomyosarcomas, three were categorized as fibrosarcomas, and two were categorized as angiosarcomas. Eighty-three of 113 tumors were located in the extremities. Ninety-five of 113 patients presented with no evidence of metastases. After a median follow-up of 6.8 years (interquartile range [IQR], 3.5-9.8 years), the 5-year overall survival rate for patients with localized disease was 68.4% (IQR, 56.9%-77.5%), and it was 71.7% (IQR, 58.1%-81.6%) for patients with UPS and 54.9% (IQR, 29.5%-74.5%) for patients with leiomyosarcoma. Grade III-IV hematologic toxicity was reported in 81% patients; 23% had grade II-III neurotoxicity, and 37.5% had grade I-II nephrotoxicity. Five-year overall survival was significantly better for patients with localized disease, for patients who obtained surgical complete remission, and when the primary tumor was located in the extremities.

CONCLUSIONS

The survival of patients who had RPMBS in the current series was similar to that of age-matched patients who had high-grade osteosarcoma treated according to the same protocol. An osteosarcoma-like chemotherapy may be proposed in patients who have RPMBS.

A global collaboRAtive study of CIC-rearranged, BCOR::CCNB3-rearranged and other ultra-rare unclassified undifferentiated small round cell sarcomas (GRACefUl)

BACKGROUND

Undifferentiated small round cell sarcomas (URCSs) represent a diagnostic challenge, and their optimal treatment is unknown. We aimed to define the clinical characteristics, treatment, and outcome of URCS patients.

METHODS

URCS patients treated from 1983 to 2019 at 21 worldwide sarcoma reference centres were retrospectively identified. Based on molecular assessment, cases were classified as follows: (1) CIC-rearranged round cell sarcomas, (2) BCOR::CCNB3-rearranged round cell sarcomas, (3) unclassified URCSs. Treatment, prognostic factors and outcome were reviewed.

RESULTS

In total, 148 patients were identified [88/148 (60%) CIC-rearranged sarcoma (median age 32 years, range 7-78), 33/148 (22%) BCOR::CCNB3-rearranged (median age 17 years, range 5-91), and 27/148 (18%) unclassified URCSs (median age 37 years, range 4-70)]. One hundred-one (68.2%) cases presented with localised disease; 47 (31.8%) had metastases at diagnosis. Male prevalence, younger age, bone primary site, and a low rate of synchronous metastases were observed in BCOR::CCNB3-rearranged cases. Local treatment was surgery in 67/148 (45%) patients, and surgery + radiotherapy in 52/148 (35%). Chemotherapy was given to 122/148 (82%) patients. At a 42.7-month median follow-up, the 3-year overall survival (OS) was 92.2% (95% CI 71.5-98.0) in BCOR::CCNB3 patients, 39.6% (95% CI 27.7-51.3) in CIC-rearranged sarcomas, and 78.7% in unclassified URCSs (95% CI 56.1-90.6; p < 0.0001).

CONCLUSIONS

This study is the largest conducted in URCS and confirms major differences in outcomes between URCS subtypes. A full molecular assessment should be undertaken when a diagnosis of URCS is suspected. Prospective studies are needed to better define the optimal treatment strategy in each URCS subtype.

Pathological fracture due to primary bone lymphoma in a patient with a history of prostate cancer: A case report and review of literature

Primary bone lymphoma (PBL) is a rare extranodal presentation within lymphomas and primary bone malignancies. Pathologic fracture (PF) is a common complication of metastatic bone disease but is, rarely, the presentation of a primary bone tumor. We report a case of an 83-year-old man with a history of untreated prostate cancer, presenting with atraumatic fracture of his left femur after months of intermittent pains and weight loss. Radiographic workup revealed a lytic lesion suspicious for PF secondary to metastatic prostate cancer; however, initial core biopsy results were inconclusive for malignancy. A complete blood count with differential and complete metabolic panel was within normal limits. During surgical fixation and nailing of the femur, a reaming biopsy was performed as a repeat measure and revealed diffuse large B-cell lymphoma. Staging with positron emission tomography and computed tomography found no evidence of lymphatic or visceral involvement and chemotherapy was promptly initiated. This case highlights the diagnostic workup challenges for PF secondary to PBL, especially in the setting of concurrent malignancy. Because of the non-specific presentation of a lytic lesion on imaging associated with atraumatic fracture, we highlight PBL as an important diagnostic consideration.

Modification and Functionalization of Polymers for Targeting to Bone Cancer and Bone Regeneration

Bone is one of the most complex, inaccessible body structures, responsible for calcium storage and haematopoiesis. The second highest cause of death across the world is cancer. Amongst all the types of cancers, bone cancer treatment modalities are limited due to the structural complexity and inaccessibility of bones. The worldwide incidence of bone diseases and bone defects due to cancer, infection, trauma, age-related bone degeneration is increasing. Currently different conventional therapies are available for bone cancer such as chemotherapy, surgery and radiotherapy, but they have several disadvantages associated with them. Nanomedicine is being extensively researched as viable therapeutics to mitigate drug resistance in cancer therapy and promote bone regeneration. Several natural polymers such as chitosan, dextran, alginate, hyaluronic acid, and synthetic polymers like polyglycolic acid, poly(lactic-co-glycolic acid), polycaprolactone are investigated for their application in nanomedicine for bone cancer treatment and bone regeneration. Nanocarriers have shown promising results in preclinical experimental studies. However, they still face a major drawback of inadequate targetability. The paper summarizes the status of research and the progress made so far in modifications and functionalization of natural polymers for improving their site specificity and targeting for effective treatment of bone cancer and enhancing bone regeneration.

