Paolo Ascierto, MD of the National Tumor Institute Fondazione G. Pascale, Naples, Italy discusses biomarkers in melanoma as part of his overview of his talk on the best use of immunotherapy in melanoma held at the World Congress on Cancers of the Skin (WCCS) and the Congress of the European Association of Dermato-Oncology (EADO) in Vienna, Austria. Biomarkers are an important issue – if you want to optimize treatment with immunotherapy, you have to weigh patient selection and increase activity of immunotherapy. Prof. Ascierto explains that a biomarker is a marker that is able to predict, which patient can have benefit from treatment. At the moment, there is no biomarker for ipilimumab; PD-L1 is being discussed as a possible biomarker. However, according to Prof. Ascierto, this is not the right marker because the data available for PD-L1 shows that 20-30% of patients respond despite their PD-L1 negative status and in terms of overall survival (OS), they show a good survival curve. Therefore, there is no reason to select patients based on PD-L1 status. For the combination of ipilimumab and nivolumab, which is an emerging treatment, there is a lot of discussion for the treatment of the PD-L1 positive patient because the progression-free survival (PFS) data are similar and because the combination is toxic; therefore the question is why to use this combination rather than monotherapy with the same PFS. This question is very complicated according to Prof. Ascierto. The response rate and duration of response is in favor of the combination. In general, toxicity is not the concern – the main concern is the progression of the disease. In the future, the choice between monotherapy and combination will be done on the basis of patient characteristics. If toxicity is a concern for a patient, then the monotherapy may be the best option.