Consensus and controversies regarding the treatment of rhabdomyosarcoma

Systemic therapy in pediatric-type soft-tissue sarcoma

Soft-tissue sarcoma (sts) is rare and represents approximately 7% of cancers in children and in adolescents less than 20 years of age. Rhabdomyosarcoma (rms) is most prevalent in children less than 10 years of age and peaks again during adolescence (16-19 years of age). Multi-agent chemotherapy constitutes the mainstay of treatment for rms. In other non-rhabdomyosarcoma soft-tissue tumours, such as synovial sarcoma, evidence for routine use of chemotherapy is less robust, and alternative treatment options, including targeted agents and immunotherapy, are being explored. In this review, we focus on chemotherapy for pediatric-type rms and discuss the advances and challenges in systemic treatment for select non-rhabdomyosarcoma soft-tissue tumours in children and adolescents. We support an increasingly cooperative approach for treating pediatric and adult sts.

Primary cutaneous alveolar rhabdomyosarcoma in an adolescent - A challenging diagnosis

Primary cutaneous alveolar rhabdomyosarcoma is an extremely rare and highly aggressive soft tissue sarcoma that predominantly arises on the extremities and perineum of adolescents and young adults. Dermatologists should be aware of these tumors in order to promptly make the diagnosis and initiate treatment.

Neurofibromatosis-1 and Rhabdomyosarcoma: An Unusual Recurrence

Neurofibromatosis-1 has a known increased risk of malignancy with rhabdomyosarcoma occurring in up to 6% of patients. Here we report on an 8-year-old male with a history of Neurofibromatosis-1 and previously treated stage 3, group III bladder/prostate embryonal rhabdomyosarcoma (diagnosed at 18 months old) who presented with penile swelling concerning for priapism. Imaging and subsequent biopsy confirmed embryonal rhabdomyosarcoma of the penile corporal bodies. Penile rhabdomyosarcoma is exceedingly rare, with less than 15 case reports in the literature. Our patient received chemoradiation per D9803 with organ preserving local control and is doing well 3 months after treatment.

Functional and anatomical imaging in pediatric oncology: which is best for which tumors

Functional imaging techniques are playing an increasingly important role in the management of pediatric cancer. Technological advances have pushed the development of hybrid imaging techniques, including positron emission tomography (PET)/CT, PET/MR and single-photon emission computed tomography (SPECT)/CT. Together with an increasing need to identify surrogate biomarkers for response to novel therapies, the use of functional imaging techniques, which had been reserved primarily for lymphoma patients, is now being recognized as standard of care for the management of many other pediatric solid tumors. The purpose of this review is to summarize recent data describing the use of functional and metabolic imaging strategies for the staging and response assessment of common pediatric solid tumors, and to offer some guidance as to which techniques are most appropriate for which tumor types.

Laparoscopic Radical Trachelectomy for Embryonal Rhabdomyosarcoma of the Cervix in a 2-Year-Old Girl

BACKGROUND

Embryonal rhabdomyosarcoma of the cervix is a rare and aggressive malignancy that usually affects children and young adults.

CASE

We describe a 2-year-old patient who presented with a mass protruding through the vaginal introitus. Preoperative investigations including vaginoscopy, hysteroscopy, magnetic resonance imaging, and biopsies confirmed embryonal rhabdomyosarcoma, botryoid subtype, arising from the cervix. She was successfully treated with neoadjuvant chemotherapy and interval laparoscopic radical trachelectomy to achieve remission.

CONCLUSION

Collaboration between the pediatric and adult surgical and medical oncology teams was critical to implement this fertility-sparing treatment strategy in such a young girl having this rare tumor.

