PDCD1 and diffuse large B-cell lymphoma: Recent studies have shown that, blocking the interaction of PD‐1 with its ligands, PD‐L1 and PD‐L2, led to impressive antitumor responses and clinical benefit in a subset of patients,33 including those with relapsed and refractory DLBCL.16, 17 However, predicting tumor responses to PD‐1 blockade remains a major challenge.