With the ever-increasing use of immuno-oncology agents, our knowledge of biomarkers to direct their use is essential. We spoke to Martin Reck, MD, PhD, of the Lung Clinic Grosshansdorf, Grosshansdorf, Germany, about emerging biomarkers in non-small cell lung cancer at the European Society for Medical Oncology (ESMO) 2018 Congress, in Munich, Germany. Prof. Reck covers PD-L1, tumor mutational burden, circulating markers for liquid biopsy and even the microbiome.