KRAS mutations as prognostic and predictive markers in non-small cell lung cancer

A greater understanding of non-small-cell lung cancer at a molecular level has led to the identification of an increasing number of driver mutations. Extensive research of the KRAS gene as well as specific mutations has established its role in tumorigenesis. Nevertheless, the role of KRAS oncogene in non-small-cell lung cancer remains unclear. Recent studies indicated that mutant KRAS could be predictive of lack of response to chemotherapy, but large pooled analysis failed to confirm this result. The predictive value of KRAS mutation and EGFR-TKI treatment is more ambiguous with some recent evidence suggesting that it may be a negative predictive biomarker. This review provides an overview of RAS biology, assesses the utility of KRAS as a prognostic marker, and evaluates its role as a predictive marker for response to chemotherapy and EGFR-TKIs. In addition, we review some current studies that are targeting the KRAS pathway.

The role of irreversible HER family inhibition in the treatment of patients with non-small cell lung cancer

Small-molecule tyrosine kinase inhibitors (TKIs) of the human epidermal growth factor receptor (HER) include the reversible epidermal growth factor receptor (EGFR/HER-1) inhibitors gefitinib and erlotinib. EGFR TKIs have demonstrated activity in the treatment of patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations; however, multiple mechanisms of resistance limit the benefit of these drugs. Although resistance to EGFR TKIs can be intrinsic and correlated with molecular lesions such as in Kirsten rat sarcoma viral oncogene homolog (KRAS; generally observed in a wild-type EGFR background), acquired resistance to EGFR TKIs can evolve in the setting of activating EGFR mutations, such as in the case of EGFR T790M mutations. Several irreversible inhibitors that target multiple members of the HER family simultaneously are currently in clinical development for NSCLC and may have a role in the treatment of TKI-sensitive and TKI-resistant disease. These include PF00299804, an inhibitor of EGFR/HER-1, HER-2, and HER-4, and afatinib (BIBW 2992), an inhibitor of EGFR/HER-1, HER-2, and HER-4. Results of large, randomized trials of these agents may help to determine their potential for the treatment of NSCLC.