KRAS is the most frequently mutated oncogene in NSCLC, occurring in around a third of patients. However, this largest genomically defined subgroup of lung cancer patients seem to remain 'undruggable', with any effective targeted therapy approved at the moment. The prognostic and predictive power and thus the clinical utility of KRAS oncogenic mutations in lung cancer are highly debated issues, not supportive of KRAS testing in clinical practice of NSCLC therapy. Areas covered: A phase II trial in KRAS-mutant NSCLC had shown significant improvements in PFS and ORR in patients treated with selumetinib plus docetaxel compared to docetaxel alone. Disappointing data emerged from the next phase III trial in which the addition of selumetinib to docetaxel in patients with advanced KRAS mutant lung cancer did not improve survival or show clinical benefit. Expert opinion: Promising strategies against this common mutation are under evaluation in clinical trials. Combination therapies represent a potential approach for overcoming this complex pathway and potentiating the activity of other antitumor agents, by simultaneous inhibition of the RAS-RAF-MEK-MAPK pathway. Identifying predictive biomarkers, and delineating de novo and acquired resistance mechanisms are essential for future clinical development of MEK inhibitors.
Keywords: KRAS; MEK-inhibitors; non-small cell lung cancer; selumetinib; targeted therapy.