PDCD1 and primary cutaneous T-cell non-Hodgkin lymphoma: A recent Cancer Immunotherapy Trials Network (CITN) multicenter phase II clinical trial (NCT02243579) of the anti-PD-1 immunotherapy, pembrolizumab, in advanced cutaneous T cell lymphoma (CTCL) showed that 38% of patients achieved a sustained clinical response, whereas 25% experienced disease progression13.