NEUROD1 and small cell lung carcinoma: Using this approach, binding site accessibility of NEUROD1, an SCLC lineage defining TF [29], was significantly correlated with NEUROD1 gene expression in the corresponding time point matched tumor (Spearman’s r = − 0.58, P = 0.0003; higher cfDNA read depth indicates less binding of TFs predicting less gene expression) (Fig. 6 J).