CTLA4 and undifferentiated pleomorphic sarcoma: In the past decade, immunotherapies such as checkpoint inhibitors have shown promise in some patients, such as those diagnosed with metastatic alveolar soft part sarcoma, undifferentiated pleomorphic sarcoma (UPS) and liposarcoma (LPS); however, the majority of sarcomas demonstrate no meaningful response to first-generation checkpoint inhibition targeting PD-1, PD-L1, and CTLA-4 [13,14,15].