In lung cancer or melanoma, programmed cell death protein-1 (PD-1)/programmed death-ligand 1 (PD-L1) expression and activation is an indicator of poor prognosis for patients,145,146 but their inhibition has become a strategy to stimulate the immune response and increase cell death.147,148 There is a growing body of evidence suggesting intricate regulation processes between TRAIL and PD-L1 expression. The gene discussed is PDCD1; the disease is lung cancer.