CTLA4 and undifferentiated pleomorphic sarcoma: A subsequent single institution randomized phase II trial sought to assess whether there was a difference in pathological complete response to treatment with single-agent nivolumab (a PD-1 inhibitor similar to pembrolizumab) or combination ICI therapy with both nivolumab and ipilimumab (a CTLA-4 inhibitor) for patients with either extremity undifferentiated pleomorphic sarcoma (UPS) or retroperitoneal DDLPS histologies that were undergoing preoperative RT [70].