Reproducibility of academic preclinical translational research: lessons from the development of Hedgehog pathway inhibitors to treat cancer

Academic translational research is growing at a great pace at a time in which questions have been raised about the reproducibility of preclinical findings. The development of Hedgehog (HH) pathway inhibitors for the treatment of cancer over the past two decades offers a case study for understanding the root causes of failure to predict clinical outcomes arising from academic preclinical translational research. Although such inhibitors were once hoped to be efficacious in up to 25% of human cancer, clinical studies showed responses only in basal cell carcinoma and the HH subtype of medulloblastoma. Close examination of the published studies reveals limitations in the models used, lack of quantitative standards, utilization of high drug concentrations associated with non-specific toxicities and improper use of cell line and mouse models. In part, these issues arise from scientific complexity, for example, the failure of tumour cell lines to maintain HH pathway activity in vitro, but a greater contributing factor appears to be the influence of unconscious bias. There was a strong expectation that HH pathway inhibitors would make a profound impact on human cancer and experiments were designed with this assumption in mind.

18F-FDG PET-CT in paediatric oncology: established and emerging applications

Accurate staging and response assessment is vital in the management of childhood malignancies. Fluorine-18 fluorodeoxyglucose positron emission tomography/CT (FDG PET-CT) provides complimentary anatomical and functional information. Oncological applications of FDG PET-CT are not as well-established within the paediatric population compared to adults. This article will comprehensively review established oncological PET-CT applications in paediatric oncology and provide an overview of emerging and future developments in this domain.

Cell growth potential drives ferroptosis susceptibility in rhabdomyosarcoma and myoblast cell lines

PURPOSE

Ferroptosis is a programmed form of iron-dependent cell death caused by lipid hydroperoxide accumulation, which can be prevented by glutathione peroxidase 4 (GPx4) activity. Here we investigated the effects of ferroptosis inducers called erastin and RSL3, which act by glutathione depletion and GPx4 inactivation, respectively, on muscle-derived cell lines of embryonal and alveolar rhabdomyosarcoma (RMS), and mouse normal skeletal C2C12 myoblasts.

METHODS

Myogenic lines were exposed to stepwise increasing concentrations of ferroptosis inducers either alone or in combination with iron supplementation, iron chelating agents (bathophenanthrolinedisulfonic acid, BPS), antioxidant molecules (glutathione, N-acetylcysteine), lipid peroxidation inhibitors (ferrostatin-1), and chemotherapeutic agents (doxorubicin and actinomycin D). Drug susceptibility was quantified by measuring cell viability, proliferation and differentiation via neutral red assay, crystal violet assay and Giemsa staining, respectively. The detection of lipid hydroperoxide and protein levels was performed by immunofluorescence and Western blot analysis, respectively.

RESULTS

Erastin and RSL3 increased lipid hydroperoxide levels preferentially in the embryonal U57810 and myoblast C2C12 lines, leading to ferroptosis that was accentuated by iron supplementation or prevented by co-treatment with BPS, glutathione, N-acetylcysteine and ferrostatin-1. The inhibition of extracellular regulated kinases (ERK) pathway prevented ferroptosis in U57810 and C2C12 cells, whereas its increased activation in the embryonal RD cells mediated by caveolin-1 (Cav-1) overexpression led to augmented ferroptosis susceptibility. Finally, we observed the combination of erastin or RSL3 with chemotherapeutic doxorubicin and actinomycin D agents to be effective in increasing cell death in all RMS lines.

CONCLUSIONS

Erastin and RSL3 trigger ferroptosis in highly proliferating myogenic lines through a ERK pathway-dependent fashion.

Second primary rhabdomyosarcoma of the uterine cervix presenting with synchronous ovarian Sertoli-Leydig cell tumor: An illustrative case of DICER1 syndrome

•Embryonal rhabdomyosarcoma of the uterine cervix and ovarian Sertoli-Leydig cell tumors are associated with DICER1 mutation•DICER1-associated tumors should prompt genetic counseling and testing•Somatic and germline genetic mutation profiles can be used to differentiate second primary from recurrent tumors.

A Case of mistaken identity: Rhabdomyosarcoma development from endothelial progenitor cells

Rhabdomyosarcoma (RMS) histologically resembles developing skeletal muscle and is thought to solely originate from a differentiation block in muscle progenitors. We demonstrate that RMS can arise from endothelial progenitor cells following reprogramming and myogenic transdifferentiation. These results highlight how tumors with identical morphological features can arise from different cell types and offer insight into RMS formation in non-myogenic tissue.