PD-L1 expression in lung cancer

It is with great interest that we read the recent manuscript written by Dr. Yu and colleagues in the Journal of Thoracic Oncology (1). In this manuscript Yu et al. describes different aspects of PD-L1 expression both at the protein and mRNA level in two cohorts of small cell lung cancer (SCLC) patients (1). These data are especially timely given the recent publication of Checkmate 032, a phase I/II trial of nivolumab and nivolumab plus ipilimumab in patients with recurrent small-cell lung cancer (2). Their data provides further clarification regarding PD-L1 pattern in SCLC, a cancer that has not been extensively treated with immunotherapy agents, but for which there is significant biologic rationale given the high mutation burden (3).