Bioactive Glasses as Carriers of Cancer-Targeted Drugs: Challenges and Opportunities in Bone Cancer Treatment

The treatment of bone cancer involves tumor resection followed by bone reconstruction of the defect caused by the tumor using biomaterials. Additionally, post-surgery protocols cover chemotherapy, radiotherapy, or drug administration, which are employed as adjuvant treatments to prevent tumor recurrence. In this work, we reviewed new strategies for bone cancer treatment based on bioactive glasses as carriers of cancer-targeted and other drugs that are intended for bone regeneration in conjunction with adjuvant treatments. Drugs used in combination with bioactive glasses can be classified into cancer-target, osteoclast-target, and new therapies (such as gene delivery and bioinorganic). Microparticulated, nanoparticulated, or mesoporous bioactive glasses have been used as drug-delivery systems. Additionally, surface modification through functionalization or the production of composites based on polymers and hydrogels has been employed to improve drug-release kinetics. Overall, although different drugs and drug delivery systems have been developed, there is still room for new studies involving kinase inhibitors or antibody-conjugated drugs, as these drugs have been poorly explored in combination with bioactive glasses.

Amino acid metabolism in primary bone sarcomas

Primary bone sarcomas, including osteosarcoma (OS) and Ewing sarcoma (ES), are aggressive tumors with peak incidence in childhood and adolescence. The intense standard treatment for these patients consists of combined surgery and/or radiation and maximal doses of chemotherapy; a regimen that has not seen improvement in decades. Like other tumor types, ES and OS are characterized by dysregulated cellular metabolism and a rewiring of metabolic pathways to support the biosynthetic demands of malignant growth. Not only are cancer cells characterized by Warburg metabolism, or aerobic glycolysis, but emerging work has revealed a dependence on amino acid metabolism. Aside from incorporation into proteins, amino acids serve critical functions in redox balance, energy homeostasis, and epigenetic maintenance. In this review, we summarize current studies describing the amino acid metabolic requirements of primary bone sarcomas, focusing on OS and ES, and compare these dependencies in the normal bone and malignant tumor contexts. We also examine insights that can be gleaned from other cancers to better understand differential metabolic susceptibilities between primary and metastatic tumor microenvironments. Lastly, we discuss potential metabolic vulnerabilities that may be exploited therapeutically and provide better-targeted treatments to improve the current standard of care.

Characterization of the immune cell infiltration landscape in myxofibrosarcoma to aid immunotherapy

Myxofibrosarcoma (MFS) is a highly malignant subtype of soft tissue sarcoma, accounting for 5% of cases. Immunotherapy guided by immune cell infiltration (ICI) is reportedly a promising treatment strategy. Here, MFS samples (n = 104) from two independent databases were classified as ICI clusters A/B/C and gene clusters A/B/C. Then, a close relationship between ICI and gene clusters was established. We found that the features of these clusters were consistent with the characteristics of immune-inflamed tumors (cluster C), immune-desert tumors (cluster B), and immune-excluded tumors (cluster A). Moreover, cluster C was sensitive to immunotherapy. Finally, an independent ICI score was established to predict the therapeutic effect, which has prospects for application in guiding immunotherapy during clinical practice.

Primary Malignant Peripheral Nerve Sheath Tumors of Bone: A Clinicopathologic Reappraisal of 8 Cases

Primary spindle cell and pleomorphic sarcomas of bone represent an exceedingly rare group of mesenchymal malignancies that include "soft tissue" histotypes, as malignant peripheral nerve sheath tumour. Outside the head and neck region, only 36 cases of primary malignant peripheral nerve sheath tumour of bone have been described. We retrieved from our archives eight cases of primary malignant peripheral nerve sheath tumour of bone arising outside the head and neck region, describing their clinical, radiological, and morphologic features. Our series, in which all but one patient died of diseases after a median of seven months, confirms that primary malignant peripheral nerve sheath tumours of bone are aggressive tumours. Pathologists should be aware of this rare histotype. More aggressive and active adjuvant treatments should be investigated.

A Proposed Trial Design for the Treatment of Widely Metastatic Ewing Sarcoma Inspired by Evolutionary Dynamics

Metastatic Ewing sarcoma has dismal long-term survival despite multiple attempts to intensify standard therapy through the addition of new agents to the existing chemotherapy backbone. Here, based on the application of evolutionary dynamics to pediatric sarcoma, we propose an alternative treatment strategy that varies exposure to agents and dosing intensities, termed sequential second-strike therapy (SSST). We announce an upcoming clinical trial to apply these principles to patients with widely metastatic Ewing sarcoma, those with metastatic disease beyond the lungs.

