Adolescents and young adults with rhabdomyosarcoma: A report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group

INTRODUCTION

The impact of established prognostic factors on survival outcomes for childhood rhabdomyosarcoma (RMS) have not been well described in the adolescent and young adult (AYA) RMS patient population.

METHODS

This is a retrospective analysis of patients with newly diagnosed RMS enrolled between 1997 and 2016 on seven previously reported Children's Oncology Group (COG) clinical trials. Demographics, clinical features, treatment details, and outcome data were collected. Five-year event-free survival (EFS) and overall survival (OS) were estimated for patients diagnosed at age 15-39 years and those diagnosed under age 15 years using the Kaplan-Meier method. Log-rank test was used to compare prognostic factors for EFS and OS. Factors significant in the univariable analysis were included in a Cox proportional hazards regression model. Nonsignificant covariates were removed from the multiple regression model.

RESULTS

Total 2151 patients including 402 AYAs were analyzed. AYAs were more likely to present with primary tumors ≥5 cm in size, metastatic disease, alveolar histology, and have FOXO1 fusions compared to children. Five-year EFS for the AYA cohort was 44.2% versus 67% for children (p < .001), and 5-year OS was 52% for the AYA cohort versus 78% for children (p < .001). Multivariable analysis revealed tumor site, size and invasiveness, clinical group, and histology were prognostic in AYAs.

CONCLUSION

AYAs with RMS have a poorer prognosis compared to younger children due to multiple factors. Further research focused on AYAs to better understand RMS biology and improve treatments is critical to improve survival.

Diagnostic Utility of GATA3 and ISL1 in Differentiating Neuroblastoma From Other Pediatric Malignant Small Round Blue Cell Tumors

Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and immunohistochemical (immunohistochemistry [IHC]; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.

We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.

All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n  =  17; moderate to strong staining in 26%-50% of the tumor cells, n  =  5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded.

CONCLUSIONS

GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.

Use of Perirectal Hyaluronic Acid Spacer Prior to Radiotherapy in a Pediatric Patient With Bladder Rhabdomyosarcoma: A Case Report

Rhabdomyosarcoma (RMS) treatment involves surgery, chemotherapy, and radiotherapy. A radioprotective space between the bladder/prostate and rectum reduces postradiation complications, as reported in adult patients. Describe pediatric preradiotherapy perirectal hyaluronic acid (HA) spacer injection for bladder/prostate RMS. We present a case of a 17-month-old male with bladder/prostate RMS. Before radiotherapy, an HA spacer was injected peri-rectally. Under general anesthesia, a transrectal ultrasound was positioned and 1mL of HA spacer was injected into the perirectal space. No complications were reported at 6-month follow-up. This is the first report of pre-radiation therapy spacer injection for pediatric bladder/prostate RMS.

Epithelioid and spindle cell rhabdomyosarcoma with EWSR1::TFCP2 fusion mimicking metastatic lung cancer: A case report and literature review

Rhabdomyosarcoma (RMS) with EWSR1/FUS::TFCP2 fusion is an emerging, molecularly defined, rare subtype of RMS. It can affect patients in a wide age range and follows an aggressive clinical course according to the reported cases. Due to its unusual clinical and pathohistological features, with a typical intraosseous presentation and common cytokeratin expression, the diagnosis is challenging, and metastatic undifferentiated/sarcomatoid carcinoma can be an important differential diagnosis. We report here a case of a 55-year-old woman with an RMS with EWSR1::TFCP2 fusion mimicking metastatic lung cancer in view of the clinical and microscopic presentation. However, further molecular workup, including RNA sequencing, led to the proper diagnosis. Although these tumors are rare, knowledge of their unique features is essential for correct diagnosis as a basis for clinical management and optimization of therapeutic approaches.

Facial deformation following treatment for pediatric head and neck rhabdomyosarcoma; the difference between treatment modalities. Results of a trans-Atlantic, multicenter cross-sectional cohort study

BACKGROUND

The four different local therapy strategies used for head and neck rhabdomyosarcoma (HNRMS) include proton therapy (PT), photon therapy (RT), surgery with radiotherapy (Paris-method), and surgery with brachytherapy (AMORE). Local control and survival is comparable; however, the impact of these different treatments on facial deformation is still poorly understood. This study aims to quantify facial deformation and investigates the differences in facial deformation between treatment modalities.

METHODS

Across four European and North American institutions, HNRMS survivors treated between 1990 and 2017, more than 2 years post treatment, had a 3D photograph taken. Using dense surface modeling, we computed facial signatures for each survivor to show facial deformation relative to 35 age-sex-ethnicity-matched controls. Additionally, we computed individual facial asymmetry.

FINDINGS

A total of 173 HNRMS survivors were included, survivors showed significantly reduced facial growth (p < .001) compared to healthy controls. Partitioned by tumor site, there was reduced facial growth in survivors with nonparameningeal primaries (p = .002), and parameningeal primaries (p ≤.001), but not for orbital primaries (p = .080) All patients were significantly more asymmetric than healthy controls, independent of treatment modality (p ≤ .001). There was significantly more facial deformation in orbital patients when comparing RT to AMORE (p = .046). In survivors with a parameningeal tumor, there was significantly less facial deformation in PT when compared to RT (p = .009) and Paris-method (p = .007).

INTERPRETATION

When selecting optimal treatment, musculoskeletal facial outcomes are an expected difference between treatment options. These anticipated differences are currently based on clinicians' bias, expertise, and experience. These data supplement clinician judgment with an objective analysis highlighting the impact of patient age and tumor site between existing treatment options.

Survival and Analysis of Prognostic Factors for Bladder Malignancies in Children and Adolescents: A Population-based Study

OBJECTIVE

To explore the clinicopathological features and prognosis of pediatric patients with malignant bladder tumors in a population-based cohort.

