PD-L1 overexpression predicts activity as well as better survival for patients treated with immune checkpoint inhibitors.

Taking this data in account, PD-L1 overexpression could not be currently considered a robust biomarker to tailor the immune checkpoint inhibitors treatment.

The use of PD-L1 expression as a biomarker increases cost-effectiveness of immunotherapy but also diminishes the number of potential life-years saved.

The available data reinforce nivolumab activity against NSCLC in first-line or subsequent lines. Although PD-L1 expression is related to greater response, PD-L1 negative patients had also some benefit.

Lung cancer is the leading cause of cancer-related deaths in the world. Immune checkpoint inhibitors (ICI) stimulate cytotoxic lymphocyte activity against tumour cells. These agents are available for the treatment of non-small cell lung cancer (NSCLC) after failure of platinum-based therapy. One recent study has demonstrated that ICI monotherapy was superior to platinum-based chemotherapy for first-line treatment. Nevertheless, this benefit was only for a minority of the population (30%) whose tumour programmed death receptor ligand-1 (PD-L1) expression was above 50%. Therefore, several strategies are under investigation. One option for patients with PD-L1 expression lower than 50% may be the combination of ICI with platinum-based chemotherapy or with ICIs against different targets. However, all of these combinations are at an early stage of investigation and may be very expensive or toxic, producing several harmful adverse events.