Despite the similarities that it shares with the PD-1/PD-L1 pathways, CTLA-4 inhibitors have not yet been adequately studied in the population of PTCL within clinical trials despite there being pharmacological agents such as ipilimumab available in the market for the treatment of other malignancies (128). This evidence concerns the gene PDCD1 and mature T-cell and NK-cell non-Hodgkin lymphoma.