KRAS mutations are the most frequent molecular abnormalities found in one out of four nonsmall cell lung cancers (NSCLC). Their incidence increases in cases of adenocarcinoma, smokers and Caucasian patients. Their negative value in terms of prognosis and responsiveness to both standard chemotherapy and targeted therapies remains under debate. Many drugs have been developed specifically for KRAS-mutated NSCLC patients. Direct inhibition of RAS activation failed to show any clinical efficacy. Inhibition of downstream targets of the mitogen-activated protein kinase (MEK) pathway is a promising strategy: phase II combinations of MEK 1/2 kinase inhibitors with chemotherapy doubled patients' clinical outcomes. One phase III trial in such a setting is ongoing. Double inhibition of MEK and epidermal growth factor receptor proteins is currently being assessed in early-phase trials. The association with mammalian target of rapamycin pathway inhibition leads to non-manageable toxicity. Other strategies, such as inhibition of molecular heat-shock proteins 90 or focal adhesion kinase are currently assessed. Abemaciclib, a cyclindependent kinase 4/6 inhibitor, showed promising results in a phase I trial, with a 54% disease control rate. Results of an ongoing phase III trial are warranted. Immunotherapy might be the next relevant step in KRAS-mutated NSCLC management due to the high burden of associated mutations and neo-antigens. @ERSpublications MEK inhibition and immunotherapy are very promising therapeutic advances in KRAS-mutated nonsmall cell lung cancer http://ow.ly/U2ohp
KRAS mutations in lung cancer: epidemiology and clinical outcomesSince the beginning of the 21st century, the paradigm of precision medicine has shaken up the landscape of lung cancer classification and treatment. The discovery of cancer-related driver molecular abnormalities led to the development of efficient targeted therapies. RAS proteins are GTP kinases, discovered in the 1960s, whose GTP-RAS active isoform stimulates several pathways involved in cellular growth. V-Ki-ras2 Kirsten rat sarcoma viral oncogene homologue (KRAS) mutations are found in ∼25-35% of newly diagnosed nonsmall cell lung cancer (NSCLC), with a higher proportion in the adenocarcinoma subtype [1,2]. Figure 1 summarises the main amino acid substitutions and genomic features that are associated with KRAS mutations in NSCLC [3,4]. Other molecular abnormalities related to RAS pathway activation are diagnosed in 25% of NSCLC cases, such as epidermal growth factor receptor (EGFR) (10-23%), BRAF mutations (2%), MET amplifications (2%), human epidermal growth factor (HER)2 (1%) and NRAS (0.2%) mutations. Loss of the negative regulator neurofibromin is found in ∼11% of other cases.