The impact of local control in the treatment of children with advanced infantile and adult-type fibrosarcoma: Experience of the cooperative weichteilsarkom studiengruppe (CWS)

Therapeutic benefit of larotrectinib over the historical standard of care in patients with locally advanced or metastatic infantile fibrosarcoma (EPI VITRAKVI study)

BACKGROUND

Patients with infantile fibrosarcoma (IFS) have shown strong and long-lasting responses to larotrectinib, a tropomyosin receptor kinase inhibitor (TRKi), in single-arm clinical trials. Conventional chemotherapy has also shown important efficacy. But, until now, no comparative data exist. This study aims to assess the therapeutic benefit of larotrectinib over the current standard of care (SOC) of chemotherapy in paediatric patients with locally advanced or metastatic IFS.

PATIENTS AND METHODS

EPI VITRAKVI is a retrospective, observational, externally controlled study (NCT05236257). Data of patients aged ≤21 years with locally advanced or metastatic IFS treated with larotrectinib in the phase I/II SCOUT trial (NCT02637687) were compared with those of an external historical control group (data of Institut Curie and Cooperative Weichteilsarkom Studiengruppe) treated with a chemotherapy-based regimen. Between-group differences were assessed after balancing groups using inverse probability of treatment weighting (IPTW).

RESULTS

In total, 93 patients were compared, 51 in the larotrectinib arm and 42 in the external control arm. After therapy, 4 patients (7.8%) in the larotrectinib group had a medical treatment failure event [start of new systemic treatment (2 cases), mutilating surgery (2 cases)] versus 15 (35.7%) in the external control group [start of new systemic treatment (6 cases), mutilating surgery (5 cases), radiation therapy (2 cases), and death (2 cases)]. Larotrectinib was associated with an 80% reduced likelihood of encountering a medical treatment failure event, when compared to the external control group (weighted and stratified hazard ratio 0.20, 95% confidence interval 0.06-0.63, P = 0.0060). These results were confirmed by sensitivity analyses, including exact matching, and subgroup analyses for number of lines of treatment.

CONCLUSIONS

Treatment with larotrectinib reduced the need of subsequent therapies compared to SOC with chemotherapy in children with locally advanced or metastatic IFS, regardless of the line of treatment.

Larotrectinib versus historical standard of care in patients with infantile fibrosarcoma: protocol of EPI-VITRAKVI

The EPI VITRAKVI study is a retrospective study designed to place the results of the single-arm Phase I/II larotrectinib SCOUT trial into context by comparison with external historical controls. Its primary objective is to compare the time to medical treatment failure between larotrectinib and the historical standard of care (chemotherapy) in patients with infantile fibrosarcoma. External historical cohorts have been selected by using objective criteria. The Inverse Probability of Treatment Weighting method will be used to adjust for potential confounding. The current publication illustrates how an external control arm study can complement data from a single-arm trial and addresses uncertainties encountered in the assessment of therapies targeting rare abnormalities where randomized controlled trials are considered not feasible. Clinical Trial Registration: NCT05236257 (ClinicalTrials.gov).

Limb salvage of an infant with infantile fibrosarcoma using TRK inhibitor larotrectinib

Infantile fibrosarcoma (IFS) is an extremely rare locally aggressive soft tissue tumour of childhood. Primary therapy involves complete surgical resection with or without chemotherapy. However complete surgical resection might not be feasible in all cases and so requires other modalities for further management. We report the case of a male infant from Bangladesh with a locally advanced IFS of the leg which was partially resected. The patient received adjuvant chemotherapy which was complicated by the development of chemotherapy-related veno-occlusive disease and had to be discontinued. Thereafter he was referred to our dedicated sarcoma oncology clinic in India for further management. The parents of the child refused amputation of the limb. The tumour tested positive for NTRK3-ETV6 gene fusion and after discussion in multidisciplinary clinic, targeted therapy using oral NTRK inhibitor larotrectinib was started. The patient had complete response at the end of 8 months of treatment with larotrectinib. This is the first report from the Indian subcontinent and we encourage that these children should be referred to specialist clinics for appropriate multidisciplinary management for best outcomes.

Identification and validation of a nomogram predicting cancer-specific survival for elderly patients with adult fibrosarcoma: a multicenter retrospective study

Background

Due to the low incidence of adult fibrosarcoma (AFS), it is difficult for clinicians to assess cancer-specific survival (CSS) in elderly patients based on this study. The study aimed to develop nomograms capable of accurately predicting 3-, 5-, and 8-year CSS in patients over 40 years of age with AFS.