METHODS

The database Surveillance, Epidemiology, and End Results was used to evaluate all pediatric patients diagnosed with malignant bladder tumors between 1975 and 2018. The log-rank test was used to compare survival curves. Kaplan-Meier estimations were used to create survival curves based on various parameters. The Cox proportional hazards model was utilized to determine the factors that were independently related to mortality.

RESULTS

A total of 263 children and adolescents with bladder malignancies were assessed. Papillary urothelial neoplasms of low malignant potential were the most frequent histologic subtype (35.1%), while embryonal rhabdomyosarcoma was more common during the first decade of life. Survival rates varied significantly by age at diagnosis, with older patients showing better outcomes. When compared to other subtypes, papillary urothelial neoplasms of low malignant potential had the highest overall survival rates (3- and 5-year were 99.2% and 98.3%, respectively). Multivariate analysis of the entire cohort showed that Surveillance, Epidemiology, and End Results stage and surgery were significant independent predictors of progression to disease-specific death in this model.

CONCLUSION

Bladder malignancies are rare in children and adolescents. The prognosis for them varies. The localized stage was independently associated with superior survival and surgery could extend survival time.

Rhabdomyosarcoma with isolated lung metastases: A report from the Soft Tissue Sarcoma Committee of the Children's Oncology Group

BACKGROUND

To determine outcomes of children with rhabdomyosarcoma (RMS) with isolated lung metastases.

METHODS

Data were analyzed for 428 patients with metastatic RMS treated on COG protocols. Categorical variables were compared using Chi-square or Fisher's exact tests. Event-free survival (EFS) and overall survival (OS) were estimated using Kaplan-Meier method and compared using the log-rank test.

RESULTS

Compared with patients with other metastatic sites (n = 373), patients with lung-only metastases (n = 55) were more likely to be <10 years of age, have embryonal histology (embryonal rhabdomyosarcoma), have N0 disease, and less likely to have primary extremity tumors. Lung-only patients had significantly better survival outcomes than patients with all other sites of metastatic disease (p < .0001) with 5-year EFS of 48.1 versus 18.8% and 5-year OS of 64.1 versus 26.9%. Patients with lung-only metastases, and those with a single extrapulmonary site of metastasis, had better survival compared with patients with two or more sites of metastatic disease (p < .0001). In patients with ERMS and lung-only metastases, there was no significant difference in survival between patients ≥10 years and 1-9 years (5-year EFS: 58.3 vs. 68.2%, 5-year OS: 66.7 vs. 67.7%).

CONCLUSIONS

With aggressive treatment, patients with ERMS and lung-only metastatic disease have superior EFS and OS compared with patients with other sites of metastatic disease, even when older than 10 years of age. Consideration should be given to including patients ≥10 years with ERMS and lung-only metastases in the same group as those <10 years in future risk stratification algorithms.

Rhabdomyosarcoma Arising in Inflammatory Rhabdomyoblastic Tumor: A Genetically Distinctive Subtype of Rhabdomyosarcoma

"Inflammatory rhabdomyoblastic tumor" (IRMT) is a recently coined name for a distinctive soft tissue neoplasm characterized by slow growth, a dense histiocytic infiltrate, scattered, bizarre-appearing tumor cells with morphologic and immunohistochemical evidence of skeletal muscle differentiation, a near-haploid karyotype with retained biparental disomy of chromosomes 5 and 22, and usually indolent behavior. There are 2 reports of rhabdomyosarcoma (RMS) arising in IRMT. We studied the clinicopathologic and cytogenomic features of 6 cases of IRMT with progression to RMS. Tumors occurred in the extremities of 5 men and 1 woman (median patient age, 50 years; median tumor size, 6.5 cm). Clinical follow-up (6 patients: median, 11 months; range 4-163 months) documented local recurrence and distant metastases in 1 and 5 of 6 patients, respectively. Therapy included complete surgical resection (4 patients) and adjuvant/neoadjuvant chemo/radiotherapy (6 patients). One patient died of disease, 4 were alive with metastatic disease, and one was without evidence of disease. All primary tumors contained conventional IRMT. Progression to RMS appeared as follows: (1) overgrowth of monomorphic rhabdomyoblasts with diminished histiocytes, (2) monomorphic spindle cell morphology with variably pleomorphic rhabdomyoblasts and low mitotic activity, or (3) morphologically undifferentiated spindle cell and epithelioid sarcoma. All but one were diffusely desmin-positive, with more limited MyoD1/myogenin expression. All RMS arising in IRMT, either primary or metastatic, demonstrated widespread loss of heterozygosity with retained heterozygosity of chromosomes 5 and 20, and all but one displayed additional gains and losses involving loci containing oncogenes/ tumor suppressor genes, most often CDKN2A and CDKN2B. RMS arising in IRMT have unique clinicopathologic and cytogenomic features, warranting classification as a distinct, potentially aggressive RMS subtype. It should be distinguished from other RMSs, particularly fusion-driven spindle cell RMS and pleomorphic RMS.

Alveolar rhabdomyosarcoma has superior response rates to vinorelbine compared to embryonal rhabdomyosarcoma in patients with relapsed/refractory disease: A meta-analysis

BACKGROUND

Patients with alveolar rhabdomyosarcoma (ARMS) have inferior outcomes compared to patients with embryonal rhabdomyosarcoma (ERMS) and more effective chemotherapy options are needed for these patients. Vinorelbine is a semisynthetic vinca alkaloid that has clinical activity in relapsed rhabdomyosarcoma (RMS) when used alone or in combination with cyclophosphamide.

AIMS

The goal of our study was to evaluate whether RMS histology subtype influences response rate to vinorelbine alone or in combination.

