PDCD1 and diffuse large B-cell lymphoma: The biological mechanisms subtending the limited activity of anti-PD1 agents in DLBCL [35] may reside in the composition of the tumor microenvironment of large B-cell lymphoma (LBCL), encompassing the “effacement” pattern for DLBCL, where the malignant cells proliferate rapidly without dependence on the microenvironment.