Methods

Data were collected from The Surveillance, Epidemiology, and End Results (SEER) registry. 586 patients were included in this study. Univariate as well as multivariate Cox regression analyses were applied to identify independent risk factors. A nomogram was constructed and validated to predict the 3-, 5-, and 8-year CSS of patients.

Results

Five variables including age, sex, stage, grade, and chemotherapy status were considered independent risk factors and were used to construct the nomogram. The nomogram was well validated. The C-indexes of the training cohort and the validation cohort are 0.766 and 0.780, respectively. In addition, the area under the curves for 3-, 5- and 8-year CSS are 0.824, 0.846 and 0.840 in the training cohort, 0.835, 0.806 and 0.829 in the validation cohort. Calibration curves were also plotted to show that predicted endings have a well fit for the true endings. Finally, decision curve analysis demonstrates that the nomogram can bring a high benefit to patients.

Conclusion

We successfully constructed a highly accurate nomogram to predict the CSS of AFS patients at 3-, 5-, and 8 years. The nomogram can greatly help clinicians and patients with AFS.

Clinical Characteristics, Treatment Considerations, and Outcomes of Infants with Rhabdomyosarcoma

RMS most commonly presents in children and adolescents, however a subset of tumors are diagnosed in infants under one year of age. Due to the rarity of infant RMS, utilization of different treatment approaches and goals, and small sample sizes, the published studies of infants with RMS have yielded heterogeneous results. In this review, we discuss the outcomes of infants with RMS treated in various clinical trials and the strategies that various international cooperative groups have employed to reduce the morbidity and mortality related to treatment without compromising the overall survival of this population. This review discusses the unique scenarios of diagnosing and managing congenitals or neonatal RMS, spindle cell RMS and relapsed RMS. This review concludes by exploring novel approaches to diagnosis and management of infants with RMS that are currently being studied by various international cooperative groups.

The significance of margins in pediatric Non-Rhabdomyosarcoma soft tissue sarcomas: Consensus on surgical margin definition harmonization from the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT)

BACKGROUND

Margin status following surgery in children, adolescents, and young adults with soft tissue sarcomas is controversial and has been defined differently by various specialties, with definitions changing over time and by cooperative group. The International Soft Tissue Sarcoma Consortium (INSTRuCT) is a collaboration of the Children's Oncology Group (COG) Soft Tissue Sarcoma Committee, European pediatric Soft Tissue sarcoma Study Group (EpSSG), and the European Cooperative Weichteilsarkom Studiengruppe (CWS) devoted to improving patient outcomes by pooling and mining cooperative group clinical trial data.

METHODS

The INSTRuCT non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) working group aimed to develop international harmonized recommendations regarding surgical margin assessment and definitions in children and adolescents with soft tissue tumors.

RESULTS AND CONCLUSION

This review addresses accepted principles and areas of controversy, including the perspectives of surgeons, pathologists, radiation oncologists, and pediatric oncologists, to develop a framework for building common guidelines for future research.

Pediatric Non-Rhabdomyosarcoma Soft Tissue Sarcomas: Standard of Care and Treatment Recommendations from the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG)

This paper describes the standard of care for patients with non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) and the therapeutic recommendations developed by the European paediatric Soft tissue sarcoma Study Group (EpSSG). NRSTS form a very mixed group of mesenchymal extraskeletal malignancies. Their rarity, heterogeneity, and aggressiveness make the management of children and adolescents with these tumors complex and challenging. The overall cure rate for patients with NRSTS is around 70%, but survival depends on several prognostic variables, such as histotype and tumor grade, extent of disease and stage, tumor size, and tumor site. While surgery remains the mainstay of treatment for most of these tumors, a multimodal therapeutic approach including radiotherapy and chemotherapy is required in many cases. The EpSSG NRSTS 2005 study was the first prospective protocol tailored specifically to NRSTS. Together with the ARST0332 study developed by the North-American Soft Tissue Sarcoma Committee of the Children's Oncology Group (COG), the EpSSG NRSTS 2005 study currently represents the benchmark for these tumors, establishing risk-adapted standards of care. The EpSSG has developed common treatment recommendations for the large group of adult-type NRSTS (including synovial sarcoma), and specific treatment recommendations for other particular adult-type histologies (ie, alveolar soft-part sarcoma, clear cell sarcoma and dermatofibrosarcoma protuberans); other highly malignant tumors with a biology and clinical behavior differing from those of adult-type NRSTS (ie, rhabdoid tumors and desmoplastic small round cell tumor); and soft tissue tumors of intermediate malignancy (ie desmoid-type fibromatosis, inflammatory myofibroblastic tumors, and infantile fibrosarcoma). New effective drugs are needed for patients whose NRSTS carries the worst prognosis, ie, those with unresectable tumors, metastases at diagnosis, or relapsing disease. Progress in this area relies on our ability to develop international integrated prospective collaborations, both within existing pediatric oncology networks and, importantly, between the communities of specialists treating pediatric and adult sarcoma.