MATERIALS & METHODS

Five Phase 2 trials that enrolled RMS patients were included in the meta-analysis. Two studies evaluated vinorelbine alone, two studies evaluated vinorelbine in combination with low dose oral cyclophosphamide, and one study evaluated vinorelbine and intravenous cyclophosphamide in combination with temsirolimus or bevacizumab. All RMS patients had relapsed or refractory disease and had received at least one prior therapy. Response was reported according to RECIST1.1 and was defined as a complete or partial response. Response data was obtained from published results or from trial principal investigator. RMS NOS patients were grouped with ERMS patients for this analysis. Summary estimates comparing differences between ARMS and ERMS response rates were generated using a random-effects model to account for heterogeneity among the studies.

RESULTS

One hundred fifty-six enrolled patients evaluable for response were included in the meta-analysis, 85 ARMS, 64 ERMS and 7 RMS-NOS. The combined effect generated from the random-effects model demonstrated a 41% increase (p = 0.001, 95% CI; 0.21-0.60) in response to vinorelbine as a single agent or in combination in patients with ARMS compared to patients with ERMS. There was no significant difference in the rate of progressive disease between patients with ARMS compared to ERMS (p = 0.1, 95%CI; -0.26-0.02).

DISCUSSION

Vinorelbine is an active agent for the treatment of relapsed or refractory RMS and a meta-analysis of Phase 2 studies shows that radiographic responses in patients with ARMS were significantly higher than ERMS or RMS-NOS.

CONCLUSION

These data support further investigation of vinorelbine in newly diagnosed patients with RMS particularly those with alveolar histology.

Adaptive Proton Therapy for Pediatric Parameningeal Rhabdomyosarcoma: On-Treatment Anatomic Changes and Timing to Replanning

PURPOSE

To characterize on-treatment changes in GTV morphology in children with parameningeal rhabdomyosarcoma receiving upfront proton therapy with concurrent chemotherapy and thereby provide guidance on the timing of on-treatment imaging and adaptive replanning.

METHODS AND MATERIALS

GTV was delineated on 86 simulation and weekly MR images of 15 prospectively enrolled patients (aged 1-21 years). Temporal changes from baseline in volume and surface (95% Hausdorff distance) were analyzed in relation to the need for plan verification and the resultant doses with hypothetical no treatment adaptation.

RESULTS

The median time was 6 days from the initiation of chemotherapy to CT+MR simulation and 15 days from the simulation to the start of radiotherapy. All but 1 patient showed a continuous decrease in GTV (0.16-1.52%/day) after simulation. At 3 weeks from simulation, 10 of 15 patients exhibited a significant reduction in volume (median, 20%; range, 6-29%). Without replanning, these changes could lead to a reduction in CTV V95 by 7-14% (n = 2) and/or an increase in D0.01 cc/Dmean of adjacent organs at risk by 6-21% of the prescribed target dose (n = 7). Significant dosimetric consequences occurred in cases with (1) a considerable weight gain, (2) shrinkage of the skin surface, or (3) tumor regression in the oral or nasal cavity and sinus that altered air-tissue components in the beam path. The subsequent GTV and dosimetry after 3 weeks from simulation (4 weeks from chemotherapy initiation) demonstrated a relatively stable trend.

CONCLUSIONS

On-treatment imaging at 3 weeks after simulation is recommended, if the simulation is performed at 1 week after the initiation of chemotherapy, to detect significant anatomic changes that could result in >5% deviation from planned target coverage and/or organ doses in pediatric patients with parameningeal rhabdomyosarcoma receiving early proton therapy.

Cytomorphology of spindle cell/sclerosing rhabdomyosarcoma, including MYOD1 (LI22R) mutation result

Spindle cell/sclerosing rhabdomyosarcoma (RMS), characterized by MYOD1 (L122R) mutation in a subset of cases is a newly described subtype of RMS. Presently, there is no documentation of cytomorphological features, especially of sclerosing RMS. Case 1: A 24-year-old male presented with pain and swelling in his wrist for a one-year duration. MRI revealed a well-defined soft tissue lesion measuring 5.3 cm, encasing the lower end of the ulna. Fine-needle aspiration cytology (FNAC) smears revealed clusters of tumor cells with round to oval to spindle-shaped nuclei, scant to moderate amount of cytoplasm with the wisps of the metachromatic stroma. Histopathological examination revealed a malignant tumor comprising cells with polygonal to spindle-shaped nuclei, arranged in a sclerotic stroma. Immunohistochemically, the tumor cells were positive for desmin, myogenin, and MYOD1. A diagnosis of sclerosing RMS was offered. Furthermore, the tumor revealed MYOD1 (L122R) mutation. Case 2: A 43-year-old male presented with a 4-month history of "nasal stuffiness" and pressure. Imaging revealed a poorly defined infiltrative lesion in his nasal cavity. FNAC smears revealed loose and tightly cohesive clusters of malignant cells with oval to spindle-shaped nuclei, a moderate amount of ill-defined bluish to finely vacuolated cytoplasm, and focal streak artifact with interspersed stromal fragments. Histopathological examination revealed a malignant tumor composed of oval to spindle-shaped nuclei, embedded in a variably hyalinized stroma. Immunohistochemically, the tumor cells were positive for desmin, and myogenin. Diagnosis of spindle cell/sclerosing RMS was offered. The present study constitutes one of the first documentation of cytomorphological features of two rare cases of spindle cell/sclerosing RMS. The differential diagnoses and treatment-related implications are presented.

