KRAS as a druggable target in NSCLC: Rising like a phoenix after decades of development failures.

Cancers of nearly all lineages harbor alterations that deregulate mitogen-activated protein kinase signaling, a crucial signaling pathway for tumor formation and maintenance. Of these, KRAS mutations are the most frequent gain-of-function alterations found in patients with cancer. In particular they represents the most common molecular alteration detected in non-small cell lung cancer (NSCLC) accounting for up to 25% of all oncogenic mutations. They were identified decades ago and prior efforts to target these proteins have been unsuccessful. KRAS mutation profiles (i.e. frequency of specific codon substitutions) in smokers and never-smokers are distinct and not all KRAS alterations are driver mutations. KRAS has evolved from a mutation with possible predictive value to a therapeutic target with great promise. Here, we will discuss the biology of KRAS in lung cancer and its clinical implications in oncology today and in the foreseeable future.