Treatment at relapse for synovial sarcoma of children and adolescents: A multi-institutional European retrospective analysis

PURPOSE

Though the prognosis for pediatric patients with localised synovial sarcoma (SS) is generally good, the chances of being cured after relapse are limited. This study describes a retrospective multi-institutional series of relapsing SS patients treated at six selected European referral centers for pediatric sarcoma.

PATIENTS AND METHODS

The study included 41 patients <21 years with relapsing SS, treated between 2002 and 2022. The analysis included patient's characteristics at first diagnosis, first-line treatments, clinical findings at relapse, and second-line treatment modalities.

RESULTS

The first relapse occurred within 3-132 months (median 18 months) after first diagnosis and was local in 34%, metastatic in 54%, and both in 12%. Treatment at first relapse included surgery in 56% of cases, radiotherapy in 34%, and systemic therapy in 88%. In all, 36 patients received second-line medical treatment, that was chemotherapy in 32 cases (with 10 different regimens) and targeted therapy in four. No patient was included in an early-phase clinical trial as second-line therapy-line therapy. Overall response rate was 42%. Median event-free survival (EFS) was 12 months, postrelapse 5-year EFS was 15.8%. Median overall survival (OS) was 30 months, postrelapse 5-year OS was 22.2%. At the Cox's multivariable regression analysis, OS was significantly associated with time and type of relapse.

CONCLUSION

Pediatric patients with relapsed SS have a poor prognosis and generally receive an individualized approach, due to the lack of a uniform standardized approach. New comprehensive strategies are needed to improve the knowledge on the biologic landscape of SS and develop tailored prospective clinical trials.

Inflammatory Myofibroblastic Tumor With ROS1 Gene Fusions in Children and Young Adolescents

PURPOSE

Inflammatory myofibroblastic tumors (IMTs) are often driven by anaplastic lymphoma kinase fusions and less frequently by alternative fusions such as ROS1. We describe the clinical characteristics, treatment approach, and outcome for a series of young patients with IMTs and ROS1 alterations.

METHODS

This was a retrospective, international, multicenter study analyzing young patients (younger than 21 years) with ROS1-altered IMTs treated in 10 European referral centers between 2014 and 2022. Patients were included in the European pediatric Soft tissue sarcoma Study Group NRSTS-2005 protocol or registered in the Soft Tissue Sarcoma Registry. Primary surgery was recommended if a microscopic radical resection was feasible without mutilation. No standard systemic treatment protocol was available, but several medical options were recommended.

RESULTS

A total of 19 patients (median age 8.3 years) were included. Most patients had a biopsy at diagnosis (Intergroup Rhabdomyosarcoma Study [IRS] I; n = 2, IRS II; n = 1, IRS III biopsy; n = 11, IRS III resection; n = 3, IRS IV; n = 2). Twelve patients received neoadjuvant systemic therapy in first line (four received multiple treatments): high-dose steroids (n = 2), vinorelbine/vinblastine with methotrexate (n = 6), or ROS1 inhibitors (n = 8). After a median follow-up of 2.8 years (range, 0.2-13.4), seven patients developed an event. The 3-year event-free survival was 41% (95% CI, 11 to 71), and the 3-year overall survival was 100%.

CONCLUSION

Outcome for ROS1-altered IMTs appears excellent. A complete resection at diagnosis was often not feasible, and most patients needed neoadjuvant therapy. Patients who developed a tumor event could be cured with reinitiation of systemic therapy and/or surgery. This approach illustrates a switch in treatment philosophy moving from immediate, often mutilating, surgery to systemic (targeted) therapy as a bridge to more conservative surgery later in the treatment course.

Maintenance Chemotherapy for Patients with Rhabdomyosarcoma

Maintenance chemotherapy (MC) defines the administration of prolonged relatively low-intensity chemotherapy with the aim of "maintaining" tumor complete remission. This paper aims to report an update of the RMS2005 trial, which demonstrated better survival for patients with high-risk localized rhabdomyosarcoma (RMS) when MC with vinorelbine and low-dose cyclophosphamide was added to standard chemotherapy, and to discuss the published experience on MC in RMS. In the RMS2005 study, the outcome for patients receiving MC vs. those who stopped the treatment remains superior, with a 5-year disease-free survival of 78.1% vs. 70.1% (p = 0.056) and overall survival of 85.0% vs. 72.4% (p = 0.008), respectively. We found seven papers describing MC in RMS, but only one randomized trial that did not demonstrate any advantage when MC with eight courses of trofosfamide/idarubicine alternating with trofosfamide/etoposide has been employed in high-risk RMS. The use of MC showed better results in comparison to high-dose chemotherapy in non-randomized studies, including metastatic patients, and demonstrated feasibility and tolerability in relapsed RMS. Many aspects of MC in RMS need to be investigated, including the best drug combination and the optimal duration. The ongoing EpSSG trial will try to answer some of these questions.