Uterine sarcomas and rare uterine mesenchymal tumors with malignant potential. Diagnostic guidelines of the French Sarcoma Group and the Rare Gynecological Tumors Group

The landscape of uterine sarcomas is becoming increasingly complex with the description of new entities associated with recurrent molecular alterations. Uterine sarcomas, as well as soft tissue sarcomas, can be distinguished into complex genomic sarcomas and simple genomic sarcomas. Leiomyosarcoma and pleomorphic type undifferentiated uterine sarcoma belong to the first group. Low-grade and high-grade endometrial stromal sarcomas, NTRK, COL1A1::PDGFB, ALK, RET, ROS1 associated sarcomas, and SMARCA4 deficient uterine sarcoma belong to the second group. Leiomyosarcoma is the most common uterine sarcoma followed by endometrial stromal sarcomas. Three different histologic subtypes of leiomyosarcomas are recognized with distinct diagnostic criteria and different clinical outcomes, the myxoid and epithelioid leiomyosarcomas being even more aggressive than the fusiform type. The distinction between low-grade and high-grade endometrial stromal sarcoma is based first on morphology and immunohistochemistry. The detection of fusion transcripts helps in the diagnosis. Definitely recognized as a separate entity, uterine PEComa is a rare tumor whose diagnostic criteria are being recently defined. Uterine PEComa has a specific algorithm stratifying the tumors into uncertain malignant potential and malignant tumors. Embryonal rhabdomyosarcomas of the uterine cervix are not restricted to children but can also be observed in adult women and are almost always DICER1 mutated, unlike embryonal rhabdomyosarcoma of the vagina which are DICER1wild-type, and adenosarcoma which can be DICER1 mutated but with less frequency. As sarcomas associated with fusion transcripts involving the NTRK, ALK, COL1A1::PDGFB genes can benefit from targeted therapy, systematic detection are now relevant especially for patients with high risk of relapse or in recurrent setting. The integration of molecular data with dedicated expert pathology review for histology and clinical data allows better identification of uterine sarcomas in order to better treat them.

Molecular Characterization of Circulating Tumor DNA in Pediatric Rhabdomyosarcoma: A Feasibility Study

PURPOSE

Rhabdomyosarcomas (RMS) are rare neoplasms affecting children and young adults. Efforts to improve patient survival have been undermined by a lack of suitable disease markers. Plasma circulating tumor DNA (ctDNA) has shown promise as a potential minimally invasive biomarker and monitoring tool in other cancers; however, it remains underexplored in RMS. We aimed to determine the feasibility of identifying and quantifying ctDNA in plasma as a marker of disease burden and/or treatment response using blood samples from RMS mouse models and patients.

METHODS

We established mouse models of RMS and applied quantitative polymerase chain reaction (PCR) and droplet digital PCR (ddPCR) to detect ctDNA within the mouse plasma. Potential driver mutations, copy-number alterations, and DNA breakpoints associated with PAX3/7-FOXO1 gene fusions were identified in the RMS samples collected at diagnosis. Patient-matched plasma samples collected from 28 patients with RMS before, during, and after treatment were analyzed for the presence of ctDNA via ddPCR, panel sequencing, and/or whole-exome sequencing.

RESULTS

Human tumor-derived DNA was detectable in plasma samples from mouse models of RMS and correlated with tumor burden. In patients, ctDNA was detected in 14/18 pretreatment plasma samples with ddPCR and 7/7 cases assessed by sequencing. Levels of ctDNA at diagnosis were significantly higher in patients with unfavorable tumor sites, positive nodal status, and metastasis. In patients with serial plasma samples (n = 18), fluctuations in ctDNA levels corresponded to treatment response.

CONCLUSION

Comprehensive ctDNA analysis combining high sensitivity and throughput can identify key molecular drivers in RMS models and patients, suggesting potential as a minimally invasive biomarker. Preclinical assessment of treatments using mouse models and further patient testing through prospective clinical trials are now warranted.

[Clinical features and prognosis in 20 children with rhabdomyosarcoma]

OBJECTIVES

To study the clinical features of children with rhabdomyosarcoma (RMS) and the influencing factors for prognosis.

METHODS

A retrospective analysis was performed on the clinical and follow-up data of 20 children with RMS who were admitted to the Department of Pediatric Hematology, Xiangya Hospital of Central South University, from June 2014 to September 2020.

RESULTS

The most common clinical symptoms of the 20 children with RMS at the first visit were painless mass (13/20, 65%), exophthalmos (4/20, 20%), and abdominal pain (3/20, 15%). According to the staging criteria of Intergroup Rhabdomyosarcoma Study Group (IRSG), there was 1 child (5%) with stage I RMS, 4 (20%) with stage II RMS, 9 (45%) with stage III RMS, and 6 (30%) with stage IV RMS. The median follow-up time was 19 months for the 20 children (range: 3-93 months), with a 2-year overall survival (OS) rate of 79.5% (95%CI: 20.1-24.3) and a 2-year event-free survival (EFS) rate of 72.0% (95%CI: 19.5-23.9). Pleomorphic RMS was associated with the reduced 2-year OS rate (P<0.05), and distant metastasis, IRSG stage IV RMS, and high-risk RMS were associated with the reduced 2-year EFS rate (P<0.05).

CONCLUSIONS

RMS has no specific clinical symptoms at the first visit, with painless mass as the most common symptom. Distant metastasis, IRSG stage, and risk degree may be associated with the prognosis of children with RMS.

