PDCD1 and undifferentiated pleomorphic sarcoma: Recent trial results indicate patients with undifferentiated pleomorphic sarcomas (UPS) may be more responsive to anti-PD-1 therapy than patients with other sarcoma subtypes.11,14 Not only is UPS the most common subtype amongst patients with ESTS, it is also associated with the highest rates of systemic relapse and poorest survival outcomes.4 As such, strategies to optimize the response to immunotherapies in this sarcoma subtype are of great interest.