PDCD1 and neoplasm: Moreover, increasing clarity is being provided in research on the association of eligible biomarkers, such as PD-1/PD-L1 expression,[20] tumor-infiltrating lymphocytes,[21] oncogenic driver mutations,[22] mismatch repair deficiencies,[23] and microsatellite instability,[24] with the efficacy of PD-1/PD-L1 inhibitors in treating NSCLC.