[Analysis of 18 cases of malignant rhabdoid tumor in children]

Objective: To investigate the clinical characteristics, treatment and prognosis of malignant rhabdoid tumor (MRT) in children. Methods: Clinical data total of 18 children with MRT treated in the Department of Hematology and Oncology, Children's Hospital, the First Affiliated Hospital of Zhengzhou University between June 2015 to June 2021 were analyzed retrospectively. The patients were grouped according to age, gender, tumor type, clinical stage and other factors.Progression free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier method, survival differences among different groups were compared by Log-rank test, and prognostic factors were analyzed by Cox regression model. Results: Among the 18 patients, there were 5 males and 13 females. The age of disease onset was 30.5 (12.0, 75.0) months, the tumor diameter was (80±29) mm, and no integrase interactor 1 (INI-1) expression was detected by immunohistochemistry. There were 7 cases of malignant rhabdoid tumor of the kidney (MRTK), 6 cases of atypical teratoid rhabdoid tumor (ATRT) and 5 cases of extrarenal extracranial rhabdoid tumor (EERT). At the time of early diagnosis, 12 patients were clinically stage Ⅲ-Ⅳ, 11 patients had local or distant metastasis, and 4 patients had metastasis during treatment. Surgical excision is the preferred treatment. There were 3 cases with preoperative puncture biopsy, 13 cases with complete resection, 4 cases with partial resection, and 1 case without operation. Thirteen patients were treated with the domestic conventional chemotherapy regimen for Wilms' tumor, medulloblastoma and rhabdomyosarcoma, and 5 patients were treated with the international conventional chemotherapy regimen. Nine patients received radiotherapy, including 1 case of MRTK, 4 cases of ATRT and 4 cases of EERT. By the end of follow-up in January 2022, 7 patients survived and 11 patients died. The 3-year PFS and OS rates were (8±8) % and (14±12) %. Log-rank test showed that the 5-year OS of EERT group was higher than ATRT and MRTK groups (χ²=16.31, P<0.001), the tumor diameter <80 mm group was higher than that of the ≥80 mm group (χ²=4.49, P=0.034), and the radiotherapy group was higher than no radiotherapy group (χ²=3.97, P=0.046). The differences were statistically significant. There was no significant difference in the influence of tumor type, age, tumor diameter, radiotherapy and chemotherapy on OS by Cox regression model (all P>0.05). Log-rank test showed that the 3-year PFS of EERT group was higher than ATRT and MRTK groups (χ²=11.14, P=0.004),>3 years group was higher than ≤3 years group (χ²=10.10, P=0.001), the differences were statistically significant. Tumor type, clinical stage, tumor diameter, age, tumor rupture and radiotherapy were included in the Cox regression model, and the results showed that clinical stage (HR=0.49, 95%CI 0.26-0.94, P=0.031), tumor diameter (HR=8.67, 95%CI 1.84-40.89, P=0.006), age (HR=0.01, 95%CI 0.00-0.15, P=0.001) had statistical significance on PFS. Conclusions: MRT is one of the most aggressive and fatal cancers in early childhood and infancy. There is no standard treatment and the prognosis is extremely poor. Clinical stage, tumor size and age are risk factors for disease progression.

Is Detection of Relapse by Surveillance Imaging Associated With Longer Survival in Patients With Rhabdomyosarcoma?

BACKGROUND

We investigated whether surveillance imaging had an impact on post-relapse survival in patients with rhabdomyosarcoma (RMS). We hypothesized that relapse detected by imaging (group IM) would be associated with longer survival compared with relapse detected with a clinical sign or symptom (group SS).

MATERIALS AND METHODS

We performed an observational multi-institutional study in 127 patients with relapsed RMS comparing overall survival (OS) after relapse using Kaplan-Meier and Cox proportional hazards analyses.

RESULTS

Relapse was detected in 60 (47%) group IM and 67 (53%) SS patients. Median follow-up in survivors was 4 years (range 1.0 to 16.7 y). Four-year OS rates were similar between group IM (28%, 95% confidence interval [CI]: 14%-40%) and SS (21%, 95% CI: 11%-31%) ( P =0.14). In multivariable analyses accounting for institution, age at diagnosis, time to relapse, risk group at diagnosis, and primary site, not receiving chemotherapy (hazard ratio [HR]: 6.8, 95% CI: 2.8-16.6), radiation (HR: 3, 95% CI: 1.7-5.3), or surgery (HR: 2.8, 95% CI: 1.6-4.8) after relapse were independently associated with poor OS.

CONCLUSION

These results on whether surveillance imaging provides survival benefit in patients with relapsed RMS are inconclusive. Larger studies are needed to justify current surveillance recommendations. Chemotherapy, radiotherapy and surgery to treat recurrence prolong OS.

Single-cell analysis and functional characterization uncover the stem cell hierarchies and developmental origins of rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is a common childhood cancer that shares features with developing skeletal muscle. Yet, the conservation of cellular hierarchy with human muscle development and the identification of molecularly defined tumor-propagating cells has not been reported. Using single-cell RNA-sequencing, DNA-barcode cell fate mapping and functional stem cell assays, we uncovered shared tumor cell hierarchies in RMS and human muscle development. We also identified common developmental stages at which tumor cells become arrested. Fusion-negative RMS cells resemble early myogenic cells found in embryonic and fetal development, while fusion-positive RMS cells express a highly specific gene program found in muscle cells transiting from embryonic to fetal development at 7-7.75 weeks of age. Fusion-positive RMS cells also have neural pathway-enriched states, suggesting less-rigid adherence to muscle-lineage hierarchies. Finally, we identified a molecularly defined tumor-propagating subpopulation in fusion-negative RMS that shares remarkable similarity to bi-potent, muscle mesenchyme progenitors that can make both muscle and osteogenic cells.

DICER1-Mutated Botryoid Fibroepithelial Polyp of the Parotid Duct: Report of the First Case

DICER1, a member of the ribonuclease III family, is involved in the biogenesis of microRNAs and, hence, it influences gene expression regulation. DICER1 germline (associated with the inherited DICER1 syndrome) or somatic mutations have been linked to tumorigenesis in histogenetically diverse benign and malignant neoplasms in different organs including pleuropulmonary blastoma, cystic nephroma, embryonal rhabdomyosarcoma, nasal chondromesenchymal hamartoma, poorly differentiated thyroid carcinoma, thyroblastoma, intracranial sarcoma and gonadal Sertoli-Leydig cell tumors in addition to others. Moreover, rare botryoid (giant) fibroepithelial polyps may harbor this mutation. Herein, we describe the first reported case of a DICER1-mutated botryoid fibroepithelial polyp occurring within the parotid duct of a 65-year-old female who has no other features or family history of the DICER1 syndrome. Based on its distinctive morphology, we tested this lesion specifically for DICER1 mutations and confirmed the presence of a pathogenic DICER1 variant with a low allele frequency, consistent with a somatic mutation.

