TMB has been suggested as capable of predicting the response to PD-1/PD-L1 blockade in patients with NSCLC.7–10 In addition, other potential biomarkers have been investigated, such as PD-L1 expression,11–13 tumor-infiltrating lymphocytes,14 15 specific gene mutations,16–18 and inflammatory cytokines.19 However, all these potential biomarkers require an invasive biopsy combined with time-consuming and labour-intensive laboratory and clinical testing. Here, PDCD1 is linked to neoplasm.