A League of Its Own? Established and Emerging Therapies in Undifferentiated Pleomorphic Sarcoma

Over the last decade in soft tissue sarcoma (STS) research, the shifting landscape towards more precise subtype classification and the increasing study of novel therapeutic strategies has prompted a need to highlight current knowledge of effective subtype specific therapies. Undifferentiated pleomorphic sarcoma (UPS), formerly known as malignant fibrous histiocytoma (MFH), is among the most common subtypes of STS arising in the trunk or extremities of adults. Administration of systemic chemotherapy is the primary management in locally advanced and metastatic UPS. While anthracycline-based chemotherapy continues to be standard of care in this setting, outcomes in locally advanced or metastatic UPS remain poor. Recent studies highlight the unique characteristics of UPS that may contribute to its greater sensitivity to immune checkpoint inhibition (ICI) compared to other STS subtypes. With the promise of benefit from novel therapies, including ICI or ICI plus chemotherapy, for a subset of patients with UPS comes the need to identify biomarkers predictive of response to therapy. Ongoing and future clinical trials should place strong emphasis on correlative biomarker studies to learn more about the unique biology of UPS and to identify patients for whom ICI-based therapy will be effective.