Emergence of immunotherapy into systemic treatment of lung cancer represents a major breakthrough. Unfortunately, benefit of this treatment is observed in only minority of patients.
Thus, we are facing a task to select optimal candidates for immunotherapy. Immunohistochemical detection of PD-L1 in tumor tissue seems to be a promising approach for selection of patients potentially treated with molecules blocking the PD-1-PD-L1 interaction.
There are, however, several issues, such as heterogeneity of expression, potential changes of expression due to concurrent treatment (chemotherapy, steroids, etc.) and availability of several methods of detection.