PDCD1 and non-small cell lung carcinoma: Interestingly, in patients with NSCLC that respond to anti-PD-1 therapy but not in non-responders, increased number of pre-exhausted T cells were observed.37 It has been suggested that pre-exhausted T cells do not arise from the reinvigoration of terminally exhausted cells; rather, they accumulate through local expansion and replenishment by peripheral T cells with both new and pre-existing clonotypes.37