Immune checkpoint inhibitors of the PD-1/PD-L1-axis in non-small cell lung cancer: promise, controversies and ambiguities in the novel treatment paradigm

Immune checkpoint inhibitors (ICIs) have received much attention not least for melanoma since the award of the Nobel prize in 2018. Here, we review the current state of knowledge about the use of these monoclonal antibodies (mAbs) in non-small cell lung cancer (NSCLC). These drugs have generally been conditionally approved on limited early data and there are few long-term follow-up data from randomized clinical trials. The effect observed for NSCLC thus far is, on average, moderately better than that obtained with chemotherapy. Severe side-effects are more common than might have been expected. The drugs themselves are expensive and are associated with time-consuming histopathologic testing even though the predictive value of these tests can be discussed. In addition, monitoring for side-effects involves increased workload and budgetary expense for clinical chemistry laboratories. Here, we review and summarize the current knowledge, controversies and ambiguities of ICIs for the treatment of NSCLC.