What are the Optimal Systemic Treatment Options for Rhabdomyosarcoma?

Rhabdomyosarcoma, a soft tissue sarcoma commonly observed in childhood, requires multidisciplinary treatment, including surgical tumor resection, chemotherapy, and radiation therapy. Although long-term survival can be expected in patients with localized rhabdomyosarcoma, the clinical outcomes in patients with metastatic or unresectable rhabdomyosarcoma remain unsatisfactory. To improve the outcomes of rhabdomyosarcoma, it is important to explore effective systemic treatments for metastatic rhabdomyosarcoma. Currently, multiagent chemotherapy comprising vincristine, actinomycin D, and ifosfamide/cyclophosphamide remains standard systemic treatment for rhabdomyosarcoma. On the other hand, new treatment, such as immune checkpoint inhibitors and molecular targeted drugs, have demonstrated superior clinical outcomes compared to those of standard treatments in various type of malignancies. Therefore, it is necessary to assess the efficacies of these treatments in patients with rhabdomyosarcoma. Recent clinical studies have shown efficacies and safeties of temozolomide combined with vincristine/irinotecan, olaratumab combined with doxorubicin or vincristine/irinotecan, and long-term maintenance therapy. Furthermore, basic researches demonstrated new therapeutic targets. Future studies using these approaches are required to assess their clinical significances.