Tumor microenvironments of NSCLC are more heterogeneous than you would think—supported by image analysis-based assessment of PD-L1 and tumor-associated immune cell densities

In the recent years, blockade of immune checkpoints to reinstitute host antitumor immunity has been extensively investigated in a variety of tumors (1). In the field of lung cancer, monoclonal antibodies targeting the programmed death 1 (PD-1) (also known as CD279) receptor and its ligand, programmed death-ligand 1 (PD-L1) (also known as B7-H1) have been most studied. High profile clinical trials have shown impressive anti-tumor activity of PD-1/PD-L1 blockade and significant improvements in overall survival (OS) of non-small cell lung cancer (NSCLC) patients in the first-line and/or second or more line settings (2-6), leading to approval of nivolumab, pembrolizumab and/or atezolizumab for treatment of NSCLC in the US, Europe and some other countries (7). Clinical trials with two other agents, durvalumab and avelumab, have also shown promising results (7).