Radical Resection of Pediatric Fibrosarcoma Is Not Associated With Survival Benefit: A Nationwide Database Analysis

INTRODUCTION

Fibrosarcoma is one of the most common nonrhabdomyosarcoma soft tissue sarcomas in the pediatric population. Surgical resection is the cornerstone of treatment; however, optimal factors regarding the extent of fibrosarcoma resection in localized versus regional disease is poorly understood.

METHODS

The Surveillance, Epidemiology, and End Results database was queried for patients who are 19 y old or younger with a diagnosis of fibrosarcoma from 1975 to 2016. Kaplan-Meier analyses were performed for disease-specific survival on clinical and pathologic variables. Multivariate analysis was performed based on significant predictors of disease-specific survival.

RESULTS

There were 1290 patients (median age 13 [7-17] y) identified with fibrosarcoma. The overall survival rate at 20 y was 93%. Radical resection was performed on 22%, 40%, and 52% of patients with localized, regional, and distant Surveillance, Epidemiology, and End Results disease stage, respectively. Chemotherapy (P < 0.001), radiation (P < 0.001), histology (P < 0.001), and stage (P = 0.004) were significant predictors of increased mortality using univariate Kaplan-Meier analysis. Most patients (86%) with localized or regional stage who underwent radiation had fibrosarcomas of nondermatofibrosarcoma histology (P < 0.001). Dermatofibrosarcoma subtype comprised most radical resections (41%). Excluding distant stage, nondermatofibroma histology (hazard ratio 16.94, 95% confidence interval 3.77-76.01) and regional stage (hazard ratio 8.15, 95% confidence interval 2.93-22.69) were independent prognostic factors of mortality (both P < 0.001). Radical resection was not a significant independent prognostic indicator of survival.

CONCLUSIONS

Nondermatofibrosarcoma subtype is independently associated with increased mortality. Although surgery remains the mainstay of treatment, the extent of resection is not a predictor of survival for patients with the localized and regional stage of disease.

Genomic Evolution and Personalized Therapy of an Infantile Fibrosarcoma Harboring an NTRK Oncogenic Fusion

Precision medicine for infantile fibrosarcoma by monitoring of spatial and temporal clonal evolution (requested from authors: Would you be so kind to let us know when the article is announced via Twitter?).

Laparoscopic excision for multiple intra-abdominal juvenile fibrosarcoma: A case report

Introduction and importance

Fibrosarcoma is a rare malignant tumor comprising spindle-shaped fibroblasts exhibiting variable collagen production. Adult-type fibrosarcoma (AFS) mainly occurs in people aged between 30 and 80 years, primarily in the deep soft tissues of the trunk, neck, and extremities, especially in areas surrounding bones. Juvenile fibrosarcoma(JFS) is a type of AFS that occurs in adolescents and rarely develops in the abdominal cavity.

Case presentation

A 13-year-old girl presented with right upper quadrant pain for 5 days. Abdomen and pelvis computed tomography showed a 12 × 6-cm, ill-defined, lobulated, solid, cystic mass in the abdominal cavity. On laparoscopy, there were two masses in the abdominal cavity. One abutted the stomach and severely adhered to the gallbladder. The second mass was located between the transverse colon and duodenum, and it was surrounded by the omentum. The tissues surrounding the masses were finely dissected, and the two masses were excised completely. The patient was discharged without complications on post-operative day 7.

Clinical discussion

JFS, AFS in adolescents, is a rare malignant tumor. And there have been no reported cases of multiple JFS in abdominal cavity. Surgical excision is the gold standard of treatment for localized AFS, and the laparoscopic approach for minimal tumor handling is beneficial.

Conclusion

We describe a rare case of multiple intra-abdominal juvenile fibrosarcoma, managed through laparoscopic surgery.

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Fibrosarcoma is a rare malignant tumor composed of spindle-shaped fibroblasts with variable collagen production.

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Juvenile fibrosarcoma(JFS) is a type of AFS occurring in adolescents, and it rarely develops in the abdominal cavity.

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Curative surgical excision is the gold standard treatment for localized fibrosarcoma, and laparoscopic approach is benefitial.