Targeting farnesylation as a novel therapeutic approach in HRAS-mutant rhabdomyosarcoma

Activating RAS mutations are found in a subset of fusion-negative rhabdomyosarcoma (RMS), and therapeutic strategies to directly target RAS in these tumors have been investigated, without clinical success to date. A potential strategy to inhibit oncogenic RAS activity is the disruption of RAS prenylation, an obligate step for RAS membrane localization and effector pathway signaling, through inhibition of farnesyltransferase (FTase). Of the major RAS family members, HRAS is uniquely dependent on FTase for prenylation, whereas NRAS and KRAS can utilize geranylgeranyl transferase as a bypass prenylation mechanism. Tumors driven by oncogenic HRAS may therefore be uniquely sensitive to FTase inhibition. To investigate the mutation-specific effects of FTase inhibition in RMS we utilized tipifarnib, a potent and selective FTase inhibitor, in in vitro and in vivo models of RMS genomically characterized for RAS mutation status. Tipifarnib reduced HRAS processing, and plasma membrane localization leading to decreased GTP-bound HRAS and decreased signaling through RAS effector pathways. In HRAS-mutant cell lines, tipifarnib reduced two-dimensional and three-dimensional cell growth, and in vivo treatment with tipifarnib resulted in tumor growth inhibition exclusively in HRAS-mutant RMS xenografts. Our data suggest that small molecule inhibition of FTase is active in HRAS-driven RMS and may represent an effective therapeutic strategy for a genomically-defined subset of patients with RMS.

Left cheek sclerosing rhabdomyosarcoma and development of isolated free flap donor site metastasis

Rhabdomyosarcoma is a rare mesenchymal malignancy with four different morphological subtypes: alveolar, embryonal, pleomorphic and spindle cell/sclerosing. It is the most common soft tissue sarcoma of children and adolescents but occurs less commonly in adults. We describe a male patient in his 20s with sclerosing rhabdomyosarcoma of the left cheek who developed an isolated free flap donor site metastasis in the first instance but subsequently progressed with bilateral pulmonary metastases. Multidisciplinary team involvement in a sarcoma specialist centre is essential and collaboration between the pathologist, radiologist, head and neck surgeon, orthopaedic surgeon, radiation oncologist and medical oncologist were integral in providing optimal management in this patient. Furthermore, this case report highlights this phenomenon of implantation metastasis in a patient with rhabdomyosarcoma, and emphasises the importance of surgical barriers between the resection and reconstruction teams in an oncological case.

SIX1 reprograms myogenic transcription factors to maintain the rhabdomyosarcoma undifferentiated state

Rhabdomyosarcoma (RMS) is a pediatric muscle sarcoma characterized by expression of the myogenic lineage transcription factors (TFs) MYOD1 and MYOG. Despite high expression of these TFs, RMS cells fail to terminally differentiate, suggesting the presence of factors that alter their functions. Here, we demonstrate that the developmental TF SIX1 is highly expressed in RMS and critical for maintaining a muscle progenitor-like state. SIX1 loss induces differentiation of RMS cells into myotube-like cells and impedes tumor growth in vivo. We show that SIX1 maintains the RMS undifferentiated state by controlling enhancer activity and MYOD1 occupancy at loci more permissive to tumor growth over muscle differentiation. Finally, we demonstrate that a gene signature derived from SIX1 loss correlates with differentiation status and predicts RMS progression in human disease. Our findings demonstrate a master regulatory role of SIX1 in repression of RMS differentiation via genome-wide alterations in MYOD1 and MYOG-mediated transcription.

Clinical and pathological characteristics, treatment outcome and prognostic factors in adult rhabdomyosarcoma: a monocentric retrospective study

Rhabdomyosarcoma (RMS) is rare in adults. Our study is the first in Tunisia to report outcomes of adult RMS. We retrospectively analyzed clinical data of adult RMS patients. We collected data regarding clinical characteristics, treatment outcome and prognostic factors. Survival was assessed using the Kaplan Meier method. Forty-seven patients were included. Median age was 39. Twenty-five patients were young adults (53%). Sex ratio (M/F) was 1.9. RMS was localized in 33 patients (70%) and metastatic in 14 patients (30%). Extremities were the most frequent tumor site (40%) followed by trunk (23%). Median tumor size was 9 cm. Pleomorphic RMS was the major subtype (36%). Twenty seven of 33 patients with localized RMS underwent surgery (82%). Relapse free survival (RFS) was 38%. Young adults had a significantly worse RFS than adults aged ≥40 (p = 0.045). Surgery was associated with a significantly better RFS (p = 0.023). Five year overall survival (OS) was 35% and 27% in localized and metastatic RMS respectively. RMS localized in the extremities had significantly poorer OS (p = 0.041), same as non-operated patients (p = 0.025). OS for metastatic RMS was significantly worse after surgery of the primary tumor (p = 0.002). In multivariate analysis, surgery (HR = 0.108; 95%CI (0.023-0.519); p = 0.005) and non-extremity localization (HR = 0.238; 95%CI (0.075-0.751); p = 0.014) were independent prognostic factors for OS in localized RMS. Adults with RMS have poor 5 year OS. Surgery and non-extremity localization were independent prognostic factors for OS in localized RMS.