Primary synovial sarcoma of bone: A retrospective analysis of 25 patients

AIMS

To evaluate diagnostic accuracy of SSX and SSX-SS18 antibodies in decalcified surgical specimens and outcome of synovial sarcomas (SS) of bone.

METHODS AND RESULTS

Twenty-five cases were classified as bone SS (prevalence 0.32% among malignant primary bone sarcoma). Median age was 34 years (range 9 -79) . 24/25 patients presented with non-metastatic tumors, one with lung metastases. The majority of tumors involved the long bones of extremities with metaphyseal origin. Mean size of the tumor was 7.1 cm. 20 cases (80%) were monophasic and 5 (20%) biphasic. SS18-SSX fusion-specific antibody had 92% sensitivity and 99% specificity for primary bone SS, whereas SSX C-terminus antibody had 100% sensitivity and 94% specificity. FISH analysis was feasible in 9 (36%) cases and detected SS18 rearrangement in all 9 cases. All patients underwent surgical removal of their primary tumor, with adequate margins in 18 (72%) patients. Chemotherapy with metothrexate, cisplatin, doxorubicin, ifosfamide was used in the 7 patients. Two patients with inadequate surgical margins received radiotherapy. With a median follow-up of 80 months (range 6-428), 5-year and 10-year overall survival (OS) were 66.6% and 47.9% respectively and 5-and 10-years disease-free survival (DFS) were 36.8% (95% C.I.: 18.0-55.7%), and 32.2% (95% C.I.: 14.6-51.2%) respectively A significant improvement in 10-years DFS in patients undergoing chemotherapy as compared with patients who did not was observed (p 0.039).

CONCLUSIONS

Our series highlights the utility of SS18-SSX fusion-specific and SSX C-terminus antibodies to support the diagnosis of SS, Adjustment chemotherapy was associated with improved prognosis in this series.

Extracellular Vesicles in Bone Tumors: How to Seed in the Surroundings Molecular Information for Malignant Transformation and Progression

Bone is a very dynamic tissue hosting different cell types whose functions are regulated by a plethora of membrane-bound and soluble molecules. Intercellular communication was recently demonstrated to be also sustained by the exchange of extracellular vesicles (EVs). These are cell-derived nanosized structures shuttling biologically active molecules, such as nucleic acids and proteins. The bone microenvironment is a preferential site of primary and metastatic tumors, in which cancer cells find a fertile soil to “seed and blossom”. Nowadays, many oncogenic processes are recognized to be sustained by EVs. For example, EVs can directly fuel the vicious cycle in the bone/bone marrow microenvironment. EVs create a favourable environment for tumor growth by affecting osteoblasts, osteoclasts, osteocytes, adipocytes, leukocytes, and endothelial cells. At the same time other crucial tumor-mediated events, such as the premetastatic niche formation, tumor cell dormancy, as well as drug resistance, have been described to be fostered by tumor-derived EVs. In this review, we will discuss the main body of literature describing how the cancer cells use the EVs for their growth into the bone and for educating the bone microenvironment to host metastases.

Primary Angiosarcoma of Humerus - A Case Report and Literature Review

INTRODUCTION

Osseous angiosarcoma is a very rare tumor of bone with aggressive behavior, propensity for recurrences, and distant metastasis. The etiology of osseous angiosarcoma is uncertain; however, specific risk factors have been recognized. The diagnosis of angiosarcoma of bone demands multimodality imaging in conjunction with histopathological and vascular marker evaluation to aptly differentiate them from other vascular tumors. Treatment of osseous angiosarcoma remains controversial.

CASE REPORT

A 53-year-old male presented with pain and swelling of the right upper 1/3rd of the arm following heaviness while lifting weight for 3 months. He had a history of significant weight loss and appetite with no history of inciting trauma or irradiation in the past. On examination, a diffuse swelling was noted in the right shoulder and right scapular aspect with varied consistency and ill-defined borders and margins. The skin over the swelling was stretched and shiny with dilated engorged veins over it. The plain radiograph of the right shoulder with humerus revealed a large expansile lytic soft-tissue mass in the right proximal humerus with a wide zone of transition without sclerotic margins. Magnetic resonance imaging showed T1 hypointense, T2/PDFS hyperintense large well-defined expansile lytic lesion with multi-loculated cysts, and multiple blood-fluid levels involving right proximal humerus. The patient underwent an incisional biopsy which exhibited angiosarcoma of the humerus. The patient was treated with six cycles of chemotherapy with a mesna, doxorubicin, ifosfamide, and dacarbazine regimen. The patient was still under follow-up.

CONCLUSION

Being a rare clinical entity, controversy exists in angiosarcoma of humerus regarding its etiology and recommended management protocols. Histopathology and immunohistochemistry remain the gold standard in differentiating osseous angiosarcoma from other osseous vascular tumors. The treatment protocol has to be standardized to decrease morbidity and to improve the functional quality of life of the patient.