Biological Role and Clinical Implications of MYOD1L122R Mutation in Rhabdomyosarcoma

Major progress in recent decades has furthered our clinical and biological understanding of rhabdomyosarcoma (RMS) with improved stratification for treatment based on risk factors. Clinical risk factors alone were used to stratify patients for treatment in the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS 2005 protocol. The current EpSSG overarching study for children and adults with frontline and relapsed rhabdomyosarcoma (FaR-RMS NCT04625907) includes FOXO1 fusion gene status in place of histology as a risk factor. Additional molecular features of significance have recently been recognized, including the MYOD1^L122R gene mutation. Here, we review biological information showing that MYOD1^L122R blocks cell differentiation and has a MYC-like activity that enhances tumorigenesis and is linked to an aggressive cellular phenotype. MYOD1^L122R mutations can be found together with mutations in other genes, such as PIK3CA, as potentially cooperating events. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, ten publications in the clinical literature involving 72 cases were reviewed. MYOD1^L122R mutation in RMS can occur in both adults and children and is frequent in sclerosing/spindle cell histology, although it is also significantly reported in a subset of embryonal RMS. MYOD1^L122R mutated tumors most frequently arise in the head and neck and extremities and are associated with poor outcome, raising the issue of how to use MYOD1^L122R in risk stratification and how to treat these patients most effectively.

PAX3-NCOA1 alveolar rhabdomyosarcoma of the tongue: A rare entity with challenging diagnosis and management

Alveolar rhabdomyosarcoma (ARMS) is associated with PAX3/PAX7-FOXO1 fusion, which confers specific clinic and biologic characteristics with inferior outcomes. A minority of tumors still histologically classified as "true" ARMS lack the canonical PAX-FOXO1 fusion but have new molecular alterations. We present the first case of PAX3-NCOA1 ARMS with clinical data and follow-up in a two-year-old girl with ARMS of the tongue and nodal extension, treated with chemotherapy, hemi glossectomy, lymph node dissection, and brachytherapy to conserve oral function and limit long-term sequelae. Given the rarity of such variant fusion in ARMS, international collaboration is required to evaluate its prognostic value.

Melanoma in Adolescents and Young Adults: Evaluation of the Characteristics, Treatment Strategies, and Prognostic Factors in a Monocentric Retrospective Study

The "Veneto Cancer Registry" records melanoma as the most common cancer diagnosed in males and the third common cancer in females under 50 years of age in the Veneto Region (Italy). While melanoma is rare in children, it has greater incidence in adolescents and young adults (AYA), but literature offers only few studies specifically focused on AYA melanoma. The aim of this study was to describe the characteristics, surgical treatment, and prognosis of a cohort of AYA melanoma in order to contribute to the investigation of this malignancy and provide better patient care. This retrospective cohort study included 2,752 Caucasian patients (702 AYA and 2,050 non-AYA patients) from the Veneto Region who were over 15 years of age at diagnosis, and who received diagnosis and/or treatment from our institutions between 1998 and 2014. Patients were divided in adolescents and youth (15-25 years), young adults (26-39 years) and adults (more than 39 years) for the analysis. We found statistically significant differences in gender, primary site, Breslow thickness, ulceration, pathologic TNM classification (pTNM) stage and tumor subtype among the age groups. Disease-specific survival and disease-free survival were also different among the age groups. Our findings suggest that the biological behavior of melanoma in young people is different to that in adults, but not such as to represent a distinct pathological entity. Additional and larger prospective studies should be performed to better evaluate potential biological and cancer-specific differences between AYAs and the adult melanoma population.