Rhabdomyosarcoma of the Cervix in a Post-Menopausal Woman-An Unparalleled Phenomenon

Rhabdomyosarcoma of the cervix is a soft tissue sarcoma that usually occurs in young women. It is very rare in adulthood. We discuss symptoms, the process of diagnosis of rhabdomyosarcoma embryonale of the cervix in a 61-year-old women and differences in treatment dependent on patient’s age. A 61-year-old woman with symptoms such as palpable mass in the external cervical opening and post-menopausal hemorrhaging was admitted to the oncology ward where excision of the polyp was performed. Embryonal rhabdomyosarcoma (ERMS) was diagnosed by histopathological examination of obtained tissues. The diagnosis was complemented by chest computed tomography and pelvis magnetic resonance imaging to exclude metastases. A Wertheim–Meigs operation and excision of the ovaries, the fallopian tubes and the surrounding tissue was performed in the course of treatment. In the patient’s follow-up of 25 months to date, there have been no signs of recurrence or symptoms connected to ERMS. Based on the therapeutic outcome, the decision to limit the treatment to a surgical resection was adequate for a post-menopausal patient. Because of the rarity of ERMS in the post-menopausal age, we think that the patient should be carefully followed up to further examine this issue and develop diagnostic and treatment guidelines.

Pediatric head and neck rhabdomyosarcoma: An analysis of treatment and survival in the United States (1975-2016)

INTRODUCTION

Rhabdomyosarcoma (RMS) is the most common soft tissue head and neck sarcoma in children. Stringent analysis of survival data is imperative to optimize treatment.

METHODS

The National Cancer Database (NCDB, 2004-2016) and the Surveillance, Epidemiology, and End Results Program (SEER, 1975-2016) were queried for patients ages 0-19 with RMS of the head and neck. Survival trends were analyzed using univariable logistic regression and Chi-square pairwise comparisons. Survival by treatment was analyzed using log-rank tests, Kaplan Meier, and multivariable Cox-proportional hazards regression.

RESULTS

1147 (63.3% age <10 years, 54.3% male) and 459 (71.4% age <10 years, 53.6% male) patients were identified in NCDB and SEER, respectively. In NCDB, embryonal (n = 625, 54.5%) and alveolar (n = 300, 26.2%) were the most common histology and nonparameningeal/non-orbital (n = 634, 55.3%), followed by parameningeal (n = 303, 26.4%) and orbital (n = 210, 18.3%) the most common location. Five-year overall survival (OS) was 70.3% with lower mortality risk for embryonal histology (adjusted HR [aHR] = 0.69, p = 0.0038). Orbital tumors had greatest survival (5-year OS = 92.4%) of all sites, and their mortality risk was higher with chemotherapy and radiation compared to surgery and radiation (aHR = 6.27, p = 0.0302). SEER analysis showed average increased survival by 4% per year (p < 0.0001), but no significant 5-year OS difference when comparing 1976-1980 and 2006-2010 (p = 0.0843).

CONCLUSIONS

Major prognostic factors for survival in childhood RMS of the head and neck were embryonal histology, orbital site, extent of disease, and use of SRT for orbital tumors. Larger population studies are required to demonstrate survival differences between treatment modalities for other sites.

Scientists See Human Cancer in Zebrafish

Researchers have developed an immune-deficient adult zebrafish model that engrafts a variety of human cancers, allowing them to visualize tumor growth at single-cell resolution and track responses to drug therapy. Using the model, they identified a possible treatment for rhabdomyosarcoma.

[Paratesticular embryonal rhabdomyosarcoma: report of 5 cases and review of the literature]

OBJECTIVE

To improve the diagnosis and treatment of paratesticular embryonal rhabdomyosarcoma (PER).

METHODS

We retrospectively studied the clinical data of 5 cases of PER treated from 1997 to 2009 and reviewed the relevant literature, focusing on its clinical manifestations, diagnosis and treatment.

RESULTS

The 5 cases of PER, 2 involving the spermatic cord, 2 the testis and 1 the tunica vaginalis, were all treated by radical orchiectomy. Pathologically, 2 cases were classified as stage I, 1 as stage II and 2 as stage IV. Postoperatively, 2 of the patients received chemotherapy and the other 3 refused adjunctive therapy. The patients were followed up for 6, 12, 18 and 28 months, respectively. Four of them remained free from relapse and metastasis, and 1 stage IV patient died of multiple metastasis at 6 months.

CONCLUSION

Early diagnosis, radical orchiectomy and adjunctive chemo- or radio-therapy are effective means to the treatment of PER.

Adult embryonal rhabdomyosarcoma of the ethmoid: a rare entity

Embryonal rhabdomyosarcoma is an exceedingly rare tumor in adult. We report an embryonal rhabdomyosarcoma of the ethmoid in a 59-year-old Iban lady who presented with proptosis and complete ptosis of her left eye for two months. Imaging investigations showed left ethmoidal and left orbital soft tissue mass with extradura and dura involvement. The patient was planned for chemotherapy. Unfortunately, in such an advanced disease, she succumbed before treatment.

HSP90 antagonist, geldanamycin, inhibits proliferation, induces apoptosis and blocks migration of rhabdomyosarcoma cells in vitro and seeding into bone marrow in vivo

In this study, geldanamycin (GA) was found to have an antiproliferative effect on both embryonal and alveolar rhabdomyosarcoma (RMS) cell lines. The maximum level of inhibition reached 80% for both embryonal and alveolar RMS. After GA treatment, cells also became apoptotic as judged by Annexin V-positive staining, activation of caspase-3 pathway and poly(ADP ribose) polymerase cleavage. GA was responsible for the arrest of RMS cells in both G1 and G2/M phases of the cell cycle. G1 blockade, however, was transient and was seen only in the first 24 h of GA treatment. RMS often gives distant metastases to various organs including bone marrow. RMS cells express high levels of MET receptor and respond to hepatocyte growth factor with increased motility. In our study, we found that GA decreased the level of MET expression and inhibited the chemotaxis of RMS cells toward the hepatocyte growth factor gradient. GA also blocked the homing of RMS cells into bone marrow of severe combined immune deficient mice. In all our experiments embryonal RMS cell lines were significantly more sensitive, and lower concentrations of GA were sufficient to block embryonal RMS cell proliferation, induce apoptosis and inhibit motility. Our data show that the HSP90 inhibitor GA has the potential to become a new drug in RMS treatment. It blocks RMS proliferation, decreases cell survival and inhibits motility of RMS cells.

