Anti-angiogenic drugs and biomarkers in non-small-cell lung cancer: a 'hard days night'.

The discovery of specific molecular alterations (i.e. EGFR activating mutations, EML4/ALK translocation, ROS1 rearrangements) in a selected population of patients affected by non small cell lung cancer (NSCLC) translated into effective treatments for this small but well defined fraction of patients, driven by the use of predictive biomarkers of efficacy for targeted agents. Unfortunately, the same reliable predictive biomarkers are lacking for anti-angiogenic drugs. Angiogenesis plays a major role in the progression of NSCLC, however, anti-angiogenic agents provided a minimal, although significant, clinical benefit in unselected populations, burdened by a not negligible toxicities. In this context, no validated angiogenic factor or other molecular biomarker of angiogenesis can reliably predict clinical outcome, sensitivity, early response or resistance to any of the investigated anti-angiogenic therapies currently used. Moreover, the available clinical data are prevalently retrospective, underpowered, and, in many cases, contradictory, thus underscoring that the understanding of the complex architecture of angiogenic signaling is still incomplete. We here review the currently available studies on the effect of anti-angiogenic drugs in NSCLC, with a particular focus on bio-molecular factors that are regarded as potential predictors of treatment efficacy.