DIPG-61. RESCUE REGIMENS AFTER BIOMEDE: POSSIBLE INFLUENCE ON OS ASSESSMENT

BIOMEDE is a multicentric randomized phase II trial to evaluate in DIPG the OS of patients treated with dasatinib, erlotinib or everolimus. The OS is the result of the first line treatment but it could also be affected by re-irradiation and the second line treatment received after progression, especially in case of a possible crossover outside of the trial. This preliminary analysis focuses on the first patients enrolled at Gustave Roussy (n=37). The median age at diagnosis was 7 years, median interval from diagnosis to progression and median survival after progression were 7 (1–20) and 2 (0–13) months respectively. Initial treatment was everolimus for 13, dasatinib for 20, erlotinib for 4 patients. The most frequent targetable molecular alterations were mTOR pathway in 6, PDGRFA in 4, ACVR1 in 3 patients. Out of the 31 patients who relapsed and were evaluable, 18 and 13 had a median survival < 3 and > 3 months respectively. At relapse patients have received different types of therapies, in 6 cases matching the molecular profile of the tumour obtained by sequencing. At progression, seven patients switched from dasatinib to mTOR inhibitors and 2 patients switched from everolimus to dasatinib. Patients with OS after progression > 3 months had higher rate of reirradiation (77% vs 5%), steroid weaning (69% vs 33%) and Lansky/Karnowsky > 50% (85 vs 67%). Extended results on the entire cohort will be presented. It will be important to consider the distribution of reirradiation to interpret the results of the randomisation on OS.

Acute Cervical Longitudinally Extensive Transverse Myelitis in a Child With Lipopolysaccharide-Responsive-Beige-Like-Anchor-Protein (LRBA) Deficiency: A New Complication of a Rare Disease

Lipopolysaccharide responsive beige-like anchor protein (LRBA) deficiency is a primary immunodeficiency disorder (PID) that can cause a common variable immunodeficiency (CVID)-like disease. The typical features of the disease are autoimmunity, chronic diarrhea, and hypogammaglobulinemia. Neurological complications are also reported in patients affected by LRBA deficiency. We describe a 7-year old female with an acute cervical longitudinally extensive transverse myelitis (LETM) as a feature of LRBA deficiency. This is the first case of LETM associated with LRBA deficiency described in literature.

Prognostic role of pleural effusion or ascites in localized rhabdomyosarcoma

PURPOSE

The presence of pleural effusion or ascites at the time of diagnosis is generally considered a poor prognostic factor for children with rhabdomyosarcoma (RMS), and treatment is usually intensified despite the fact that there are no published studies to support this decision. We investigated the prognostic role of the presence of pleural effusion or ascites at diagnosis in patients with localized RMS consecutively enrolled in the Italian Soft Tissue Sarcoma Committee protocols over a 30-year period.

METHODS

We reviewed the radiological reports at diagnosis of 150 children with supradiaphragmatic and infradiaphragmatic RMS, noting any presence of effusion and its extent (minimal, moderate, or massive). All patients received intensive chemotherapy, surgery, and standard or hyperfractionated radiotherapy.

RESULTS

Effusion was identified in 32 children (21.3%), 14 with pleural effusion and 18 with ascites. As for its extent, 13 children presented with minimal, 12 with moderate, and 7 with massive effusion. The 5-year progression-free survival (PFS) rate was 49.8% (confidence interval [CI] 31.7-65.5) and 49.5% (CI 40-58.2) for patients with and without effusion, respectively (P = .5). When only patients with moderate or massive effusion were considered, however, their PFS was 36.8% (CI 16.5-57.5) versus 51.2% (CI 42.2-59.5) in patients with minimal or no effusion (P = .01). On the whole, patients with pleural effusion had a very poor outcome with a 5-year PFS of 35.7% (CI 13-59.4).

CONCLUSIONS

The presence of moderate or massive effusion seems to be an unfavorable prognostic factor in children with RMS, and justifies their inclusion in experimental studies.

Management and follow-up of urothelial neoplasms of the bladder in children: a report from the TREP project

BACKGROUND

Urothelial neoplasms of the bladder (UNB) are rare in patients under 20 years of age, and even rarer in the first decade of life. The present series was investigated to provide recommendations on patient management in terms of therapeutic strategy and follow-up.

PROCEDURE

This is a retrospective analysis on 12 patients with UNB under 18 years of age. Data were extracted from the national database of the TREP (Tumori Rari in Età Pediatrica) Project.

RESULTS

Ten of the 12 patients presented with a single episode of hematuria, while the discovery of the lesion was incidental in two. Eleven of the 12 lesions were G1 and one was G2/G3; none of the lesions invaded the lamina propria. All lesions were removed completely by transurethral resection. No further treatment was administered in nine children but three received a single dose of intravesical chemotherapy (epirubicin in 2, mitomycin in 1). Only one patient experienced a recurrence and all patients are alive in complete remission with a median follow-up of 30 months (range 4-112). Follow-up investigations varied at the different centers and included abdominal ultrasound in nine patients, cystoscopy in seven, and additional radiological investigations in a few cases.

CONCLUSIONS

UNB in children seems to be a low-grade, scarcely aggressive disease with an excellent prognosis. The role of intravesical chemotherapy is debatable. Follow-up can be based on ultrasound. The adoption of shared recommendations should enable unnecessary treatment and invasive investigations to be avoided.