We have designed the following non-comparative, open-label, randomized phase II study to assess the pathologic response to nivolumab (anti-PD1) monotherapy and nivolumab in combination with ipilimumab (anti-CTLA4) administered in the neoadjuvant setting with and without concurrent neoadjuvant radiation in patients with immunotherapy-naïve primary or locally recurrent resectable undifferentiated pleomorphic sarcoma of the extremity/trunk (ET UPS) or dedifferentiated liposarcoma of the retroperitoneum (RP DDLPS). The gene discussed is CTLA4; the disease is undifferentiated pleomorphic sarcoma.