For instance, HL has shown durable responses to anti-PD-1 antibodies (31–33), whereas other lymphoma subtypes, such as small lymphocytic lymphoma (SLL), peripheral T-cell lymphoma (PTCL), follicular lymphoma (FL), and diffuse large B-cell lymphoma (DLBCL), have demonstrated limited therapeutic efficacy from PD-1 blockade (34). This evidence concerns the gene PDCD1 and follicular lymphoma.