Effect of medium pH on the cytotoxicity of hydrophilic statins

PURPOSE

The aim of this study was to examine the mechanism of pravastatin- and rosuvastatin-induced cytotoxicity and the relationship between pravastatin- and rosuvastatin-induced cytotoxicity and medium pH using human prototypic embryonal rhabdomyosarcoma cell line (RD) and rat myoblast cell line (L6) as a model of in vitro skeletal muscle.

METHODS

Statin-induced reduction of cell viability and apoptosis was measured by 3-(4,5-dimethylthiazol-2-yl)2,5 -diphenyl tetrazolium bromide (MTT) assay and caspase assay. Intracellular accumulation of statins was determined using an HPLC system.

RESULTS

Rosuvastatin cytotoxicity, reduction of cell viability, morphological changes and caspase activation at acidic pH (pH 6.8) were significantly greater than those at neutral pH (pH 7.4). Rosuvastatin accumulation at acidic pH was greater than that at pH 7.4. On the other hand, medium pH had no effect on pravastatin accumulation.

CONCLUSIONS

Rosuvastatin cytotoxicity at acidic pH is associated with increasing intracellular accumulation of rosuvastatin. On the other hand, medium pH had no effect on cytotoxicity of pravastatin.

Double modification of adenovirus fiber with RGD and polylysine motifs improves coxsackievirus-adenovirus receptor-independent gene transfer efficiency

Adenoviral vectors based on serotype 5 (Ad5) have been widely used to deliver therapeutic genes to different organs and tissues. However, many tissues are poorly infected with Ad5 because of low-level expression of its primary receptor, coxsackievirus-adenovirus receptor (CAR). Two motifs, RGD and polylysine (pK7), have been shown to enhance Ad5 infection via CAR-independent pathways when incorporated into fiber separately. Because the two motifs bind to different cell surface proteins (RGD motif binds to integrins, and pK7 binds to heparan sulfate-containing receptors), we hypothesized that the two motifs function additively to improve gene transfer efficiency. In this study, we sought to improve infectivity of Ad5 by incorporating both RGD and pK7 motifs into fiber. We created an Ad5 vector containing an RGD motif in the HI loop and a pK7 motif at the C terminus of fiber (Ad5.RGD.pK7). Compared with unmodified and singly modified Ad5 vectors Ad5.RGD and Ad5.pK7, the doubly modified Ad5 demonstrated the highest infectivity in both CAR-positive and CAR-negative cells. The enhanced infectivity appeared to be mediated by additive effects of the two motifs. More importantly, Ad5.RGD.pK7 lost the natural CAR-dependent pathway while employing novel targeting mechanisms. This strategy thus may be used to overcome CAR deficiency and to achieve vector retargeting.

[Pelvic malignant ectomesenchymoma: a case report]

We report the case of a 19 month old boy referred to our institution because of a pelvic tumor initially identified as an embryonal rhabdomyosarcoma and treated with surgery and chemotherapy. Eight years after the initial surgery, a local tumor recurrence with bone metastasis was found. Histological examination and immunohistochemistry showed a double differentiation with both muscular and neuronal cells. This double differentiation was retrospectively found in the initial tumor, then allowing the diagnosis of malignant ectomesenchymoma also called gangliorhabdomyosarcoma. This rare tumor, occurring mainly during childhood, is composed of neuroblasts and / or ganglion cells and of malignant mesenchymal cells (usually rhabdomyosarcomatous cells).

IgG from "seronegative" myasthenia gravis patients binds to a muscle cell line, TE671, but not to human acetylcholine receptor

Antibodies to acetylcholine receptor (AChR) are found in 85% of patients with myasthenia gravis (seropositive MG [SPMG]) and are thought to be pathogenic; but in 15% of MG patients, the standard immunoprecipitation test for anti-AChR is negative (seronegative MG [SNMG]). Here, we used a novel approach, fluorescence-activated cell sorting analysis, to measure binding of SPMG and SNMG IgG antibodies to rhabdomyosarcoma cell lines that express human adult (TE671-epsilon) or fetal (TE671-gamma) AChR, and to human embryonic kidney (HEK) fibroblasts that express adult human AChR (HEK-AChR). We found that whereas most SPMG antibodies bind to all three cell lines, IgG from 8 of 15 SNMG sera/plasmas bind to the surface of both TE671 cell lines but not to HEK-AChR cells. These results indicate that SNMG antibodies bind to a muscle surface antigen that is not the AChR, which strongly supports previous studies that suggest that SNMG should be considered a distinct subtype of MG.

Botryoid sarcoma of the vagina

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The potential for bidirectional promoter activity of the human PDGF-A chain gene

Platelet-derived growth factor (PDGF) is a heterodimeric glycoprotein consisting of A and B chains. A functional promoter had been identified in the 5' flanking region of the human PDGF-A chain gene. We found that the PDGF-A chain promoter region possesses the potential for bidirectional activity. This bidirectional promoter activity is influenced by the 5'-untranslated region (5'-UTR) and serum concentration. The 5'-UTR may regulate expression of the PDGF-A chain by transcription in the opposite direction.