PD-L2 Expression in Human Tumors: Relevance to Anti-PD-1 Therapy in Cancer

Purpose: Tumor-associated PD-L1 expression is predictive of clinical response to PD-1–directed immunotherapy. However, PD-L1–negative patients may also respond to PD-1 checkpoint blockade, suggesting that other PD-1 ligands may be relevant to the clinical activity of these therapies. The prevalen…