PDCD1 and diffuse large B-cell lymphoma: Despite the impressive clinical efficacy of anti-PD-1 antibodies (e.g., nivolumab) in cHL, and, to a lesser extent, in non-relapsed/refractory DLBCL patients [7,8,23,24], the lack of defined mechanisms of action for checkpoint blockade has impaired the prediction of therapeutic response and introduced a need to define the global status of IE for stratifying patients.