Current and emerging systemic treatment options for malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma.

Undifferentiated pleomorphic sarcoma (UPS)/malignant fibrous histiocytoma (MFH) is the second most common soft-tissue sarcoma. The standard treatment options for UPS/MFH include tumor excision with appropriate surgical margins, radiation therapy, and chemotherapy. Preferable clinical outcomes can be expected in patients with resectable disease, whereas the clinical outcomes in patients with metastatic disease are unsatisfactory despite multidisciplinary treatment. Although patients with metastatic diseases require chemotherapy, the response rate to conventional chemotherapy has been reported to be only 27-33% in previous reports. Systemic treatment is required to eliminate metastatic disease and improve clinical outcomes in patients with UPS/MFH. Recent clinical studies have investigated the optimal period of conventional chemotherapy and the efficacy of various combinations of anticancer agents. Furthermore, molecular targeted drugs and immune checkpoint inhibitors have shown superior outcomes compared to standard treatments for various types of malignancies. Therefore, these anticancer agents are considered as new treatment options for patients with UPS/MFH. Recent clinical trials have demonstrated the safety and efficacy of these agents in patients with soft-tissue sarcomas, including UPS/MFH. In particular, a high response rate to immune checkpoint inhibitors combined with doxorubicin has been reported in recent clinical trials; however, combination therapy needs to be assessed in a large number of patients with UPS/MFH. In this review article, recent clinical studies on the systemic treatment of UPS/MFH are discussed.