PDCD1 and non-small cell lung carcinoma: An anti-CTLA-4 antibody, ipilimumab, may overcome the decrease in T-cell activity and CD8-positive T cells due to decreased methionine uptake caused by impaired nutritional status, which may contribute to the low efficacy of anti-PD-1/PD-L1 antibody monotherapy for NSCLC in PS 2 (Figure 1).